GB2049713A

GB2049713A - Non Metallic Bearing and Retarding Materials

Info

Publication number: GB2049713A
Application number: GB7905871A
Authority: GB
Original assignee: Pennington J D
Current assignee: Pennington J D
Priority date: 1979-02-20
Filing date: 1979-02-20
Publication date: 1980-12-31
Also published as: AU5531480A

Abstract

An asbestos free composition for the manufacture of bearing, brake or clutch lining materials, comprises a plastics material, cellulosic fibres, and metal and/or carbon fibres. The plastics material will have good heat resistance and dimensional stability, for example phenol formaldehyde, melamine formaldehyde, urea formaldehyde, silicone resin, polyester resin or epoxy resin. The metal or carbon fibres can be continuous filament, in woven form or chopped fibres and the metal fibres can be made by drawing, cutting from sheet metal, or be formed directly by a melt extract process. Fillers may be added.

Description

SPECIFICATION Improvements in and Relating to Non Metallic Bearing and Retarding Materials This invention relates to moulding compositions for the manufacture of fibre reinforced plastics bearing, braking or clutch lining materials, of the type which in the past have used asbestos or cellulosic fibres for reinforcement.

Bearings, wear strips, brake and clutch linings and so on made from these materials have been used with advantage hitherto for applications where in the case of bearings there is a risk of dry running and seizure with metallic materials, where water and dirt are likely to gain ingress, and where resistance to chemical attack and corrosion is desirable. Those materials reinforced with cellulosic fibres are however unsuitable for operating at higher temperatures whereas those reinforced with asbestos fibres are suitable for sustained running at temperatures up to 1750C.

However asbestos reinforced materials are not acceptable in some situations because of concern about possible health hazard and the present invention relates to compositions for making bearing, wearing and brake and clutch lining materials without the use of asbestos fibres and without the disadvantage of cellulosic fibres as used hitherto.

The invention resides in a composition comprising a plastics material, cellulosic fibres, metal and/or carbon fibres and fillers.

The plastics material is selected in relation to the needs of the end product and usually will have relatively good resistance to heat and dimensional stability for example such plastics as phenolformaldehydes, melamine-formaldehydes, ureaformaldehydes, silicone resins, polyesters, epoxy resins and so on. The cellulosic fibres include those produced from wood pulps as used in paper making, recycled waste paper pulp, cotton, flax, jute, hemp and paper mill effluent or sludges. The metal and/or carbon fibres are either in chopped lengths or as continuous filament. The continuous filament may be orientated randomly or in preferred directions or may be in woven form according to the end use of the product. In the case of metal fibres these would be of diameter up to 0.75 mm and the carbon fibre individual filaments would be up to 1 50 microns in diameter.

The metal fibres may comprise drawn wire in continuous or chopped form, or be made by slitting metal sheet into fibres of approximately square or rectangular cross section, or by the melt extract process used by Johnson and Nephew (Ambergate) Limited, which produces fibres of irregular and varying cross section directly from molten metal.

The metal fibres can be selected from a wide variety of metals including copper based alloys (such as lead and tin bronzes, brasses and gun metals), Babbits metals (tin based and lead based alloys) and aluminium alloys. Optionally metal and/or carbon fibres may be incorporated selectively at and just under the surface of the material which is to be subject to wear.

Where the process for manufacturing the material includes the step of first forming a felt or web predominantly of cellulosic fibres, impregnating this with the plastics material and then plying the impregnated layers or webs together, the metal and/or carbon fibres can be mixed with the cellulosic fibres in the layer or web, and/or can be laid onto the webs or layers before these are plied together in multi layer form, so that they are interspersed between layers in the finished product. Optionally additional plastics material can be scattered or sprayed or otherwise applied simultaneously with the laying of the metal and/or carbon fibres.

Optionally fillers can be added dependent on the particular end use of the resultant product. In the case of wearing and bearing materials the preferred fillers will include graphite, metal powders, mica, molybdenum disulphide, lignum vitae and wood particles, polytetrafluoroethylene and oil or grease. With the latter this can be accomplished by subsequently impregnating the finished material and is most easily accomplished when the formulation and process are adjusted to produce a more porous material than would normally be produced, for example by using a lower consolidating pressure in the press or moulds when plying layers together to make multi layer materials.

When making brake or clutch linings fillers may be incorporated to enhance frictional resistance and general braking properties such as inorganic grits and powders.

According to the present invention a composition is provided for the manufacture of bearing, wearing, braking and clutch lining materials comprising a plastics material, cellulosic fibres, metal and/or carbon fibres, and fillers. The ingredients are preferably present in the following ranges of proportions by dry weight: plastics material 3070% cellulosic fibres 1 5-70% metal and/or carbon fibres as herebefore defined 3-30% fillers up to 40% Materials made from compositions according to this invention avoid the use of asbestos fibres.

Claims

1. An asbestos free composition suitable for the manufacture of bearing, braking or clutch lining materials comprising a plastics material, cellulosic fibres and metal and/or carbon fibres.

2. A composition as claimed in claim 1 in which the plastics material is phenol formaldehyde, melamine formaldehyde, urea formaldehyde, silicone resin, polyester resin or epoxy resin.

