In an article reporting on the Ninth Euromold Fair, we read, [1] “Mold and die making is alive and well in Germany.” The innovative strength of the field speaks for this claim. Even if production, and the know-how that goes with it, are being shifted out of the country, the truth is, “Much more significant for securing long-term perspectives are: continued technological progress with respect to production cost cutting and product functionality, as well as unbending and far-sighted training to motivate the next generation.” [2] From its very inception, the “Gastrow”, being a reference work and source of ideas, has been dedicated to the goal of disseminating knowledge. This new edition aims to do so more as a collection of examples to help find design solutions. Computer methods, i.e., CAD, can at best supplement and optimize a design concept with, for example, rheological, thermal, and mechanical mold configuration, but, as all experience shows, cannot replace it. Moreover, it remains the case that the results of CAD have to be critically evaluated - a task that requires sophistication and practical experience. Thus it remains common practice in the production of precision-made injection molded parts to build a test mold, or at least a test cavity, in order to optimize dimensional stability, for example, and adapt to requirements (in several steps). CAD results often indicate only the determination for shrinkage (warping), a characteristic of molded parts, especially those made from semi-crystalline polymers, that is quite diffcult to quantify. Even so, development time and costs can undoubtedly be reduced by suitable computer methods. For information on applying computer methods, the reader should consult the relevant literature.
A stripper plate surrounding the mold core presses on a large portion of the part rim during demolding. Thus the part is not subject to high local stress during demolding, such as individual ejector pins would generate.
The cover with dimensions 141mm x 87 mm x 12 mm high (Fig. 1) has an approximately oval shape. On the upper side, it has an inwardly projecting lip that forms an undercut around the entire part. The elasticity of polyethylene is used to release this undercut, thereby permitting release from the core without the use of complicated part release mechanisms.
