The present disclosure relates to a closed loop system and method for controlling a position of a susceptor in an aerosol-generating article, in particular in a rod-shaped aerosolgenerating article. In particular, the disclosure relates to such a system and method in a manufacturing process of an aerosol-generating article.

For inductively heated tobacco consumables, an inductively heatable susceptor has to be provided in an aerosol-forming substrate. A susceptor should be allocated in the center of a rodshaped article and should not be damaged or deformed. The position and integrity of the susceptor in the consumable may alter a heating efficiency, a temperature distribution or may lead to inconsistency of the performance of the consumable. Also a reduction of waste may be achieved by enhancing the quality of the manufactured consumables.

Thus, there is need for a system and method to manufacture aerosol-generating articles that allow for consistent positioning of a susceptor in an aerosol-generating article, in particular at high production volume.

According to an aspect of the present invention, there is provided a closed-loop system for controlling a position of a susceptor in an aerosol-generating article. The system comprises: a supply for continuous sheet material; a supply for a continuous susceptor; a crimping device for crimping the continuous sheet material; a shaping device for gathering the continuous sheet material and for forming the continuous sheet material with inserted continuous susceptor into a continuous rod; a cutting device for cutting the continuous rod into aerosol-generating articles; a control unit comprising an output control for detecting a condition of the susceptor in an aerosol-generating article, and for comparing a detected condition with quality specifications. The system further comprises a positioning device for manipulating the position of the continuous susceptor. The control unit is adapted for triggering the positioning device to adjust the position of the continuous susceptor or for triggering the crimping depth adjuster to adjust a crimping depth of the sheet material in the crimping device, when the detected condition do not meet quality specifications.

The closed-loop system according to the invention measures, preferably in real time, a condition of a susceptor in a manufactured aerosol-generating article. This information is used to adjust production parameters to keep the susceptor in the predefined position in the manufactured article. Preferably, the predefined position of the susceptor corresponds to a central position in the article.

Adjustable production parameters are either a positioning of the continuous susceptor when said continuous susceptor is inserted in the continuous sheet material upon rod forming or it is an adjustment of a crimping depth of the continuous sheet material. Adjustable production parameters may be both a positioning of the continuous susceptor when said continuous susceptor is inserted in the continuous sheet material upon rod forming and an adjustment of a crimping depth of the continuous sheet material.

Thus, at least one, preferably several physical properties of the articles being produced are measured or determined and used to adjust other production parameters to keep the susceptor in the predefined position.

The output control may detect, for example, an absolute position of the susceptor in the article. For example, the output control may detect a displacement of the susceptor out of the center of the article and in the direction of the circumference of a rod-shaped article. The output control may also detect a form of the susceptor, for example if the susceptor has a deformed, for example bent, shape. These parameters have to be within a certain predefined threshold in order to be acceptable and accepted by the output control or in the control unit, respectively. If the predefined threshold is exceeded, the article is detected as not meeting the predefined quality specifications. Depending on acceptable deviations from a threshold, for example a percentage of articles exceeding the predefined threshold, adjustment signals to the positioning unit or the crimping depth adjuster may be given and a position of the susceptor is adapted. Alternatively, if a threshold is exceeded the article may be rejected as waste.

Preferably, the output control comprises a rejection system, rejecting defective articles that comprise conditions of the susceptor that do not meet at least minimum quality specifications.

Preferably, the output control is adapted for rejecting the aerosol-generating article as waste when the detected condition of the susceptor exceed a predefined waste threshold. Thus, a waste threshold may correspond to minimum quality specifications that must be fulfilled in order for an article to be acceptable.

The detected condition of the aerosol-generating article may comprise any one or several of a position of the susceptor in the aerosol-generating article, a form of the susceptor in the aerosol-generating article, an eccentricity of the susceptor in the aerosol-generating article or a shape of gathering of sheet material surrounding the susceptor. An absolute displacement of the susceptor from a center of the article to a more radial position in the rod, a deformation of the susceptor, in particular a deformation of the cross-section of the susceptor or a bending of a susceptor band or also an inhomogeneous distribution of the gathered sheet material around the susceptor may lead to inhomogeneous heating of the aerosol-forming substrate of the article.

Accordingly, the output control is preferably adapted to capture information of a crosssection of the aerosol-generating article. Preferably, the output control is adapted to capture information of a cross-section of at least one end of the aerosol-generating article. The output control may also be adapted to capture information of a cross-section of both ends of the aerosol-generating article.

To detect the condition of the susceptor in the article, the output control may comprise any detection system suitable for capturing information on the condition of the susceptor in the article, in particular of the position of the susceptor in in the article, for example on the crosssection of the susceptor in the article. The output control may comprise, for example, an optical system, an infrared system, an X-ray system or an induction detection system.

Preferably, the output control comprises one or several cameras.

The output control may comprise a detection system to determine the orientation of the susceptor in the article for positioning the article to be controlled by the output control in a defined control position. The information on the orientation of the susceptor in the article may either be used as correction factor in the output control when determining the condition of the susceptor in the article. Alternatively, the information on the orientation of the susceptor may be used to align the articles, for example before capturing information on a cross-section of an end of the article.

For example, a visual system may detect an overlap of a wrapper wrapping the rodshaped aerosol-generating article. In a manufacturing process of the continuous rod of aerosolforming substrate containing a continuous susceptor, a mutual position of continuous wrapping material relative to its content remains substantially constant. Thus, by visually detecting an overlap, rough information on the position of the susceptor in the article may be gained. This may be used for adapting a detection system to an orientation of the susceptor in the article to perform the output control. An orientation of the susceptor in the article may also be gained by other means, for example by induction means, infrared means or similar. Accordingly, the closed-loop system, in particular the control unit may comprise article rotation means for rotating the articles in order to align them preferably all at a same orientation for passing the output control.

In addition, a position of the susceptor, in particular or a susceptor band, that is defined and consistent for all articles may be advantageous or even mandatory for articles that have to be cut or processed otherwise, for example for assembly with other segments, wherein a specific mutual relative position of the susceptor band with another segments is desired or mandatory. It has been found that a random orientation of a susceptor band in the article may lead to irregular cutting, deformation of the susceptor or even a reduced lifetime of a cutting knife. It has been found that the relative position of a susceptor band with respect to a cutting knife has a large impact on the quality of the cut.

Thus, a defined position of the article corresponds to an optimized cutting angle of the susceptor band with respect to the cutting device. Accordingly, it may be beneficial to provide an optimized rotational positioning of the article for the output control but also before cutting the article or otherwise further processing the article.

As mentioned above, the position of a continuous susceptor in the sheet material may be adjusted by a positioning device or by a crimping depth adjuster. In some embodiments of the closed-loop system, the system comprises the positioning device and the crimping depth adjuster. Accordingly, in these embodiments, the control unit is adapted for triggering the positioning device to adjust the position of the continuous susceptor and for triggering the crimping depth adjuster to adjust the crimping depth of the sheet material in the crimping device, if the detected condition do not meet quality specifications.

