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Thermoplastic Characteristic
YaMa-Design
The choice of a particular resin can be influenced by many things such as strength, stiffness, electrical and physical characteristics amongst others. Some examples to give primary guidance are:
Elasticity
If your product requires a fair degree of flexibility, you have a good choice from polyethylene, vinyl, polypropylene, acetal and nylon. You can also use some of the more rigid plastic so long as the section is correctly designed.
Flame Resistance
The Underwriters Laboratory and similar regulations require the use of self-extinguishing plastic for components holding electrical contacts and also for other critical areas. Nylon, polyphenylene oxide, polysulphone and polycarbonate are some of the plastic that may be suitable.
Gears And Bearings
Highly stressed gears can be produced in nylon and acetal especially when reinforced with glass fillings. Other useful reinforcements include graphite and molybdenum disulphide. Acetal resin is good for small, precisely dimensioned gears.
Impact Resistance
Polycarbonate, ABS and polyphenylene oxide (in its impact modified form) have good impact characteristics.
Odour And Taste
Primarily these will be of concern if you design for the food industries, either in packaging or in food processing machinery. Polystyrene, polyethylene, ABS, acrylic and polysulphone are among the satisfactory resins for such use.
Surface Wear
Scratch resistance does not necessarily equate with hardness. Acrylic, ABS and SAN resins generally have good resistance against scratches due to handling.
Temperature
Some materials will be eliminated from your choice because of thermal restrictions. For products operating above 250°C, the silicones, polyimides, hydrocarbon resins or mica may be required. At the other extreme polyphenylene oxide can be used at temperatures as low as -180°C.
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