Plastics Processing Lubrication
Plastics processing lubrication is an important factor for providing quality parts and improving the production efficiency of plastics manufacturing. There are several different types of lubrication available for use in plastics processing; coolant lubricants, external lubricants, and internal lubricants. A lubricant is also necessary in order to reduce heat generated during the molding process and to reduce wear and tear on the plastic injection molding equipment. It is important to select the right lubricant for the specific application and ensure that its use is careful and proper.
Coolant lubricants, also known as cutting fluids, provide a thin film between the cutting tool and the work piece that minimizes friction and prevents tool wear. These types of lubricants are used to improve the cutting performance and tool life of a cutting tool. The three common types of coolant lubricants are mineral oil-based lubricants, water-soluble lubricants, and semi-synthetic lubricants. Mineral oil-based lubricants are the most common type of coolant lubricant used in plastics processing. They can provide high film strength and excellent lubricity, but tend to be very expensive. Water-soluble lubricants are more economical and are typically formulated for specific types of operations, including those that require high pressure or a high-extreme pressure (EP) composition. Semi-synthetic lubricants are formulated to provide a low-cost yet effective solution to plastics processing needs.
External lubricants, also known as mold release agents, are used to reduce the adhesion between the molded part and the mold cavity, thus making part ejection easier from the injection mold. These lubricants are applied as a thin film to the molding cavity, which then coats the finished part as it is ejected from the tooling. Mold release agents come in the form of liquid and powder, each offering its own unique advantages. Powder release agents provide superior abrasion and corrosion resistance, while liquid release agents are more effective at providing lubricity and reducing out-of-mold forces.
Internal lubricants, also known as parting agents, are used to reduce wear mechanism on the injection molding equipment. Internal lubricants are added to the polymer or resin during production, forming a lubricant layer during the molding process that reduces the transfer of heat and friction. Most commonly, a polyethylene wax, such as polyethylene glycol (PEG), is used as an internal lubricant, although other types of polymers and additives can also be used.
When selecting the lubricant for a specific application, it is important to consider the physical properties, such as viscosity, which must match the plastic material, as well as its lubricity characteristics and compatibility. The lubricant must also be compatible with the injection molding system, as some materials can corrode the equipment. Additionally, it is important to select a lubricant that provides the specific performance characteristics necessary for a given application, such as wear protection, heat transfer reduction, or reduced friction.
Plastics processing lubrication plays an important role in providing quality parts and improving productivity in plastics manufacturing. It is important to select the right lubricant for the specific application and ensure that its use is careful and proper.