The closed-loop system may comprise a positioning device directly manipulating the position of the continuous susceptor when the susceptor is combined with the continuous sheet material. For example, the position of the continuous susceptor may be adjusted upon insertion of the continuous susceptor into partially gathered sheet material. Preferably, insertion and positioning of the continuous susceptor occurs in the shaping device while or upstream of the rod forming process.

Preferably, the continuous susceptor is guided by the positioning device. Preferably, position of the continuous susceptor is adjusted by moving the positioning device.

The positioning device may be movably arranged to be movable in at least two directions perpendicular to each other, for example along an x-axis and y-axis.

Preferably, the positioning device is movable relative to a supply direction of the continuous susceptor. Thus, the x-axis may correspond to a transport direction of the continuous materials along a manufacturing line. This allows to change an insertion position of the continuous susceptor into the partially gathered sheet material. Adjusting the location, where the continuous susceptor is inserted into the sheet material, may result in insertion of the continuous susceptor in more or less densely gathered sheet material in a more upstream or more downstream location along the rod forming process. By this, an insertion depth in the sheet material may be adjusted or an insertion resistance may be reduced. By reducing an insertion resistance, also risk that the continuous susceptor is damaged upon insertion into the sheet material may be reduced.

Preferably, the positioning device is movable in three directions perpendicular to each other. This allows an adjustment of the position of the continuous susceptor in all three dimensions.

In order to combine a rod-forming and an adjustment of the position of the continuous susceptor, preferably, the shaping device and the positioning device are combined.

Preferably, the positioning device is moveably arranged in the shaping device.

The positioning device may also include rotation means for rotating the continuous susceptor along a longitudinal direction of the continuous susceptor. Preferably, the positioning device is rotatable and thereby rotating the continuous susceptor. For example, the positioning device may comprise an opening, where the continuous susceptor passes through. The opening of the positioning device may have a shape corresponding to the shape of the cross-section of the continuous susceptor. When the positioning device is rotated or sideways displaced, the continuous susceptor automatically follows the movement of the positioning device.

Preferably, the positioning device has the shape of a cone.

Preferably, the shaping device has the shape of a cone, for example embodied as garniture tongue.

Preferably, the positioning device is arranged in the cone of the shaping device.

To simplify insertion of the continuous susceptor in the sheet material or to reduce an insertion resistance, the shaping device may comprise a channel former for forming a channel in partially gathered continuous sheet material. The continuous susceptor may then be inserted into the channel.

A crimping device may provide a sheet material with various kind of crimps. Preferred crimps extend in a longitudinal or transverse direction of a crimped sheet material. Since the crimping of sheet material is often used to support a later gathering of the sheet material, a sheet material is preferably crimped in longitudinal or transport direction.

Preferably, the crimping device is adapted to provide the continuous sheet material with longitudinally running crimps. The longitudinally running crimps are arranged in transport direction of the sheet material. The further downstream arranged gathering process, which is a gathering of the flat sheet material mainly from both lateral sides, may follow along crimps and lead to a more defined gathering and a accordingly to a homogeneously gathered rod.

The crimping device may comprise two interacting crimping elements. The crimping elements are arranged to allow the continuous sheet material to pass in between the two interacting crimping elements thereby crimping the continuous sheet material.

Preferably, a crimping depth adjuster is adapted to vary a distance between the two interacting crimping elements. A small distance of the crimping elements enhances a crimping depth of the sheet material, a large distance reduces a crimping depth of the sheet material.

Preferably, the two interacting crimping elements are crimping plates or crimping rollers.

Preferably, the crimping elements are interlocking crimping elements preferably comprising interlocking crimping structures.

Preferable, the control unit further comprises a moisture sensor for measuring a moisture of the continuous sheet material. It has been found that several parameters may influence a crimping depth of the sheet material. While sheet thickness only has a minor effect on a crimping depth, moisture content of the sheet material may significantly influence the crimping depth. The control unit may be adapted for triggering the crimping depth adjuster to adjust a crimping depth of the sheet material in the crimping device, depending on a moisture content of the continuous sheet material.

The control unit may comprise reference data stored in the control unit. The reference data may comprise information on a crimping behaviour of several kinds sheet material. For example, the reference data may comprise information on physical characteristics on specific compositions of sheet material, such as, for example, tobacco blends used in a tobacco material containing sheet material, at different moisture contents.

A moisture sensor may be arranged at different location along a manufacturing line. Preferably, a moisture sensor is arranged upstream or downstream of the crimping device.

The closed-loop system may further comprise a substance introduction device for introducing a substance to the continuous sheet material.

Preferably, the substance introduction device is a liquid introduction device.

A substance introduced into the continuous sheet material may be a flavour such as for example, menthol, fruit flavour or tobacco flavour. A substance may also be, for example water, nicotine or an aerosol-formers, such as for example glycerin. With the substance introduction device, a sheet material may be adapted to the consumable to be formed. In particular, original characteristics of the sheet material may be changed or adapted to a desired product. For example, by adding humidity, the manufacturing process of the aerosol-forming articles, such as, for example, the crimping process or the susceptor positioning process, may be influenced. Article comprising different flavours may be manufactured from a same basic sheet material. Yet further, an originally non-aerosol-forming sheet material may be changed into an aerosolforming sheet material by adding an aerosol-forming substance. While tobacco-based materials already comprise aerosol-forming substances, sheet material made, for example from cellulose- based materials do not.

The closed-loop system may comprise a wrapping device for wrapping the continuous rod with a wrapper. The wrapper may be made of wrapping material as known in the art, for example a wrapping paper or wrapping plastics.

In order to further improve the manufacturing process, the closed-loop system may comprise various controls, for example control sensors. The control system may in particular comprise measurement devices for measuring sheet material parameters before or after the sheet material is crimped, susceptor parameters before the susceptor is inserted into the sheet material, device parameters, such as for example of the crimping device or of a liquid insertion device, or parameters of the formed rod-shaped article.

For example, the control unit may comprise at least a further measurement device for measuring or detecting any one of a thickness or width of the continuous sheet material; displacement of the continuous sheet material relative to a predefined transport position; defect in the continuous sheet material, in particular holes and slits; crimping depth of the continuous sheet material; thickness of the continuous susceptor; width of the continuous susceptor; discoloration of the continuous sheet material; substance flow in a substance introduction device; position of crimping elements; electrical specification of the susceptor, in particular resistance or impedance, for example as part of the output control; resistance of susceptor insertion into partially gathered continuous sheet material; susceptor splice portion; adhesive flow in an adhesive application device of a wrapping device; specification of an aerosol-generating article, in particular diameter or ovality of the article, presence or absence of a susceptor; porosity of the article; fragmentation of gathered and crimped sheet material in the article.

According to another aspect of the present invention, there is provided a method for controlling a position of a susceptor in an aerosol-generating article, the method comprising: providing a continuous sheet material; crimping the continuous sheet material; providing a continuous susceptor; gathering the continuous sheet material and inserting the continuous susceptor into the continuous sheet material thereby forming a continuous rod; cutting the continuous rod into aerosol-generating articles; performing an output control, thereby detecting a condition of the susceptor in an aerosolgenerating article and comparing a detected condition with quality specifications; thereby, when the detected condition do not meet quality specifications for an aerosol-generating article: adjusting a position of the continuous susceptor or adjusting a crimping depth of the continuous sheet material.

