Wilhelm Plastic: integration of manual steps enables a low-cost turnkey solution

Economic efficiency during parts manufacture and during procurement were equally important requirements when it came to the development of a turnkey system for Wilhelm Plastic. The concept was put into practice in a “cost efficient” way by linking upstream manual process steps using an individual automation concept from ARBURG that was tailored to the specific task in collaboration with the customer.
Wilhelm Plastic GmbH & Co. KG in Floh-Seligenthal, Germany, has been an exclusive ARBURG customer for two generations and has already equipped around half of its ALLROUNDERs with robotic systems.

Improving productivity and quality
In the case of threaded flanges, a turnkey system was the obvious next step, according to managing director, Jana Pfannstiel: “For more than a year we placed the parts for overmoulding in the mould by hand. However, because demand doubled within the same period, we inevitably needed to automate the production process. In addition, we wanted to harmonise the process by introducing smoother cycles. The aim was to avoid stoppages due to checks or packing and differing work practices among our employees. In addition, the transparent material is highly susceptible to discolouration. Automation had a positive effect in this case, because it allowed us to handle this material in a smooth, high-quality process with no stoppages or delays.” A measured approach was taken to automation in order to keep a tight rein on investments.

Manual provisioning
In order to make production as efficient as possible, automation was combined with manual activities performed upstream. Firstly, two separate parts are supplied one above the other in two alternately unlockable drawers on component insertion platens: the first is a metal external thread with central bore, while the second is a plastic peg with four chambers, which is inserted into the central bore. A pneumatic stamp presses the two parts together to form inserts. The operating personnel can lock either of the two drawers in four press positions during manual placement in the mould. In the end, the drawer is fully inserted and the vertical MULTILIFT V robotic system picks up the pressed inserts from there. This ensures continual production. The drawer component insertion method corresponds to the mould cavity spacing and was adapted to the physiognomy of the gripper.

Automated overmoulding
After the mould is opened, the MULTILIFT V first removes the finished parts, including the sprue, from the moving half of the mould, then moves vertically downwards and transfers the pressed inserts. The mould closes and the head area of the insert is overmoulded with a plastic cap nut. This joins the two pressed parts together in a permanent bond.
The robotic system places the finished parts on a conveyor belt and then discards the sprue in a container. The cycle time for the production of the four threaded flanges is around 30 seconds and the system is operated in three shifts. This solution shows: in order to achieve optimum economic efficiency, it is worthwhile taking a detailed look at processes: which activities can be carried out manually and which need to be automated? Wilhelm Plastic treated both factors with equal importance.
The result is “cost efficient” in the truest sense of the word.