Thickness of Section and Rib

Plastic products should be designed with the minimum wall thickness that will provide the specified structural requirements. This results in saving material and higher molding 

Holes are often required in molded products. They should be designed and located so as to introduce a minimum of weakness and to avoid complication in production. This means, for example, that several holes should not be located close together unless a thicker wall section is provided. Where many design problems posed problems due to holes, it is often less expensive to drill after molding, particularly when holes must be deep in proportion to their diameter. However incorporating holes in a mold can be routine. 

Designing bucket By way of another example consider a common household bucket. The analysis that a typical molder might make follows. The mechanical properties required are moderate namely tensile strength of 6,000-8,000 psi and impact strength of about 1 ft-lb/in. (Izod). It must be sufficiently rigid to hold 2 gal of water but some flexibility is desirable in order to absorb bumps and knocks during its use. Electrical properties are clearly unimportant, but water resistance and dimensional stability at moderately elevated temperatures must be good. Heat resistance must be adequate to deal with very hot water (80° C) but not necessarily with any heat over 100° C. 

It must he produced in large quantities, over 100,000 per year and, being a domestic utility item, it should be priced low such as 3.00 at retail. Market studies indicate that it should be available in a wide range of colors. The size, quantity needed, and price suggest an IM in a TP material. A study of the cost and properties of the various plastics will show that in general the TPs will have the required properties at a lower cost than will the TSs. In addition they are more adaptable 

In order to fabricate a cost-performance effective molded product and understand potential problems vs. solutions, it is helpful to consider the relationships of machine-to- 

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