In some embodiments of the method, the method comprises adjusting the position of the continuous susceptor and adjusting the crimping depth of the continuous sheet material, when the detected condition do not meet quality specifications. While one of the two measures may suffice to adjust the position of the susceptor in the article, both measures may provide an even more precise result. In particular, the adjustment of the crimping depth may improve stability of the susceptor in an article and keeping a centred position of the susceptor in an article.

Advantages and features of the method have been discussed relating to the closed-loop system and are applicable also to the method. The method according to the invention allows adjustment of the position of the susceptor in real time. Thus, a manufacture of aerosol-generating article may continuously and inline be optimized or corrected.

The method may comprise rejecting the aerosol-generating article as waste, when the detected condition of the susceptor in the aerosol-generating article exceed a predefined waste threshold.

Preferably, detecting the condition of the susceptor in the aerosol-generating article comprises any one or several of: detecting a position of the susceptor in the aerosol-generating article, a form of the susceptor in the aerosol-generating article, an eccentricity of the susceptor in the aerosol-generating article or a shape of gathering of sheet material surrounding the susceptor.

Preferably, the method comprises capturing information of a cross-section of the aerosolgenerating article. In particular, the method may comprise capturing information of a crosssection of at least one end of the aerosol-generating article. Preferably, the method comprises capturing information of a cross-section of both ends of the aerosol-generating article.

The method may comprise detecting the condition of the susceptor in the aerosolgenerating article by visual inspection of the article, by infrared measurements of the article, by X-ray measurement of the article or by inductivity measurements of the article.

Preferably, the method comprises detecting the condition of the susceptor in the aerosolgenerating article by optical means, in particular using a camera.

The method according to the invention may comprise adjusting the position of the continuous susceptor before the continuous rod is formed. For example, the method may comprise adjusting the position while gathering the continuous sheet material.

Preferably, the method comprises adjusting the position of the continuous susceptor by moving the continuous susceptor along at least two directions perpendicular to each other.

More preferably, the method comprises adjusting the position of the continuous susceptor by moving the continuous susceptor along three directions perpendicular to each other.

The method may comprise adjusting the position of the continuous susceptor by guiding the continuous susceptor in and along a movable positioning device.

The method may comprise adjusting the position of the continuous susceptor by rotating the continuous susceptor along a longitudinal direction of the continuous susceptor.

Crimping the continuous sheet material preferable performed in a longitudinal or transverse direction of the sheet material, thus in a transport direction or perpendicular to a transport direction of the sheet material. Preferable, the method according to the invention comprises providing crimps in the continuous sheet material in transport direction of the continuous sheet material. Preferably, the method comprises gathering the continuous sheet material along crimps formed in the continuous sheet material.

The method may comprise forming a channel in partially gathered continuous sheet material and inserting the continuous susceptor into the channel.

Preferably, the method comprises inserting the continuous susceptor in between folds of the continuous sheet material.

The method may comprise crimping the continuous sheet material by guiding the continuous sheet material in between crimping elements. For example, the method comprises thereby guiding the continuous sheet material in between crimping rollers or crimping plates.

Preferably, adjusting a crimping depth is performed by varying a distance between crimping elements.

The method may further comprise measuring a moisture content of the continuous sheet material and adjusting the crimping depth depending on the moisture content of the continuous sheet material. Measuring a moisture content of the continuous sheet material may be performed, for example, before or after crimping or before and after crimping.

The method according to the invention may further comprise wrapping the continuous rod with a wrapper. Preferably, the wrapper is a continuous paper sheet or a continuous plastics sheet.

The method according to the invention may further comprise adding a substance to the continuous sheet material.

Preferably, the substance is a liquid.

Preferably, the substance comprises a flavour, nicotine or an aerosol-former.

The continuous susceptor may, for example, be a continuous band, a continuous filament or a wire. Preferably, the continuous susceptor is a continuous band.

The continuous susceptor may, for example, comprise metal, a magnetic material or a magnetic metal. For example, susceptor material is stainless steel, in particular ferromagnetic stainless steel, or aluminium.

The continuous sheet material is a substantially flat sheet, which is crimped and then gathered into a rod-shape. In embodiments, where a positioning device is used to adjust the position of the continuous susceptor in the sheet material, an already crimped sheet material may be supplied for the rod manufacturing process.

The continuous sheet material may be provided as a non-aerosol-forming sheet material or as an aerosol-forming sheet material.

The method may comprise changing a non-aerosol-forming sheet material into an aerosol-forming sheet material by adding an aerosol-forming substance to the non-aerosol- forming sheet material before forming the continuous rod. The continuous sheet material may, for example, be a tobacco material containing sheet material, a plant-based sheet material, a cellulose-based sheet material, a fibrous material containing sheet material or a combination of these materials.

The method according to the invention may comprise further measuring or detecting any one of a thickness or width of the continuous sheet material, displacement of the continuous sheet material relative to a predefined transport position; defect in the continuous sheet material, in particular holes and slits; crimping depth of the continuous sheet material; thickness of the continuous susceptor; width of the continuous susceptor; discoloration of the continuous sheet material; substance flow in a substance introduction device; position of crimping elements; electrical specification of the susceptor, in particular resistance or impedance; resistance of susceptor insertion into partially gathered continuous sheet material; susceptor splice portion; adhesive flow in an adhesive application device of a wrapping device; specification of an aerosol-generating article, in particular diameter or ovality of the article, presence or absence of a susceptor; porosity of the article; fragmentation of gathered and crimped sheet material in the article.

Preferably, the electrical specification of the susceptor, in particular resistance or impedance, may be measured or detected as part of detecting the condition of the susceptor in the aerosol-generating article. In particular, such resistance or impedance measurements may be part of an output control. Measurements of the electrical specification of the susceptor may also be performed on the continuous susceptor as quality check before the continuous susceptor is used in the manufacturing process for aerosol-forming articles.

The method may further comprise detecting a susceptor splice portion in the continuous susceptor or in the aerosol-generating article. Articles comprising splice portions are to be eliminated as these do not fulfil any quality specification.

Splice portions may be detected before the continuous susceptor is inserted into a continuous sheet material. They may be detected when the continuous susceptor is in the continuous rod. Alternatively, or in addition, they may be detected when the susceptor is in the aerosol-forming article, for example as part of an output control.

The continuous sheet material is an aerosol-forming continuous sheet material when formed into a continuous rod. The continuous sheet may be an aerosol-forming sheet material when being supplied to the manufacturing process or may be transformed into an aerosolforming sheet material before or upon being gathered into a rod.

The continuous sheet material forms an aerosol-forming substrate in the article.

Preferably, the continuous sheet material is a tobacco sheet in particular a sheet of homogenised tobacco material.

A tobacco sheet forming the aerosol-forming substrate may comprise tobacco particles, fiber particles, aerosol former, binder and for example also flavours.

Preferably, the tobacco sheet is a cast leaf. Cast leaf is a form of reconstituted tobacco that is formed from a slurry including tobacco particles, fiber particles, aerosol former, for example glycerol or propylene glycol, binder and for example also flavours.

