Plastic Material and Equipment Variable

The subject of plastic materials and equipment variables are important to understand so products can be properly designed and processed. Details on MATERIAL 

VARIABLE are in Chapter 6 and on EQUIPMENT/PROCESSING VARIABLE are in Chapter 8. 

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There is continuous progress in regard to reducing the existing plastic material and equipment variabilities (as there are for steel and other... 

These failures could be due to the variability of the plastic material and/or fabrication control of equipment. Applying an approach such as the IVoubleshooting Guide reviewed, can direct you to the solution. 

Even though equipment operations have understandable but controllable variables that influence processing, the usual most uncontrollable variable in the process can be the plastic material. The degree of properly compounding or blending by the plastic manufacturer, converter, or in-house by the fabricator is important. Most additives, fillers, and/or reinforcements when not properly compounded will significantly influence processability and fabricated product performances. 

The approach to accelerated testing was to use the Atlas Xenon Arc WeatherOmeter. This equipment is fitted with a 6 kW Xenon Arc which with suitable filters provides a UV light source with a spectral distribution almost identical to that of sunlight. Variable atmosphere control for ozone and sulphur dioxide had been fitted to the equipment to enable the machine to simulate as closely as possible the more severe conditions encountered in industrial areas. The WeatherOmeter conditions are thus a severe test of any plastics material since they combine cyclic exposure to UV light, humidity, temperature and atmospheric contamination. Typical exposure conditions are given in Table 26.10 below. 

As reviewed throughout this book, designing acceptable products requires knowledge of the behavior of the different plastics and their processing characteristics (Chapter 6, MATERIAL VARIABLE and Chapter 8 EQUIPMENT/PROCESSING VARIABLE). 

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. 

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