Injection compression molding

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The injection compression molding is a development of injection molding for the production of highly accurate or very large components from plastic . The plastic melt is injected as a so-called mass cake into the practically pressureless, not completely closed tool . It is only completely closed during the solidification process. The closing pressure , which builds up evenly as a result, ensures that the molded part is finally shaped.

advantages

Injection compression molding can be done on machines of all types. The workflow on the locking side is particularly easy to control on machines with a fully hydraulic locking system, as these are "softer". The workflow is programmable and can also be easily adapted to the conversion process of the molding compound to the molded part and the respective hardening characteristics when processing thermosets. The fiber orientation that occurs in the injection molding process with fiber-reinforced molding compounds is partially canceled during injection compression molding. Injection compression molding supplies molded parts with a very good surface, low mechanical anisotropy and low internal stresses for all plastics . Furthermore, the required clamping force is reduced so that larger components can be produced on a given machine or a smaller machine can be used for a given component.

variants

In one variant, the cavity can be completely filled. The increasing internal pressure opens the tool by a controlled small path. By increasing the closing force, pressure is exerted on the molding compound and a relatively low-stress molded part is formed. This variant is used in the production of data carriers made of polycarbonate (PC) ( CD , DVD ).

Applications

Injection compression molding is used for thermoplastics and thermosets . In the case of thermosets, volatile components are removed, e.g. B. air or water vapor that arises from the moisture in the molding compound and the reaction water during the beginning of the hardening in the tool. The final compression of the thermosetting molding compound is particularly advantageous here in terms of quality.

In the case of thermoplastics, the high contour molding of the tool structure is particularly crucial, as it is, for. B. is required for the production of cat eyes . In addition, large or thick-walled components are also used in optical applications such as B. discs or lenses manufactured with the injection compression molding process.

See also

Web links

Individual evidence

  1. a b Helmut Schüle: Special process in injection molding . In: Peter Eyerer, Thomas Hirth, Peter Elsner (Eds.): Polymer Engineering . Technology and practice. Springer, Berlin / Heidelberg 2008, ISBN 978-3-540-72402-5 , 4.1.3.1.2.8 Injection compression molding , p. 234 ( limited preview in Google Book search).
  2. a b Christoph Jaroschek: Injection molding for practitioners . 2nd Edition. Hanser Verlag, Munich 2008, ISBN 978-3-446-40577-6 , 4.4 Injection compression molding , p. 108–115 ( limited preview in Google Book search).