Made in Germany 05/2004

Space Puzzle Molding Shortens Production of Original Plastic Parts

Whether individual prototypes as series-identical plastic parts or fast short series from the prototype mold, both are produced by Protoform using the Space Puzzle Molding (SPM) procedure. With recently obtained series ranging up to 3.000 pieces, the patent protected prototyping procedure has also passed its graduation examination for series production as a fast and easy shortcut to plastic products of all kinds.

Using the patented Space Puzzle Molding procedure, Protoform Konrad Hofmann GmbH concentrates on producing one-offs as well as prototypes in small numbers or short series. In the company's plastic injection molding plant, plastic parts are produced piece-by-piece (to a large extent manually) as well as in series up to 3.000 pieces. Compact, inexpensive to build SPM-molds are manufactured at Protoform. Puzzle is installed by a lifting device in normal injection molding machines. The mold is fixed in a standard frame and prepared for the injection molding procedure.

Following the injection molding process the complete mold is released and lifted out with a handling device. On a special workbench with holding device, the mold is opened and disassembled (manually) to release the plastic part. Production parameters of the injection molding process are adjusted and controlled carefully - to satisfy customers' and quality assurance requirements. Parameters are documented to assist future series production. This rather complicated manual process is rationalized to a large extent in Protoform's production. In fact, it takes trained personnel only minutes to reassemble the SPM-mold for the next part to be produced. Locking force used for the injection molding machines is from 300 to 6.500 kN. Because internal pressure can develop up to 1.000 bar or more, which the SPM-mold an machine-integrated mold frame must withstand, plastic parts (such as automobile center consoles) are limited to 800 by 400 millimetres in size and 2.200 grams in weight. Usually plastics such as PC+ABS as well as PEEK and PP, but mainly PA, PBT, and PPS are used. Ever more frequently, customers also express a desire for reinforcement with fillers. Molds manufactured for such cases have proven their performance.

SPM procedures used exclusively at Protoform have long supplied one-offs, a few unique pieces, or short series up to 500 parts. Now the procedure is advancing into series production. Its advantage: after a few working days a fully functional mold that can supply authentic parts in original materials is available for production. Release of the plastic parts form the mold is usually associated with a varying degree of disassembly of the mold which sets some limits on the maximum output. In some cases, the number of parts produced has been sufficient, because no mass production was required, for example, in medical apparatuses, such as computer tomographs. So far the output produced in the SPM procedure was 500 to 1.000 parts. The first case in which this limit was exceeded significantly and thus shifted into the series range was a project for the U.S. enterprise Pitney Bowes: There Protoform leaped into the breach as an emergency helper, because a series injection mold was not available in time. With a large sized SPM tool, 3.000 units of a complex plastic housing insert for a paper sorting machine were produced very quickly.

Protoform manufactures 250 to 300 Space Puzzle Molds a year.