Citizen Lathes Help Metaltech Boost Productivity

Metaltech Precision has invested in six new machines over the last two years, including mill-turn centres and a Citizen A20-VII CNC sliding-head lathe. At the same time, the heavy fabrication area has been expanded and a second paint shop established on the company's four-acre site in Chard, Somerset. Metaltech purchased the A20-VIIPL to improve productivity on an existing contract for oil-filter spindles destined for truck engines.

The machine, now installed in a one-operator cell with a centre-less grinding machine, has reduced cycle times by some 20 per cent from previous machining methods. According to machine setter Olly Facey, there are other immediate benefits from the Citizen installation. He said: 'For me and my opposite number on the second shift, the operator interface at the control could have almost have been written for us. 'Access for tool change is ideal and very quick [through the Citizen-/Sandvik-developed QS system, which can take as little as 40 seconds to complete] and, through a typical batch of 3,000 parts, the machine is so consistent that offsets and tweaks to maintain SPC targets are rare,' added Facey.

The Citizen A20 is also said to be recording an improvement in tool life of some 30 per cent, even when using identical cutting oil; the same proven speeds and feeds are used as on the previous sliding-head machines. Here, stability was a key element in the design of the machine with its compact structure and the inherent rigidity of the casting, particularly with its ability to absorb any vibration generated under cutting conditions. The Citizen A20 offers rapid traverse rates of 32m/min, achieved by very high rates of acceleration.

It can also cut with two tools simultaneously and, through the faster processing capability of the Streamline Control, has the ability to overlap different sequences. Both the main spindles and sub-spindles of the machine have maximum speeds of 8,000rev/min with full C-axis and four 6,000rev/min-driven tools. One of these tool positions can also accept rotary-, face- or slitting-style tools. Two of the filter shaft components produced on the machine are very similar; the third is 168mm long and requires a major reset.

All three are produced from 16mm-diameter Hitenspeed 45A and have critical sealing diameters of 13mm that are turned to a process size of +0.08/0.10mm in diameter, ready for heat treatment followed by plunge-feed centre-less grinding. Each end of the larger 168mm-long shaft threads of M10 x 1.5 and M12 x 1.75 is respectively cut in the main spindle and sub-spindle positions. There are also undercuts, relief diameters and various blend radii and chamfers.

A deep hole of 5mm in diameter by 55mm in depth has a 5mm diameter through-cross hole. The Citizen Coolblaster II high-pressure coolant system enables a high penetration rate to be achieved and ensures a good clearance of swarf. As a result of its programmable nature, the Coolblaster is also used to flush the sub-spindle collet and to keep tools and the machining area clear of swarf. Metaltech supplies parts to the pump, machine-tool, medical, print, tobacco, hydraulic, rail, automotive and high-end motorsport sectors.