POWER TRANSMISSION 49
Plus chain is also delivered with a wax lubricant applied so that it can be used straight from the box. Since debris cannot adhere to the dry wax finish, this helps to protect against premature failure. Precision grinding of the chain pins gives a high-grade surface that helps to retain the wax lubricant and extend the life of the chain.
Lubricant-free chains
A lubrication-free version of Fenner Plus chain is also available with sintered bushes that retain lubricant, thereby negating the need for external lubrication and avoiding the problems associated with maintenance teams failing to adhere to relubrication regimes. An added benefit of using sintered bushes is that the chain can operate at linear speeds of up to 2.5 m/s – which is more than twice the speed of a composite bush chain. To complement the Fenner Plus chain, Fenner Plus
sprockets are manufactured from C45, a 0.45 per cent plain carbon steel that is suitable for through-hardening. The teeth are flame-hardened to just below the tooth root, helping to improve the chain and sprocket life by up to 50 per cent. Eriks is not alone in offering chains with oil- impregnated sintered rollers; Tsubakimoto Chain has a similar range, plus this company also supplies chains manufactured from a combination of engineered plastic and stainless steel. These are said to protect food products and packaging from marking and contamination, and reduce the expense associated with
continual lubrication with costly food-grade lubricants in food and beverage processing plants. According to Tsubakimoto, a de-palletising machine
at one of the UK’s largest butter processing sites uses Tsubaki corrosion-protected drive chain to overcome issues relating to lubrication and corrosion. The company imports over 26 000 tonnes of butter into the UK every year, with the butter arriving on pallets holding 50 blocks each. Machines in the butter processing plant are washed
down using high-pressure salt water at 70°C after each shift. Thanks to its sintered, oil-impregnated rollers and protective finish, the Tsubaki Lambda WP chain requires no external lubrication or other protection against corrosion. For its PC grade of non-lubricated chain aimed
at lighter-duty applications, Tsubakimoto uses an engineering plastic for the inner links and stainless steel for the side plates and pins (Fig. 2). This chain has no rollers; instead it relies on the self-lubricating properties of the engineering plastic. PC chain also has the added advantage of being 50 per cent lighter than all-stainless steel chain, which results in easier handling and installation. Available in drive, conveyor and attachment
variations, the PC chains provides high resistance to water, acids, alkalis and food ingredients. Tsubakimoto also manufactures specialist types of chain in various materials, offering a variety of properties to solve application-specific problems. These include a titanium- based engineering plastic combination chain for increased acid resistance and the KV series for operation in temperatures up to 140°C. The UMW and E series PC chains have lower magnetic properties than all-stainless versions, discharging static electricity built up during use to avoid interference with products and systems, especially in the electronics industry.
Elevated temperatures
Fig. 2. Tsubaki PC non-lubricated chain for lighter-duty applications uses a self-lubricating polymer for the inner links and stainless steel for the side plates and pins.
High temperatures can be problematic for chains and lubricants but, once again, manufactures have developed specialist grades to suit. Tsubakimoto offers a heat-resistant version of its non-lube Lambda chain with an operating temperature range of 150 to 230°C (Fig. 3). Typical applications for this type of chain include heat sealing in packaging, semiconductor production, steel furnaces and die casting. Prior to heat-resistant chains being available, such applications would have required the use of standard chains with costly coatings that did not offer good wear life and necessitated the derating of the chain due to standard rollers and plates losing their strength at elevated temperatures. Of course, the need to derate chains also required the specification of larger chains than would otherwise be needed, leading to more space being required and higher energy consumption. In tests performed at 230°C, the Tsubaki HT Lambda chain achieved about three and half times the life of
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