More efficiency, process reliability and quality: An automotive supplier in the Czech Republic is handling the higher order volumes optimally by means of a new highly automated manufacturing cell. To manufacture oil level sensors, the company invested in a turn-key solution by ENGEL.
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Injection moulding, metal processing, quality control and automation were integrated on a very compact space. |
Housings for oil level sensors, which use ultra sound to check the fill level and measure the oil temperature at the same time, are among the most challenging components the automotive supplier is producing at its Czech facility. Both the part geometry and the connector elements required for integration into the car pose a considerable challenge for the injection moulding process. Geometrically speaking, the pocket for the NTC sensor is particularly tricky. It is 12 mm high, has an outer diameter of just 3 mm at its peak and the wall is only 0.5 mm thick at its thinnest point. 12 pins in five different designs with regard to coating and shape project downwards from the component. They are used to connect the sensor with the car's electronic system. Three pins lead to the lateral connector and therefore require four-fold bending. In addition, the housing requires three bushes for mounting it on the oil pan. Sums up to a total of 15 metal inserts which have to be inserted into the mould for every component.
As recently as one year ago, the single cavity mould used back then was filled manually. 12,000 parts were produced per week. Then the requested numbers rose steeply and it became clear that a simple scale-up of the existing manufacturing process would not provide efficient production. "The cycle times vary in the manual process. Furthermore, the risk of rejects was high and the quality control was time-consuming," says the project manager at the automotive supplier company. "By increasing the number of units we reached the break-even point for an automated manufacturing cell."
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The rotary table reduces the cycle time. During the injection moulding process the 4-cavity mould is filled outside of the clamping unit. |
Machine, mould and automation mesh perfectly
In order to meet the diverse requirements of the component equally, the decision for a turn-key solution was made. "With such complex insert applications the injection moulding machine, mould and automation need to mesh perfectly," stresses the technical expert. "Therefore it was important for us to match all plant components right from the outset. We wanted the overall responsibility to lie with a single supplier." As a system supplier with a lot of experience in automation and mould manufacturing, ENGEL came into the focus of the project decision makers. Another reason for the decision was the strong local presence of the machine manufacturer in the Czech Republic. "It makes things a lot easier if our employees can speak to our suppliers in Czech."
Petr Odehnal, sales engineer at ENGEL CZ, is the main contact person for the plastics processor. He coordinates the project plan, the involved partner companies and his colleagues at ENGEL's head office in Schwertberg, Austria. The mould technology team is based there, which is an important interface in the system solution business, because often factors in the mould decide how efficient the interplay of injection moulding machine and automation is going to be. "As a system supplier we usually don't get the simple tasks," says Johann Holzer, member of the ENGEL mould technology team. "People in the industry know that we have a lot of experience with complex components and always know the right partners to meet specific requirements." For the oil level sensor project ENGEL took IKO Isidor Kurz Werkzeugund Formenbau from Haigerloch-Owingen, Germany, and automation specialist MKE from Heidenreichstein, Austria, on board.
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Four Scara robots carry out the complete handling of inserts and finished parts. From metal processing to injection moulding, quality control and removal of parts. |
60 metal inserts at once
The manufacturing of the sensor housings starts with bending and cutting the pins. On a very small footprint, ENGEL integrated metal processing equipment, a vertical ENGEL insert 650V/130 rotary injection moulding machine with a 1200 mm rotary table, four Scara robots, a rotary table for preparing and feeding insert parts, another rotary table with five quality-control stations and a data matrix printer, a camera for monitoring the gripper, as well as a tray system for discharging finished parts.
The new mould has four cavities, each comprising a slide unit to form the connectors as well as an underfloor slider for lateral perforation. In total, 60 metal inserts are handled in each cycle. The Scara robots take parts directly from the conveyor belts of the bending and cutting unit. The 15 insert parts required per cavity are pre-sorted and picked up by the gripper all at once. Before positioning them, the camera system checks whether the set is complete to avoid producing rejects due to pick-up errors. The inserts are charged in parallel to the injection moulding process, in the bottom half of the mould, which is outside of the clamping unit at that time. The comprehensive, fully automated quality control and the laser labelling also run in parallel. Every 36 seconds the manufacturing cell produces four new polyamide housings ready to be installed – with maximum process reliability and reproducible quality. The tolerances of this component are between 0.1 and 0.05 mm.
Also in the Czech Republic there is a trend towards automation when it comes to high unit numbers. The reason, however, is not just rising labour costs. Rather the increasing functional integration which leads to ever more complex components is driving this development. The automation competency helps the plastics processors to acquire new orders, to increase their competitiveness and to continue to grow.
