1991-11-01

Production Technology Aiming at High Productivity and Saving Manpower in Producing Plastic Parts 912605

Among the plastic automotive parts which are finding increased use these days, the bumper is a key large-size part upon which the car depends for collision safety. Its design is important for the car's individuality and attractiveness. Also, its appearance is as important as that of the steel body. To achieve production efficiency of high-quality injection molded polypropylene bumpers, prime considerations are: a tool design to allow molding with an undercut, a tooling process capable of building high precision moulds in a minimum amount of time, manpower savings in the molding operation, etc.
Ease of design and quality enhancement are especially demanded for the instrument panel. Conventionally, pads for component parts of the instrument panel have been produced by infusing semi-rigid urethane into the vacuum-formed or slush-moulded skin to integrate with the base material. This process, however, has disadvantages in that many steps are required and defects tend to occur due to the chemical nature of liquid urethane.
To dramatically upgrade production efficiency for plastic bumpers, the process of using vacuum forming to simultaneously join the polypropylene foam-laminated polyvinyl chloride sheet to the adhesive-precoated base material was developed. Its features include the use of material other than urethane and a minimum number of steps. This paper presents this new process by describing the moulding tools, the sheet material, the production line and the product trimming method.

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