Until the development of electrical discharge grinding (EDG) technology, polycrystalline diamond (PCD) tipped tooling was manufactured and sharpened by grinding with diamond wheels.
This is difficult, time-consuming and expensive and it is not possible to produce complex forms of tooling – which limited the potential applications for PCD tooling.
EDG answered these problems. The technology involves generating a high-energy electrical spark that discharges between an electrode (a rotary disc or a wire) and the PCD. The spark vaporises the PCD in a controlled manner to produce the desired shape and sharp cutting edge.
Vollmer has played a leading role in developing EDG machines for efficient and economic manufacture and sharpening of PCD tooling and sawblades. Its first machines were the QF and QR models for the tooth sides and tops, respectively, of circular sawblades. These were followed by the QW eight-axis universal machine, which erodes shank and tapered tooling, cutterblocks and hogging tools as well as sawblades; and then the QM, which handles the same range of tooling as the QW but is designed particularly for sharpening.
Further development
These machines use rotary disc electrodes, but Vollmer has also developed machines that use a wire electrode. The QWD and the latest QWD76P (designed specifically for metalworking tooling) produce profile tooling, milling cutters, shank and disc-shaped tooling.
The QWDs produce complex profile tooling with great precision because the ‘E’ axis (which moves the wire) maintains a constant position at the point of the cutting edge currently being machined. This means the required clearance angle is precisely produced at any point on the profile.
Vollmer machines incorporate metrology systems which measure the tooling before and after machining – which minimises tool handling and ensures accuracy. They also include a fire extinguishing system to provide essential safety during unattended automatic operation. In addition to multi-national customers like Leitz, Leuco and Unimerco, UK customers for ‘Q’ machines include Lynden Tooling Services, Prima Tooling, Systco-Unilap and Supreme Saws.
Lynden Tooling Services of Gilberdyke in East Yorkshire was established five years ago by partners John Thompson and Paul Hillerby, both former employees of a major UK furniture manufacturer, where John was group tooling manager for 20 years and Paul was involved in designing tooling. ‘Our former employer was one of the first in the UK to use it,’ said Mr Thompson. ‘With large batch production, tool changing was a major factor, and PCD tooling only had to be changed once a month compared with two or three times per shift for TCT tooling. We also found that when routing PVC-coated MDF doors, PCD gave a much better finish than TCT and eliminated a lot of sanding work.’
Lynden bought its QW in May last year to meet demand for tooling such as shear tip routers which were time consuming and uneconomic to produce to the required quality on the company’s wire erosion machine.
‘The QW measures tooling before and after erosion and the tooling is rotated during the process, which our fixed axis wire erosion machine could not do,’ said Mr Hillerby. ‘We used to send this work out for sharpening, and the QW has allowed us to bring it all in-house.
‘We have also been able to expand into other areas by making PCD tooling that we could not produce before. Since installing the QW we have quadrupled our business: PCD tooling is now a major part of what we do, and 60% of it is done on the QW.’
Lynden Tooling is taking over the adjacent factory to double its floor area which, together with investment in a new QWD, will allow expansion into other industries as well as providing capacity to meet growing demand from the woodworking sector.
Prima Tooling was established in 1979 and was one of the first UK companies to offer PCD services. The company has always specialised in woodworking tooling and applies this knowledge to PCD. ‘At first customers baulked at the cost, but PCD suits a lot of applications and we have worked with many companies to help them understand the overall benefits,’ said director Brian Belbeck.
‘We take great care to make the tooling properly – producing all our own blanks on a CNC milling machine and backing off the bodies to give good clearance all round to eliminate burning problems.
‘More woodworking companies are using PCD sawblades and tooling, but the industry is still on a learning curve and needs to be shown what it can achieve with this material.’
Prima Tooling moved to its present site at Brentwood, Essex in 1987, first occupying a 3,400ft² factory. As demand grew the unit next door was purchased and considerable investment was made in wire erosion machines.
‘About two and a half years ago we decided to increase capacity on rotary erosion and installed a QM on a trial basis,’ said Mr Belbeck. ‘Before purchasing it we visited Vollmer in Germany and saw the QM with the new automatic loading magazine and decided this was the machine for us.
‘We are the only company in the UK to manufacture our own range of standard PCD tooling as well as specials, and without the QM and loading magazine – the only one in the UK – we could not keep up with demand. It does the work of three of our wire machines and to tighter tolerances.’
For manufacturing, the QM’s magazine is loaded with 30 tools for an over-night run and 50 for unattended weekend work. In the day it is also used for servicing work.
Erosion technology
Systco-Unilap has invested around £300,000 in erosion technology in the last year. Not bad for a company that Darrell Hughes started 26 years ago with a £300 loan and now operates from a 3,500ft² factory with 17 employees. The com-pany manufactures special router cutters, cutterblocks and knives and also offers a sharpening service on sawblades and tooling. It added PCD capacity to its existing services about five years ago, installing a QW in 1997.
‘We didn’t have room for it in our existing factory so we built an extension,’ said Mr Hughes. ‘The QW gave us greater flexibility, increased output and improved the quality of our manufacturing and sharpening services.’
In April last year the company bought the QWD wire erosion machine to increase capacity for profile tooling. However, most servicing work is on straight router cutters and cutter-blocks, and in August Systco-Unilap purchased a QM which is designed for servicing.
‘A significant part of our business is now in PCD tooling, and our investment in three Vollmer machines has put Systco-Unilap on the map as a leading manufacturer and service company in this field,’ said Mr Hughes.
‘We supply customers who process solid timber as well as panel products, but woodworking is still a young market and there is plenty of room for growth. However, we need to educate customers about the importance of training their staff to store and handle the tooling properly. Accidental damage is expensive and can cause companies to go back to TCT, which is frustrating for us.’
For Supreme Saws, investment in Vollmer erosion machines has continued since 1990, when the company became the first in the UK to install the QF and QR models. ‘These were the first machines designed specifically for PCD sawblades, and this investment was the start of our successful growth into the manufacture and servicing of PCD tooling,’ said managing director Richard Lee.
Since then the company has added a second QR, a QW, two QWDs and two QMs – and in May this year it became the first in the world to install the new QWD76P for tooling used in the metalworking industry. ‘We have invested heavily in Vollmer machines in order to meet demand and to ensure that no competitor can achieve a better finish than us,’ said Mr Lee.
‘We bought the QMs for servicing helical tooling so that we could free up the QW for manufacturing; and we bought the QWD76P to meet growing demand from the engineering industry – particularly the automotive sector where the finish and tolerances required are more exacting than those needed for cutting wood. Compared with our existing QWD, the QWD76P can produce the same finish at twice the speed; or it can be run at the same speed to produce twice the finish.’
Over the last five years Supreme Saws has seen rapid growth in demand from UK and export customers in the woodworking, printed circuit board, automotive, electronic and non-ferrous metal industries. Turnover has increased threefold but volumes are up even more as prices for PCD tooling have fallen.
The company has invested in a waterjet cutter for producing sawblade blanks without the risk of heat problems associated with laser cutting; and in a state-of-the-art balancing machine. Balanced tooling means less wear on the bearings of the production machine, producing a smoother surface finish.
PCD is finding a place among HSS, TCT and Stellite tooling, says Mr Lee. PCD tooling can reduce costs through less frequent replacement and sharpening, and improve efficiency by reducing downtime for tool changing.
For many applications on metals and alloys or abrasive products such as chipboard and MDF, PCD tooling will be the most cost-effective option.
