Rösler Oberflächentechnik GmbH

Partial shot blasting of cylinder heads

The two compact turning chamber shot blast machines were integrated into existing manufacturing lines.

A leading car manufacturer based in Southern Germany has integrated two turning chamber shot blast machines into existing manufacturing lines allowing the partial shot blasting of cylinder heads.

After a first machining process cylinder heads are contaminated with metal shavings and residual sand from the casting process. To remove both from the part surface this car manufacturer integrated two identical shot blast systems into existing manufacturing lines. Since space was very tight, the equipment design had to be extremely compact. Another requirement was the precisely defined surface area that had to be blasted, namely the combustion chamber side of the cylinder head. In addition, three bore holes and an existing matrix code had to be protected from the blast stream. With the compact turning chamber blast machine RWK 6/12-2 with an allowable work piece diameter of 600 mm (24”) and allowable height of 1,200 mm (48”), Rösler offered the ideal solution. Each machine has two chambers so that the loading/unloading of a part can take place while another part is processed. Two Hurricane® turbines, type H 32, with 7.5 kW each provide the required blast intensity.

Part loading, placing protective covers and shot blasting in 60 seconds

A robot equipped with a gripper system that was specially designed by Rösler, picks up the work pieces so that the area on the parts to be blasted is always in an ‘up position’. The three bore holes and the matrix code are automatically protected with built-in pins and a cover. After the cylinder head has been placed into a work piece fixture, the carousel rotates to move the cylinder head into the blast chamber. For wear protection the blast chamber is made from manganese steel and lined with overlapping wear plates. During the blast process the work piece fixture makes an oscillating movement, thus ensuring that only the pre-defined area of the cylinder head is exposed to the blast stream. After the blast process the carousel rotates to move the part back to the load/unload station where the robot removes the finished cylinder head. The overall cycle time including part loading & unloading, placing the protective covers and shot blasting amounts to only 60 seconds.

To prevent that the sand and shavings removed from the part surface contaminate the blast media, the two shot blast machines are equipped with classification systems for removal of the sand and shavings from the media.