Universal Lathe Improves Turning Capability

Peter Brotherhood (Peterborough, United Kingdom), a steam turbine manufacturer, recently discovered a bottleneck when turning a range of power-generation components. When the company implemented a Gildemeister CTX 620 V4 linear universal turn-mill center by DMG, however, the problem fixed itself. The machine not only eliminates secondary operations because of its heavy-duty, Y-axis turret cross-feed capability, but also reduces subcontracting expenses.

Although Peter Brotherhood already used a turning center to produce land-based turbine and gas compressor parts, features such as keyways had to be machined as an additional operation. Furthermore, despite running its existing machine continuously during three shifts, the company still had to outsource components to subcontract suppliers in order to meet its customers’ demands. The current lathe has about 11,000 component programs on file, which gives an indication of the company’s scale of turned part requirements.

Dave Head, production manager, says, “We looked at a number of CNC lathes that we thought would solve our capacity problem, but the turn-mill center from DMG stood out because of its specifications, capacity and price. With a swing of 800 mm and Y-axis cross feed of ± 70 mm, we could easily see it would accommodate our work, and therefore negate the need for secondary operations.” The driven tool unit on the machine is also between 3 and 4 times more powerful than the company’s existing lathe, so the turn-mill machine can easily produce the type of features Peter Brotherhood has to machine.

The machine features a 2,100-mm bed and a Fanuc 160i control. It has a 43-kW direct-drive spindle with 2,500 rpm and 2,200 Nm of torque. Idle times are reduced to a minimum because of the high dynamics of the linear drives that enable rapid traverse rates as high as 60 m/min to be reached with an acceleration of 1.5 G in the Z axis. Preloaded precision guides combined with direct measuring systems guarantee high accuracy at rapid metal removal rates.

The turbine and compressor parts that are turned on the unit have a tolerance requirement of 0.025 mm. Most of the components, including valve covers, gear shafts and valve cages, are machined out of hard steels demanding a turning platform with high levels of rigidity and significant levels of power.

By implementing this turn-mill center from DMG, Peter Brotherhood has saved time and money by eliminating secondary operations. The company is now producing more components on a more efficient machine than the lathe the company used prior to this purchase.