GB2615793A

GB2615793A - Methods of leather working and products produced thereby

Info

Publication number: GB2615793A
Application number: GB2202233.9A
Authority: GB
Inventors: James Wilson Liam; Patrick Brown Graham
Original assignee: Bayerische Motoren Werke AG
Current assignee: Bayerische Motoren Werke AG
Priority date: 2022-02-18
Filing date: 2022-02-18
Publication date: 2023-08-23
Also published as: GB202202233D0

Abstract

Method of creating a recess in a piece of leather having a first side and a second, side, comprising applying a form to the first side of a piece of leather and conforming the leather piece thereto to form an assembly having a first side and a second side, wherein the first side of the assembly comprises the exposed portions of the first side of the leather piece and the exposed portions of the form; positioning cutting means so that the cutting path of the cutting means is in 10 parallel spaced separation from the surface of the first side of the assembly; moving the cutting means along the cutting path to remove a section of leather from the second side of the leather. A method or manufacturing a form for use in the disclosed method comprising the steps of cutting three or more pieces of substantially planar material and stacking the pieces together in concentric layers from largest to smallest on top. An apparatus for installation in a vehicle comprising a piece of leather produced via the disclosed method. Uses of the invention in the manufacture or maintenance of a vehicle, preferably an automobile are also described.

Description

Methods of Leather Working and Products Produced Thereby The present invention relates to methods and apparatus for altering the dimensions of a piece of leather and, specifically, by causing the leather to be thinner in certain defined areas of the leather piece. The invention relates to methods of thinning the leather in defined areas in order to yield desirable and/or definable engineering properties of the leather in the modified areas. The invention also relates to equipment and forms for use in concert with methods of the invention. The invention also relates to products produced according to methods of the invention. Thus embodiments of the invention relate to producing a recessed area in a piece of leather. The invention also considers use of methods, products, and apparatuses of the invention in automobile manufacture and maintenance. In particular, the modified leather is suitable for use in automotive interiors and such as instrument panels and upholstered areas of automobiles.

The properties of leather and other equivalent materials have long been included in the interiors of automobiles because of their properties relating to comfort and insulation from sound and temperature changes.

Accordingly, leather is used on interior panels within a vehicle both as a decorative covering and as insulation. However, such coverings also cover engineering subassemblies hidden behind the leather within compartments and bulkheads of the vehicle.

However, it is unusual for there ever to arise a need for the leather to be weakened or otherwise penetrated during the normal use of the automobile. A particular exception to this is deployment of an airbag during rapid deceleration or other unexpected movement of an automobile that might imperil the occupant.

Airbags are, typically, envelopes of textile material that are inflated at great speed by an explosive charge that releases a non-toxic gas to near immediately inflate the envelope in the bath of the moving occupant in order to absorb their movement during a crash. In order to better absorb this movement, the envelope of material is often perforated in a controlled manner in order to better control egress of the inflating gas.

Frequently, the inflating gas is developed by decomposition of an azide compound into nitrogen gas.

Necessarily, deployment of an airbag is a most unusual event in the life of an automobile. Similarly, an airbag assembly may be used only once. Similarly, an airbag assembly will typically be installed behind the covering of an instrument panel or other bulkhead within the vehicle and, upon deployment, the force of the expanding air deploying the airbag will move the material of the cover aside or away in order that the airbag can deploy in the path of the moving occupant.

Accordingly, typically, the airbag will be installed behind a section of leather that has been thinned in order to modulate its mechanical properties so that it will give way upon deployment of the air bag. That is, the leather is weakened in this area. Typically, this provides intact leather with an effectively invisible 'tear line' in the leather piece.

In this way, a deploying airbag will rupture the leather and pass through it in order to be deployed within the cabin of the vehicle during a crash.

Heretofore leather stock has been thinned using a grinding machine (e.g. as made by ABO) such that a defined area of a piece of leather stock is reduced in thickness in a particular area to provide a section of leather for mounting in a vehicle in a location suitable for an airbag to deploy though the piece of leather rupturing it in the process. A process for producing such leather sections for this purpose is described in DE19944371 entitled "Thinning vehicle interior cladding to produce completely invisible preferential tearing line over airbag, is carried out by milling rear of leather" This technique requires a large and specialised piece of grinding machinery in which a rotating metal (typically steel) brush or diamond-loaded rotary disc cutter is rotated and moved against the surface of the leather in a defined pattern in order to thin the leather over the course of a number of passes. This requires a piece of equipment of a large size whose procurement, storage and operation require significant resources to be expended. Furthermore it is a relatively time-consuming process that is not well suited to mass production.

