SYSTEM AND METHOD FOR EVALUATING SUITABILITY OF PACKAGING FOR PRODUCTION PROCESS

FIELD OF THE INVENTION

[0001] The invention relates generally to systems and methods for conducting limited- volume validation or "bench" testing of product packaging to evaluate its suitability for use in a production packaging process.

BACKGROUND OF THE INVENTION

[0002] Many current packaging processes employ induction heating to close an opening in a container, for example, by heating a sealing membrane, usually containing foil and disposed over the opening, using induction heating to thereby fuse the sealing membrane to a periphery of the container proximate to the opening. In some instances, a pressure is applied directly to the sealing membrane during induction heating; in other instances, for example, when the sealing membrane is disposed between a threaded cap and the mouth of a container, the pressure is indirectly applied to sealing membrane via a capping torque applied to the threaded cap.

[0003] The induction sealing process is often problematic in that many variables can potentially interfere with the sealing process, producing, for example, a package characterized by an inadequate seal between the sealing membrane and the container, or an insufficient burst strength, or an inconsistent peeling force for "easy-peel" applications. To create an effective seal using the induction sealing process, the operating ranges for each of the variables needs to be minimized. Examples of these variables are: temperature, pressure, dwell time, bottle finish variability, cap variability, product contamination on neck finish, and thread inconsistency in bottle or cap. Further, known "cappers" for applying the desired capping torque to the threaded cap are often inconsistent in their torque application, further increasing the production variability of induction sealing processes which rely upon capping torque for indirect pressure on the sealing membrane.

[0004] Because of these many variables, in order to qualify new packaging for use in a production packaging process, for example, a package incorporating a new threaded cap, the prior art teaches testing the new packaging in the commercial production plant. Such in-plant testing of new packaging is extremely costly, for at least the reasons that such a trial run of perhaps as many as hundreds of thousands of packages to determine if the new materials perform equivalently to, or better than, the existing material; and the production line obviously cannot be used to produce saleable product during such in- plant testing.

[0005] Unfortunately, because of the many variables of such commercial production processes, the prior art has been unable to adequately simulate the in-plant performance of new packaging in a laboratory setting for purposes of evaluating the suitability of such new packaging. Rather, known testing approaches evaluate small batches of sample materials and attempt to re-create any package deficiencies observed in the commercial plant production line.

[0006] What is needed, then, is a low-volume method and system for evaluating the suitability of new packaging for a production packaging process in a laboratory setting, thereby obviating the need to conduct in-plant "trial" production runs.

SUMMARY OF THE INVENTION

[0007] In accordance with an aspect of the invention, a method for evaluating the suitability of a package for use in a production packaging process includes determining a minimum and maximum value for one or more parameters, and preferably for at least two parameters defining at least one process step of the production packaging process, whereby the minimum and maximum values for a given parameter are representative of a range of production variability for the parameter. The method also includes generating discrete sets of parameter values including unique combinations of the maximum and minimum values and, preferably, at least one additional set of parameter values using a nominal value for each parameter.

[0008] The method according to the invention also includes performing the process steps on a plurality of sample packages using the sets of parameter values at suitable laboratory stations, i.e., stations featuring highly repeatable and accurate performance of

such process steps. Preferably, the process steps are performed on at least two sample packages, and most preferably on several sample packages, using each set of parameter values.

[0009] The method further includes evaluating each processed sample package to determine at least one characteristic of each processed sample package. By way of example only, while the invention contemplates determining any suitable characteristic by which the performance of the package can be evaluated (including its suitability to the intended application of the packaged product), an exemplary method for practicing the invention for packages that include a container whose opening is covered with an airtight sealing membrane, the method generates values characterizing the resulting package's leak test performance, burst-strength test performance, and package appearance.

