Lubricant for Plastic and Compatibility
To reduce friction and limit wear and tear

What is certain is that over the decades, plastics have come to conquer all industries. Improved production technologies and the development of new materials have made it possible to replace fields of application that were once the exclusive domain of metallic materials.

Having ascertained the effectiveness of plastics over metals, however, there remains great doubt as to their compatibility with the lubricants applied to ensure optimal friction performance and durability.

Are you sure that the lubricating grease you are currently using for plastics won't alter their mechanical properties?

Very often the processes behind a structural weakening of plastics caused by chemical interactions with lubricating fluids are slow and not easy to predict.

The possibility of premature damage to plastic parts is not always easy to analyse given that a range of variables can synergistically combine and produce very significant alterations in the mechanical properties of plastics.

One important distinction between plastic polymers is made between:

• Amorphous plastics, with an absence of order in the position of the atoms or molecules that comprise the body;
  
  
• Crystalline plastics, with a regular and ordered scaffolding of the atoms and molecules.

Plastics consist of a combination of the two structures, where the lower the percentage of the crystalline component, the higher the risk of chemical attack by lubricants in contact

Here are some examples of structure composition based on the average level of crystallinity:

What are the effects of using the wrong plastic lubricant? A concentration of the destructive effects and/or depletion of mechanical characteristics due to weathering combined with the effect of lubrication is called Environmental Stress Cracking (ESC).

The most common effects that can occur are:

• Bulges
• Embrittlement
• Softening
• Corrosion
• Colour change

Which plastics are most commonly used for the production of mechanical components?

The numerous chemical varieties available on the market today make organic classification and subdivision difficult.

Amongst the most common are:

• Polycarbonate (PC) – amorphous plastic, which is hardly ever used in friction systems but is widely utilised in the construction of components in the automotive industry in combination with other polymers (ABS, PBT) due to its high stability against heat and high impact resistance;
  
  
• Polyoxymethylene (POM) – commonly used for the fabrication of structural parts subjected to load and friction with metals, due to its good mechanical strength and ease of fabrication processes;
  
  
• Polyamide 66 (PA66) – one of the best-known and most broadly used structural plastic polymers in the manufacture of gears, bushings and bearings. Characterised by a good compromise between ductility and rigidity.