This invention relates to articles, materials, and methods for sealing wall or bulkhead wiring feedthroughs, for example those described in our co-pending British Patent Applications No.9603629.8 (RK552 GB1), No.9606393.8 (GB2), No.9611111.7 (GB3), No.9613580.1 (GB4), and the corresponding International Application No. PCT/GB97/00476, which may for example comprise a substantially rigid collar assembly of at least two hinged or separate pieces assembled to surround a portion of the bundle, (ii) a rubber or plastics sleeve surrounding and gripping part of the collar assembly and part of the bundle adjacent to the said portion, the collar assembly either having (iii) an integral substantially rigid clamping portion adapted for attachment to a wall or bulkhead in use, or being assembled with (iii) a similarly-adapted separate substantially rigid clamping member of at least two hinged or separate parts surrounding and gripping that part of the sleeve which is between the collar and the clamping member.

One aspect of the present invention provides an assembly for sealing a wiring bundle bulkhead feedthrough, comprising (I) a substantially rigid collar assembly of at least two hinged or separate pieces surrounding a portion of the bundle, and (II) a rubber or plastics tape or sleeve wrapped around and gripping at least part of the said collar assembly and part of the bundle adjacent to the said portion.

The materials and construction techniques for the collar and clamping member are not critical and may be selected according to convenience, with routine modifications where necessary, for use with the sleeve of the present invention. Preferred features may include, individually or in any appropriate combination, an assembly (1) wherein the sleeve is at least partly composed of heat-shrinkable plastics material and has been heat shrunk to grip the collar assembly and the adjacent part of the wiring bundle; (2) wherein the collar assembly includes a generally plate-like part which is adapted to be secured face-to-face against a bulkhead through which the wiring bundle is to extend in use; (3) wherein the collar assembly carries sealant material (a) at a position to be capable of forming a seal against a bulkhead through which the wiring bundle is to extend in use. and/or (b) at a position forming a seal between mutually-abutting surfaces of the

assembled collar assembly parts; (4) wherein the sealant material carried by the collar assembly at one or more (preferably all) of the said positions is gel; (5) wherein the sleeve or tape carries sealant material forming a seal between the sleeve and the collar assembly and/or between the sleeve and the part of the wiring bundle gripped thereby; (6) wherein sealant material substantially blocks the interstices between the wires in the wiring bundle; (7) wherein the sealant material carried by the sleeve and/or substantially blocking the said interstices is heat-activated adhesive material, preferably a hot melt adhesive or a thermoset adhesive; (8) wherein the heat-activated adhesive material carried by the sleeve and/or that substantially blocking the said interstices carries inductively-heatable particles and has been inductively heated to form the said sleeve seal(s) and/or to substantially fill the said interstices; (9) wherein at least the heat-activated adhesive material substantially blocking the said interstices is not itself significantly inductively-heatable and has been activated at least partly by heat derived from inductive heating of the wires forming the wiring bundle; (10) comprising a tapering formation, preferably of flexible fingers, extending from (and preferably integral with) the collar assembly towards the said gripped part of the wiring bundle to provide a graduated transition of the sleeve from the collar assembly to the bundle, the sleeve and the said gripped part of the bundle preferably extending beyond the end of the tapering formation; (11) comprising the collar assembly (I) surrounding a wiring bundle and the sleeve (II) surrounding the collar assembly and the adjacent pan of the bundle, prior to heat shrinking of the sleeve; or a kit of parts comprising a collar assembly and a sleeve suitable for incorporation in an assembly as aforesaid, possibly additionally comprising sealant material in a form suitable for insertion between wires in the said wiring bundle to substantially block interstices between the wires as aforesaid; or a method of making a wiring bundle bulkhead feedthrough assembly as aforesaid, comprising the steps of (a) assembling the said collar assembly around the wiring bundle, and (b) placing the said sleeve around, and (c) causing it to grip, the collar assembly and the said adjacent part of the wiring bundle, possibly additionally including the step of (d) activating heat-activatable adhesive material present in the assembly by inductive heating as aforesaid and/or possibly additionally including the step of (e) securing (and preferably sealing) the collar assembly against a bulkhead through which the wiring bundle extends.

The preferred tapering formation, preferably of flexible fingers, extending from (and preferably integral with) the collar assembly towards the said sleeve-gripped part of the wiring bundle, in addition to providing strain relief and a graduated transition of the sleeve from the collar assembly to the bundle, has been found advantageously to improve the sound-proofing qualities of the feedthrough, compared with more abrupt, less tapered transitions.

