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TOP - Environment / Energy, Topic Enviroment, Energy & Safety, Topic Lost Foam

09. October 2007

KLEIN Stoßwellentechnik GmbH

KLEIN Stoßwellentechnik GmbH

Final Decoring Cleaning and Discharging of Metal Chips at Castings

 

To fulfil the environmental and economical aspects for engines, in particular the cylinder heads got more complex cavities. The design of water channels of a thickness of only 2 to 3 mm which are hard to access from the outside is not seldom. On the other hand, engine parts need extremely higher cleanness levels because of smaller tolerances between all moving parts in the engine and because of more sensitivity to impurities of the installed new developed components. While 0.4 g of maximum impurities were allowed for 6 cylinder heads in the past, today the automobile industry is discussing about 10 mg or less. Only some sand grains or one or two small metal chips from tooling process will not fulfil the new automobile quality standard. A plug inside any channel of the casting will under no circumstances be allowed.

To solve this cleaning problem, KLEIN Shockwave Technology offers the CERABITE® process which has been used worldwide in the lost foam foundry industry for the last 11 years. The experience of this technology today is more than 8 million cleaned cylinder heads and blocks. Since July 2006 the same shock wave technology has been installed in the foundry of DaimlerChrysler at Esslingen-Mettingen for final removing of remaining core sand and layer. The process is proved also for the removal of thin inorganic cores at not accessible areas with guaranteed repeatability. These good results are based on the special form of hydraulic energy application of shock waves generated by underwater capacitor discharge.

The shock wave is characterized by an extremely short rise time up to 400 bar/µs and a high pressure amplitude up to 1,000 bar. Additionally, the shock wave is always reflected inside the casting which enables it to reach every area. Hard and brittle materials inside the casting are destroyed by the shock wave because they do not withstand the quick pressure change of the shock wave front.

Reflection of the shock wave inside the casting

 

Parts2Clean: Stand E 541, Hall 9

To make most efficient use of the shock wave energy, two castings like cylinder heads are immersed contemporaneously into the water and positioned on each side of the electrode. The worldwide installed CERABITE® plants are running with a cycle time of 25s for one cylinder head. The handling of the cylinder heads is done by robots and casting fixtures which position the castings in front of shock wave generation.

CERABITE® plant are always designed for customer purposes and are programmable for chaotic charging with different castings at the same time.

One more special difficulty is the removal of chip jams which consist of long spiral chips. These chips can by no means be pressed through narrow passages unless they are destroyed with the help of the applied technique. Special tests show that such spiral chips up to a maximum thickness of approx. 0.3 mm are broken by the shock wave treatment and then pressed outwards through the inner channels of the casting by subsequent shock waves, supposed the channels are not constructed as dead ends.

The result of more than 8 million cleaned motor blocks and cylinder heads applied in the automobile industry has proved to be effective also for the removal of core and sand plugs from the most difficult areas in highly complex cylinder heads.

Due to the high degree of cleanness – with regard to sand and coat residues – that can be realized, as well as the reliability in removing metal chips, the CERABITE® process provides the solution for achieving the high cleanness levels required for the final cleaning of cylinder heads to fulfil the new automobile quality standards.

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