12V power distribution

Stamping, insertion & overmoulding

Power distribution in the automotive truck business is something different then for a normal car. Both 12 and 24 Volt systems are used, heavy duty use is to be supported and separation between the cabin and the engine bay is important for the safety of the truck driver. Within a truck related project from our customer, KeyTec cooperated from the initial design to the series realization for a couple of components that were meant for integration in the power distribution box for 12, 24 and ground connection in the truck.

From the beginning it was clear that a copper alloy carrier was to be used for the current. For the connection of the different eyelets a kind of threaded element was to be integrated. During the prototype phase it turned out that catalogue parts did not fit the environment, machined parts were too expensive, which left over the use of copper alloy material.

To keep the costs within reasonable boundaries, it was likely to apply normal type of press-in studs. This brought a challenge as normally standard press-in bolts are designed for insertion in steel material. Considering the much softer copper, during insertion the material displacement was such that tolerances were easily out of specification. Based on a well working cooperation with the insert supplier and a trial project, two solutions were found. For some of the bolts, that turned out to be used in such high volume, the design of the bolt was slightly changed, for the ones that had not enough volume to rectify a specific design and corresponding minimum production volume, a special stamping shape in the copper material was created to realize a well fitting insertion without losing the tolerances.

These tolerances are of great importance as the parts, for isolation of the electrical current from its environment, should be overmoulded in a specific shape to fit them into the larger distribution box together with other parts. The pinch-off surfaces should be smooth and flash free to realize a hundred percent electrical connection between the copper and the mounted eyelets.

The in house combination of the stamping – insertion and the overmoulding made that our customer only has to order the end item without taking further care of different suppliers for the different processing stages.

Stamping and moulding integrated under one roof

Electrical systems, either in the industry or automotive, require the distribution of the electrical power. The mainly used carrier in this perspective are copper or copper alloy based parts, busbars connecting the different power sources and users.

As explained in the power distribution solutions, KeyTec realized specific processing for these kinds of multi-level parts. In addition to the stamping, bolts assembly, KeyTec also adds its injection moulding capability to make customer specific power distribution parts.

With this one roof concept for these specific products, the customer has only one contact for the complete assembled part, copper material – stamping – (pre- or post-)plating – bolt assembly and overmoulding this subassembly to an isolated power distribution assembly.

Challenges like burr direction in relation to the clamping position in the injection moulding tool, material displacement during bolt assembly and tolerance stacks are technical challenges that are solved by the multi-disciplinary engineering team from KeyTec.

With its specialism in special engineering plastics (e.g. reinforced with glass fiber up to 35%, flame retardant additives), a part is made to withstand its challenges in the field.