A bush or bearing is also known as a Plain Bearing, i.e. they don’t have rolling elements like a ball bearing. The primary function is to support movement by being an interface between rotating or sliding parts. This crucial component is designed to reduce friction between moving parts and act as a sacrificial wear component.
Dotmar has qualified engineers that can provide direct support with plastic bush and bearing designs, including conducting calculations and reports.
Material selection is a critical consideration when choosing bearings and bushings, as it directly impacts the performance, durability, and maintenance requirements of these components. Here are some key material selection considerations for plastic bearings and bushings:
Load and Speed
Neither load and speed can be considered without the other, as the load capacity of a material diminishes with increasing speed, and the speed capacity diminishes with increasing loads. This is known as the PV (Pressure-Velocity) value.
Time
The duration of operation is critical and will significantly affect the load and speed capability of materials for bushes and bearings.
Temperature
The surrounding temperature (opposed to heat generated from friction) for both short- and long-term exposure is important, as materials can withstand higher temperatures for short term periods compared to long term or constant exposure, which in turn affect their load carrying capacity. In the case of extreme temperatures, materials such as Sustatron and Ticomp S.
Wear and Abrasion
Abrasive conditions provide different challenges to clean environments, and therefore the material selection, which can include Sustamid and Polystone 7000.
Lubrication
Consider whether the application allows for regular lubrication or requires dry-running, and if self-lubricating materials are needed.
Friction
The co-efficient of friction of materials will vary depending on the conditions (load, speed, counter-face etc), and will influence the forces required to drive the system, as well as the heat generated.
Regulatory Requirements
Does the application have regulatory requirements such as food contact, drinking water, anti-static or flame retardant. The food industry may also require materials to be metal detectable, x-ray detectable and/or visually detectable by being coloured blue.
Other considerations
At times there may be other considerations such as chemical resistance, dimensional stability, machinability, insulation (thermal and electrical) and impact. Some high performing materials can carry and higher cost, therefore balancing the cost vs performance benefits should also be considered.
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