An innovative shot-blasting machine has expanded de-sanding and cleaning of engine blocks for a large Turkish foundry. A significant factor in its selection of the Rösler RMBS 1-6-400-30 shot-blasting system was the high degree of automation for workpiece handling and the shot-blasting process. Compared to a spinner hanger machine, the RMBS offers much shorter cycle times and require fewer workers to operate.
And by replacing two blast machines, the new system is providing valuable additional manufacturing space.
The foundry’s products include gray and ductile iron engine blocks for commercial vehicles and ships. The raw castings measure up to 900x330x140 mm and weigh up to 237 kg. De-sanding and cleaning the workpieces had been done by spinner-hanger blast machines – one for de-sanding and another for general cleaning. As production volume increased, the shot-blasting operation increased as a bottle neck. This prompted the decision to install an additional, but alternative, shot-blasting system.
Specially designed for engine blocks
Among the four options considered, Rösler Oberflächentechnik GmbH offered a novel and efficient equipment concept. The RMBS 1-6-400-30 engine block blasting machine, specially adapted to customer requirements, allows fully automatic simultaneous blast-cleaning of one large or several smaller engine blocks, with short cycle times.
The machine is equipped with a specially engineered gripper-manipulator. After a robot has precisely positioned an engine block in the blast chamber, the gripper picks up and firmly holds this engine block. Once the blast chamber door closes, the customized blast program starts. The gripper precisely rotates the workpiece through the blast media stream. To increase the exposure of certain surface areas of the engine block to the blast media, the rotation can be slowed down or interrupted for a pre-defined time period.
Several smaller workpieces can be processed simultaneously by mounting the blocks to a special fixture that is picked up by the gripper and rotated through the blast media stream.
Increased operational efficiency
With the old spinner hanger blast solution, the workpieces had to be loaded manually onto a special “hanger” before they could be blasted. The new system achieves the required blast results by the targeted movement of the engine blocks through the blast stream. The cycle time savings are such that the de-sanding and surface cleaning operation can be combined into a single process.
This has increased shot-blasting capacity significantly, such that the two spinner hanger blast machines were no longer needed. Moreover, the risk that certain workpiece areas are shielded from the blast stream by other workpieces is eliminated now. Besides higher productivity and process reliability, the foundry reports that Rösler system needs considerably fewer personnel to operate it.
Minimize maintenance costs
Shot-blasting achieves the desired results quickly thanks to the six, type Gamma 400G-8 HD blast turbines, each with an installed drive power of 30 kW. Specially developed for shot blasting in foundries, these turbines are equipped with eight throwing blades in the typical Y-design (versus the standard Gamma turbines with six blades.)
Another feature of the HD turbine is that its housing is lined with highly wear-resistant tool steel.
Thanks to this special design the throwing blades achieve up to three times longer uptime than their standard equivalent, which minimizes work for maintenance and ensures significantly higher productivity and cost-efficiency. The special throwing blade design generates up to 20% higher blast intensity and lower energy consumption.
Another feature of the Gamma turbines is that both sides of the throwing blades can be used, resulting in significant cost savings for spare parts. Blades are changed in a quick-change procedure that requires no removal of the turbine from its housing.
The blast chamber was designed for high wear resistance, too, with manganese steel and lined with easily replaceable plates made from wear-resistant steel. Areas directly exposed to the blast stream are lined with special cast wear plates.