Testing and Meaning of Test Data

This chapter will present examples of testing and their behavior that influence decisions to be made by designers when analyzing data. Testing methods have been prepared and used for over 2,000 years with probably more in the past century that in all the past. Examining and properly applying property test data of plastics is important to designers. 

The technology of manufacturing the same basic type or grade of plastics (as with steel and other materials) by different suppliers may not provide the same results. In fact a supplier furnishing their material under an initial batch number could differ when the next batch is delivered and in turn could effect the performance of your product. Taking into account manufacturing tolerances of the plastic, plus variables of equipment and procedure, it becomes apparent that checking several types of materials from the same or from different sources is an important part of material selection and in turn their use. 

Based on past performances it has been proven that the so-called interchangeable grades of plastics have to be evaluated carefully by the designer as to their affect on the performance of a product. An important consideration to include as far as equivalent 

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