Woolston, Christchurch company Custom Cutting Formes has been serving the print industry in New Zealand for over 20 years in the production of steel-rule cutting dies for use in specialized presses in the production of packaging and printed labels.

Director Alan Pearce took over the company in 1993 and his partner Clint O’Loughlin joined him a year later as an apprentice.

Up until May 2008 their dies were handmade using large jigsaws in a process largely unchanged in preceding centuries. This method required a steady hand and a good eye, and accumulated skill in the tradesmen as extreme accuracy is necessary. The lines cut through 18mm MDF or plywood have to be perfectly straight and vertical to prevent the pressures of the cutting process from collapsing the die. This is even more critically important in dies for kiss-cutting labels - to cut the label but not the backing sheet – demanding work that Custom Cutting Formes has made a specialty.

Alan had been weighing up the benefits and costs of installing a laser or CNC Router to replace the old methods for several years, resisting the usual industry tactic of buying the only purpose-built equipment available – a high priced machine from Europe poorly supported through an Australian distributor. Lasers are very high cost to both purchase and run, and there are some disadvantages in their output.

The arrival into the market of PreciseCam machines supported locally by James Dowle of Waka NZ Ltd opened the door to a new combination of machine, software and tooling.

Australian engineer Mark Ross, who has extensive experience in the print die-forme industry but is now focussed on building high-quality CNC routers, built the machine. May 2008 saw the commissioning of the new PreciseCam RSV1325 router fitted with a 50,000rpm liquid-cooled HSD spindle and an 8-tool carousel toolchanger on a heavy and robust table that includes concrete-filled sides to absorb vibration. X and Y axes are driven by 1.5kW Yaskawa servos through top quality Swiss-made helical racks and pinions, and a ballscrew on the Z axis. A PVR305 cu/m/hr vacuum pump from VABS delivers high-efficiency vacuum to the phenolic deck through electric zone valves to hold the plywood worksheets flat to the deck. Machine control is by an LNC industrial machine controller similar to those used in CNC Machining centres.

The modern CNC die-forme manufacturing process differs from the old method in that the body of the die is now made from 2 layers of 9mm high-grade plywood that are machined side by side in bookmatched layout and then sandwiched together in a vacuum press to create the 18mm thick die.

This bookmatching method creates its own new set of problems.

Any inaccuracy of the cut line is doubled when the halves are put together, and since the tiny 5-fluted router cutter is only 0.7mm in diameter there is significant flexing and deflection of the cutter as it moves through the plywood – it ‘climbs’ into the wood fibres bending the cutter and pulling the cut offline. The software to calculate the G-Code toolpath for the machine has to be able to compensate for this climbing tendency by offsetting the cut line in the opposite direction to the cutter deflection. With the software provided accuracy to 0.1mm is commonly achieved, even in this variable and challenging medium.

This specialised software and training was supplied by Melbourne-based CamTek Pacific (see www.pepsau.com). Michael Kritchevsky installed an adaptation of the program PEPS with the deflection compensation module especially adapted for this print-industry purpose, and the results have met all expectations.

To further assist the workflow the steel knife-edged rule is bent and notched in a CNC bender to match the routed layout, using the same CAD drawings as the router software.

Productivity has been increased with lower staff numbers, and turnaround times are kept to a minimum as the machine has excess capacity and is available to do other contract CNC routing work.

The machine setup has been very reliable and it has maintained its extreme accuracy. Maintenance obligations are minimal.

Alan Pearce -

“These guys have provided us with an excellent package and outstanding support that surpasses our expectations. The overall cost has come in well under the alternatives and we are confident that we get superior results”.

Showing the process and operation of a PreciseCam CNC Router using deflection-compensating PEPS software and PreciseBits router cutters to make die-boards for the print industry. The results have been exceptionally accurate and reliable. This setup has been operating for over 4 years in Christchurch, New Zealand.