DE2017661 entitled "Cutting leather at a slant" describes a device for bevelling the edges or other parts of pieces of leather or similar flexible material fixed by depression on a forming tool.

Accordingly, there is a need for an improved method of thinning leather pieces to form recesses in defined locations and/or with defined shapes.

It is therefore an object of the invention to provide an improved method of leatherworking. In particular there is a need for controlled thinning of leather in certain areas in order that the engineering properties of the leather in those areas can be well-defined and reliably specified. This is particularly in order to produce leather pieces for inclusion in automobiles that meet specific engineering and design parameters. Most particularly there is a need for improved methods of thinning leather used to upholster or clad vehicle interiors in order to produce a preferential tearing line in a leather cover mounted over an airbag exit portal.

The invention provides method of creating a recess in a piece of leather having a first side and a second, side, comprising the steps of: a) applying a form to the first side of a piece of leather and conforming the leather piece thereto to form an assembly having a first side and a second side, wherein the first side of the assembly comprises the exposed portions of the first side of the leather piece and the exposed portions of the form; b) positioning cutting means so that the cutting path of the cutting means is in parallel spaced separation from the surface of the first side of the assembly c) moving the cutting means along the cutting path to remove a section of leather from the second side of the leather.

Recess is defined to mean a hollow or depression formed in an object that does not penetrate the thickness of the object. The bases of recesses may be substantially concave, substantially bowl-shaped, or substantially flat bottomed. The perimeter of recesses may be straight, curved, contoured, or a combination of these.

Form is defined to mean a tool for imparting a particular shape or configuration to another object, preferably a piece of leather.

Conforming is defined to mean that an object is shaped to fit the form of another object, preferably one which it abuts with.

That is bring a form into contact with a piece of leather and conforming it thereto moulds the leather into a defined, desired configuration.

Leather is a strong, flexible and durable material obtained from the tanning, or chemical treatment, of animal skins and hides to prevent decay. Preferably the tanning process leaves the leather material's natural fibres intact. Also preferably, leather is mostly made using the derm is layer of the skin. The most common leathers come from cattle, sheep, goats, equine animals, buffalo, pigs and hogs, and aquatic animals such as seals and alligators.

Alternatively, artificial leather materials may be used in the context of the present invention. Thus the term leather as used herein is also defined to encompass artificial leather materials.

There are many terms for non-animal leather including: faux leather, synthetic leather, leatherette, PU leather and pleather (a portmanteau word mixing the words "plastic" and "leather"). Vegan leather refers to any leather-like material that is made without the use of animal skins or processes that use animal products.

Thus alternative leather materials (also "leathers") may be made from either plant-based material, such as cork, pineapple and walnut, sometimes collectively referred to as "plant leathers". Or, they may be made from materials made from fungus, such as mushroom leather, or from algae.

Synthetic leather refers to a material, such as PU leather, which is made from polyurethane, or other plastics material, such as vinyl. Typically, such plastics materials are made from petrochemicals, but may also or alternatively be made from recycled plastics.

Section of leather is defined as a piece or fillet of leather Thus an improved method of leatherworking is provided. This method allows controlled thinning of leather in certain areas in order that the engineering properties of the leather in those areas can be well-defined or specified. Previously, grinding techniques have been employed to thin the leather in a defined area. Such techniques require a piece of equipment of a large size whose procurement, storage and operation require significant resources to be expended. Furthermore thinning leather by grinding is a relatively time-consuming process that is not well suited to mass production. In contrast the present invention is requires a single cutting action to form the recess in the leather.

Accordingly, the present inventors have developed a technique for using an existing leather splitting machine to make a recess in a piece of leather. A leather splitting machine is a tool which uses a blade in order to remove part of the surface of a piece of leather in order to make the material passing through it be of a defined thickness.

Preferably the leather splitter is a power tool. Unpowered, hand-operated splitters may be used.

Thus the methods of the present invention require fewer passes/actions to be performed on the leather workpiece than the previously known methods for thinning leather based that are based on grinding. Preferably only a single cutting action/pass is required. Thus the methods of the present invention are more efficient and better suited to mass production.

Furthermore, the form can be reused, yielding a further efficiency to producing leather pieces with recesses of the desired dimensions.

Furthermore, the existence of the form provides a physical record of the modification made to the leather that can be simply stored and reused. Thus later production of leather pieces with recesses of exactly the same dimensions can be achieved conveniently. Therefore production and repair/retrofitting of producing leather pieces with recesses of the desired dimensions can be more simply and reliably achieved than by previously known methods.