[0010] The method further includes recording, as a data set for each sample package, a value representative of each evaluated characteristic and the parameter values used to process the sample package; and analyzing the recorded data sets. While the invention contemplates any suitable analysis of the data set, by which to confirm the suitability of using the new packaging, in an exemplary method, the recorded data sets are compared to a control data set, for example, to determine which packaging is characterized by less leakage and a higher burst strength

[0011] In accordance with another aspect of the invention, a system is provided for testing a package for use in a production packaging process that includes process steps defined by a plurality of process parameters, at least two of which have minimum, nominal, and maximum values. The system includes at least one processing station for performing the process steps defined by the process parameters on a sample package using a set of parameter values, for example, by which a sealing membrane or other suitable closure member is attached to a container. The system further includes an evaluation station for generating at least one value characterizing each processed sample package selected from the group consisting of a sealing-membrane peel strength value, a package leak test value, a package burst strength value, and a value correlated with a visual attribute of the package.

[0012] The system further includes a controller in communication with the at least one processing station and the evaluation station, wherein the controller is arranged to

(1) generate a plurality of unique sets of parameter values based on the minimum and maximum parameter values, as well as a set based on the nominal parameter values;

(2) provide each set of parameter values to the processing station; (3) receive the at least one value representing the characteristic of each processed sample package from the evaluation station; and (4) record the at least one value and the sample's process parameters as a unique data set. Preferably, the system's controller is further arranged to generate an output characterizing the recorded data sets, perhaps by performing one or more statistical operations on the recorded data sets.

[0013] In accordance with yet another aspect of the invention, the system's controller is further preferably arranged to generate a unique sample identifier, for example, a unique reference number, for each sample package to be process by the system. The controller provides the unique sample identifier for use at a labeling station, where sample packages are labeled with either or both of the unique sample identifier and its given set of parameter values, most preferably before the sample package is processed at the processing station. The system's controller is also preferably further arranged to receive information from the labeling station, the processing station, and the evaluation station, with which to track the progress of a given sample package through the system, perhaps as aided by machine-readable indicia imprinted on the package at the labeling station.

[0014] By way of further example, in an exemplary system for evaluating the suitability of using a revised "peel-off' sealing membrane in an production packaging process featuring induction sealing of a threadably-capped container, the first process parameter is representative of a pressure achieved by pressing the sealing membrane against a periphery of the container opening, specifically, a torque value to be achieved when tightening the cap onto the container at a first process station. The second and third process parameters are, respectively, the induction energy level and dwell time used to heat the sealing membrane at a second processing station (after the sealing membrane is compressed by capping torque against the container). Thus, in accordance with an

aspect of the invention, the system's controller generates sets of the parameter values, for example, a first set including the minimum values for tightening torque, induction energy, and dwell time, and a second set including maximum values for tightening torque, induction energy, and dwell time. The controller further generates a set of parameter values for each permutation of the minimum and maximum parameter values, to thereby provide sets of "extreme" parameter values that are more likely to identify production issues than known laboratory tests, along with a set of nominal parameter values.

[0015] The controller provides each set of parameter values to the labeling station at least twice, each time with a unique controller-generated set identifier, whereupon a label is generated and applied to a sample package that includes the revised sealing membrane. Each labeled package is transferred to a first processing station, where the cap is tightened to a torque specified by the set's first parameter value. The capped package is then transferred to a second processing station, where the sealing membrane is induction heated in accordance with the induction energy and dwell time specified by the set's second and third parameter values.

[0016] Upon transfer to the evaluation station, the cap is removed and the package is subjected to vacuum leak testing, burst-strength testing, and a visual inspection, in order to evaluate the quality of the package and/or the seal achieved with the revised sealing membrane. A peel strength test may also be conducted on random samples, to confirm that the sealing membrane exhibits a suitable peel strength. The torque required to loosen the cap of each sealed package may also be recorded, where desired. Values characterizing the performance of the sample package in these evaluations are generated at the evaluation station, for use by the controller.

[0017] The controller receives the values representing the characteristics of each processed sample package from the evaluation station, and records these values, the sample's process parameters, and perhaps also the sample's unique sample identifier as a unique data set. After further processing the recorded data sets in any suitable manner, for example, by suitably weighting individual data sets, the controller generates

an output characterizing the likely performance of the revised sealing membrane, preferably for comparison with a control.

