Defining self-lubricating plastics
Self-lubricating mechanical parts or components are made of a material that allows them to function without the use of lubricants. A self-lubricating part therefore allows a system to operate efficiently without the need to add grease or oil, for example. Since the lubrication of parts and systems is necessary to reduce friction and wear, self-lubricating plastics are more suitable than standard materials when it comes to highly demanding applications.
Self-lubricating plastics are a range of polymers that contain lubrication additives. These allow the plastic to lubricate itself through its movement without having to add an external agent. As for plastics used in food applications, there are nontoxic additives that meet Canadian, American and European food standards. To reduce their coefficient of friction, the base resin of a self-lubricating plastic is enriched with of oil or wax. The lower the coefficient of friction, the easier it is for materials to slide over its surface. Replacing standard parts with equivalents made of self-lubricating plastics allows you to benefit from the advantages of lubrication while avoiding the drawbacks.
" The use of self-lubricating plastics allows for higher speed and pressure while reducing the frequency of maintenance. "
Alex Tremblay Frenette, Eng.
Types of self-lubricating plastics
Since lubrication additives can be added to a wide variety of plastic resins, it is possible to choose the most suitable polymer according to stress and mechanical properties. The use of self-lubricating plastics allows for higher speed and pressure while reducing the frequency of maintenance.
While there are many options for lubrication additives, this article will focus on those specifically designed for food applications. Self-lubricating plastics are primarily developed from three resins: nylon, ultra-high-molecular-weight polyethylene (UHMW) and polyester (PET-P).
Nylons
Since high-performance nylons possess excellent mechanical properties, they are often a more suitable choice than stainless steel. This is in part due to their high resistance to wear, abrasion and corrosion. They are also much more machinable than metal parts.
NYCAST® NYLOIL FG (Food Grade) is an excellent example of a high-performance self-lubricating material. As the name implies, NYLOIL contains vegetable oil, which is added directly into its resin during production. The result is a homogeneously lubricated polymer that lubricates itself through its movement.
NYCAST® NYLOIL FG is food grade approved and can therefore come into direct contact with food. As mentioned earlier, lubrication is necessary to reduce friction. In food environments, options are more limited because external lubricants (grease or oil) may represent an increased risk of contamination. NYCAST® NYLOIL FG was developed to provide the benefits of added lubricant without the disadvantages. It is a material adapted to food environments with demanding constraints. Due to its extremely low coefficient of friction (0.12), NYCAST® NYLOIL FG is frequently used in the manufacturing of mechanical parts, liners and bushings.
UHMWs
Made from ultra-high-molecular-weight polyethylene, UHMW is prized for its mechanical properties, particularly its resistance to abrasion. Like nylons, not all UHMWs are intended for food environments.
To learn more about food grade UHMW, see our article: Can UHMWs Be Used in Food Environments?
TIVAR® HPV is an excellent example of a UHMW designed for the food industry. Blue in color and therefore easy to identify, this high-performance plastic has excellent mechanical strength and is designed specifically for extremely demanding production environments. The resin of TIVAR® HPV contains a dry lubricant additive that reduces the coefficient of friction by up to 80% compared to standard UHMW. Its dynamic coefficient of friction of 0.09 allows it to reduce system wear and the frequency of maintenance while minimizing the risk of food contamination. It is used to manufacture chain guides, liners and mechanical parts specifically for the food industry.
Polyesters
Ertalyte® TX is part of the polyester family (PET-P) and used in the design of machined parts for the food industry. This polymer is ideal for parts that are subject to significant mechanical and chemical stress. It is a high-performance plastic that can withstand a wide variety of chemicals. Its thermal resistance is superior to the two other families of materials presented above. Its excellent wear resistance is comparable and sometimes even superior to that of nylons. Ertalyte® TX is therefore more suitable than nylon for applications that come in contact with corrosive agents.
Ertalyte® TX has been specially developed to be in direct contact with food and therefore complies with the standards and requirements of the food sector. It can withstand a variety of stresses, including speed, pressure and friction, which is significantly reduced thanks to its lubrication additive. Ertalyte® TX is also much more rigid than both nylon and acetal while offering better thermal performance.
The advantages of self-lubricating plastics
1. Reduce wear:
Friction is a normal phenomenon that results from the repetitive rubbing of one surface against another. High levels of friction generate more stress, wearing down surfaces that come in contact with parts and systems. Self-lubricating plastics are materials with extremely low coefficients of friction, allowing them to facilitate sliding naturally while reducing friction.
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Self-lubricating plastics are particularly useful in food environments where lubricants potentially represent an increased risk of contamination. Choosing a self-lubricating material with a low coefficient of friction often eliminates the need for external lubrication, such as grease and oil that could cross-contaminate foodstuffs.
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Since self-lubricating materials greatly reduce friction, they also increase the service life of mechanical parts and system components.
Another solution for the food industry
If minimizing the risks of contamination is a priority, it may be wise to use magnetically detectable plastics. These advanced polymers have improved traceability, allowing them to reduce the risk of foreign object contamination.To learn more about various magnetically detectable plastics, see our article: Safer Food Production with Metal Detectable Plastics.
