GMC : ELX Valve Body

Gujarat Metal Cast (GMC) is a foundry specializing in lost foam aluminum casting based out of Gujarat, India. Rollamo Engineering has been machining variety castings for GMC for more than 20 years. In 2007, Rollamo worked on a critical project for machining an aluminum casting called ELX valve body, which was a hydraulic system part for its end customer Wabtec Corporation in USA


ELX valve body had a critical lost foam mold with size of 1m x 1m x 1m. The casting had an overlapping slide core on all four sides which were synchronized with a PLC system. Additionally, the 108 features on the valve body casting amplified the manufacturing complexity.


Critical machining of the ELX valve body involved 84 operations from all 6 sides. This involved 12 different setups with 0.1 mm to be maintained from one setup to the other. Rollamo developed fixtures in-house to maintain this criticality between all setups and hence the overall quality of the machined casting.


The engineering team changed the manufacturing process for a critical taper bore, with a tolerance of + 10 micron and surface profile within 7 micron, from vertical milling to CNC turning. This significantly reduced the non-conformance of the component from 10-12% to 0.25%.

A special 3 point air gauge measuring system was developed to maintain the quality for on-line inspection of the parts

A special probe, compatible with height master, was developed and manufactured to measure and control the groove depth in micron