[0018] From the foregoing, it will be appreciated that the invention advantageously provides a system and method by which large-scale production or in-plant processes are simulated very effectively in a laboratory setting. Further, because a system and method in accordance with the invention permits validity testing of packaging components with a relatively small sample size, a packaging developer can beneficially test potential replacement components and/or component materials at the likely extreme ranges of production operating conditions and, thus, effectively simulating in-plant process variability, in a short amount of time, and at a significantly lower cost than prior art in- plant trials.

[0019] Further, because a system and method in accordance with the invention tests samples using combinations of extreme process parameter values, the system and method beneficially exposes concerns regarding production processes and/or packaging components/materials whose relatively infrequent occurrence, even during an eight-hour in-plant trial, might otherwise prevent their detection.

[0020] Other objects, features, and advantages of the invention will be readily appreciated upon a review of the subsequent description of the preferred embodiment and the appended claims, taken in conjunction with the accompanying Drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIGURE 1 is a flowchart setting forth the main steps of a method in accordance with the invention for evaluating the suitability of a package for use in a production packaging process;

[0022] FIGURE 2 is a flowchart illustrating in greater detail an exemplary method for evaluating the suitability, for use in an induction sealing packaging process that includes process steps defined by three process parameters, of a package including a container, a threaded cap, and a foil sealing membrane disposed between the container and cap; [0023] FIGURE 3 is a three-dimensional representation showing production process variability with respect to the three processing parameters used in the exemplary method shown in Figure 2;

[0024] FIGURE 4 is a schematic diagram of an exemplary system for performing the exemplary method of Figure 2;

[0025] FIGURE 5 is a flowchart showing a preferred method for generating the minimum, nominal, and maximum values for the capping torque, for use in the exemplary method of Figure 2;

[0026] FIGURE 6 is a flowchart showing a preferred method for generating the minimum values for the induction sealing energy and dwell time, for use in the exemplary method of Figure 2; and

[0027] FIGURE 7 is a flowchart showing a preferred method for generating the nominal and maximum values for the induction sealing energy and dwell time, for use in the exemplary method of Figure 2.

DETAILED DESCRIPTION OF THE INVENTION

[0028] Referring to Figure 1 , a method 10 in accordance with the invention for evaluating the suitability of a package for use in a production packaging process generally includes determining, at step 12, a minimum value and a maximum value for each of at least two parameters defining process steps utilized in the production process, and generating, at step 14, a plurality of unique sets of sealing parameter values based on the minimum and maximum sealing parameter values. The method 10 also includes, at step 16, the low-volume processing of sample packages by performing the process steps on a plurality of sample packages using the sets of parameter values at suitable laboratory stations, i.e., stations featuring highly repeatable and accurate performance of such process steps, with each set of process parameters being used to process at least two sample packages. At step 18, the method includes determining at least one characteristic of each processed sample evaluative of the quality of the package, for example, its performance in a vacuum leak test, a burst-strength test, a peel strength test, or the overall appearance of the processed sample. [0029] The method 10 further includes, at step 20, recording, as a data set for each processed sample, a value representative of each such determined characteristic and the parameter values used to process the sample; and, at step 22, analyzing the recorded data sets. While the invention contemplates any suitable analysis of the data

set, by which to confirm the suitability of using the new packaging, the recorded data sets are conveniently compared to a control data set, to determine which packaging is characterized by less leakage and a higher burst strength.

