_News

Wear resistant connections

Bright deposits of a 0.3% cobalt-gold alloys are produced by the latest addition to the range of gold plating processes available. According to the manufacturers, the cyanide based process gives extremely good wear resistance in electronic connector applications.

Alloys deposited using IMASA's Acid Gold C plating solution have a hard- ness of 140-180 VPNand minimum porosity. At 8 -10 g/litre gold con- centrations, IMASA claim that con- sistent 50 55% cathode efficiencies can be achieved.

IMASA Ltd, 188 Bath Road, Slough, Buckinghamshire SL1 4DU, UK

Swarf trap

Swarf circulating in lubricants, cutting oils and coolants can shorten machine tool life. A recently announced minia- ture swarf trap could help protect valves, manifolds, pipework, and bearings.

The Regis Swarf Trap, which measures only 38 × 28 × 25 mm, contains a powerful permanent magnet. Immersed at a convenient point, it will collect ferrous swarf, chips, and machining scrap.

Regis Machinery (Sussex) Ltd, Richmond Road, Bognor Regis, Sussex, UK

Low wear acetal copolymer Acetal copolymers are widely used in applications which require a low coefficient of friction. The recently introduced Kemetal® C-245 silicon oil containing grade is claimed to further improve wear characteristics and bearing properties for compon- ents such as gears, cams, and bearings.

Kemetal C-245 is a concentrate con- taining 20% silicone oil and acetal copolymer. The desired silicone level

for a specific application can be obtained by 'letting down' with other grades of acetal copolymer. According to the manufacturers, a 2% silicone concentration, for example, gives dramatically improved wear character- istics and limiting PV values, unchanged elongation, and better impact and toughness with only a slight reduction in tensile strength at yield and flexural modulus.

These intrinsically safe vibration analysers, which have received approval from the British Approvals Service for Electrical Equipment in Flammable Atmospheres, can be used for condition monitoring o f ro rating plan t in hazardous zones.

Environmental Equipment Ltd, Eastheath Avenue, Wokingham, Berkshire, UK

It is suggested that the product helps provide a solution to 'stick-slip' problems in plastics components, and virtually eliminates squeaking and other noises that are common with acetal bearing on acetal.

Amcel Ltd, 78-80 St Allans Road, Watford, Hertfordshire WD2 4AP, UK, or Celanese Plastics Co, 26 Main Street, Chatham, 07928 New Jersey, USA

Rolling mill bearing problem solved Phosphor bronze bearings on a rod rolling mill in Rotherham, Yorkshire, were being replaced every two weeks. A change of lubricant, however, extended bearing life by 600%.

Rod coils manufactured at the mill pass over the conveyor rollers at about 900°C. This heat is transferred to the 3 in x 1¼ in internal diameter phosphor bronze support bearings operating at 100 rpm and, after cooling by fans, about 200°C. The graphite based grease originally used was quickly burnt and carbonised, leading to heavy wear, frequent bearing

replacement, and lost production due to machine down time.

In an attempt to improve bearing life, the company decided to use Rocol HT 70", a lubricant specially formul- ated for applications designed for grease lubrication where difficulty is met with deposit build up from lubricant degradation at elevated temperatures. The product is a combination of high molecular weight hydrocarbon polymers and 1% by weight molybdenum disulphide, with no thickeners. The manufacturers claim that, provided there is reasonable

access to atmosphere, the lubricant does not thicken or form resinous deposits on heating, but evaporates slowly.

Since changing the lubricant, consider- able savings have been made at the mill. Over a three month period only 14 sets of bearings have been replaced: previously this number would have been replaced in two weeks.

*Rocol Ltd, Rocol House, Swillington, Leeds LS26 8BS, UK

HT- 70. Operating temperature range: 20-250°C : Solid lubricant: 1% MoS 2 by weight . Particle size." 0.5 microns (average) : Viscosity: 120 000 cSt at 21.1 o C (70°F), 4000 eSt at 60°C (140°FJ

TRIBOLOGY international June 1978 199