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Fewer burrs during forging. The multi-directional forging tool moulds metal not just with pressure applied from above, but from the sides too.
© IPH - Institut für Integrierte Produktion Hannover
Material-saving forging
18.03.2015

The proportion of burrs is significantly reduced on a multi-directionally forged crankshaft (right) compared to a conventionally forged crankshaft (left).
© IPH - Institut für Integrierte Produktion Hannover

The forging of crankshafts is performed in five steps: The fourth involves the multi-directional tool, the final step an eccentric press.
© IPH - Institut für Integrierte Produktion Hannover

New forging process reduces proportion of burrs from 54 to 7 per cent

A newly developed forging process is saving material and energy. In the “multi-directional forging” process, researchers have been able to reduce the proportion of burrs when forging crankshafts from 54 to 7 per cent, with associated energy savings of roughly 20 per cent. The process has already been successfully tested in industrial application.

Developers at Institut für Integrierte Produktion Hannover (IPH) have been able to significantly reduce the proportion of burrs when forging a two-cylinder crankshaft as part of the REForCh (Resource efficient forging process chain for complicated high duty parts) EU project. Considerably less steel now needs to be used compared to the current conventional forging process. In the current process, 10.8 kilogrammes of steel is required for a crankshaft weighing seven kilogrammes. In the new, multi-directional forging process, 7.5 kilogrammes of steel is sufficient: The proportion of burrs is reduced from 54 per cent in the current process to 7 per cent. As less steel needs to be heated, the new procedure achieves energy savings of approx. 20 per cent.

Multi-directional in place of conventional forging

In the conventional forging process, the workpiece is reshaped exclusively via pressure applied from above. Burrs are produced during the forging process as a result of excess material escaping to the sides when the die is filled completely. On more complicated moulds such as with crankshafts, the proportion of burrs can top 40 per cent. These burrs must be subsequently removed.
In multi-directional forging, the heated steel is shaped not only from above, but simultaneously by pressure applied from the sides. This facilitates greater control of the steel mould and uses less material.

Video of the process:

New process saves material and energy

Reduction in the proportion of burrs from approx. 54 to approx. 7 per cent equates to a saving of around 3.8 kilogrammes of steel per crankshaft. As less raw material needs to be used, the energy consumption per workpiece is reduced by around 20 per cent, although the relative energy consumption for heating is up to 15 per cent higher than in the conventional forging process.
The process chain with the multi-directional tool was tested at Turkish forging company Omtaş Otomotiv Transmisyon Aksami. Following the pre-moulding process, the workpieces were uniformly reheated in an induction heater in order to offset the temperature loss during the pre-moulding processes and to heat the workpiece through consistently. Energy expenditure in the multi-directional process consequently could be kept low. The final forging stage followed in an eccentric press with a force of up to 40,000 kN.
Omtaş produced prototypes of two-cylinder crankshafts for quad bikes and snowmobiles. The company also hopes to manufacture other types of crankshaft using the technique. 
Material consumption accounts for the lion’s share of the production costs in forging. In the case of steel, this can be as much as 50 per cent of total costs.
For an annual production capacity of 10,000 crankshafts of this design, the researchers expect potential savings of 34 tonnes of steel. Reduced energy consumption will save a further 2,000 euros.

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Addresses

Project management, forging tool development
IPH – Institut für Integrierte Produktion Hannover GmbH

Moulding tool manufacture
Aurrenak

Forging of crankshafts
Fa. OMTAŞ A.Ş

Material research, process engineering
Metav

Inductive heating processes
Leibniz Universität Hannover, ETP

Induction heater manufacture
EMA-TEC GmbH

Links

 REForCH project
EU project website

REFORCH Report Summary
Project interim report