In the interests of resisting "milk-off' of the shrinking sleeve from the collar assembly, it may be advantageous that the collar assembly have ridges or grooves or other formations which interlock with the shrunk sleeve.

Further aspects of the present invention provide an assembly, kit, or method as hereinbefore described or according to any claim of the co-pending application, wherein the said sleeve is provided by a rubber or plastics tape or slit sleeve wrapped around, or suitable for wrapping around, the stated components of the assembly. In these "wraparound" embodiments of the invention, it may often be preferable that the said tape or slit sleeve is secured in its wrapped arrangement by an adhesive bond, preferably an overlap adhesive bond. It may also be preferred, especially when such adhesive bonding is used, that the said tape or slit sleeve is shrinkable (preferably heat-shrinkable) in the direction of wrapping by not more than 50% , preferably not more than 30%, more preferably not more than 20%, and preferably by at least 5%, more preferably at least 10%, of its unshrunk length in that direction. Some degree of shrinkability is preferable to assist blocking of the wiring bundle by driving sealants into it, while a moderate or low degree of shrinkage enhances the ability of the adhesive bonds, when used, to survive the shrinkage process. Other means of fastening the wraparounds may be used if preferred, for example clamps, staples, or stitching.

The slit sleeve or tape may be made of materials and may carry sealants or adhesives similar to those described in the aforesaid co-pending applications or known for heat- shrinkable articles generally. PVC tapes may be desirable for cost-saving reasons in

circumstances where they can meet the temperature and other physical performance requirements.

Further aspects of the invention may provide an assembly, kit, or method as hereinbefore described or according to any claim of the co-pending application, wherein the said collar or collar assembly and/or the said tapering formation if present, is or are curved or angled to cause or follow a change in the direction of the wiring bundle extending through the assembly in use. The tape or sleeve will accordingly follow the same change of direction.

The invention includes use of an assembly, kit, or method as hereinbefore described to form an automotive bulkhead feedthrough, preferably between the engine compartment and the passenger compartment of a land vehicle.

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings wherein: -

Figure 1 A and IB shows a form of moulded plastics collar assembly for blocking a side- entry access slot in a vehicle bulkhead; and

Figures 2A to 2E show curved or angled extensions for directing or following changes in direction of die wiring bundle;

Referring to Figures IA and IB, a rubber-over-moulded steel or glass-filled nylon collar assembly 14 formed in two separate pans is assembled around a wiring bundle 12 to form a collar boss 16 projecting along the bundle. An inductively-heatable spirally- wrapped adhesive-coated tape 20 of known heat-shrinkable material capable of about 10- 20% shrinkage on heating, carrying an inductively-heatable adhesive (not shown) on its inner surface, is wrapped to form a sleeve around the wiring bundle 12 and the projecting collar boss 16 and is secured by an adhesive overlap bond with the wrapped-tape sleeve 20 covering any blocking adhesive inserts (not shown) which may be inserted between the wires of the bundle as hereinafter described. This assembly is then subjected to inductive heating by known methods to shrink the sleeve and drive the blocking adhesive in amongst the wires of the bundle to produce a sealed assembly. The collar assembly 16 has integral

flexible tapering fingers 17 to provide some strain relief and a smoother transition of the resulting wrapped-tape sleeve between the collar assembly and the wire bundle 12. The lateral extension 18 is shown blocking side-entry access slot 24 in bulkhead 22 and tends to reduce or prevent potentially seal-breaking lateral movement of the opposite edges of the slot.

Figures 2A to 2C show in perspective three possible forms of tapering fingered moulded plastics collars which are curved or angled for the purposes hereinbefore described. It will be understood that such collars could be fitted onto or formed integrally with the projecting collar boss of Fig. IB. Fig. 2D shows a hinged two- part curved collar which can be closed around a wiring bundle and covered with a suitable sleeve as shown in Fig, 2E.

WALLORBULKHEADFEEDTHROUGH GB3

The collar assembly may be made from various materials, for example relatively dense mouldable material such as glass-filled polypropylene, polyamide, or ABS engineering plastics to give desirable clamping rigidity and sound-insulating properties, and more flexible plastics materials for the flexible tapering formation, enabling it to flexibly adjust to various wiring bundle sizes.

