Injection molding product design

Many injection molded products will influence the final product s performance, dimensions, and other characteristics. The mold includes the cavity shape, gating, parting line, vents, undercuts, ribs, hinges, and so on (Table 3-17). The mold designer must take all these factors into account to eliminate problems. At times, to provide the best design... 

There are far too many applications for injection molded products to thoroughly cover here. However, a few examples will help provide an idea of some of the important mold design and machining considerations. 

Preparing a complete list of design constraints is a crucial first step in the design failure to take this step can lead to costly errors. For example, a designer might have an expensive injection mold prepared, designed for a specific material s shrink value to meet specific product dimensions, only to discover belatedly that the initial material chosen did not meet some overlooked design requirement or constraint. 

There are many important points to consider when designing a new injection molded product. Before starting, consider the following requirements and parameters ... 

Molded articles in a wide variety of sizes and shapes can be produced by injection molding. Production of these articles tmder optimum conditions requires alternative designs for the various sizes of injection molding machines, as well as their respective auxdiary equipment. 

The position of the gate as well as the type of gate is very important for the mold design and the economic efficiency of the injection molding production. An overview is shown in Figure 1.29. 

The benefits of new materials will only be fully expressed in products if weak spots, such as weld lines in injection molded products, can be properly addressed. Weld lines may be critical with regard to product quality for some thermoplastics. Therefore, research into the effects of variations in injection molding settings, combined with mechanical testing, will be helpful for developing design guidelines for injection molded bioplastics products. 

An example of the latter is the boost in the development of thermoplastic elastomers in the last decade of the Twentieth Century, driven by product applications obtained by multi-component injection molding. The design guidelines for such products originally included recommendations to make the material components mutually enclose each other so as not to rely on adhesion between dissimilar materials only. Later grades of thermoplastic elastomers have been improved with respect to the adhesion to thermoplastics, allowing more design flexibility and processability improvements. 

MOLDEST Provides product design, mold design, and injection molding process control by Fujitsu Ltd., Tokyo, Japan. 

Snap fits are widely used for both temporary and permanent assemblies, principally in injection and blow molded products. Besides being simple and inexpensive, snap fits have superior qualities. Snap fits can be applied to any combination of materials, such as plastic and plastic, metal and plastics, glass and plastics, and others. All types of plastics can be used (Chapter 3, DESIGN CONCEPT, Snap Joint). 

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