Speed steers choice of CNC

Tight tolerances and a high throughput of 500,000 parts a year led subcontractor Morris Ashby Castings to choose a CNC tapping centre with pallet changer, rather than a lathe with single-point machining, to turn the end features on an L-shaped aluminium diecasting used in a vehicle power steering pump.

Two special tools in the turret of the Brother tapping centre are used first to machine an internal 13mm diameter groove and two external diameters (one at 16mm) as well as spot facing and chamfering the end.

By performing the OD operation last, burrs from grooving are neatly removed. Special fixturing holds two sets of 12 parts on a rotating pallet. Overall cycle times are 9.11 seconds per part. A Horn bell milling cutter with four heads carries out critical groove milling in 3.03 seconds, almost double the speed of a single-point recessing head one option considered using the machine’s Z-axis. To meet production targets the 6kW, 10,000rpm machine with its 30m/min traverse in all linear axes runs uninterrupted over two or three-shift working.


A special-purpose machine with trunion fixturing produces two components every 16 seconds to ensure a US volume producer meets an annual target of three million universal joints for cars.

The Gnutti carousel machine reams two cross-holes 27mm wide in cast steel ball joints, accurate to 7um. Tooling in the 8-station carousel includes pre-ream cutters used to straighten drilled holes.

Reaming is done using Brunswick’s AFP Reamer coated with TiN for long life. The 1700rpm spindle produces an equivalent surface speed of 25m/min and feeds of 1.5mm/rev.


A combined brake drum and wheel bearing assembly developed by steel producer SKF should cut inventories and assembly times and improve vehicle performance by lowering the unsprung mass.

The Hub Unit 5 combines the low weight benefit of a flanged bearing assembly with the operational stability of conventional brake drum design, the company says.


Vehicle test systems company Anthony Best Dynamics has developed a computer-controlled steering robot used to simulate industry standard steering inputs to vehicles during track tests. Providing more reliable test data than a human driver, the robot ensures reliable comparison between vehicle setups. It can be used in trucks.