Sandwich moulding high quality products with a new tool technique using recycled plastics decreases product cost

Purpose and goal

Co-injection of parts with surface and core layers and injection moulding of family parts with different size, shape and weight in a multi-cavity tool, have a fair potential to provide lower costs, less environment load and resources needed. The object of the project is to develop a new tool technique called FLEXIJECT Technology that make it possible to - vary melt flow in the feed system, - apply a holding pressure individually in each cavity, and - compress the feed system plastic residue = less amount to recycle. Runs in a test tool have proved that these goals have been essentially reached.

Expected results and effects

Co-injection test runs of a complex shaped part resulted in a 50%share for the core layer of recycled PC/ABS with a minor admixture of a high viscous polymer. Hereby material cost is reduced by 15% and a contribution to less environment load is achieved. Runs with the test tool version comprising cavities for two family parts proved that optimum weight for the parts and their surface quality was quite identical compared to the parts when they were moulded each individually. Acquisition cost is about 30% lower for a family tool compared to one tool for each part for moulding them separately.

Planned approach and implementation

A full scale cell to be run automatically was the basis of carrying through the project. The cell comprises - a machine, - a double-cavity tool for family parts, one large with a complex shape and a small one with a simple shape, which tool also has a gate designed for flow front control of the melt filling the cavity especially used for the Mono Sandwich co-injection test runs, - peripheral equipment such as a robot for picking out the parts and the feed system residue, a grinder for fragmenting the residue and a conveyor with a mixer for recycling the ground residue directly back into the machine.