[0030] Figure 2 shows a flowchart of an exemplary method 30 for evaluating the suitability of a package including a container, a threaded cap, and a foil sealing membrane disposed between the container and cap (all not shown) for use in an induction sealing packaging process. Specifically, the packaging process includes process steps defined by three process parameters: the first process parameter is representative of a pressure achieved between the tightened cap and the mouth of the container, as it compresses the sealing membrane against the periphery of the container's mouth, as expressed in terms of an applied capping torque T; and the second and third process parameters are representative of the heat applied to the sealing membrane such that the sealing membrane, pressed by the tightened cap against the container's mouth, fuses to the container's mouth, as expressed in terms of an induction energy E applied to the capped package for a dwell time t. [0031] As seen in Figure 2, at step 32, the exemplary method 30 determines the minimum, nominal, and maximum production values T _m j _n ,T _no m,Tmax for capping torque T; the minimum, nominal, and maximum production values E _m j _n) Enom,E _m ax for induction sealing energy E; and the minimum, nominal, and maximum production values tmin,tnom,tmax for induction sealing dwell time t. For an established production packaging process, one or more of these values may be known; may be ascertained through a review of plant records; or may be established through an in-plant process analysis. Alternatively, as discussed more fully in connection with Figures 5-7, working values for these process parameters may be determined in a separate laboratory method. [0032] At step 34 of Figure 2, the exemplary method 30 generates sets of parameter values including all unique combinations of minimum and maximum parameter values, and a combination of nominal parameter values. The several generated sets of parameter values, by which the exemplary method 30 seeks to replicate all "extreme" combinations of parameter values, are graphically illustrated in Figure 3. It will be appreciated that, where desired, additional nonduplicative sets of parameter values can

also be generated, for example, those containing one nominal parameter value in combination with a minimum or maximum value for each of the other parameters (and, hence, lying on one of the broken lines defining the three-dimensional element shown in Figure 3), or those containing two nominal parameter values in combination with a minimum or maximum value for a third parameter (and, hence, lying on a "face" of the three-dimensional element shown Figure 3), or even those containing parameter values other than the nominal parameter values but intermediate the maximum and minimum values (and, hence, disposed somewhere within the three-dimensional element shown in Figure 3).

[0033] At step 36, at least two unique sample identifiers are also generated for each set of parameter values, so that a like number of sample packages processed using the same set of parameter values can each be individually identified. In this regard, it is noted that the number of samples processed using the same parameter values should be determined based on production process consistency observed in the production facility, with a higher in-plant error rate corresponding to an increased sample size in the exemplary method 30. By way of further example only, when evaluating the suitability of a new packaging component such as a new sealing membrane with the exemplary method 30, a sample size of about ten packages may be appropriate. At step 38, each sample is labeled with the unique sample identifier generated at step 36. [0034] At step 40 of Figure 2, the exemplary method 30 includes capping each sample container using a given set's capping torque parameter T; and, at step 42, induction sealing each sample package using the given set's energy and dwell time parameters E,t. At step 44, the exemplary method 30 includes generating a first value characterizing an applied torque required to loosen each sample package's cap. After uncapping the sample package at step 46, the exemplary method 30 includes vacuum leak testing each uncapped sample package at step 48, and generating a second value characterizing each sample's vacuum leak test performance at step 50. After visually inspecting the sealing membrane of each processed sample at step 52, the exemplary method 30 includes generating a third value characterizing the visual inspection of each uncapped sample package. Finally, after burst-strength testing each sample package at

step 56, the exemplary method 30 includes generating a fourth value characterizing each uncapped sample packages burst-strength test performance. [0035] At step 60 of Figure 2, the exemplary method 30 includes tabulating the first, second, third, and fourth characterizing values with the sample parameter values using the sample identifier, for example, by recording the characterizing values, the sample parameter values, and the sample identifier together as a data set in an appropriate computer-and readable medium. And, at step 62, the exemplary method 30 includes statistically comparing the tabulated data sets, which, as noted above, include plural samples processed using like process parameter values, to a tabulated control data set. [0036] It will be appreciated that the foregoing description of the exemplary method 30 shown in Figure 2 is merely illustrative, and that the invention contemplates altering the order in which many of the exemplary method's individual process steps are performed. By way of example only, the labeling step 38 may conveniently be performed after the loosening torque is determined at step 44. Similarly, the order in which the specific leak, visual, and burst-strength characterizing steps 48,50,52,54,56,58 are performed may be modified, perhaps even within a given method in order to improve package workflow and/or method throughput.

