Gienanth Company located in Eisenberg, Germany, has been producing castings for nearly 280 years. It is not surprising that with its long history, combined with comprehensive knowhow and state-of-the-art manufacturing facilities, this steel foundry is the global technological leader in the fields of machine and hand molding. The hand molding division specializes in the serial production of heavy engine blocks. Frank Koch, the manager of the hand molding division at Gienanth, comments: “We are currently manufacturing about 25 different types of these engine blocks. Our latest product has dimensions of approximately 3.5 (L) x 1.0 (W) x 1.1 (H) m, equivalent to 12 (L) x 3.3 (W) x 3.6 (H) ft and weighs around 5,000 kg (11,000 lbs). Our existing shot blast machine was too small to handle such big components and a constant bottle neck in our overall manufacturing process. We had no choice but to invest in a new shot blast system.” Therefore Gienanth decided to buy the custom engineered engine block shot blast system RMBS 1-842 from Rösler Oberflächentechnik GmbH.
New shot blast system for cleaning engine blocks
Gienanth uses the engine block shot blast system RMBS 1-842 for de-sanding of the largest crank case housings as well as for blast cleaning and descaling of all engine block versions for example after the fettling operation. Eight high performance blast turbines, type EVO 38, with a drive power of 30 kW each, provide an optimum blasting result. Since all blast turbines are equipped with shell valves, the media flow to the turbines can be adjusted for each individual engine block and shot blasting task: For example, when components must be de-sanded, including core sand removal, the system has not only to cope with the work piece weight of 5,000 kg (11,000 lbs) but also with a sand quantity of about 4,000 kg (9,000 lbs). In this application the process begins with 2 turbines and, depending on the blast program, the other turbines are automatically turned on in a pre-determined sequence. This prevents a sudden sand surge and helps to “peel” off the sand in small layers ensuring that the integrated magnetic separator can remove the sand from the blast media to the specified cleanliness – residual sand content in the blast media < 0.20% - without being oversized for blast applications with less or no sand.
Component rotation and oscillation during the blast process
Highlight of the Rösler shot blast system is the specially designed manipulator with two built-in grippers allowing the treatment of one large or two smaller engine blocks. The components are placed by a cart into their exact position within the blast chamber where they are picked up by the gripper. As soon as the blast chamber is closed, the gripper precisely rotates the engine block(s) under the blast stream. The manipulator also allows an oscillating gripper movement which is especially important for processing of smaller components. After completion of the blast cycle the media flow to the turbines is stopped, and the components rotates for another 10 seconds to shake out all residual blast media. Depending on the respective blast program the cycle times are usually between 12 and 20 min.