Lights-Out Machining Boosts Turning Capacity

A Colchester Tornado A50 CNC lathe, equipped with a bar feed, Renishaw probing, tool monitoring, pickoff unit, swarf conveyor and production-scheduling software, is providing lights-out production capability for Altex Engineering, a (Calne, Wiltshire) U.K. precision subcontractor that specializes in turning and milling in addition to sheet metal fabrication using laser cutting, punch press and folding equipment. With the new CNC lathe, Altex has increased productivity by more than 50 percent on a range of turned components, some 80 percent of which are now completely machined in a single setup. Altex expects even better results as it gains more experience with all of the machine’s automation features. The turning side of Altex’ business includes a range of components for vending machines, office equipment, lighting, materials handling, health care and other products, in batch sizes from 500 to 1,000. Materials machined include mild steel, stainless, aluminum, brass and nylon. The components produced on the A50 range in size from around 0.4 inch to 1.5 inches in diameter.

The machine runs largely unattended during the day. Depending on production schedules and the type of work being run, the lathe may run completely unattended at night. ‘Lights-out working’ is seen as providing additional turning capacity at virtually no extra cost, and it is an important factor in helping to shorten delivery schedules on certain jobs. During the day shift, one operator looks after the A50 and two other Colchester Tornado lathes in addition to performing setup, bar replenishment and part inspection.

Once the A50 is set up and running, it rarely needs any offset adjustments to maintain tolerances. A torque-based tool monitoring system senses worn or broken tools. When an established limit is reached, the software stops the machine for replacement of the worn tool by the operator or tells the machine to use a backup tool mounted in another turret position.

The operator can check the screen of the Fanuc control at any time to monitor actual tool loadings in real time. Tool wear registers as an increase in the level of torque demanded. Altex finds that it gets very consistent results with the system in terms of both surface finish and tool wear patterns.

The bar feed system is fully integrated with the machine, enabling it to be programmed at the Fanuc control. There are no mechanical stops to set, and change-over takes less than 15 minutes. Each bar is measured, and the software computes the number of pieces that can be produced from each bar. From this information, the system automatically recalculates how many pieces are left for the Tornado to machine and then stops the cycle.

The Toronado A50, available from Clausing Industrial Inc. (Kalamazoo, Michigan), has a 42-mm diameter bar capacity and a 12-station turret. Constant surface speed from the 6,000-rpm spindle powered by a 7.5-hp motor ensures good surface finish. Control is from a Fanuc 21-Ti system. The short, Colchester-designed, magazine-type bar feed allows the lathe to run at optimum speed without vibration, so workpiece surface finish standards are always maintained.