One problem this invention addresses is that of positioning a cable-blocking heat- shrinkable driver sleeve onto a long, multi limbed wiring harness without having to manoeuvre the harness through the sleeve. This is achieved by making the heat-shrinkable driver out of a side-entry ("wrap-around") sleeve. The side-entry concept is known in itself and many attempted designs use a mechanical clip or an adhesive backing or a separate piece of adhesive tape to hold the sleeve together. For the present feedthrough purposes, the mechamcal fastening technique is unsatisfactory since it hinders formation of a seal to the side entry feedthrough. The adhesive closure techniques have usually failed in the past because the adhesive cannot prevent the joined sleeve edges from sliding over

each other when the usual hot air. flame, or IR heating is applied to heat shrink the sleeve.

The preferred induction heating techniques hereinbefore referred to provide a unique solution to this problem in as much as the heat is generated within the bundle to be sealed and heat flows from the inside to the outside of the sleeve. Moreover, the temperature can be advantageously controlled by means of the magnetic field, because both the field strength and flux density can be controlled as well as the heating cycle. This is achieved with a side-entry solenoid coil (e.g. a U-shaped coil or a so-called "clam-shell" design) by varying the diameter of the coil and the separation of the turns of the coil. Low heating levels around the collar of the feedthrough assembly may be achieved by using a larger coil diameter, thus reducing the field strength, and the coil's diameter may be reduced to follow the tapered section of the collar, thus increasing the field strength in the central region where the sealant block is to be formed in the harness. Finally, in the last section of the coil surrounding the part of the sleeve beyond the blocked region of the harness, the spacing between each coil turn may be increased to decrease the field strength. Hence, a temperature profile over the length of the sleeve can be designed to meet the requirements of each part and the amount of heating in any one position can be precisely controlled and regulated. This means a temperature can be achieved inside the bundle that causes the blocking sealant (e.g. hot-melt adhesive) to melt and flow whilst the wrap around outer sleeve can be at a lower temperature which is less likely to cause the adhesive closure bond to fail. This facilitates the selection of a suitable adhesive to hold together the wrap around sleeve.

One technique for achieving this wrap-around sleeve closure uses a slit tube of heat-shrinkable extruded tubing, preferably made of a low-temperature EVA compound with a liner of hot-melt adhesive loaded with inductively-heatable particles (as known per se). The tubing preferably has a 3:1 shrink ratio to accommodate the transition from the collar to the harness surface. By way of example, this tubing is positioned around a collar whose diameter is 35 mm, so that the heat-shrinkable tube so formed is as long as the harness region to be blocked. A strip of known high-temperature pressure-sensitive

adhesive tape is used to secure the slit tube together. During the induction heating cycle the slit tube shrinks to conform to the shape of the collar of the side-entry feed through and to the cable being blocked. The heat in this sleeve is controlled by the field applied to the collar where the shrink forces would be greatest. A mechanical feature such as a tie wrap may be employed to fix the slit tube in place prior to recovery and to help prevent movement during the heating and recovery process. Heat generation would be maximized by concentrating the field in the region where the cable is being blocked, i.e. where the blocking sealant is located on or among the wires. At the end of the cycle, after cooling, the adhesive tape could be removed.

An alternative technique is to use a tape that has longitudinal shrinkage of about 50%, this tape could contain the inductively-heatable material within it so that this tape would heat in the magnetic field, or alternatively could contain no inductively-heatable material if used with an inductively-heatable hot melt adhesive coating. This heating could be controlled by the magnitude and concentration of the field (achieved by varying the coil design locally). This tape could be coated either with a pressure-sensitive hot melt, or with a hot melt adhesive coating having strips of pressure-sensitive adhesive to aid location. A suitable tape may be formed by methods known per se, for example it may be extruded and orientated prior to electron beam cross-linking and then given a beam dose such that most of the longitudinal shrinkage is locked in and only 25 to 50% remains. This tape would be wrapped around the collar and spiral wrapped down the fingers onto the cable, over the part of the cable carrying the blocking sealant and ending on the cable surface. During the induction heating process, heat would be concentrated by the coil design on the portion of the cable to be blocked and minimized at the two ends to reduce the risk of excessive shrinkage forces causing the tape to move or slip on the collar or the cable surface. The tape would attempt to shorten in length and hence compress and conform to the underlying components, and the adhesive coating would seal the wrapped tape together and help seal it to the cable bundle and the interior of the collar. An additional benefit of the relatively low tape shrinkage ratios would be that the forces applied to the blocked part of the cable during the process would be relatively low, so reducing the risk of damage to heat-sensitive wire insulation.

