What are the considerations in the design of a Plastic part?


A designer or engineer will often use design equations that work with metals while a plastic part is being designed. Metals behave like a spring, that is, the force generated by the spring is proportional to its length. A plot of the force as a function of length is a straight line and is called “linear” behaviour. However, plastics do not behave like a spring – that is they are “non-linear”. Temperature changes the behaviour even more so that any designer or engineer needs to be very careful to consult the performance charts for a plastic material to obtain the correct input.

How much load or force will the part be required to carry?

How will the part be loaded?

What are the direction and size of the forces in the part?

Will the part have to withstand impact?

Will the part see cyclic loading?

What temperatures will the part be operating in and for how long?

Will the part be exposed to chemicals or moisture?

Will the material be used in an electrical design?

Will the part be used as a bearing or need to resist wear?

Does the part have to retain its dimensional shape?

Will the material have to stretch and bend a lot?

Will the part have to meet any regulatory requirements?

Does the material or film have to prevent certain gases or liquids from passing through?

Will the part be exposed to radiation?

Does the material need to have a special colour and / or appearance?

Does the part have any optical requirements?

Will the part be used outdoors?

Can any volatiles be given off by the material?