Pounding of cast iron

Jointly with some large customers, Römheld & Moelle addresses the development subject "Machine hammered peening of cast iron", also called "Pounding of cast iron surfaces".
This production process is continuously gaining importance and is increasingly used by more and more companies in tool making because it represents a minimized effort for the processing of cast iron surfaces that come in contact with the sheet metal when the tool is used.

In the past, the milling paths had to be ground manually after these surfaces were machined, which required effort and which was time-consuming. Since the result of the work step depends on the technical ability and the skill of the tool maker, the result of this work is individual and not reproducible and therefore it will be repeated several times until the result is in accordance with the required high accuracy. This means that the effort per component is on average more than two weeks in shift operation.

A reproducible process achieves a highly precise result since the cast iron surfaces will be pounded by a machine and no longer be ground manually after the milling process. The time required for the mechanical system in contrast to the manual processing is a total processing duration of only approximately 70 hours, which - provided by a machine - can be performed during a weekend or at night. In addition, the surface processed this way provides a surface structure that is very hard and which - due to its structuring - supports the flow of the sheet metal and reduces the tool wear.

We are interested in a technical cast and metallurgical optimization of the surface-adjacent cast iron quality. The hammering results in an extremely high punctual stress of the cast matrix. Small discontinuities in the micro-structure result, for example, in dents and bulges, which can have a negative impact on the results of the forming process. These finest discontinuities are hardly or not at all determinable before the hammering.

After several years of work, we have developed a method, which results in an especially fine and dense basic matrix of our cast iron near the surface. We were also able to apply experiences of our business segment "Machine casting", which produced for many years highest stressed machine parts such as gas turbines and ship propulsions with very high metallurgical requirements.

Jointly with some large customers, we have so far produced internal and structure parts as well as large external skin parts in "pounding cast iron quality". We were able to meet the high quality requirements in all cases.

This is an exciting result.


Picture 1: Machine-hammered surface sample body