Preferably, an aerosol-forming tobacco sheet contains volatile tobacco flavour compounds, which are released from the tobacco substrate upon heating. The aerosol-forming tobacco substrate may comprise or consist of blended tobacco cut filler or may comprise homogenised tobacco material. Homogenised tobacco material may be formed by agglomerating particulate tobacco. An aerosol-forming substrate may consist of or additionally comprise a non-tobacco-containing material, for example homogenised plant-based material other than tobacco.

Fiber particles may include tobacco stem materials, stalks or other tobacco plant material, and other cellulose-based fibers such as wood fibers having a low lignin content. Fiber particles may be selected based on the desire to produce a sufficient tensile strength for the cast leaf versus a low inclusion rate, for example, an inclusion rate between approximately 2 percent to 15 percent. Alternatively, fibers, such as vegetable fibers, may be used either with the above fiber particles or in the alternative, including hemp and bamboo.

Aerosol formers included in a slurry forming a cast leaf or used in other aerosol-forming substrates may be chosen based on one or more characteristics. Functionally, the aerosol former provides a mechanism that allows it to be volatilized and convey nicotine or flavouring or both in an aerosol when heated above the specific volatilization temperature of the aerosol former. Different aerosol formers typically vaporize at different temperatures. The aerosolformer may be any suitable known compound or mixture of compounds that, in use, facilitates formation of a dense and stable aerosol and that is substantially resistant to thermal degradation at the operating temperature of an inductive heating device the inductively heatable tobacco substrate shall be used with. An aerosol former may be chosen based on its ability, for example, to remain stable at or around room temperature but able to volatize at a higher temperature, for example, between 40 degree Celsius and 450 degree Celsius.

The aerosol former may also have humectant type properties that help maintain a desirable level of moisture in an aerosol-forming substrate, in particular but not exclusively, when the substrate is composed of a tobacco-based product, particularly including tobacco particles. In particular, some aerosol formers are hygroscopic material that functions as a humectant, that is, a material that helps keep a substrate containing the humectant moist.

One or more aerosol former may be combined to take advantage of one or more properties of the combined aerosol formers. For example, triacetin may be combined with glycerin and water to take advantage of the triacetin's ability to convey active components and the humectant properties of the glycerin.

Aerosol formers may be selected from the polyols, glycol ethers, polyol ester, esters, and fatty acids and may comprise one or more of the following compounds: glycerin, erythritol, 1 ,3- butylene glycol, tetraethylene glycol, triethylene glycol, triethyl citrate, propylene carbonate, ethyl laurate, triacetin, meso-Erythritol, a diacetin mixture, a diethyl suberate, triethyl citrate, benzyl benzoate, benzyl phenyl acetate, ethyl vanillate, tributyrin, lauryl acetate, lauric acid, myristic acid, and propylene glycol.

The aerosol-forming substrate may comprise other additives and ingredients, such as flavourants. The aerosol-forming substrate preferably comprises nicotine and at least one aerosol-former.

A crimped sheet material, in particular a crimped aerosol-forming sheet material, more particularly a crimped tobacco sheet, for example a cast leaf, may have a thickness in a range of between about 0.5 millimeter and about 2 millimeter, preferably between about 0.8 millimeter and about 1.5 millimeter, for example 1 millimeter. Deviations in thickness of up to about 30 percent may occur due to manufacturing tolerances.

As used herein, the term 'susceptor' refers to a material that is capable to convert electromagnetic energy into heat. When located in an alternating electromagnetic field, typically eddy currents are induced and hysteresis losses occur in the susceptor causing heating of the susceptor. As the susceptor is located in thermal contact or close thermal proximity with the aerosol-forming substrate, the aerosol-forming substrate is heated by the susceptor such that an aerosol is formed. Preferably, the susceptor is arranged in direct physical contact with the aerosol-forming substrate.

The susceptor may be formed from any material that can be inductively heated to a temperature sufficient to release material from the aerosol-forming substrate. Preferred susceptors comprise a metal or carbon. A preferred susceptor may comprise or consist of a ferrous or ferromagnetic material, for example ferritic iron, a ferromagnetic alloy, such as ferromagnetic steel, stainless steel or aluminium. The susceptor preferably comprises more than 5 percent, preferably more than 20 percent, preferably more than 50 percent or 90 percent of ferromagnetic or paramagnetic materials. Preferred susceptors may be heated to a temperature between about 150 degree Celsius and about 300 degree Celsius. Preferably, the susceptors may be heated to a temperature between about 200 degree Celsius and about 270 degree Celsius, for example 235 degree Celsius. A susceptor is preferably a metal such as stainless steel, in particular ferromagnetic stainless steel or aluminium. Preferably, a susceptor is a magnetic material or comprises magnetic material.

Preferably, the continuous susceptor is a filament, rod, sheet or band. If the susceptor is of constant cross-section, for example a circular cross-section, it has a preferable width or diameter of between about 1 millimeter and about 5 millimeter.

Preferably, a susceptor is a metallic band.

Preferably, a susceptor is a stainless steel band. However, susceptor materials may also comprise or be made of graphite, molybdenum, silicon carbide, aluminum, niobium, Inconel alloys (austenite nickel-chromium-based superalloys), metallized films, ceramics such as for example zirconia, transition metals such as for example Iron, Cobalt, Nickel, or metalloids components such as for example Bor, Carbon, Silicium, Phosphor, Aluminium.

Preferably, the susceptor band in an article has a basic rectangular shape having a width preferably between about 2 millimeter and about 8 millimeter, more preferably, between about 3 millimeter and about 5 millimeter, for example 4 millimeter.

The width of the susceptor band is smaller than a width or diameter of a rod-shaped aerosol-generating article the susceptor band is arranged in.

A thickness of a susceptor material is preferably between about 0.03 millimeter and about 1 millimeter, more preferably between about 0.05 millimeter and about 0.5 millimeter, for example between about 0.07 millimeter and about 0.2 millimeter.

As a general rule, whenever the term ‘about’ is used in connection with a particular value throughout this application this is to be understood such that the value following the term ‘about’ does not have to be exactly the particular value due to technical considerations. However, the term ‘about’ used in connection with a particular value is always to be understood to include and also to explicitly disclose the particular value following the term ‘about’. Preferably, the aerosolgenerating article has the form of a rod with a rod diameter, preferably in the range between about 3 millimeters to about 12 millimeters, more preferably between about 4 millimeters to about 8 millimeters, for example 7 millimeters. Preferably, the rod has a circular or oval crosssection. However, the rod may also have the cross-section of a rectangle or of a polygon.

Preferably, the aerosol-forming article is a rod-shaped article, preferably having a circular cross-section.

The aerosol-generating article comprises an aerosol-forming substrate, capable of forming an aerosol. The aerosol-forming substrate is a solid and may comprise a tobacco-containing material containing volatile tobacco flavour compounds, which are released from the substrate upon heating. Alternatively, the aerosol-forming substrate may comprise a non-tobacco material. The aerosol-forming substrate may further comprise an aerosol former. Examples of suitable aerosol formers are glycerine and propylene glycol. The aerosol-forming substrate is formed by the continuous sheet material.

