Engineering plastics supplier challenges rusted-on traditionalists to lift their game. *Brent Whyte writes for Dotmar Engineering
A thermoplastic engineering specialist Dotmar EPP is throwing out a challenge to metals traditionally used in materials handling applications including cranes, draglines and minerals and materials processing applications.
It is offering high performance engineering plastics that don’t corrode and never need lubrication as an alternative to phosphor bronze, stainless steel and other metals in applications where metals have been incumbent for decades.
Dotmar EPP engineering director Bruce Armstrong says the advantages of super plastics such as Ertalon and Nylatron families include low wear characteristics, light weight, low friction, low inertia and long operational life.
Sheaves made from Nylatron GSM, for example, offer two to three times the lifespan of a cast iron sheave, while ensuring wire rope lasts anywhere from three to five times longer (depending on application) – and the plastic sheave is much simpler to lift because it is one-seventh the weight of iron.
Members of the Ertalon and Nylatron families are being successfully employed as: bearings or bushes, where the materials have found extensive uses in cranes, forklifts, rolling stock, earthmoving equipment and processing machinery; wear pads on side guides, rollers, conveyors, presses and telescopic booms; gears on winders, lifts and escalators, and in drives for processing equipment; and pulleys and sheaves for overhead cables, or as rollers for electric hoists, conveyor components, boring and bolting equipment, and heavy duty sections on draglines.
“The change is happening in a myriad of applications where long-life products such as the Ertalon and Nylatron families of plastics are displacing costlier counterparts in grimy environments where reliability is at a premium, a smooth flow of material is essential, and downtime is an enormous liability,” says Armstrong, whose company operations include 10 sites throughout Australasia and a complementary distributor network.
Ertalon and Nylatron
Polyamide Ertalon’s scope is virtually endless because each application’s requirement can almost always be facilitated by subtle variations in physical properties afforded by a different molecular chain structure in each grade of the product.
The range of Ertalon polyamide (commonly recognised as nylon) stock shapes can be engineered to suit applications requiring high mechanical strength, stiffness hardness and toughness, fatigue resistance, high mechanical damping ability, good sliding properties, noise damping, electrical insulating, dielectric properties and excellent wear resistance.
The complementary family of Nylatron thermoplastics can be similarly formulated for outstanding performance characteristics suiting different applications, such as wear resistance and fine motion control in the construction, production and processing equipment industries.
Nylatron®703 XL, for example, features ‘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.
Telescoping or sliding parts — such as those in cranes and materials handling equipment — move smoothly over pads made from Nylatron 703XL, without sticking or jumping.
Such precision is made possible by the 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.
Operators of cranes and other lifting and elevating equipment are also drawing on the user friendly properties of sheaves made from Nylatron GSM — a partially cross-linked nylon 6 material that increases the wire rope life normally limited by metal sheaves.
The Nylatron GSM compound, engineered into sheaves by Dotmar EPP, gives excellent wear resistance, is self-lubricating, and shows low friction characteristics.
“Wear and tear of wire rope has always been such a problem with sheaves made of cast iron, SG iron, aluminium, and fabricated mild steel, that operators are turning to towards Nylatron GSM,” said Armstrong.
“Even applications near or on the sea pose no problem as Nylatron GSM is a non-corrosive product,” said Armstrong.
Lubricity of Nylatron GSM is kept at an optimum level by finely divided particles of molybdenum disulphide (MoS2) solid lubricant which impregnates the high-strength cast nylon. Casting to configuration can be done in a wide range of sizes with minimal machining, ensuring the material stays price competitive with cast and forged steel sheaves.
Nylatron GSM is an ideal product for dynamic bearing applications common with cranes, elevators and other lifting equipment,” said Armstrong. It not only has the properties necessary to operate at temperatures up to 100°C, it maintains stable physical properties by exhibiting a very low rate of moisture absorption.
Draglines themselves are host to a myriad of uses for Ertalon and Nylatron, which are virtually maintenance-free and hardly ever suffer from high wear, corrosion, lubrication breakdowns, dirt or dust effects, splitting or abrasion.
Uses on draglines have expanded to encompass slap blocks for drag ropes, drag rope sheaves, deflection rollers, tower sheaves, fair lead sheaves, drag tunnel wear blocks, shoe alignment sheaves, walking shoe wear blocks and wear pads for pedestal and brake arrangements.
Apart from cranes and lifting equipment, Nylatron GSM has been used in industries including shipping, automotive, military, mining and resources, chemical, building and construction, railway, agriculture, and engineering.
“The advantages of engineering plastics in many applications are so compelling that the only reason metals are used is old habit,” says Armstrong.
“In line with world trends, we are mounting a determined campaign in Australasia to change these old habits by revealing the new reality of superior performance and superior value from engineering thermoplastics,” he said.
* Brent Whyte is the principal of Whyte Public Relations.
Dotmar Engineering Plastics Pty Ltd