For this system to be optimally effective, it is preferred to use an adhesive blocking profile that is as wide as possible to reduce the height of the block adhesive within the sleeve before the shrinking process. When blocking adhesive bodies are stacked together to achieve a desired blocking sealant volume, the total stack height may be much larger than the diameter of the cable, which would necessitate a higher-than-desirable shrink ratio for the tape. This can be avoided by using a single layer of blocking sealant, for example a sealant tape having a substantially flat profile, or having multiple projections for insertion between the wires (colloquially known as "millipede tape"), of width preferably substantially equal to the optimum width of the block and with a low profile compared to stacked smaller bodies of blocking sealant, e.g. only 7mm wide. The single profile also makes the process simpler by reducing the number of components.

A further aspect of the present application accordingly relates to the securing of wrap-around sleeves, for example those mentioned hereinbefore or those using adhesive overlap bonds as hereinbefore described. This aspect accordingly provides an assembly or kit as hereinbefore described, wherein the said sleeve is provided by a sheet or longitudinally-slit sleeve wrapped around, or suitable for wrapping around, the wiring bundle and the collar or collar assembly, and securing means are provided in the form of a pressure-sensitive adhesive tape or a tie wrap to secure the wrapped sleeve in place, especially when inductive heating is to be subsequently applied.

It has been noted above that single-wrapped closures such as the aforementioned sheet or slit sleeve secured by adhesive tape or overlap adhesive bond, for example with pressure-sensitive adhesive, work suφrisingly well, with or without additional securing tie wraps or tapes, when the wrapped sleeve is to be heat shrunk by inductive heating of the assembly as described in the aforementioned co-pending applications. This unexpected success of adhesive wrap-around closures for heat-shrinkable sleeves, which may be due to the inductive heating generating the shrinkage heat from the inside of the assembly, is in shaφ contrast to the external application of hot air or flame which notoriously caused adhesive wrap-around closures to fail in the past.

Such inductive heat shrinkage of adhesive-closed side-entry ("wrap-around") heat- shrinkable sleeves may thus be regarded as an invention in itself. The inductive heat may be generated by inductively-heatable material (for example particles carried by the sleeve, preferably on or near its inner surface; or carried on or in a coating, for example a hot melt adhesive coating, on the inner surface of the sleeve; or carried by sealant material on or within the wiring bundle, which may have the puφose of sealing interstices within the wiring bundle) or by the metal conductors of the wires within the bundle, or by any combination of these.

A further aspect of this application provides an assembly or kit as hereinbefore described, or according to any of claims 1 to 16 of British Patent Application No. 9603629.8, or any of claims 1 to 14 and 18 to 22 of British Patent Application No. 9606393.8, wherein the said sleeve is provided in a tapering form which in use can be arranged tapering from the said collar assembly towards the surface of the wiring bundle, prior to any heat shrinkage of the sleeve.

Use of a tapered tube or tapered slit sleeve in this way may alleviate large unresolved shrinkage which could occur in straight tubular sleeves when applied to a tapered collar or assembly. A preferable solution, however, may be to use the aforementioned spirally-wrapped tape to form the said tapering sleeve.

Accordingly, a further aspect of this application provides an assembly or kit as aforesaid in which the aforementioned tapered form of the said sleeve is provided by wrapping two or more laps of a rubber or plastics tape around a correspondingly tapering part of the said collar or collar assembly, the said tape preferably carrying heat-activatable sealant or adhesive material.

The tape will preferably carry a coating of inductively-heatable sealant, preferably as described hereinbefore and/or in the aforementioned British Patent Applications, the disclosures of which are incoφorated herein by reference. The tape will preferably be

wrapped spirally all the way from the surface of the wiring bundle, over the narrower end of the tapering collar or assembly, to its wider end, with the successive spiral wraps preferably arranged to minimise potential leakage paths.

A further aspect of this application provides a method of making a wiring bundle bulkhead feedthrough assembly by inductive heating, preferably to form an assembly as hereinbefore referred to, wherein (i) the inductive heating is effected on a tapering formation by means of a correspondingly tapering coil and/or (ii) the inductive heating is effected by means of a coil having varied spacing between its adjacent turns, so as to vary the field produced along the coil length in use. Use of an induction coil which tapers more or less to follow the taper of the assembly to be inductively heated may enable more effective application of the induction heating field to the assembly. The tapered or variably-spaced induction coil itself may accordingly be regarded as an inventive feature in its own right, the invention accordingly including such a coil, preferably suitable for inductively heating a wiring bundle bulkhead feedthrough assembly as hereinbefore described.

