plastic mould and custom injection moulding tips

Advantages and Disadvantages of Plastics The growth of the polymer industry in  the  latter half of the 20th century has been phenomenal and shows no signs of decreasing. If the advantages of synthetic polymers over competing materials such as metals and ceramics are considered, it is reasonable to predict that polymers will take an even greater share of the total materials market in the future. Some of these advantages and disadvantages will now be discussed. Strength and stiffness  in plastics should be discussed in terms of strength/weight or strength/cost ratios to be significant. unfilled plastics cannot approach structural metals in absolute values of strength or stiffness (where stiffness is proportional to modulus of elasticity). It also shows that plastics tend to be inferior to metals and to wood in stiffness/weight ratio (E/S g ). Only costly polymer composites (fiber reinforced plastics) approach alloy steels or hardened aluminum in strength/weight ratio (a/Sg). Increasing

plastic molding term Heat-distortion temperature (°F) at fiber stress of 264 psi (ASTM D 648) is a statement of the temperature required to permit an arbitrary standard amount of deflection by a standard load, in a test in which the specimen is subjected to a gradually increasing temperature. It is thus an indication of the ability of a material to retain its stiffness, or resistance to deformation, against the weakening influence of high temperature. A similar test，under the lower load of 66 psi (ASTM D 648), in which, of course, a higher temperature is recorded, has similar significance for material subjected to lighter load. Values determined by this second test are shown, for some materials, in the 6th column of the table. A large difference between heat-distortion temperatures in these two tests gives warning of the need to pay particular attention to designing so as to minimize the stress in service of articles subjected to heat. Impact strength , Izod {ft-lb per iti. of notch&