The invention is defined in the claims. However, below there is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

Example Ex1 : Closed-loop system for controlling a position of a susceptor in an aerosolgenerating article, the system comprising: a supply for continuous sheet material; a supply for a continuous susceptor; a crimping device for crimping the continuous sheet material; a shaping device for gathering the continuous sheet material and for forming the continuous sheet material with inserted continuous susceptor into a continuous rod; a cutting device for cutting the continuous rod into aerosol-generating articles; a control unit comprising an output control for detecting a condition of the susceptor in an aerosol-generating article, and for comparing a detected condition with quality specifications; wherein the system further comprises a positioning device for manipulating the position of the continuous susceptor or a crimping depth adjuster, and wherein the control unit is adapted for triggering the positioning device to adjust the position of the continuous susceptor or for triggering the crimping depth adjuster to adjust a crimping depth of the sheet material in the crimping device, when the detected condition do not meet quality specifications.

Example Ex2: Closed-loop system according to Example Ex1, wherein the output control is adapted for rejecting the aerosol-generating article as waste when the detected condition of the susceptor exceed a predefined waste threshold.

Example Ex3: Closed-loop system according to any one of the preceding Examples, wherein the detected condition of the aerosol-generating article comprise any one or several of: a position of the susceptor in the aerosol-generating article, a form of the susceptor in the aerosol-generating article, an eccentricity of the susceptor in the aerosol-generating article or a shape of gathering of sheet material surrounding the susceptor.

Example Ex4: Closed-loop system according to any one of the preceding Examples, wherein the output control is adapted to capture information of a cross-section of the aerosolgenerating article.

Example Ex5: Closed-loop system according to Example Ex4, wherein the output control is adapted to capture information of a cross-section of at least one end of the aerosolgenerating article. Example Ex6: Closed-loop system according to any one of Example Ex4 to Ex5, wherein the output control is adapted to capture information of a cross-section of both ends of the aerosol-generating article.

Example Ex7: Closed-loop system according to any one of the preceding Examples, wherein the output control comprises an optical system, an infrared system, an X-ray system or an induction detection system.

Example Ex8: Closed-loop system according to Example Ex7, wherein the output control comprises a camera.

Example Ex9: Closed-loop system according to any one of the preceding Examples, wherein the system comprises the positioning device and the crimping depth adjuster, and wherein the control unit is adapted for triggering the positioning device to adjust the position of the continuous susceptor and for triggering the crimping depth adjuster to adjust the crimping depth of the sheet material in the crimping device, if the detected condition do not meet quality specifications.

Example Ex10: Closed-loop system according to any one of the preceding

Examples, wherein the positioning device is movably arranged to be movable in at least two directions perpendicular to each other.

Example Ex11 : Closed-loop system according to Example Ex10, wherein the positioning device is movable relative to a supply direction of the continuous susceptor.

Example Ex12: Closed-loop system according to any one of Example Ex10 to

Ex11, wherein the positioning device is movable in three directions perpendicular to each other.

Example Ex13: Closed-loop system according to any one of Examples Ex10 to

Ex12, wherein the positioning device is moveably arranged in the shaping device.

Example Ex14: Closed-loop system according to any one of the preceding

Examples, wherein the positioning device includes rotation means for rotating the continuous susceptor along a longitudinal direction of the continuous susceptor.

Example Ex15: Closed-loop system according to Example Ex14, wherein the positioning device is rotatable thereby rotating the continuous susceptor.

Example Ex16: Closed-loop system according to any one of Examples Ex10 to

Ex15, wherein the positioning device has the shape of a cone.

Example Ex17: Closed-loop system according to any one of the preceding

Examples, wherein the shaping device has the shape of a cone.

Example Ex18: Closed-loop system according to Example Ex17, wherein the positioning device is arranged in the cone of the shaping device.

Example Ex19: Closed-loop system according to any one of the preceding

Examples, wherein the shaping device comprises a channel former for forming a channel in partially gathered continuous sheet material. Example Ex20: Closed-loop system according to any one of the preceding

Examples, wherein the crimping device is adapted to provide the continuous sheet material with longitudinally running crimps.

Example Ex21 : Closed-loop system according to any one of the preceding

Examples, wherein the crimping device comprises two interacting crimping elements arranged to allow the continuous sheet material pass between the two interacting crimping elements thereby crimping the continuous sheet material.

Example Ex22: Closed-loop system according to Example Ex21 , wherein the crimping depth adjuster is adapted to vary a distance between the two interacting crimping elements.

Example Ex23: Closed-loop system according to any one of Examples Ex21 to

Ex22, wherein the two interacting crimping elements are crimping plates or crimping rollers.

Example Ex24: Closed-loop system according to any one of the preceding

Examples, wherein the control unit further comprises a moisture sensor for measuring a moisture of the continuous sheet material.

Example Ex25: Closed-loop system according to Example Ex24, wherein the control unit is adapted for triggering the crimping depth adjuster to adjust a crimping depth of the sheet material in the crimping device, depending on a moisture content of the continuous sheet material.

Example Ex26: Closed-loop system according to any one of Examples Ex24 to

Ex25, wherein the moisture sensor is arranged upstream or downstream of the crimping device.

Example Ex27: Closed-loop system according to any one of the preceding

Examples, further comprising a substance introduction device for introducing a substance to the continuous sheet material.

Example Ex28: Closed-loop system according to Example Ex27, wherein the substance introduction device is a liquid introduction device.

Example Ex29: Closed-loop system according to any one of the preceding

Examples, further comprising a wrapping device for wrapping the continuous rod with a wrapper.

Example Ex30: Closed-loop system according to any one of the preceding

Examples, wherein the control unit comprises at least a further measurement device for measuring or detecting any one of a thickness or width of the continuous sheet material, displacement of the continuous sheet material relative to a predefined transport position; defect in the continuous sheet material, in particular holes and slits; crimping depth of the continuous sheet material; thickness of the continuous susceptor; width of the continuous susceptor; discoloration of the continuous sheet material; substance flow in a substance introduction device; position of crimping elements; electrical specification of the susceptor, in particular resistance or impedance; resistance of susceptor insertion into partially gathered continuous sheet material; susceptor splice portion; adhesive flow in an adhesive application device of a wrapping device; specification of an aerosol-generating article, in particular diameter or ovality of the article, presence or absence of a susceptor; porosity of the article; fragmentation of gathered and crimped sheet material in the article.

Example Ex31 : Method for controlling a position of a susceptor in an aerosolgenerating article, the method comprising: providing a continuous sheet material; crimping the continuous sheet material; providing a continuous susceptor; gathering the continuous sheet material and inserting the continuous susceptor into the continuous sheet material thereby forming a continuous rod; cutting the continuous rod into aerosol-generating articles; performing an output control, thereby detecting a condition of the susceptor in an aerosolgenerating article and comparing a detected condition with quality specifications; thereby, when the detected condition do not meet quality specifications for an aerosol-generating article adjusting a position of the continuous susceptor or adjusting a crimping depth of the continuous sheet material.

