Mar 31 2008
Fabrication and machining of metals for some applications can be a time-consuming and expensive process.
Not only is the job messy and potentially hazardous in some instances, but also the sheave, bush, gear or wear component involved may need ongoing lubrication to function properly and prevent corrosion.
If special alloys are employed to overcome these inherent problems, costs rise not only for the material involved, but also for the specialist skills required to do the job properly.
Engineering thermoplastics can provide an alternative that is clean, easily worked, and have excellent dimensional stability, high reliability, low wear characteristics and long operational life
Engineered from stock shapes provided by Dotmar EPP, these long-life super plastics products are displacing costlier counterparts such as phosphor bronze in many industries – including food and beverage processing, mining and minerals processing, materials handling, earthmoving, marine, transport, packaging and water and waste water applications.
“High durability and extremely low downtime is a major advantage of materials such as Ertalyte, Polystone and polyamides (nylons) such as Ertalon and Nylatron, These are all high performance plastics that are quick and clean to machine and can be fashioned into either simple or complex shapes, ” said Dotmar EPP General Manager-Sales Mr Scott Foster.
Tough and versatile low-friction engineering plastics such as Ertalyte are increasingly appealing to heavier industries encountering wear problems occurring within industrial machinery used in construction, mining and quarrying processes.
Ertalyte offers high mechanical strength, stiffness and hardness, very good creep resistance, a low and constant coefficient of friction and low stick slip sensitivity, says Mr Foster. These properties, coupled with outstanding wear resistance and very good dimensional stability, make the material ideally suitable for the manufacture of mechanical precision parts which have to sustain high loads and/or are subject to wear.
Typically such parts include bearings, bushings, wear plates, thrust washers, guides, gears, rollers, sheaves, pump components, valve parts and electrical insulating components.
Polystone plastics, meanwhile, are part of the versatile and user-friendly family of Ultra High Molecular Weight Polyethelynes (UHMW-PE), which also score highly for machinability.
Polystone is odourless, non-toxic, and tasteless. Made of unusually long molecular chains, these chains serve to transfer load more effectively to the polymer’s backbone by strengthening intermolecular interactions. This results in one of the most durable thermoplastic polyethylenes on the market.
Different formulations of these plastics can not only provide the perfect performance for particular jobs, but also often cut costs compared with specialist metals - as well as low co-efficients of friction.
Uses of UHMW-PE cover a diverse spectrum of applications, including bulk material handling; food processing and beverage machinery; mining and mineral processing equipment; manufacturing equipment; civil engineering and earthmoving equipment; and transport-related applications, including truck trays, bins and hoppers.
The broad family of nylons also performs remarkably well in 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.
“Any application requirement can be facilitated by different grades of the product affording variations in physical properties,” says Mr Foster.
In mechanical engineering, Ertalon nylons have been machined into the form of :
• wear pads on side guides, rollers, conveyors, and presses and telescopic booms
• gears on winders, lifts and escalators, and textile and printing machines and in drives for processing equipment
• bearings or bushes in cranes forklifts, rolling stock in railways, earthmoving equipment and manufacturing machinery
“The mining industry has had us machine Ertalon to use in pulleys and sheaves for overhead cables, or as rollers for electric hoists, conveyor components, boring and bolting equipment, and heavy duty sections on draglines. 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.”
“Even in the harsh environs of foundries and open cast mines, Ertalon has been used to engineer replacements for existing steel bearings due to its impregnated lubricant. Whereas traditional roller bearings carry a wet lubricant that traps the abundant dirt and dust, Ertalon obviates this problem.
“The same result is achieved on conveyor systems and entry guides, which in many industries are subjected to similar working environments.”