Twin-spindle lathe maximises flexibility

Citation

(1998), "Twin-spindle lathe maximises flexibility", Aircraft Engineering and Aerospace Technology, Vol. 70 No. 6. https://doi.org/10.1108/aeat.1998.12770fab.002

Twin-spindle lathe maximises flexibility

Twin-spindle lathe maximises flexibility

Keywords Aeroengines, Machine tools, Whitehouse

The ability to maximise production efficiency, whatever the circumstance, has been the major benefit of investment by aero engine pipework specialist B & D Patterns Ltd in a Biglia B200F twin-spindle lathe from Whitehouse Machine Tools. Having the footprint of a conventional single-spindle CNC machine, the B200F's twin spindles offer a genuine doubling of capacity due to its front loading format and facility to operate each spindle/turret pairing as a separate machine (Plate 1).

B & D Patterns' operations director Mike Stripp commented, "The big strength of the Biglia design is that we can ring the changes on how we operate it according to our production requirements. If we have a job that can conveniently be split into two balanced operations, then we can perform Op 1/Op 2 sequentially and get a finished part off with no floor time.

"Equally, if we have a job where the first operation is long but a short second operation is needed, we can maximise productivity on the Op 1 by having both spindles running an identical program and performing Op 2 on one of our other single-spindle machines. Either way, the Biglia is a major asset in reducing lead time."

Hinckley-based B & D Patterns is a leading supplier of fuel and lubrication pipework for aircraft engines, working almost exclusively in stainless steel. Pipework is produced to customer order and comprises a combination of precision bent tube and machined unions including elbows and tee pieces. Manufacture is to the highest standards with assemblies subjected to thorough visual and non-destructive tests.

Plate 1 The machining area of the Biglia B200F twin-spindle, front-loading lathe installed at B & D Patterns

The company manufactures all its fittings from a mix of bar stock and forgings. Machining operations comprise turning (80 per cent) and second operation milling and drilling (20 per cent), almost entirely using CNC machining facilities. Batch quantities average around 75-off and operational cycle times range from three to ten minutes. According to the component, tolerances may be tenths or ten thousandths of an inch.

Mr Stripp explained, "The motivation for purchasing a twin-spindle machine such as the B200F came from a need for higher production efficiency. Because of the lathe's configuration, one operator can do what would otherwise require two men and two machines. Being able to separate operation of the two spindles is very important to us as it allows us to machine completely different components simultaneously and to load and unload each spindle independently. This would have been impossible with a horizontally-opposed spindle layout."

All components produced on the B200F are chucking work, some of it utilising special turning fixtures and jaw sets produced in-house. Programming is carried out off-line, B & D's programmers having quickly become familiar with the machine.

One typical component, an elbow machined from a stainless steel forging, is representative of the work allocated to the B200F. It is produced in two sequential operations, taking six minutes for Op 1 and 4.5 minutes for Op 2. For the first set-up, on the left-hand spindle, tightest tolerance is on the spherical union which is held to 0.0005 inches. The undercut diameter is produced to a tolerance of 0.005 inches on diameter with the same tolerance on its radius. The bore diameter is held to 0.0025 inches.

The component is completed on the right hand spindle. Op 2 machines the weld lip for assembly of the elbow to the pipe. Tightest tolerance is 0.0015 inches on the lip depth. Other key dimensions are the lip end diameter and the bore diameter, both of which are held to 0.0025 inches.

Mr Stripp concluded, "The machine is perfect for producing this type of component as we can set-up and finish a batch in around two thirds of the time needed for separate operations on single-spindle machines. We are very pleased with the efficiency improvement that the Biglia has brought to our manufacturing operation and have been equally pleased with the back-up that Whitehouse has provided."

Further details are available from White house Machine Tools Ltd. Tel: +44 (0) 1926 852725; Fax: +44 (0) 1926 850620.