Example Ex32: Method according to Example Ex31, comprising adjusting the position of the continuous susceptor and adjusting the crimping depth of the continuous sheet material, when the detected condition do not meet quality specifications.

Example Ex33: Method according to any one of Examples Ex31 to Ex32, therein rejecting the aerosol-generating article as waste, when the detected condition of the susceptor in the aerosol-generating article exceed a predefined waste threshold.

Example Ex34: Method according to any one of Examples Ex31 to Ex33, wherein detecting the condition of the susceptor in the aerosol-generating article comprises any one or several of: detecting a position of the susceptor in the aerosol-generating article, a form of the susceptor in the aerosol-generating article, an eccentricity of the susceptor in the aerosol-generating article or a shape of gathering of sheet material surrounding the susceptor. Example Ex35: Method according to any one of Examples Ex31 to Ex34, therein capturing information of a cross-section of the aerosol-generating article.

Example Ex36: Method according to Example Ex35, therein capturing information of a cross-section of at least one end of the aerosol-generating article.

Example Ex37: Method according to any one of Examples Ex35 to Ex36, therein capturing information of a cross-section of both ends of the aerosol-generating article.

Example Ex38: Method according to any one of Examples Ex31 to Ex37, therein detecting the condition of the susceptor in the aerosol-generating article by visual inspection of the article, by infrared measurements of the article, by X-ray measurement of the article or by inductivity measurements of the article.

Example Ex39: Method according to Example Ex38, wherein the condition of the susceptor in the aerosol-generating article is detected by optical means, in particular a camera.

Example Ex40: Method according to any one of Examples Ex31 to Ex39, comprising adjusting the position of the continuous susceptor before the continuous rod is formed.

Example Ex41 : Method according to Example Ex40, comprising adjusting the position while gathering the continuous sheet material.

Example Ex42: Method according to any one of Examples Ex31 to Ex41, comprising adjusting the position of the continuous susceptor by moving the continuous susceptor along at least two directions perpendicular to each other.

Example Ex43: Method according to Example Ex42, adjusting the position of the continuous susceptor by moving the continuous susceptor along three directions perpendicular to each other.

Example Ex44: Method according to any one of Examples Ex31 to Ex43, comprising adjusting the position of the continuous susceptor by guiding the continuous susceptor in and along a movable positioning device.

Example Ex45: Method according to any one of Examples Ex31 to 44, comprising adjusting the position of the continuous susceptor by rotating the continuous susceptor along a longitudinal direction of the continuous susceptor.

Example Ex46: Method according to any one of Examples Ex31 to Ex45, therein crimping the continuous sheet material in a longitudinal direction.

Example Ex47: Method according to Example Ex46, comprising gathering the continuous sheet material along crimps formed in the continuous sheet material.

Example Ex48: Method according to any one of Examples Ex31 to Ex47, therein forming a channel in partially gathered continuous sheet material and inserting the continuous susceptor into the channel. Example Ex49: Method according to any one of Examples Ex31 to Ex48, therein inserting the continuous susceptor in between folds of the continuous sheet material.

Example Ex50: Method according to any one of Examples Ex31 to Ex49, therein crimping the continuous sheet material by guiding the continuous sheet material in between crimping elements.

Example Ex51 : Method according to Example Ex50, thereby guiding the continuous sheet material in between crimping rollers or crimping plates.

Example Ex52: Method according to any one of Examples Ex50 to Ex51 , wherein adjusting a crimping depth is performed by varying a distance between crimping elements.

Example Ex53: Method according to any one of Examples Ex31 to Ex52, therein measuring a moisture content of the continuous sheet material and adjusting the crimping depth depending on the moisture content of the continuous sheet material.

Example Ex54: Method according to Example Ex53, therein measuring a moisture content of the continuous sheet material before or after crimping or before and after crimping.

Example Ex55: Method according to any one of Examples Ex31 to Ex54, further comprising wrapping the continuous rod with a wrapper.

Example Ex56: Method according to Example Ex55, wherein the wrapper is a continuous paper sheet or a continuous plastics sheet.

Example Ex57: Method according to any one of Examples Ex31 to Ex56, further comprising adding a substance to the continuous sheet material.

Example Ex58: Method according to Example Ex57, wherein the substance is a liquid.

Example Ex59: Method according to any one of Examples Ex56 to Ex58, wherein the substance comprises a flavour, nicotine or an aerosol-former.

Example Ex60: Method according to any one of Examples Ex31 to Ex59, wherein the continuous susceptor is a continuous band, a continuous filament or a wire.

Example Ex61 : Method according to any one of Examples Ex31 to Ex60, wherein the continuous susceptor comprises metal, a magnetic material or a magnetic metal.

Example Ex62: Method according to Example Ex61, wherein susceptor material is stainless steel, in particular ferromagnetic stainless steel, or aluminium.

Example Ex63: Method according to any one of Examples Ex31 to Ex62, wherein the continuous sheet material is a substantially flat sheet, which is crimped and then gathered into a rod-shape.

Example Ex64: Method according to any one of Examples Ex31 to Ex63, wherein the continuous sheet material is provided as a non-aerosol-forming sheet material or as an aerosol-forming sheet material. Example Ex65: Method according to Example Ex64, therein changing a non- aerosol-forming sheet material into an aerosol-forming sheet material by adding an aerosolforming substance to the non-aerosol-forming sheet material before forming the continuous rod.

Example Ex66: Method according to any one of Examples Ex31 to Ex65, wherein the continuous sheet material is a tobacco material containing sheet material, a plant-based sheet material, a cellulose-based sheet material, a fibrous material containing sheet material or a combination of these materials.

Example Ex67: Method according to any one of Examples Ex31 to Ex66, further measuring or detecting any one of a thickness or width of the continuous sheet material, displacement of the continuous sheet material relative to a predefined transport position; defect in the continuous sheet material, in particular holes and slits; crimping depth of the continuous sheet material; thickness of the continuous susceptor; width of the continuous susceptor; discoloration of the continuous sheet material; substance flow in a substance introduction device; position of crimping elements; electrical specification of the susceptor, in particular resistance or impedance; resistance of susceptor insertion into partially gathered continuous sheet material; susceptor splice portion; adhesive flow in an adhesive application device of a wrapping device; specification of an aerosol-generating article, in particular diameter or ovality of the article, presence or absence of a susceptor; porosity of the article; fragmentation of gathered and crimped sheet material in the article.

Example Ex68: Method according to Example Ex67, wherein the electrical specification of the susceptor, in particular resistance or impedance, are measured or detected as part of detecting the condition of the susceptor in the aerosol-generating article.

Example Ex69: Method according to any one of Examples Ex67 to Ex68, therein detecting the susceptor splice portion in the continuous susceptor or in the aerosol-generating article.

Examples will now be further described with reference to the figures in which:

Figure 1 shows a schematic closed loop control system;

Figure 2 shows a schematic cross section along a shaping device with positioning device;

Figure 3 shows a crimping closed loop control system;

Figure 4 shows an output control;

Figure 5 shows a cross section of a rod-shaped article with position control; and Figure 6 shows a cross section of a rod-shaped article with eccentricity and deformation control.