Thus leather pieces with recesses of exactly the same dimensions can be produces with the effect that the leather pieces are reliably and reproducibly thinned in a particular location. Such leather pieces can then, advantageously, simply and reliably be used to produce multiple copies of leather upholstered or clad items.

Furthermore, leather pieces with recesses of exactly the same dimensions can be produce with the effect that the leather pieces are reliably and reproducibly weakened in a particular location, area or at a particular line. Thus leather can be thinned in line with precise engineering specifications. This is advantageous when producing leather that must physically perform in a predictable and reproduceable manner. A particular example is producing leather pieces for mounting in a vehicle to cover the exit or deployment portal of a vehicular airbag system for ameliorating the effects of vehicle collision (i.e. car crashes), wherein the leather pieces will rupture in a defined and reliable manner upon deployment (expansion) of the airbag from its stored position to its inflated form via a portal, aperture, or hole formed by rupturing the surface of the leather piece at a defined location area or line of the leather piece. A further advantage is that the weakened portion, area, or line of the leather is invisible before rupture of the leather and thus the weakening does not have a negative effect on the aesthetic quality of the leather product of the method.

The leather pieces are typically between 1.4 and 0.6mm in thickness. Therefore, the leather that is suitably for use in the context of the present invention may be 2mm, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2mm thick. The thickness chosen may depend on the intended use of the leather. In a specific embodiment the thinned leather is 0.46mm thick following a process of the invention.

Thus leather products produced according to this method are particularly advantageous for leather pieces used in automobile manufacture or repair, preferably for upholstering or cladding parts of the automobile cabin.

The form may comprise an adhesive layer for temporarily affixing the form to the first side of the piece of leather and the method may additionally comprise the step of temporarily attaching the form to the first side of the piece of leather. Preferably the form is stuck onto the leather with an adhesive that does not damage the leather upon removal of the form.

During the development of the present invention, it was unexpectedly found that forms comprising an adhesive layer for temporarily affixing the form to the first side of the piece of leather were particularly advantageous in terms of their working reliably to thin the leather when passed through the cutting means (preferably a leather splitting machine).

The method may additionally comprise the step of removing the form from the leather piece. Conversely, providing a product where the form is left in place yields a flat product that can be more easily stacked and/or stored and wherein there is greater stability imparted to the thinned (and therefore weakened portion) until the form is removed prior to installation or mounting of the leather piece in its intended location.

The method for making the form may be combined with other aspects of the invention and therefore the method may comprise the additional steps of manufacturing the form of: a) Cutting out three or more pieces of substantially planar material b) stacking the pieces of material together in concentric layers, wherein the largest piece forms the base piece of the stack and the remaining pieces are stacked on top of the largest piece in order from smallest to largest Preferably, the circumference of each piece of substantially planar material that is 25 stacked on the base piece contacts the same planar surface of the base piece.

The planar material may be flexible.

The pieces comprised in the stack may be laminated together. That is the stack may be manufactured by bonding layers of material together.

The planar layers may be laminated concentrically. Concentrically is defined as meaning that the edges of the different planar layers in the laminated form do not intersect when the form is viewed from a point perpendicular to the plane of the layers.

Producing the form in this way has the advantage of yielding a form with a smoothly curving exterior surface. That is, while produced from stacked flat, planar pieces the contoured exterior surface of the form does not have 'steps' in it. Were there to be steps then this stepped shape might show through on the "A" side of the leather; this would be aesthetically unacceptable. The smoothly shaped form described herein does not have this disadvantage and yields a similarly smoothly shaped recess in leather worked according to the present invention.

During the development of the present invention, it was unexpectedly found that forms produced from laminated pattern film were particularly advantageous in terms of their working reliably to thin the leather when passed through the cutting means (preferably a leather splitting machine) over forms made from additional leather pieces, laminate pouches, silicone masks or fillets, card, paper, or silicone filled moulds.

By employing methods of the invention, multiple recesses may be made in the second side of the leather. That is a form may be produced that will cause two separate sections of the second side of the leather work piece to be placed in the path of the cutting means. Thus, advantageously, two or more recesses may be formed in the second side of the leather piece during a single cutting step.

Preferably, the first side of the leather is the "A" side, and the second side of the leather is the "B" side.

