Engineering Plastics become More Attractive Alternatives as Metal Prices Soar

As metal prices continue to climb, process and production engineers are more willing then ever to contemplate cost-efficient alternatives.

This is particularly so where expensive metals such as stainless steel and performance alloys are involved – such as in the food and beverage, dairy, electrical and electronic, pharmaceutical, primary processing, packaging, sterile manufacturing and water industries.

The benefits of tough and versatile low-friction engineering plastics such as Ertalyte are also 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, he says. 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.

Manufactured under a quality system approved to ISO 9002, physiologically inert (suitable for food contact) Ertalyte is precision machined by Dotmar EPP to individual customers' requirements. Being totally free of centreline porosity – another major advantage for the food industry - Ertalyte’s dimensional stability enables close tolerance parts to maintain their tolerance very well after machining. It is less affected by temperature changes, absorbs less moisture (less than a tenth of that of Polyamides, for example) and is more stable than both acetal and polyamides. Problems it has been used to solve include:

Problem 1 – Wearing of bushes in harsh environments. Bushes used in the pivot points of a cradle used to transport product from a quarry to cement plant were subject to corrosion and excessive wear. A solution: Tough, non-corrosive bearings made from a thermoplastic in the Ertalyte family, Ertalyte TX, because of its self-lubricating properties, low friction, and wear resistance. Because no external lubrication is required, lubricants do not attract dirt and grit that can hasten wear and, ultimately, failure.

Problem 2 Slide bearing failure: Steel and polyamide slide bearings in water and other liquid purification systems significantly inhibit filtration efficiency. Steel fails owing to corrosion, and the polyamide due to excessive swelling from moisture. A solution is provided by various crystalline thermoplastic polyester bearings from the Ertalyte family, part of a new generation advanced engineering plastic.

Problem 3 Maintenance overload: A cup filling line includes stainless steel nest plates with acetal cup inserts held in place with four screws. The plates must be disassembled and reassembled daily, in order to be cleaned. This procedure wastes time and ties up personnel unnecessarily, exacerbating production costs. Solution: A single piece Ertalyte nest plate, to simplify maintenance.

Problem 4 Short stock guide life: In the manufacture of rubber tyres, acetal guides help align the stock as it passes through huge four roll Z calendars. The guides last only about two months. Solution: Ertalyte guides. Offering equivalent product movement, the replacements last between six and 12 months.

Problem 5 Sprocket degradation: Primary product is moved in baskets through acidic processing areas. Due to the corrosive attack from the acid, steel sprockets on the chain drives must be replaced every four months. Solution: Ertalyte sprockets. These last longer than nine months, can carry the same load and achieve quieter operation.

Problem 6 – Tablet discharge system: A leading manufacturer of pill production machines uses Eralyte for several components, including the tablet discharge system. Because of the material’s good machinability, mechanical strength and ease of cleaning, the Courtoy company decided to replace the formerly welded stainless steel components with a single part made of Ertalyte. The substitution resulted in a high performance part that also eliminated time-consuming assembly and welding operations.

For unlubricated moving part applications, a premium, internally lubricated bearing grade material called Ertalyte TX, is used, as in application 1 above. Incorporating a uniformly dispersed solid lubricant, Ertalyte TX is particularly suitable for the manufacture of sliding parts where low friction, long wear, high load bearing capacity and a very good dimensional stability are required. Application examples include precision engineering and machine construction.

Engineering thermoplastics such as Ertalyte have always offered strong advantages over metals for particular applications – but the material has been overlooked in many cases until Australasian industry has been forced to look at metal alternatives. Now industry here is discovering efficiencies that industry internationally has appreciated for a long time and are widely applicable here.

The Ertalyte series, which forms part of the Quadrant EPP family of engineering plastics stock shapes, is available as rods (10 mm 150 mm), sheets (thickness 8 mm 100 mm) and tubes (outside diameter 20 mm 200 mm). Dotmar EPP can also supply non standard configurations on request.

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