Fig. 1 illustrates a manufacturing line for aerosol-generating articles and a closed control loop system for a position control of a susceptor in a crimped and gathered sheet material forming the aerosol-generating article.

In Fig. 1 , black arrows 77 indicate a physical flow of products. Dotted arrows 88 indicate information flow from various measurement devices 81 ,82,83,84,85,86,89 including sensors to the control unit 8. The two dash-dotted arrows 99 indicate information flow from the control unit 8 to actuators of the crimping device 4 or to the positioning device 6 in the shaping device 5, which may be embodied as cone formation module.

In the supply unit 7, a continuous sheet material, for example a tobacco containing sheet material, in particular a cast leaf, is unwound from a bobbin. In an optional flavour module 78, flavours, but also nicotine, aerosol-formers or other substances may be applied to the continuous sheet material. For example, with the flavour module 78, an originally non-aerosol- forming sheet material may be changed into an aerosol-forming sheet material and this into an aerosol-forming substrate.

The sheet material is further transported to a crimping device 4, where the sheet material is crimped. The sheet material is preferably provided with longitudinal crimps along the length and transport direction of the sheet material. Further downstream in the manufacturing line, a susceptor band insertion module 76 is arranged. The susceptor band insertion module 76 is preferably integrated in a shaping device 5, which shaping device 5 also includes a positioning device 6 for the susceptor band in the partially gathered sheet material. With the positioning device 6 the position of the continuous susceptor relative to the sheet material may be adjusted. In the shaping device 5, the aerosol-forming sheet material is gathered, mainly along the crimps and aerosol-forming sheet material and the susceptor are formed into a continuous rod, The continuous rod is further downstream cut into individual rod-shaped articles in the cutting device 79. The articles may, for example be single or double rods of aerosol-generating articles, thus having single or double length.

The cut rods are subject to an output control 86. The output control 86 is preferably a visual inspection of a cross-section of the rod. The output control 86 controls the condition of the susceptor in the rod-shaped article, preferably mainly by controlling the position of the susceptor in the article. The measured and determined conditions of the susceptor are compared with quality specifications in the output control 86 or in the control unit 8.

The information of the output control 86 is fed to the control unit 8. The control unit 8 will, - dependent on the result of the quality control, - send according signals to the positioning device 6 or to the crimping device 4, or to both, the positioning device 6 and the crimping device 4, in order to adjust the position of the continuous susceptor into the sheet material upon rod forming, or to adjust a crimping depth of the sheet material in the crimping device 4.

Next to the output control 86, the various measurement devices 81 ,82,83,84,85,89 arranged along the manufacturing line may provide input for the control unit 8. This information may be used to adjust the individual devices 7,78,4,5,6,76,79 arranged along the manufacturing line. The various measurement devices 81 ,82,83,84,85,89 are:

- A measurement device 81 for detecting the travel position of the sheet material, such as a left or right deviation from a central transport direction. A deviation of the travel position of the sheet material may be corrected by repositioning the sheet material to a more central transport direction. Information of a deviation of the travel position of the sheet material may also be input into other further downstream arranged devices, such as for example, the flavour module 78.

- A measurement device 82 for measuring a width and a thickness of the sheet material. This information may, for example, be used in the crimping device 4 and the susceptor strip insertion module 76. Exemplary values for a cast leaf are a width of 125 mm and a thickness of 200 pm.

- A discoloration measurement device 83, for example following the flavour module 78;

- A measurement device for measuring a crimping depth 84 and a moisture sensor 87 measuring the moisture content of the sheet material. While humidity information of the sheet material may have a significant influence on the crimping process, information on the crimping depth may directly be used for adjusting the distance of crimping elements in the crimping device 4. An exemplary value for a crimping depth for a cast leaf is 250 pm (mean peak; thickness of 200 pm) at a moisture content of 8 percent of water.

- An impedance measurement device 89 may be provided to control the susceptor before the susceptor is inserted into the sheet material. By this measure, it may be avoided that defective susceptors or susceptors of inadequate quality are used for the manufacturing of articles. An exemplary value for a metallic susceptor sheet impedance and resistance is 600 mOhm.

A resistance measurement device 85 is provided at the location of the susceptor strip insertion module 76. The resistance measurement device 85 measures an insertion resistance of a susceptor into the sheet material. A high insertion resistance may deform a susceptor during the insertion process or may result in a susceptor having an insufficient insertion depth in the sheet material. Adjusting, for example, the location, where the susceptor is inserted into the sheet material, may reduce said risks as the sheet material is more or less densely gathered in a more upstream or more downstream location.

The system shown in Fig. 1 comprises several measurement devices arranged along the manufacturing line of aerosol-generating articles. These devices may be present to enhance the accuracy and reliability of the system but may also be optional, may be positioned at other process stages of the manufacturing line or of the control system, or may, for example, be duplicated to be available also at other process stages in the manufacturing line. As an example only, the moisture sensor 87 may be provided before or upon supplying the sheet material, shortly before crimping the sheet material or after crimping the sheet material but before rod formation. A moisture sensor may also be provided at some or all of these locations. It has also been found that width and thickness of the sheet material have a minor impact on the crimping process of the sheet material, such that measurement device 82 may possibly be omitted. In addition, for example, the insertion module 76 for susceptor insertion also comprises a positioning device. Preferably, deviations from a reference in a range of about 0.2 millimeter distance from a reference travel distance are detected.

Fig. 2 is a schematic view of a shaping device 5 in the form of a shaping cone 51. In the shaping cone 51 , a continuous crimped sheet material 70 is gathered and a continuous susceptor 72 is inserted into the partially gathered continuous sheet material 70. Both materials are formed into a continuous rod 71. The continuous susceptor 72 is preferably centrally arranged in the rod 71 along a central longitudinal axis of the rod and entirely surrounded by sheet material 70. Preferably, the continuous susceptor 72 is arranged in between crimps or folds of the partially gathered aerosol-forming sheet material 70.

The continuous crimped sheet material 70 may, for example, be an aerosol-forming sheet, such as, for example, a cast leaf comprising homogenized tobacco material and an aerosolformer. The continuous susceptor 72 may be a continuous metal band, for example a ferromagnetic stainless-steel band.

A positioning device 6 in the form of a movable cone 61 is arranged in the shaping cone 51. The outlet 52 of the shaping cone 51 of the shaping device 5 is co-centrically arranged with the outlet 63 of the movable cone 61 of the positioning device 6. The two outlets 52,63 may, but are generally not arranged at a same position along the X-axis, which X-axis corresponds to the travel direction of the sheet material 70 and the susceptor 72 in Fig. 2. Generally, the outlet 63 of the movable cone 61 is arranged upstream of the outlet 52 of the shaping cone 52.

The movable cone 61 guides the continuous susceptor 72 during insertion of the susceptor 72 into the sheet material 70 and by this defines the position of the susceptor in the rod 71.

