Polyurethane

A polyurethane product is a versatile engineering material designed to provide properties not available in conventional rubbers, metals and plastics. Polyurethane parts are made by mixing two components (a prepolymer and a curative) which are mixed together and poured into a mold where they react rapidly to form a solid elastomeric article. The major characteristic of this material is that it has extraordinary physical properties. Parts fabricated from tough, resilient polyurethane elastomers that have been subjected to abrasive or cutting action have long outlasted similar parts made from metals or plastics.

Selecting a polyurethane for a new application:

1) Decide which properties are of key importance - physical and environmental resistance.
2) Select candidate polymer/curative systems which are likely candidates
3) Consult your suppliers for recommendations and further information
4) Review your plant capabilities
5) Run whatever preliminary tests are available
6) Field test in actual service, make comparisons, get approval from future end users
7) Gear-up for production

First, look at the application very carefully and decide which properties are of key importance both in terms of the physical properties and the environmental resistance necessary in the urethane. Select a few candidate polymer and curative systems which should offer appropriate performance. Once you have done this, go to urethane suppliers for their recommendations and for more information. They will certainly be willing to help you and will welcome discussion of new applications. The suppliers may also help with suggestions of materials or test data that is not available in their published literature.

Next, review your plant capabilities. Make sure the compounds you have chosen are ones that can be run in your plant either under its present setup or, barring that, what sort of investment might be required for processing of the proposed material. Depending on the potential market for application, a new investment may be justified.

Now run whatever preliminary tests are available. If it is a new application, for example, if the part must come in contact with an unusual chemical solution, make sure that the urethane you select can tolerate this. Test the material by immersion, and again ask your suppliers for help on this. They will usually be willing to run tests of this type for you.

At this point, if everything continues to look good, make prototype units of one or more candidate materials. Make sure, of course, that your prototypes are well identified so they don't get misplaced in the field and, importantly, so that their service history can be properly tracked. Once the parts are out in actual service, make comparisons of the performance of these test units against whatever is currently being used. If it's a brand new application where nothing like it ever has been done before, test it against whatever criteria you or the end user have in mind.

Finally, make sure that the end user agrees on the test results and that they approve the part based on the prototype evaluation.

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