A further aspect of this application provides a wrap-around sheet or sleeve of heat- shrinkable plastics material carrying inductively-heatable material, preferably in a coating on the surface of the sheet or sleeve which will face inwards in use, together with adhesive, preferably pressure-sensitive, for securing the sheet or sleeve in its wrapped position, preferably by means of an overlap adhesive bond, prior to inductive heating to shrink the plastics material. This kind of wrap-around inductively heat-shrinkable sleeve may be preferred for making the assemblies hereinbefore described.

It may be preferable for induction heating coils used for forming die assemblies hereinbefore described to incoφorate or be associated with locating means for locating the components to be heated in a precise pre-determined position within the field generated by the coil in use. Such locating means might, for example, comprise a jig-like structure into which suitably-formed parts of the aforementioned collar assembly would fit, thus

requiring each successive wiring bundle passing therethrough to be placed in substantially the same position for each successive induction heating operation in an assembly line process such as an automotive harness shop.

WALLQRBULKHEADFEEDTHROUGH GB4

When the aforementioned blocking adhesive is to be used, it is usually desirable to open up the wiring bundle in order to allow the blocking adhesive to be inserted between the wires within the bundle in addition to or instead of applying bodies of the adhesive to the outside of the bundle. With this in mind, a further aspect of the present invention provides a device and method for separating a bundle of elongate flexible objects (for example the aforementioned wiring bundle) into two or more smaller sub- bundles. This aspect accordingly provides a device for separating a bundle of elongate flexible objects into two or more smaller sub-bundles, the device comprising a support having a row of at least two projections (preferably substantially rigid) upstanding from the support, which projections are capable of being inserted into (preferably extending through) the bundle to divide it into the said sub-bundles in such orientation that angular movement of the row in a plane substantially normal to the direction of insertion of the projections into the bundle increases the lateral spacing between the sub-bundles.

A flat support with substantially straight projections extending from its flat surface may be preferred as a simple embodiment of this concept, although other shapes and orientations of the support and projections are not excluded. To facilitate insertion of the projections into the bundle, it may be preferred that each of the said projections has an elongate cross-sectional shape in a plane substantially normal to the said direction of insertion and that the projections are arranged with their elongate shapes lying substantially parallel with one another so that they can be inserted in the bundle with their elongate cross-sectional shapes all pointing along the bundle prior to the said angular movement. A preferred form of this device comprises three or more of the said projections arranged in a substantially straight row.

It will be understood that a row of such projections having a total row length greater than the diameter of the bundle into which the projections are to be inserted may be inserted at an angle of less than 90° to the longitudinal axis of the bundle, thus sub¬ dividing the bundle with the ends of the row lying within or close to the original diameter of the bundle. While a row of only two such projections could be inserted with the projections aligned on the central axis of the bundle where only two sub-bundles are desired, a row of two, or three or more such projections is preferably inserted at the aforementioned acute angle across the axis if three or more sub-bundles are desired. When the inserted row of projections is rotated in a plane substantially normal to the direction of insertion of the projections to bring the row towards an angle of 90° to the longitudinal bundle axis, the length of the row will increasingly extend beyond the original diameter of the bundle, so that the respective projections will increasingly separate the sub-bundles from one another.

This aspect of the application accordingly also provides a method of separating a bundle of elongate flexible objects into two or more smaller sub-bundles, comprising inserting the row of projections of the aforementioned device into the bundle to divide it into the said sub-bundles and effecting angular movement of the row to increase the lateral spacing between the sub-bundles. This method of opening the original bundle is especially suited to a method of blocking interstices within a bundle of elongate objects using the aforementioned separating device by a method as aforesaid, inserting blocking material between the separated sub-bundles, and removing the separating device, preferably to allow the sub-bundles to close around the inserted blocking material. The extent to which the sub-bundles close around the blocking material is not critical. External pressure may be applied to pack the sub-bundles closely together around the blocking material if desired. Preferably, the blocking material is heat-activateable (preferably induction-heatable) sealant material and is heated to cause it to flow and block the interstices within the bundle, as described in the aforementioned co-pending British Applications.

This bundle-separating device and method are regarded and claimed as inventive in themselves, but are especially suited to use in a method of making a wiring bundle bulkhead feedthrough as hereinbefore referred to.