3. A composition as claimed in claim 1 in

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in and Relating to Non Metallic Bearing and Retarding Materials This invention relates to moulding compositions for the manufacture of fibre reinforced plastics bearing, braking or clutch lining materials, of the type which in the past have used asbestos or cellulosic fibres for reinforcement. Bearings, wear strips, brake and clutch linings and so on made from these materials have been used with advantage hitherto for applications where in the case of bearings there is a risk of dry running and seizure with metallic materials, where water and dirt are likely to gain ingress, and where resistance to chemical attack and corrosion is desirable. Those materials reinforced with cellulosic fibres are however unsuitable for operating at higher temperatures whereas those reinforced with asbestos fibres are suitable for sustained running at temperatures up to 1750C. However asbestos reinforced materials are not acceptable in some situations because of concern about possible health hazard and the present invention relates to compositions for making bearing, wearing and brake and clutch lining materials without the use of asbestos fibres and without the disadvantage of cellulosic fibres as used hitherto. The invention resides in a composition comprising a plastics material, cellulosic fibres, metal and/or carbon fibres and fillers. The plastics material is selected in relation to the needs of the end product and usually will have relatively good resistance to heat and dimensional stability for example such plastics as phenolformaldehydes, melamine-formaldehydes, ureaformaldehydes, silicone resins, polyesters, epoxy resins and so on. The cellulosic fibres include those produced from wood pulps as used in paper making, recycled waste paper pulp, cotton, flax, jute, hemp and paper mill effluent or sludges. The metal and/or carbon fibres are either in chopped lengths or as continuous filament. The continuous filament may be orientated randomly or in preferred directions or may be in woven form according to the end use of the product. In the case of metal fibres these would be of diameter up to 0.75 mm and the carbon fibre individual filaments would be up to 1 50 microns in diameter. The metal fibres may comprise drawn wire in continuous or chopped form, or be made by slitting metal sheet into fibres of approximately square or rectangular cross section, or by the melt extract process used by Johnson and Nephew (Ambergate) Limited, which produces fibres of irregular and varying cross section directly from molten metal. The metal fibres can be selected from a wide variety of metals including copper based alloys (such as lead and tin bronzes, brasses and gun metals), Babbits metals (tin based and lead based alloys) and aluminium alloys. Optionally metal and/or carbon fibres may be incorporated selectively at and just under the surface of the material which is to be subject to wear. Where the process for manufacturing the material includes the step of first forming a felt or web predominantly of cellulosic fibres, impregnating this with the plastics material and then plying the impregnated layers or webs together, the metal and/or carbon fibres can be mixed with the cellulosic fibres in the layer or web, and/or can be laid onto the webs or layers before these are plied together in multi layer form, so that they are interspersed between layers in the finished product. Optionally additional plastics material can be scattered or sprayed or otherwise applied simultaneously with the laying of the metal and/or carbon fibres. Optionally fillers can be added dependent on the particular end use of the resultant product. In the case of wearing and bearing materials the preferred fillers will include graphite, metal powders, mica, molybdenum disulphide, lignum vitae and wood particles, polytetrafluoroethylene and oil or grease. With the latter this can be accomplished by subsequently impregnating the finished material and is most easily accomplished when the formulation and process are adjusted to produce a more porous material than would normally be produced, for example by using a lower consolidating pressure in the press or moulds when plying layers together to make multi layer materials. When making brake or clutch linings fillers may be incorporated to enhance frictional resistance and general braking properties such as inorganic grits and powders. According to the present invention a composition is provided for the manufacture of bearing, wearing, braking and clutch lining materials comprising a plastics material, cellulosic fibres, metal and/or carbon fibres, and fillers. The ingredients are preferably present in the following ranges of proportions by dry weight: plastics material 3070% cellulosic fibres 1 5-70% metal and/or carbon fibres as herebefore defined 3-30% fillers up to 40% Materials made from compositions according to this invention avoid the use of asbestos fibres. Claims

3. A composition as claimed in claim 1 in which the metal and/or carbon fibres are in chopped lengths.

4. A composition as claimed in claim 1 in which the metal and/or carbon fibres are in the form of continuous filament.

5. A composition as claimed in claim 4 in which the metal and/or carbon fibres are in woven form.

6. A composition as claimed in any preceding claim in which the metal fibres are up to 0.75 mm in diameter and/or the carbon fibre individual filaments are up to 1 50 microns in diameter.

7. A composition as claimed in any preceding claim in which the metal fibres comprise drawn wire in continuous or chopped form, are made by slitting metal sheet into fibres of approximately square or rectangular cross section or are made by the melt extract process used by Johnson and Nephew (Ambergate) Limited which produces fibres of irregular and varying cross section directly from molten metal.

8. A composition as claimed in any preceding claim in which the metal fibres are made from lead bronze, tin bronze, brass, gunmetal, Babbits metal or aluminium alloy.

9. A composition as claimed in any preceding claim with the addition of filler materials.

10. A composition as claimed in claim 9 in which the filler materials are graphite, metal powder, mica, molybdenum disulphide, lignum vitae, wood particles, polytetrafluoroethylene, oil, grease or inorganic grit or powder.

11. A composition as claimed in any preceding claim in which the plastics material is present in the range 30% to 70%, the cellulosic fibres present in the range of 15% to 70%, the metal and/or carbon fibres present in the range 3% to 30% and filler materials up to 40% of the total dry weight of the composition.

12. A composition as claimed in claim 1 substantially as described herein.

1 3. A material for bearing, braking, or clutch lining made from a composition as claimed in claims 1 to 11.

14. A material for bearing, braking or clutch lining made from a composition as claimed in claims 1 to 11 in which the metal and/or carbon fibres are incorporated selectively at and just under the surface of the material which is to be subject to wear.

1 5. A multi layer material for bearing, braking or clutch lining made from a composition as claimed in claims 1 to 11 in which some or all of the metal and/or carbon fibres are incorporated between the layers.

1 6. A material for bearing, braking or clutch lining made from a composition as claimed in claims 1 to 1 in which the material is subsequently impregnated with oil or grease.

1 7. A method of making a bearing, braking or clutch lining material comprising pressing into shape and setting a composition according to any of the claims 1 to 11.