[0037] Referring to Figure 4, an exemplary system 70 for performing the exemplary method 30 of Figure 2 includes a controller 72 that determines the minimum, nominal, and maximum parameter values for capping torque T, induction sealing energy E, and induction sealing dwell time t; and generates the sets of parameter values that are graphically illustrated in Figure 3. The controller 72 also generates a unique sample identifier for each sample package to be processed by the system 70. The controller then forwards package label information including the unique identifier and, preferably, also the parameter values forming a given sample package's process parameters, to a labeling station 74, where a label is prepared and applied to a sample package. [0038] The labeled sample package is then transferred from the labeling station 74 to a capping station 76, where a capping device, such as a Torqo benchtop capping device, manufactured by Vibrac® Corporation of Amherst, New Hampshire, applies a controlled capping torque T to the sample package, for example, in response to a control

signal received by the capping station 76 from the controller 72 after the capping station 76 uses machine vision (not shown) to read the sample package label and send a signal identifying the arrival of the sample package to the controller 72. The capped sample package is then transferred to an induction sealing station 78, where an induction sealing device, such as the "CS Plus, Jr." induction sealing device by Lepel Corporation of Edgewood, New York, applies a controlled induction sealing energy E for a controlled dwell time t to the capped sample package, similarly in response to a control signal received in by the induction sealing station 78 from the controller 72. [0039] The sealed sample package is then transferred to an uncapping station 80, wherein another capping device, such as a Torqo device, applies a controlled torque to the sealed package's cap to thereby determine a value representative of the amount of torque required to loosen the cap, in response to a control signal from the controller 72. The cap is also fully removed at the uncapping station 80. The uncapped sample package is then transferred to a leak testing station 82, where an appropriate laboratory- quality leak testing device performs a suitable electrical-conductivity, vacuum, pressure, and/or penetrating dye leak test on the uncapped sample package, in response to a signal from the controller 72. Finally, the uncapped sample package is transferred to a burst-strength testing station 84, wherein a suitable burst-strength testing device, such as the BT-1000 leak tester by TMEIectronics, Inc., of Boylston, Massachusetts, performs a burst-strength test on the uncapped sample package, in response to a signal from the controller 72.

[0040] It will be appreciated that the several stations 76,78,80,82,84 of the exemplary system 70 feature highly repeatable and accurate performance of their designated process steps, to ensure the validity of the generated characterizing values. It will also be appreciated that the exemplary system 70 is well suited to further automation and mechanization, for example, using robotic workflow including machine vision to track the progress of a given sample through the system, and to correlate detected and observed sample characteristics with the process parameters used to obtain the given sample, thereby improving the consistency of sample data. Finally, the invention contemplates modifying the particular order in which the several stations of the exemplary system 70

process each sample package, as noted above in connection with the exemplary method 30 of Figure 2.

[0041] Referring to Figures 5-7, a preferred method 90 for generating the minimum, nominal, and maximum values Tmin.Tnom.Tmax for capping torque T, for use in the exemplary method 30 of Figure 2, is shown in Figure 5 as including the steps of tightening a cap on to the container of a sample package at step 92, such that the Is fairly tight; and first measuring an amount of applied torque required to loosen the cap, as with a Torqo device. The preferred method 90 further includes setting the minimum capping torque parameter T _m i _n at the first measured amount of applied torque at step 96, and setting, at step 98, the nominal capping torque parameter T _nO m equal to the first measured amount of applied torque (as determined at step 92) plus an incremental torque value δT, for example, about 110 Ncm (about 10 in-lbf). Then, after hand- tightening the cap back on to the container of the sample package as tight as possible at step 100, the preferred method 90 includes measuring amount of applied torque required to loosen the cap, again and is with a Torqo device, at step 102. The maximum capping torque parameter T _max is then set equal to the second measured amount of applied torque (as determined at step 102).

[0042] A preferred method 110 for generating the minimum values for induction sealing energy and dwell time, for use in the exemplary method 30 of Figure 2, is shown in Figure 6 as including the steps of initially estimating values E _n om,t _n om for the nominal induction sealing energy and dwell time parameters at step 112; and setting the minimum values E _min ,tmin for the induction sealing energy and dwell time parameters equal to the estimated nominal induction sealing energy and dwell time parameter values E _πθm> tnom, at step 114. The preferred method 110 also includes, at step 116, capping a first sample package to a minimum torque parameter T _m j _n (as determined, for example through use of the preferred method 90 shown in Figure 5), as with a Torqo device; and, at step 118, induction sealing the capped sample package using the minimum values E _min ,t _m in for the induction sealing energy and dwell time parameters. At step 120, the sealed sample package is uncapped by hand and, at step 122, the package's sealing membrane is peeled from the mouth of the package's container by

