specialist coatings

At Arrow Precision we offer several options where specialist coatings and cam followers are concerned. In addition to nitriding followers we can also offer a selection and combination of processes which will significantly lower the sliding friction element in the valve train and can offer up to a 10% saving in nominal frictional losses. Contact us here for pricing and availability

Specialist coatings make a significant contribution to the reliability and efficiency of engines and the realisation of innovative drive train concepts. Fuel consumption and pollutant emissions are minimised, performance and driveability improved.

• reduces frictional losses in the engine (these can exceed 10% of the nominal rating)
• protects engine components against wear and increases their load bearing capacity and durability
• ensures satisfactory operation with starved lubrication and on cold starting.

DLC Diamond Like Carbon coatings
Finest diamond-like carbon
Coating Properties
Coating Material a-C:H
Microhardness* (HV 0.05) > 2,000
Friction coefficient* against steel (dry) 0.1 - 0.2
Max. service temperature (°C) 350
Coating colour black

* depends on application and test conditions

DLC is suitable for the most extreme wear conditions and high relative speeds, even when running dry. The coating gives excellent protection against abrasion, tribo-oxidation and adhesion (scuffing). The coating permits surface pressures that, under normal conditions, would lead at once to scuffing and cold welding. Friction losses are reduced to a minimum. The good corrosion resistance protects the substrate from destructive attack.

Recommended applications:
• Engine components (fuel injection systems, valve trains, pistons, etc.)
• Sliding and rolling components (bearing shells, rollers)
• Pumps and compressors (pistons, cylinders, valves, shaft feed-throughs, etc.)
• Textile machines
• Medical technology
• Lubricant-free systems

Superfinishing

Whichever machining process is used, processing the surface of precision components will cause it to be altered, either improved or impaired. It is impossible to manufacture a perfectly smooth, geometrically accurate surface using conventional techniques, such as lapping, grinding, fine turning, fine milling or polishing. However, if one examines the surfaces of components that have been lapped, fine-turned, ground or polished at a magnification of 2000 times, these surfaces still resemble a mountain range, with peaks and valleys of varying depths and widths. Superfinishing is an exception. NC-controlled tools significantly improve already fine - turned or ground surfaces without any damage.

Metallurgical surface examination of components, which have been subjected to various surface finishing processes, demonstrates the tremendous differences in surface quality. It is proven that deviations from the geometrically "ideal surface" can have a significant effect on their subsequent characteristics e.g. wear characteristics, friction, stick and slip lubrication properties, noise, sealing ability, fatigue resistance, fit, corrosion resistance etc.

One essential point to keep in mind is that, as a rule, as much as 50% of the total diameter tolerance range of a component is taken up by deviations in shape (concentricity, roundness, taper and straightness), unless these factors are limited. Therefore, form improvements are desperately needed, especially for close-fitting parts, in the production process. With technical requirements for machine, engine and gear components constantly rising, it is not enough to rely solely on adherence to diameters without also considering other geometry tolerances and surface quality.

Contact us here for pricing and availability