Connecting rods for car engines are among the technical components of a car, that one rarely sees in general and which do their work in secret. The technical and mechanical requirements to the properties of a connecting rod are still quite high, since it connects the crankshaft to the pistons – A tear of this connection usually leads to a massive engine breakdown.
The trim punch, consisting of H-13 tool steel, performs real hard labor in the production of connecting rods. It punchs the still hot glowing, in Q & T steel forged blanks into the final shape. It is exposed to extraordinary mechanical and thermal stress. It`s contours and cutting edges are worn out quickly and have to be replaced constantly.
The South Korean 3D metal printer manufacturer InssTek provides a technically and economically optimized solution. The method, developed in close collaboration with a well-known automobile manufacturer, repairs not only worn trim punches but makes them even better than before.
As first step the worn surface (a) is removed mechanically. Depending on degree of wear about 10mm deep (b). It is advantageous to use CNC machines giving the possibility to use geometry data of the cut cross section for programming the 3D printing process. Afterwards the new contours and cutting edges are printed (c) with InssTek´s DMT technology. Finally mechanically finished (d) for reuse.
Video of repairing process:
All the parameters have been optimized in several steps so far that the printed layer is outclassing the original trim punch in all its mechanical and metallurgic properties. Printed 1.2344 tool steel provides a highly dense, non-porous, homogeneous structure.
This 3D repair solution has been applied for more than 2 years and the newly presented evaluation provides surprising results: While conventionally produced trim punches eject on average about 45,000 connecting rods before being replaced, the 3D repaired die lasts for about 150,000 connecting rods. This represents an increase in productivity of more than 300%!
With the DMT module SDM1200, with a build-up rate of up to 35cm³/h and thus one of the fastest in the market, its possible to repair such punches very economically, at a fraction of the cost of conventional production.
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