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21st August 2019, Nuremberg

Tool concept enables cable assembly in one fell swoop

The company incorporated additional clamping and fixing elements so that the cable can’t move around in the tool. © AdobeStock_76921385

The company incorporated additional clamping and fixing elements so that the cable can’t move around in the tool. © AdobeStock_76921385

Plug connections need to be able to withstand heavy strain in automotive engineering. When used on a vehicle’s underbody, it is especially important that plug connections comply with DIN EN 60529 specifications. In conventional production processes, plug connections are typically manufactured first before the cable is assembled in the second step. Performing these two steps separately increases the risk of leakage, according to Hans Geiger Formenbau, a specialist in the manufacture of complex components.

The company, on customer request, has overhauled its cable-assembly process. It now uses a tool that allows the cable and plug’s interior to be encapsulated with fibreglass-reinforced polyamides, eliminating the need for sealing elements like silicone rings.

It is imperative that the functionality of plug connections used in vehicles is not impaired by water, salt, ice, dust or pebbles. “Seals that prevent dust and particles from entering between the plug and the cable pose significant challenges in the production process,” explained Eva Söhnlein, a representative of Hans Geiger Formenbau. “Until now, additional seals were needed to comply with the requirements of the protection classes defined by DIN EN 60529. This not only made the production process longer, it also increased material costs considerably.”

That’s why mould-construction and injection-moulding experts have turned to a process that enables encapsulation and the assembly of the cable in the plug connection to be carried out in a single step, the company adds.

Difficulties in the encapsulation process

Until now, cables have been the cause of many problems. “Encapsulation is typically performed under immense pressure. But because cables tend to be light and malleable, they give little resistance and shift during the process,” explained Ms Söhnlein. “As a result, the cable encapsulation is not up to standard and a significant reduction in quality is to be expected.”

Plug connections need to be able to withstand heavy strain in automotive engineering. © AdobeStock_69078562

Plug connections need to be able to withstand heavy strain in automotive engineering. © AdobeStock_69078562

Geiger’s top priority was to look at many factors in the tool development phase. One of the challenges they faced was determining the best injection point and the most-suitable component filling so that the cable is exposed to as little pressure as possible. “We incorporated additional clamping and fixing elements so that the cable can’t move around in the tool. These are automatically and precisely retracted in the injection process so that the sealing capacity of the component can be ensured,” she said. Sealing during the production process also plays a major role: it is important that the insertion point for the cable as well as the cavity are sealed as tightly as possible. 

The production process is semi-automated, with the cable being inserted by hand. For this reason, it was important that the tool concept be particularly user-friendly; operating it is much like operating a conventional rotary table. The mould ejector sides are alternately fitted with cables before the apparatus is encapsulated. To monitor the process as best as possible, internal pressure sensors have been installed in each cavity.

Heat insulation panels prevent injury

The average temperature of the tool during the encapsulation process is 80 °C, though it can quickly reach temperatures of up to 280 °C. Therefore, to prevent burns from being sustained while inserting or removing the components, special heat insulation panels have been installed where the tool is being handled. Additionally, the eject mechanism was designed so that employees don’t have to touch the tool.

www.geiger-gruppe.de

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