When considering a piece of leather the "A" side is defined as the side intended to be viewed by the consumer when the leather is mounted in the finished product or automobile. This is conventionally the 'full grain' surface of the leather piece. Conversely, the "B" side of the leather is the other side, which is normally invisible to the user when the leather is used to upholster or clad an object.

The first and second sides of the piece of leather may be substantially parallel., That is, the piece of leather may be of substantially uniform thickness.

Preferably the surface of the first side of the assembly is planar during the cutting step.

The cutting means may be a leather splitter. A particular example of a leather splitter used for the methods described herein is made by Fortuna of Italy. The cutting means may be a band saw.

The invention also provides a method of manufacturing a form for use in the method of the invention, comprising the steps of: a) cutting out three or more pieces of substantially planar material b) stacking the pieces of material together in concentric layers, wherein the largest piece forms the base piece of the stack and the remaining pieces are stacked on top of the largest piece in order from smallest to largest.

Preferably, the pieces of planar material are made from pattern film. Pattern films are planar materials that can be cut to provide guides or masks for reproducing designs or configurations on other materials. An example of a suitable pattern film is Orajete -digital printed media. Different thicknesses of pattern film may be used. Preferably the pattern film is 0.09 mm thick.

Preferably the pieces of pattern film are cut out of stock material on a CNC cutting machine according to a pre-determined pattern stored on a processer comprised in the CNC cutting machine. This has the advantage of simplifying the reproduction of forms. This also has the advantage of conveniently and simply storing the precise information required to simply reproduce a pre-existing form.

The planar material may be transparent or translucent. This has the advantage of being able to mark different layers comprised in the form to denote, ensure and/or verify their correct order and/or placement in the stack.

The pattern film may be self-adhesive. Pattern films of this type may be produced with 30 a self-adhesive layer protected by a removable backing layer. An example of such a pattern film is Orajete -digital printed media.

-10 -The pieces of planar material may comprise a self-adhesive layer. Preferably, the planar material comprises a removable layer that covers a self-adhesive layer. Thus the pieces comprised in the stack may be conveniently laminated together.

Thus, advantageously, the present invention provides forms of effectively any contour and any depth. Similarly the present invention yields the ability to cut recesses in pieces of leather of effectively any contour and/or depth. This has the advantage of increasing the range of recesses that can be formed in leather compared with the known 'grinding' techniques.

The invention also provides apparatus comprising a form, as described herein, attached to a face of a substantially planar piece of leather.

The invention also provides a kit comprising a substantially planar piece of leather and a form, as described herein, for shaping the leather according to a method of the invention.

The invention further provides for the use of a leather splitter as a cutting means according to a method of the invention. Advantageously, the present invention provides a new application and facility for existing leather splitting machines.

The invention also provides apparatus for installation in a vehicle comprising a piece of leather produced according to the method of the invention. Preferably, the apparatus is a dashboard, instrument panel or steering wheel. A vehicle airbag may be comprised in the apparatus and mounted behind the recess in the leather.

The invention further provides for the use of a piece of leather, produced according to the method of the invention, in the manufacture or maintenance of a vehicle. Preferably the vehicle is an automobile.

The invention also encompasses use of the methods and apparatuses of the invention in the manufacture or maintenance of furniture. In this context furniture may include the fittings and equipment of an automobile, especially the interior of an automobile.

The invention also encompasses use of the methods and apparatuses of the invention in the manufacture or repair of leather upholstery or clothing.

Examples and Drawings The invention will now be described with reference to the following drawings and

examples in which:

Fig. 1 shows a photograph of an assembled form for defining how the leather should be thinned, wherein layers of plastics material are stacked together. The position of each stacked layer is indicated by the successive concentric solid lines. Also shown are circles labelled "A", "B", and "C", which indicate positions for testing the thickness of the apparatus before its application to a piece of leather in preparation for thinning of the leather in the area defined by the apparatus and according to the depth defined by the contours of the apparatus applied to the leather.

Fig 2. shows photograph of the layers of plastics material before their being stacked to form the apparatus shown in Fig. 1. This photograph illustrates that the concentric solid guide lines shown in Figure 1 are printed on the largest, base layer of the apparatus and the succeeding smaller layers are applied in positions successively according to the positions indicated by the succeeding concentric lines on the base layer. This photograph also shows that the succeeding layers are numbered consecutively with the numbers positioned such that they are all visible and in order in the assembled apparatus.

Fig. 3 is a photograph illustrating the process of building the form shown in Fig. 1. The largest, base layer of the apparatus is shown with a contrasting, thick line indicating a parallelogram wherein the smallest separate sheet comprised in the form (labelled "1"; not shown) is to be located within, i.e. the smallest layer is aligned according to the innermost guideline of the base layer of the apparatus.

