CastAlum to process 700,000 castings per year for automotive customers

Aluminium diecaster CastAlum has invested in machining capability to process 700,000 castings a year for automotive customers.

The contracts are for the supply of machined steering gear housings and transmission cases. It won the contracts shortly after a management buyout in 2009 and before that had supplied castings to customers in their raw state for machining further along the supply chain.

To achieve the required machining volumes the company invested in a series of Heller twin-pallet, 4-axis, horizontal-spindle machining centres. These could be installed progressively as demand ramped up and, in contrast to a transfer line, could be reconfigured to produce almost any component in the future.

The first two machines, installed in 2009, were the company’s first machine tools.

There are now 10 Heller H2000 horizontal machining centres in CastAlum’s production hall at Welshpool. Each is able to machine any type of steering gear housing or transmission case in two operations, providing flexibility of manufacture. In practice, half are devoted to machining steering gear housings and the remainder to machining transmission cases. Cranes positioned between each pair of machines allows fixtures to be changed over quickly.

Castings arrive from the foundry mounted on carriers that travel on a long, U-shaped EWAB chain conveyor running past all of the machines, creating a lean manufacturing environment in a very tight footprint. Each carrier has a chip that identifies the type of casting and the intended destination machine, automatically diverting the castings into buffer areas on both sides of the line which enable operators to access them.

A raw casting is manually loaded into a fixture on a second machine pallet ready for op 1 after a previous, fully-machined part has been unloaded and a part-machined component has been relocated into another fixture for op 2. Both operations are performed on two different components per pallet every time it visits the spindle. So after a pallet index, a finish-machined casting comes off and is sent via the conveyor to the inspection department and on to dispatch.

Keith Brown, CastAlum’s managing director said: “The Heller machining centres have an average uptime of 95%, which is very high for manually loaded, twin-pallet machines. It is due to efficient presentation of material to the second pallets and from there to the spindles, which minimises changeover times.

“Apart from being reliable, the H2000s are also accurate and repeatable machines, even the early models that have been working hard around the clock, six days a week, ever since they were installed in 2009. We easily hold tolerances down to 10 microns and achieve a process capability of 1.67 Cpk.”

Another H2000 HMC is installed in a separate area of the Welshpool factory and a twelfth is due for delivery during the first quarter of 2015.