CHIRON HIGH-SPEED
MACHINING CENTRE MAKES VALVE MANUFACTURER
WORLD-COMPETITIVE
The
capabilities of Chiron vertical machining centre technology are playing
a key role in the worldwide success of a product designed, developed and
manufactured in Britain by
Maxam Pneumatics of Cornwall.
Thanks to the high spindle speeds, fast traverse rates and super-quick tool change provided by the Chiron FZ12W Magnum - as well as the machine’s ease of use, rigidity and reliability - average cost savings of up to 38 per cent are being achieved on a series of valve bodies.
The bodies form part of Maxams’ novel design of remote valve islands, which can be configured with varying numbers of ports and which interface with PCBs to effectively create a DNet system that could control a complete factory via remote PC.
The savings being achieved with CNC machining compare with traditional vertical machining centre (VMC) routines on a series of ageing machines at the 87-employee site in Redruth, as operations director, Charles Jones, explains.
“During the product development cycle for the modular valve range, we knew that we had to achieve ambitious cycle times for valve body machining if we were to meet stringent product cost demands.
“We also recognised,” he continues, “that our existing multi-pallet VMCs couldn’t meet the twin requirements of speed and flexibility to handle this new family of parts.”
Apart from specified speeds and feeds, Charles Jones quotes the Chiron’s overall performance in the field as another main reason why it was chosen over competitor brands.
“We approached an existing Chiron user,” says Charles Jones, “not only to see the machine in action but also to quiz the owner on whether the machine actually does what Chiron says it could! We needed to be certain that we were making the right choice, because at that time (early product development) no metal had been cut and we needed to make a commitment.
“We put similar questions concerning machine rigidity, reliability and user-friendliness to a number of VMC suppliers, and ascertained their views on inter-operation workpiece handling and their machines’ ability to process small parts consistently.”
The design and production processes surrounding the new valve range actually promoted a sea change in working procedures at the site, says Charles Jones. These are based on re-arranged assembly areas as well as re-organised manufacturing methods centred around the Chiron as well as the introduction of bought-in, close-to-finished-size aluminium extrusions that minimise machining requirements.
The introduction of the Chiron was a culture shock in itself, he adds, since the operators we’re initially sceptical of the machine’s capability at such feeds and speeds - the 45 kW motor produces spindle speeds up to 20,000 revs/min, traverses of 60 m/min and a tool change time of 0.9 sec with chip-to-chip in 2.4 secs.
“Featuring Fanuc CNC, the Chiron maintained our commonality of VMC control technology, but the biggest difference today is that the operators prefer to program on the machine rather than offline - which to me is another demonstration of the machine’s ease of use.”
With X, Y and Z axes travels of 550 mm by 300 mm by 425 mm, plus 190 mm to 615 mm between spindle taper and table, the Magnum is equipped with workpiece changer, for quick and simultaneous load/unload during machining.
Valve bodies are loaded as singles or pairs, depending on size, and located on a dowel pin datum to the rotary table fixture supplied as part of the turnkey package by Chiron Werke UK. The mixture of milling and drilling operations are split across two operations on the bodies which, in this example, measure 16 mm wide by 28 mm deep and 50 mm long.
The first operation sequence embraces external milling of one face and both ends using a 50 mm diameter face mill. This is followed by:
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Drill and tap four M2.5 holes (two in each end) 8 mm deep;
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Drill two holes of 1.5 mm diameter and 25 mm deep from each end;
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Drill a 2.2 mm hole 14.5 mm deep;
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Drill and ream a 7 mm bore 50 mm long through body;
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Interpolation of five internal recesses of 4 mm wide by 8.5 mm diameter through length of body, and cut three grooves from one end of body and two from opposite end.
Operation two sequence is:
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Drill and tap five G1/8 ports 8.5 mm deep, three ports on one side and two from the opposite side;
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Slot drill five slots of 3 mm at the bottom of each port breaking into the recesses;
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Drill two holes of 2.65 mm diameter and 28 mm deep;
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Slot drill two 5.50 mm diameter by 7 mm deep counterbores from the two-port side.
Total cycle time for the complete body is 3 mins 38 secs.
The internal recess accommodates a neoprene spool seal valve that is guaranteed to offer a minimum life of 10 million cycles. High-accuracy machining is essential here so, in addition to diamond reamers, the internal recessing is achieved with the use of a special-purpose carbide cutter. Again, the tooling was supplied as part of the turnkey by Chiron Werke UK.
“The machine has lived up to all expectations,” comments Charles Jones, “and is running 22 hours a day. I would love to be able to transfer some of our older product onto it, to gain similar cycle time savings, but the fact is our new product volumes are increasing all the time.”
Within 10 months of introduction, the new valve islands were accounting for 25 per cent of production - 80 per cent being exports, including the largest order to date for a series of 41 islands for a shoe manufacturing plant.
“We have identified an enormous market for valve islands like this,” concludes Charles Jones. “This product is our future and, thanks to the Chiron, we are able to produce it at a world-beating price.”