A dedicated flexible machining cell installed at Birmingham fuel systems company SU Automotive goes into full production in November, producing 1,500 aluminium throttles a week for a new version of a V6 engine. The throttle is a two-part pressure diecast assembly made up of main-body casting and speed-control valve. It is available in three models, which can include traction and/or cruise control.
Each variant can be made without modification to the machining set-up. There are five machines in the cell, which follows the Japanese Nagare principle of using people not automation to load and unload machines for parts weighing up to 10kg in annual production runs of up to 80,000.
Together the machines carry out facing, precision boring, milling, drilling and bushing operations. The cell, developed for single-person operation, has a cycle time of 2 minutes 30 seconds per throttle, including assembly and quality checks. Machines that use twin fixtures on a common table for sequential operations have automatic ejection of the part on the second fixture. Three new machines a Kira single-axis CNC drill, an Enshu drilling/light milling centre and an Enshu horizontal machining centre supplement a machining centre and special purpose bush assembly machine.
On the Enshu E130 machining centre, rapid traverse and spindle acceleration and a one-second tool change almost eliminates idle time.
Outsourcing of its machining requirements is no longer an option for British Aerospace, Salmesbury, following a detailed costing of parts production.
The company has found that 85% of aircraft specification aluminium components which fall within a 600mm2 envelope, will benefit from five-axis machining. Armed with this knowledge, the company has invested in a £7.8m flexible machining system supplied by 600 Centre.
The cell has three Mitsui Seiki HS 5A-5X high-speed, 20,000rpm, five-axis horizontal machining centres which form a fully integrated linear FMS.
A rail-guided stacker crane services a 96-capacity Euro pallet raw material handling system. Parts are supplied to the machines from a 40-position pallet stacker by pallet transportation equipment.
There are two work setting stations, a wash machine, a 600-capacity central tool store with presetting automatic tool gantry delivery system, and full coolant and swarf management.
The cell, commissioned in January, is due to be extended by a fourth Mitsui Seiki machine, which will take production up to 80,000 parts a year in batches of up to 12 parts.
Two heads better than one
T he adage ‘biggest is best’ is often ascribed to aerospace industry subcontractors, and Crest Engineering is no exception. It bought a Sachmann T20 profile mill, with extended column and Heidenhain five-axis controller, for accurate machining of jigs and fixtures to tolerances of 0.02mm over 2m.
But almost before the ink was dry on the contract, Crest specified an additional two-axis head to provide full five-axis machining for drilling and slot milling. The machining envelope is 3.8m x 1.2m x 1.5m high to cope with future requirements.
Subcontract machinist Orbit Precision has halved production time, reducing the number of operations from six to two, by exchanging a vertical spindle machining centre for an Okuma & Howa 40H horizontal spindle machine supplied by Whitehouse Machine Tools.
The machine is being used to produce brass valve blocks for an anaesthetic delivery system. The Orbit has a 400mm2 pallet with 6 second pallet change; 560mm travels and rapids of 30m/min in each axis; a 22kW/10,000rpm spindle; a 1.7 second tool change time; and optional 80-station magazine for No 40 taper tools; and ample memory on the GE-Fanuc controller.
Woodworking power tools maker Delta has raised productivity by 35% and improved quality by replacing two machines with a modern horizontal machining centre the Ram 630 machine supplied by Giddings & Lewis.
The Ram 630 has twin pallets, each 500mm2, and a 40-tool capacity automatic toolchanger. The machine is a new process for Delta and was recommended for the purpose by the company’s new technology team.
There are fewer set-ups when machining cast-iron table tops fitted to stationary power saws. These can measure up to 686mm x 508mm and weigh 36kg.
GIDDINGS & LEWIS