Part Design

The design of a part for Thermo Pressure Forming, like the design of a part to be made by any other plastic process, starts with the designer's creation of a shape or structure that will satisfy the functional requirements of the product in its final end-use environment.

Once the functional requirements are clearly understood and a basic shape has been evolved, the designer then turns his attention to what materials and fabrication techniques are available to produce the part. There are many materials and process options available to the designer and he is not limited to plastic materials. However, for the sake of this booklet, our considerations will be limited to plastics as the medium of construction.

All successful plastic products or parts can be thought of as being surrounded or protected by the four basic elements that all plastic parts have in common

These basic elements are: (1) the design of the part; (2) the selection of the ideal plastic material; (3) the design and construction of the tooling; and (4) the processing or forming and finishing of the part. All four of these elements must be handled correctly in order to produce the optimum plastic part.

A successful product starts with a good quality part drawing. A good part drawing is the result of a designer's knowledge of the capabilities and limitations of the chosen material, tooling and process, coupled with a meticulous attention to design details. Unfortunately, it is not possible for a designer to produce the optimum part design or drawing without first acquiring at least a basic understanding of the capabilities and limitations of the specific material, the chosen process and its unique tooling. In other words, a plastic part must be proportioned according to the requirements of the material, the tooling and the process.

To ignore or mishandle any one of these four basic elements will result in a less-than-best product. There will then be a break in the inherently strong circle that should surround and protect a successful plastic product. Once the circle is broken, the product will suffer due to unnecessary high tooling or piece part cost, poor quality, inadequate strength, appearance problems, a lack of customer satisfaction, or all of the above.

While struggling to satisfy these four basic requirements, the designer must not lose sight of the functional requirements of the part in its end-use environment. Simultaneously satisfying all of these requirements often necessitates painful compromise decisions. For example, injection molding is your first choice; however, marketing will not wait for the long tool delivery schedule; the product would be stronger in polycarbonate but the competitive nature of the market will not tolerate the increased material cost, etc.

The design and development of a plastic product is never as easy as the designer is led to believe it will be. This booklet has been produced to answer the designer's questions and quickly teach him what he needs to know in order to consider the advantages of Thermo Pressure Forming for his new plastic product.