The positioning device 6 preferably comprises linear guides, which allow to adjust the position of the movable cone 61 along X,Y,Z-direction, which axes are perpendicular to each other. Preferably, by adjusting the position of the movable cone 61 , direction and orientation of the susceptor may be changed in real time. For example, the outlet 63 of the movable cone 61 has a form corresponding to the form of the cross-section of the continuous susceptor. By this, the susceptor is closely guided and any movement of the movable cone is directly transferred to the continuous susceptor. The positioning device 6 is movable along the X-direction and it is also possible to vary a tilting angle 62 between positioning device 6 and shaping device 5.

The positioning device 6, in particular the movable cone 61 may also be rotatable, preferably around the longitudinal middle axis of the cone 61.

In Fig. 2, the X-direction is parallel to the travel direction of the sheet material 70. The Y- direction directs to the lateral sides of the travel direction of the sheet material 70 and perpendicular to the travel direction. The Z-direction directs to the top/down directions compared to the travel direction of the sheet material and is perpendicular to the travel direction.

Fig. 3 illustrates an example of a control loop of a crimping process of a continuous sheet material 70. The same reference signs are used for the same or similar elements as in Fig.1.

Before the sheet material 70 is crimped, humidity, possibly also width and thickness measurements, are performed in an according measurement device, indicated by moisture sensor 87.

The sheet material 70 is then crimped in the crimping device 4 by passing in between two crimping rollers 41. The distance 40 between the crimping rollers 41 is measured and may be adjusted for adjusting a crimping depth 42 of the sheet material 70.

The information of the moisture sensor 87 is compared with reference data stored in the control unit 8. The reference data comprise settings for the crimping device 4, namely crimping roller distances 40 for specific sheet material, for example specific compositions of the sheet material, such as tobacco blends used in a tobacco material containing sheet material at specific moisture contents.

The graph indicated in the top right square in Fig. 3 indicated as control unit 8, shows crimping depth values d against moisture content M. For example, a low, medium or high moisture content M corresponds to target crimping depth values 43 between 0.20 millimeter and 0.23 millimeter. A low moisture content refers to a moisture M of lower than 7.6 percent of water and a high moisture content refers to a value M higher than 8.5 percent of water in a sheet material such as for example case leaf.

In a crimping depth measurement device 84, arranged downstream of the crimping device 4, for example, a depth profiler, the crimping depth 42 is measured. The target crimping depth 43 is compared with the measured crimping depth 42. Information of a deviation 44 of these values is provided to the control unit 8, which control unit 8 may give an according signal 99 to an actuator of the crimping device 4 to adjust the distance 40 of the crimping rollers 41. A distance 40 of crimping rollers 41 may, for example, be measured with laser sensors.

In the example shown, a measured moisture content M gives a target crimping depth value 43 of 0.204 millimeter. A measured crimping depth 42 in the measurement device 84 gives a measured crimping depth 42 of 0.173 millimeter. Thus, with this information, the distance 40 of the crimping rollers 41 in the crimping device 4 may be set to 0.2 millimeter. In an output control 86, also the cross section of the gathered rod is measured. Next to information on the position of the susceptor in the rod, also information on the gathering of the sheet material may be determined. For example, a homogeneous or non-homogeneous gathering over the cross-section of the rod may be detected. In the exemplary drawing shown left in the square indicating the output control 86, an acceptable result 91 showing a homogeneous gathering of the sheet material over the cross-section of the rod may be seen. In the exemplary drawing shown in the middle of the square indicating the output control 86, a non-acceptable result 92 is shown. The non-acceptable result shows a cross section of an article including an area 921 not comprising sheet material. Articles delivering non-acceptable results 92 may be rejected. A rejection may be actuated by an according signal from the control unit 8 actuating a rejection device (not shown). Information on acceptable or non-acceptable results 91,92 are also used in the control unit 8 for a crimping depth adjustment.

Fig. 4 shows an example of an output control 86 including an image sensor 2, for example a camera. The camera takes pictures of the cross section of an end 730 of a rod-shaped article 73, for example, a double rod of an aerosol-forming article. By this, the position of the susceptor 74 in the double rod may be measured and compared with quality specification in order to detect or determine the condition of the susceptor.

In Fig. 4, the rod-shaped articles 73 are transported in flutes of a fluted conveyor drum 30 and preferably continuously pass the camera for position measurements. The articles 73 may be exactly positioned on the conveyor drum 30, such that a susceptor 74 in the article 73 has a specific and predefined orientation on the conveyor drum 30 relative to and when passing the camera. This may simplify a quality control. In particular, it may enhance the velocity for a comparison of measurements with quality specifications, in particular with predefined thresholds for acceptance or rejection of the article 73. A predefined and consistent orientation of the susceptor in the article may also be advantageous for further processes further downstream in the manufacturing line, such as, for example, a cutting of the article or an assembly of the article with further segments of an aerosol-generating product or device.

In Fig. 5 and Fig. 6 examples of different measurements of the condition of a susceptor 74 in the rod-shaped article 73 are shown.

In Fig. 5 and Fig. 6, pictures of cross sections of a rod-shaped aerosol-forming article 73, comprising a susceptor strip 74 surrounded by crimped and gathered aerosol-forming sheet material 75, for example cast leaf, is shown. The susceptor strips 74 are not entirely straight and not exactly in the central longitudinal axis of the article 73. In Fig. 5, two rectangles 201, 202 indicate limits for quality specifications. The two rectangles 201 , 202 are symmetrically arranged around the central axis of the rod and indicate border distances for the susceptor strip position in the article 73. The inner rectangle 201 may, for example, indicate a warning threshold, indicating a measured article 73 comprising a susceptor position outside of the inner rectangle 201. These articles are still considered acceptable. However, if a certain percentage of articles 73, for example, 5 percent to 20 percent, are outside of the inner rectangle 201 and thus exceeding the warning threshold, the control unit 8 may activate a positioning device 5 to adjust the position of the susceptor 74 upon insertion into the sheet material 75. Alternatively, or in addition, the control unit 8 may activate a crimping device 4 to adjust a crimping depth 40 of the sheet material 75 before insertion of the continuous susceptor band into the sheet material 75.

The outer rectangle 200 may, for example, be a waste threshold. If a controlled article provides susceptor positions outside of the outer rectangle 200, thus exceeding a waste threshold, the article 73 is rejected.

Preferably, a position of the susceptor 73 is adjusted or a crimping depth 40 is adjusted before a waste threshold increases.

In Fig. 6, the susceptor strip 74 is bent and displaced out of the center axis of the article 73.

The output control 8 may include eccentricity measurements or deformation measurements of the susceptor 74. For example, a center 202 and the lateral ends 203 of the susceptor 74 (lateral with respect to the cross-sectional view) may be detected. From these measurements general displacement and range of bending of the susceptor 74 may be detected and compared with acceptable ranges of predefined quality specifications. Several measurements along the susceptor 74 may enhance the accuracy of the susceptor position over the cross section of the article.

For the purpose of the present description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term "about". Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein. In this context, therefore, a number A is understood as A ± 5% of A. Within this context, a number A may be considered to include numerical values that are within general standard error for the measurement of the property that the number A modifies. The number A, in some instances as used in the appended claims, may deviate by the percentages enumerated above provided that the amount by which A deviates does not materially affect the basic and novel characteristic(s) of the claimed invention. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.