-12 -Fig. 4 is a photograph showing a form for defining how the leather should be thinned located on a piece of leather. This particular piece of leather is for covering a dashboard, but substantially any piece of leather may be shaped according to the present invention.

Fig. 5 is a photograph showing a form for defining how the leather should be thinned stuck to a piece of leather being fed into a leather splitting machine in order to thin the area of leather shaped by the form. In the photograph the form is stuck to the "A" side of the leather piece to be thinned. The recess in the leather will therefore be created in the "B" side of the leather according to the shape of the form as the assembly of form and leather is passed through the splitting machine.

Example 1

In summary, a recess on the surface of a piece of leather is produced according to the shape of a form attached to the leather. The form is first located on the piece of leather by applying the form to the "A" side of the leather and temporarily securing it in place via a self-adhesive layer on the base of the form. In this example the form is stuck onto the leather with an adhesive that does not damage the leather upon removal of the form. The assembly of leather and form is then processed by passage through a leather splitting machine so that the cutter removes a section of the "B" side of the leather matching the shape of the form attached to the "A" side of the leather.

In this example the particular piece of leather is for covering a dashboard, but substantially any piece of leather may be shaped according to the method illustrated by this example, or variations thereon. Fig. 4 is a photograph showing a form for defining how the leather should be thinned temporarily stuck to the "A" side of a piece of leather for an automobile dashboard.

In more detail: Fig. 1 shows a photograph of an assembled form for defining how the leather should be thinned, wherein layers of plastics masking film or pattern film are stacked together.

-13 -In this example, the masking or pattern film was cut out of a roll of stock film on a suitable CNC cutting machine according to a pre-determined design. In this example, the particular type of pattern film used is Orajete -digital printed media and is 0.09 mm thick. This film is self-adhesive. Pattern films of this type, and Orajet0 specifically, are produced with a self-adhesive layer protected by a removable backing layer.

Once the different parts of the form are cut out, the positions of each layer in the assembled stack is indicated by the successive concentric solid lines on the bottom, largest layer. Also shown are circles labelled "A", "B", and "C", which indicate positions for testing the thickness of the apparatus before its application to a piece of leather in preparation for thinning of the leather in the area defined by the apparatus and according to the depth defined by the contours of the apparatus applied to the leather.

Similarly, once the leather product with a thinned section is produced, the thickness of the areas indicated by the circles labelled "A", "B", and "C" are tested using a micrometer or other suitable measuring device or gauge to ensure the thinned leather section meets the engineering specification required.

This level of specification of thickness is required to provide the leather piece with the properties of a preferential tearing line or area. This preferential tearing line or area that can then be located over the exit portal of an airbag apparatus mounted in an automobile behind the leather piece, which has been used to upholster or clad this part of the automobile interior.

Fig 2. shows photograph of the layers of plastics material before their being stacked to form the apparatus shown in Fig. 1 and described above. Fig. 2 shows that the concentric solid guide lines visible in the assembled form of Figure 1 are printed on the largest, base layer of the apparatus and the succeeding smaller layers are applied in positions successively according to the positions indicated by the succeeding concentric lines on the base layer. This photograph also shows that the succeeding layers are numbered consecutively with the numbers positioned such that they are all visible and in order in the assembled apparatus.

-14 -Fig. 3 is a photograph further illustrating the process of building the form/apparatus shown in Fig. 1. Fig. 3 shows the largest, base layer of the form with a contrasting (red) parallelogram indicating where the smallest separate sheet comprised in the form (labelled "1"; not shown) is to be located within, i.e. the smallest layer is aligned according to the innermost guideline of the base layer of the apparatus. Succeeding layers (2 to 7) also not shown are then aligned in turn with the concentric guide lines as they expand.

Once the layers are stacked in position and secured in place by means of their self-adhesive layer to form the assembly, the assembly/ form for defining how the leather should be thinned is temporarily stuck to the "A" side of the leather piece to be thinned in the location that is to be thinned according to the shape of the form. This is illustrated in Fig. 4.

Fig. 5 is a photograph showing the form for defining how the leather is to be thinned stuck to a piece of leather being fed into a leather splitting machine. In the photograph the form is stuck to the "A" side of the leather piece to be thinned by making a recess defined by the size of the form. Passage of the leather through the splitting machine cuts a leather piece from the "B" side of the leather that protrudes because of the presence of the form stuck to the "A" side. The recess in the leather will therefore be created in the "B" side of the leather. The leather splitting machine illustrated in Fig. 5 was made by Fortuna of Italy.

