Properties of plastics – Which plastics are suited for mechanical engineering?

Basic knowledge

Technical plastics are an indispensable part of modern industry. In custom machine construction in particular, they find a wide range of applications because they have a high degree of flexibility and formability. It is important to know what properties plastics must have in components and standard parts in custom machine construction. This article describes the most important applications for plastics in mechanical engineering.

Basic properties of plastics

Plastics consist of long-chain molecules, also called polymers. These polymers can either be synthetically manufactured or be of natural origin (e.g. cellulose). The chemical composition of the polymer significantly influences the properties of the plastic produced from it.

The mechanical properties of a plastic describe its strength and elasticity as well as its failure properties and elasticity under load. Factors such as the density of the material, its crystallinity and the presence of additives play a role here.

Thermodynamic aspects refer to the behavior of plastic materials at different temperatures or pressures. Here, it is particularly important to note whether a material reacts thermoplastically or duroplastically.

The electrical conductivity of plastic materials is often low and many of these material groups are therefore suited as electrical insulators.

Specific requirements for components and standard parts in custom machine construction

Mechanical load-bearing capacity - Machine parts such as gears or bearings must have a high degree of mechanical load-bearing capacity.
Chemical Resistance - Most plastics are chemically resistant to many acids, alkaline solutions or solvents.
Temperature Resistance - When used in high temperature environments, the plastics used must be heat resistant to maintain their function.
Weather resistance - Component applications for outdoor uses require weather-resistant material properties.
Light weight - Most types of plastic are characterized by their low weight.
Damping properties - Plastics generally have good damping properties, for example as it relates to vibration.
Transparency - Based on their partially transparent properties, plastics can provide a line of sight into closed-off machine areas.

Where are plastics used in mechanical engineering?

Plastics have a variety of positive properties that make them particularly suited for use in mechanical engineering.

Thanks to these properties, plastics are now used in different areas of mechanical engineering, for example:

Housings and enclosures - One of the most common applications for plastics in mechanical engineering is the manufacture of housings and enclosures for electronic equipment or motors.

Bearing bushings and plain bearings - Plastics also play an important role in the design of bearings: They can be used as a material for plain bearing bushings or plain bearings to minimize friction losses and to counteract wear.

Sealing elements - Due to their elasticity, certain types of plastics are particularly well suited for producing sealing elements such as O-rings or flat seals - they permanently retain their function even under difficult environmental conditions (high temperatures, aggressive media).

Engine mounting bushing, individual components

In addition to plastics, there are also fiber-reinforced composites that have become increasingly important in mechanical engineering in recent years. They are characterized by their high strength and low weight and are therefore particularly suited for applications that place a priority on the lightest possible design. This is particularly the case when components are driven rotationally and/or are frequently accelerated or decelerated. An example of this is an arm of a robot that is exposed to many motion changes and must withstand high loads.

Components with special functional properties - certain scenarios require a component with additional functionalities, such as vibration absorption or electrical conductivity. Plastics such as polyamide, PEEK or polycarbonate are used here.

Which types of plastic are particularly suited for mechanical engineering?

Plastics play an important role in mechanical engineering and plant construction. Polyamides, polyurethanes and acetal resins in particular are often used here.

Polyamides (short PA) are thermoplastics with high strength, rigidity and hardness as well as good resistance to chemicals and abrasion.

In mechanical engineering, they are often used for components such as gears, bearing bushings or screws. Particularly durable and great products from our product line include:

Polyurethanes (PURs) are characterized by their high elasticity and are therefore particularly suited for applications with dynamic loads, such as sealing rings or springs in shock absorbers.

Acetal resins (polyacetal, or POM) have similar properties to polyamide plastics, but also have good sliding properties and low friction behavior at high temperatures. They are used as guide elements, gears or hinge bolts.

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