Innovative laser surface treatment of injection molds
Products containing plastics in some form have taken on an important role in everyday life – the notion of living without a toothbrush or a remote control has become inconceivable. Such products are manufactured cost-efficiently in large lot sizes by injection molding. These injection molds are generally made of high strength or wear resistant steels. With these molds several hundred thousand parts are produced without any wear appearance at the mold. However, the manufacturing of the molds made of steel is costly and complex. The substitution of the working steel by Aluminum has not been feasible so far. Indeed the machining of Aluminum is possible with a lower energy input, but due to the low hardness the wear resistance is not adequate.
Fraunhofer IPT started in 2012 together with ModellTechnik Rapid Prototyping GmbH the SME-innovative project “InnoTool” (contract no. 02PK2246), within the frame concept “Forschung für die Produktion von morgen”, which is funded by the German Federal Ministry of Education and Research (BMBF).
The aim of the project is to substitute aluminum for steel as the material used to manufacture injection molding tools and dies for small batch manufacture of premium-quality plastic parts. For this the project partners develop a process chain to modify the Aluminum molds and inserts by a combined laser surface treatment to achieve prolong lifetimes.
The most important disadvantage of Aluminum alloys compared to steels is the low wear resistance. Therefore the areas of injection molds subjected to extreme loads shall be technologically designed not just for the manufacturing of prototypes but as well as for small lot sizes.
For this the project partners acquire a process chain of combined laser surface treatment: Using the laser alloying/dispersing process a wear protection layer at the rim zone by inserting high-strength particles is achievable. Functional microstructures, inserted by laser structuring in the surfaces of the molds reduce additionally the friction during die casting process. In contrast to conventional structuring processes it is also possible to add design structures without limitation at the laser alloyed/dispersed surfaces.
- Fraunhofer Institute for Production Technology IPT
- ModellTechnik Rapid Prototyping GmbH