hand to determine, at step 124, whether the sealing membrane is barely but sufficiently glued to the container's mouth. If the sealing membrane is not deemed to have been sufficiently glued, at step 126, the minimum value E _m j _n for the induction sealing energy is incremented by a predetermined amount δE, for example, about 20 percent of the minimum value E _m j _n , while the minimum value t _m j _n for induction sealing dwell time is likewise incremented by a predetermined amount δt, for example, about 0.20 seconds. [0043] If the sealing membrane is deemed at step 124 to have been sufficiently glued, at step 128, the preferred method 110 further includes capping a second sample package to the minimum torque parameter T _m j _n , as with a Torqo device; and, at step 130, induction sealing the capped sample package using the minimum values E _m i _ni tmin for the induction sealing energy and dwell time parameters. At step 132, the second sealed sample package is uncapped by hand and, at step 134, the uncapped sample package is subjected to burst-strength testing as perhaps about 35 kPa (about 5 psig). If it is determined at step 138 that the uncapped sample package passes the burst- strength test, the minimum value E _m j _n for the induction sealing energy is decremented by the predetermined amount δE, while the minimum value t _m j _n for induction sealing dwell time is likewise decremented by the predetermined amount δt, and the preferred method 110 returns to step 128. If, on the other hand, the sample package is not deemed at step 138 to have passed the burst-strength test, at step 126, the minimum values Emi _n .tmin for the induction sealing energy and dwell time are again incremented by the predetermined amounts δE,δt, respectively, at step 140 to arrive at the final values to be used in the exemplary method 30 of Figure 2.

[0044] Referring to Figure 7, a preferred method 150 for generating the nominal and maximum values E _nO m,t _n om for induction sealing energy and dwell time, for use in the exemplary method 30 of Figure 2, includes setting the maximum values Emaχ,t _ma χ for induction sealing energy and dwell time to the highest level available on the induction sealing device at step 152. The preferred method 150 also includes, at step 154, capping yet another sample package to the minimum torque parameter T _mi n, as with a Torqo device; and, at step 156, induction sealing the capped sample package using the maximum values E _ma χ,t _ma χ for the induction sealing energy and dwell time parameters.

At step 158, the sealed sample package is uncapped by hand and, at step 160, the package's sealing membrane is visually inspected to determine whether induction sealing has "burned" the membrane or otherwise generated holes or other breaches in the membrane indicating excessive induction heating of the membrane. If it is determined at step 162 that the sealing membrane is "burned," the maximum value E _1713x for the induction sealing energy is decremented by the predetermined amount δE, while the maximum value t _m j _n for induction sealing dwell time is likewise decremented by the predetermined amount δt; and the preferred method 150 loops back to step 154. If, on the other hand, the sealing membrane of the sample package is deemed at step 162 not to have been "burned," the maximum values E _ma χ,t _ma χ for the induction sealing energy and dwell time are incremented by the predetermined amounts δE.δt, respectively, at step 166 to arrive at the final values Emaχ,tm _a χ ^{to De} used in the exemplary method 30 of Figure 2.

[0045] While the above description constitutes the preferred embodiment, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope and fair meaning of the subjoined claims. For example, the controller 72 can advantageously compare the results of the evaluations of each of the two or more sample packages that were processed using the same set of parameter values, and, if the individual results are not within an acceptable range of one another, one or more further sample packages using the same set of parameter can be immediately processed, and further characterizing values corresponding to the set of parameter values readily obtained, before the controller generates the output. [0046] Further, while the invention is described in connection with evaluating packaging for production processes employing induction sealing, it will be appreciated that the system and method of the invention is equally applicable to evaluating packaging suitability for production processes employing conductive heating of a sealing membrane, wherein the process parameters may include a first parameter specifying an applied pressure during conductive heating, a second parameter representative of a temperature achieved during conductive heating (of either the sealing membrane or the tool), and a third parameter representing conductive heating dwell time.