TABLE OF CONTENTS John L.Hull
Hull Corporation
Warminster, Pennsylvania
The creation of a plastic part requires a series of conscious decisions regarding type of plastic, method of production, design of mold or tooling, and selection of machine or process. Reaching these decisions requires information as to the intended usage of the part and the conditions of environment (temperature, moisture, exposure to harsh atmospheres, physical and electrical requirements). Furthermore, in most cases, the cost to manufacture the part is a major consideration and is dependent on the choice of materials, the manufacturing process, and, of course, the quantities to be produced per shift, month, or year.
In this chapter, several production processes are discussed broadly, outlining the basics of each process, the equipment involved, the plastic materials for which the process is feasible, and some typical products made by each particular process. In addition, the chapter describes important aspects of plastic part design and considers the closely related topic of mold design and construction.
The first step requires a preliminary engineering drawing of the intended part, with approximate overall dimensions, section thicknesses desired, probable location of holes, ribs, bosses, and the like, as well as approximate radii of curves, corners, and so on. Tolerances are not necessary at this stage but will be incorporated before final design.
Next is a list detailing the intended requirements of the final part Physical considerations regarding stiffness; dimensions and tolerances; impact resistance; surface hardness; compressive, tensile, and torque loads; light transmittance; and so...
