Deformed Part

Some parts, when improperly processed or used, can take on a permanent deformation.

Warped part due to incorrect stoichiometry.

Potential Causes

Softened by Heat
Prolonged exposure to heat will have a deleterious effect on elastomers, which can cause them to soften and become distorted by the forces applied to them when in use.

Poor Abrasion Resistance
In extremely high-wear applications, sections of a part may wear away completely and the part will then appear to be deformed.

Elastomer Tendency to be Thermoplastic
Some elastomer formulations have a tendency to be slightly thermoplastic. This means that they will actually distort and take on a new shape with the application of heat. In some cases this is a desired property, though in general it is not desired.

High Compression Set
Some elastomers that have a high compression set will deform because of the forces being continually applied to them. High compression set may be a function of the formulation or it may be the result of poor processing.

Solutions

Reduce Exposure to Heat
Reduction of exposure to heat can sometimes be accomplished through engineering controls.

Formulate for Higher Abrasion Resistance
Some elastomers are better at withstanding abrasion than others. Consult your prepolymer supplier for prepolymer recommendations based upon the specific application. Additionally, certain additives can be formulated into an elastomer to help improve abrasion resistance.

Reduce the Load/Redesign the Part
Through proper part design, it is often possible to reduce the stress on the part to a manageable level.

Process at the Correct Stoichiometry
Processing at an incorrect stoichiometry will lead to high compression set. This in turn could lead to permanent deformation of the part. Lower stoichiometries are recommended to reduce compression set.