The form is then removed from the finished, thinned leather product. In this example the particular piece of leather is for covering a dashboard, but substantially any piece of leather may be shaped according to the method illustrated by this example, or variations thereon. In this example the area of thinned leather is 0.46mm thick at any of locations A, B or C in the finished product, as illustrated in Fig. 1.

Thus the invention provides an improved method of leatherworking. In particular it provides the ability to deliver controlled thinning of leather in certain areas to yield a recess in the surface of the leather in order that the engineering properties of the leather in those areas can be well-defined and reliably specified. Thus the invention is particularly well suited for producing leather pieces for inclusion in automobiles that -15 -meet specific engineering and design parameters. In particular the invention yields improved methods of thinning leather used to upholster or clad vehicle interiors in order to produce a preferential tearing line in a leather cover mounted over an airbag exit portal.

Claims

-16 -Claims 1 A method of creating a recess in a piece of leather having a first side and a second, side, comprising the steps of: a) applying a form to the first side of a piece of leather and conforming the leather piece thereto to form an assembly having a first side and a second side, wherein the first side of the assembly comprises the exposed portions of the first side of the leather piece and the exposed portions of the form; b) positioning cutting means so that the cutting path of the cutting means is in parallel spaced separation from the surface of the first side of the assembly; and c) moving the cutting means along the cutting path to remove a section of leather from the second side of the leather.
2 A method according to claim 1, wherein the form comprises an adhesive layer for temporarily affixing the form to the first side of the piece of leather and the method additionally comprises the step of temporarily attaching the form to the first side of the piece of leather.
3. A method according to claim 1 or claim 2, wherein the method additionally comprises the step of removing the form from the leather piece.
4 A method according to any preceding claim, comprising a method for making the form and thus wherein the method comprises the additional steps of manufacturing the form of: a) Cutting out three or more pieces of substantially planar material b) stacking the pieces of material together in concentric layers, wherein the largest piece forms the base piece of the stack and the remaining pieces are stacked on top of the largest piece in order from smallest to largest.
5 A method according to claim 4, wherein the circumference of each piece of substantially planar material that is stacked on the base piece contacts the same planar surface of the base piece.
-17 - 6. A method according to claim 4 or claim 5, wherein the pieces comprised in the stack are laminated together.
7. A method according to any of claims 4 to 6, wherein the planar layers are laminated concentrically.
8. A method according to any preceding claim, wherein multiple recesses are made in the second side of the leather.
9. A method according to any preceding claim, wherein two or more recesses are formed in the second side of the leather piece during a single cutting step.
10.A method according to any preceding claim, wherein the first side of the leather is the "A" side, and the second side of the leather is the "B" side.
11.A method according to any preceding claim, wherein the surface of the first side of the assembly is positioned so that it is planar during the cutting step.
12.A method according to any preceding claim, wherein the cutting means is a leather splitter.
13.A method of manufacturing a form for use in the method of any of claims 1 to 12, comprising the steps of: a) Cutting out three or more pieces of substantially planar material b) stacking the pieces of material together in concentric layers, wherein the largest piece forms the base piece of the stack and the remaining pieces are stacked on top of the largest piece in order from smallest to largest.
14.A method according to claim 13, wherein the pieces of planar material are made from pattern film.
15.A method according to claim 13 or claim 14, wherein the pieces of planar material comprise a self-adhesive layer.
-18 - 16.A method according any of claims 13 to 15, wherein the planar material comprises a removable layer that covers a self-adhesive layer.
17.A method according any of claims 13 to 16, wherein the pieces comprised in the stack are laminated together.
18.Apparatus comprising a form of any of claims 13 to 17, attached to a face of a substantially planar piece of leather.
19.A kit comprising a substantially planar piece of leather and a form of any of claims 13 to 17.
20.An Apparatus for installation in a vehicle comprising a piece of leather produced according to the method of any of claims 1 to 12.
21.An Apparatus according to claim 20, wherein the apparatus is a dashboard, instrument panel or steering wheel.
22.An Apparatus according to claim 21, wherein a vehicle airbag is comprised in the apparatus and mounted behind the recess in the leather.
23. Use of a leather splitter as a cutting means according to the method of any of claims 1 to 12.
24. Use of a piece of leather produced according to the method of any of claims 1 to 12 in the manufacture or maintenance of a vehicle.
25. The use according to claim 20, wherein the vehicle is an automobile.