A further aspect of this application provides advantageous tape forms of blocking material for threading between the sub-bundles and/or for wrapping around the outside of the main bundle. This aspect accordingly provides an elongate tape of sealant material per se, or for use in an assembly kit or method as hereinbefore described, having transversely- extending ridges of the sealant material projecting from one or both of its main tape surfaces or having transverse corrugations extending across its tape width, the ridges or corrugations preferably being regularly spaced along the tape, preferably at intervals within the range from 2 to 10 mm, more preferably 2.5 to 5 mm. The height of the ridges or corrugations is not critical, but the ridges may conveniently be from 2 to 5 mm high on either side of the tape and the total height from peak to trough of the corrugations may conveniently be from 4 to 10 mm. A preferred form of the ridged tape may have the said ridges projecting from both of its main tape surfaces, preferably with the ridges on one of the tape surfaces substantially aligned with those on the other surface or staggered substantially centrally between those on the other surface. Suitable heat-activateable adhesive materials and inductively heatable metal particles for rendering these adhesives inductively heatable are described in WO-A-9424837, the disclsoure of which is incoφorated herein by reference. The shaped tapes may be produced, for example, by moulding the materials in discrete lengths in suitable riged or convoluted moulds, or by continuous extrusion of a flat tape which is subsequently passed while still warm through shaping means such as intermeshing corrugating gears to produce the ridged, and especially the preferred corrugated, forms of tape.

Specific embodiments of these aspects of the invention will now be described with reference to the accompanying drawings wherein :-

Figures 3A to 3C show schematically in top, side, and end views one form of the aforementioned device for separating a wiring bundle into a number of sub-bundles;

Figures 4A and 4B respectively ^" show in top view the device of Figure 3 as initially inserted into a wiring bundle and as subsequently rotated to separate the resulting sub-bundles;

Figure 5 shows schematically in perspective a preferred form of blocking adhesive tape having aligned ridges extending from both its surfaces (the aforementioned so-called "millipede tape");

Figure 6 shows a form of blocking adhesive tape having staggered ridges projecting from its respective surfaces (so-called "centipede tape"); and

Figure 7 shows in schematic perspective an undulating or corrugated form of blocking adhesive tape (so-called "sine-wave tape")

Figures 3A to 3C schematically illustrate a bundle-separating device comprising a flat support 50 with projections 52 rising substantially vertically therefrom. The projections having an elongate cross-sectional shape generally aligned with the longer dimension of the support, on which the projections are arranged in a staggered row sloping at an acute angle to the longer dimension of the support. The device may be made of metal or of sufficiently rigid engineering plastics materials.

In Figure 4A the support 50 is overlaid by wiring bundle 60, through which the projections 52 have been inserted to sub-divide the bundle, the illustrated row of projections being inclined at an angle of less than 90° to the longitudinal axis of the wiring bundle 60. In Figure 4B, the support 50 has been rotated in the direction of the arrow, thus bringing the row of projections 52 closer to an angle of 90° to the longitudinal axis of the wiring bundle 60. Since the total length of the row of projections is greater than the original diameter of the wiring bundle, this rotation has the effect of forcing apart the sub-bundles, and this effect is enhanced by the illustrated elongate shape of the projections which now faces transversely of the longitudinal bundle axis to hold the sub- bundles further apart than would be the case if round projections were used. The simplicity of this device and this method of sub-dividing the wiring bundles may be advantageous in assembly lines such as automotive harnessing shops, where time is at a premium.

Figure 5 illustrates schematically one preferred form of inductively-heatable blocking adhesive tape for insertion between the sub-bundles as hereinbefore described. In this form, the tape 70, for example of materials as described in the aforementioned co¬ pending applications, is formed into ridges 72 on its upper (as illustrated) surface substantially in alignment with corresponding ridges 74 on its lower (as illustrated) surface. The spacing a (preferably regular spacing) between adjacent ridges may be 2.5 mm and the height b of the ridges in this example is also about 2.5 mm.

Figure 6 shows a corresponding tape 70 in which the spacing between adjacent ridges is about 5 mm, the height of the ridges being again about 2.5 mm, and the ridges 72 on the upper surface (as illustrated) are uniformly staggered between the ridges 74 projecting from the lower surface (as illustrated).

Figure 7 shows schematically in perspective one form of regularly undulating or corrugated inductively-heatable blocking adhesive tape 80, in which the distance a between adjacent peaks of the corrugations is about 5 mm and the total trough to peak height b of the corrugations is also about 5 mm.

These forms of blocking adhesive tape, especially the undulating or corrugated version shown in Figure 7, have been found advantageous for threading through sub¬ divided wiring bundles to enhance distribution of the adhesive within the bundle when heated to fuse the adhesive and shrink the sleeve in manufacture of automotive bulkhead feedthroughs, as hereinbefore described.