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Self-lubricating super plastics

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article image Gears and sheaves made from Dotmar EPP thermoplastics.

ONE of the Catch-22s of applying lubrication to metal bearings, gears and sheaves is that the lubricants themselves can contribute to the friction and wear problems they set out to cure.

While the lubricants may initially alleviate the friction causing wear, in the longer term they may provide a sticky surface to which industrial grit can adhere and worsen the problem.

One way to overcome this common conundrum is self-lubricating and ultra-low friction engineering thermoplastics being introduced by Dotmar EPP , which says Australia is well behind the rest of the world in utilising the benefits of these tough, clean materials.

Dotmar EPP engineering manager Aldo Mostacci says thermoplastic polyamide families - such as the Nylatron and Ertalon ranges - offer self-lubricating properties impregnated into the material from which gears are made.

"Super thermoplastics already available in Australia are capable of handling the toughest jobs currently undertaken with metals including iron, hardened steel, copper, stainless and expensive alloys," he says.

"Gears and bearings can be formulated for particular applications from material available off the shelf. Just as in genetic engineering you can choose the characteristics you want for particular parents, you can select from families of thermoplastics to give the superior performance characteristics you need for applications ranging from minute precision to massive strength.

"Most thermoplastics already have the prime qualities needed for bearings gears and sheaves, including low friction, high mechanical strength, excellent dimensional stability, high reliability, low wear characteristics, lightness, chemical inertness and long operational life.

“You can design in, by material selection, further accentuation of any of these properties as well as greater stiffness, hardness, fatigue resistance, mechanical damping ability, good sliding properties, noise damping, electrical insulating, dielectric properties and excellent wear resistance.

"Anything made from Ertalon or Nylatron is virtually maintenance-free, therefore it hardly ever suffers from high wear, corrosion, lubrication breakdowns, dirt or dust affectation, load peening, splitting or abrasion."

Simply machined from stock shapes, the dozens of thermoplastic materials available to production engineers include:

* Ertalon LFX, which is a specifically developed oil-filled material for manufacture of non-lubricated moving parts. The self-lubricating LFX broadens the application base of nylons due to its reduced coefficient of friction (-50%) and improved wear resistance (up to x10).

Advantages include a lower heat build up, hence a higher load carrying capability, longer operational life, less stick-slip and lower maintenance costs.

* Nylatron MC901, which permits longer usage in temperatures of up 120 degrees C, as well as low noise output, superior fatigue resistance and dimensional stability.

The lifespan of gears may be up to five times longer than the metal compound it has replaced in large-scale industrial applications where open cast-iron or steel gears show low wear tolerance levels.

The better shock resistance of Nylatron MC901 translates into a vastly improved tolerance to misalignment, as well as higher resilience. Benefits include much lower levels of vibration transmitted to the bearings.

* New Nylatron 703 XL is one of the very latest super thermoplastics, a breakthrough formulation featuring 'Zero Slip-Stick' performance for precise and efficient motion control of machinery components including wear pads, bearing blocks, wear guides and linear bearings.

Machinery equipped with Nylatron 703XL can accurately produce the smaller movements made possible by today's sophisticated control devices, with telescoping or sliding parts moving smoothly over pads made from Nylatron 703XL without sticking or jumping.

Such precision is made possible by the new material's "Zero Slip-Stick Performance" in which static and dynamic coefficients of friction approximate each other at virtually every point over the product's useful range.

Dotmar EPP's new website (www.dotmar.com) has been established to help industry catch up with the savings and production efficiencies offered by the latest international thermoplastic technologies.

It is a search tool and fast selection aid for technical staff seeking tough, lightweight, clean, quiet and non-corrosive alternatives to traditional ferrous and non-ferrous machinery components.

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