Stainless steel is a very hard metal: although the foil is only 50µm - 100µm thick, it has an adverse effect on cutters, so expect some reduction in cutter life. Heat generated by friction is the main problem; anything that reduces heat will prolong cutter life.
Sawing stainless steel Metallic Laminate does not present any special problems. TCT saw blades with a triple chip tooth profile produce good results. Always cut face-up, allowing 20mm - 25mm of blade projection above the surface of the board. Reducing the throat of the saw to the kerf width with a carrier board eliminates pulling and bending of the laminate. For double sided panels use a scoring saw.
Edge milling and trimming are the two operations which can be difficult with stainless steel. Most routers and laminate trimmers revolve at between 15,000rpm and 30,000rpm. At normal feed speeds this is too fast for stainless steel, causing friction-generated heat that quickly dulls the cutter. The solution is to reduce the cutter speed and/or increase the feed speed to achieve an acceptable finish with minimum cutter marks. Some experimentation may be needed to achieve optimum results.
With variable speed equipment, start at the lower end of the rpm scale to avoid damage to the cutter during setting up. With fixed speed equipment, feed as fast as possible within the limits of the equipment. At 15,000rpm - 18,000rpm, a feed speed of 15m/min produces acceptable results.
Retract the cutter from the workpiece as soon as the cut is complete, and do not pause mid-cut, as dwelling at one spot greatly reduces cutter life. Over-extending a dull cutter creates excessive heat that may delaminate the stainless steel foil. Use small diameter cutters to reduce peripheral speed.
For edge milling of laminated panels on CNC routers use solid carbide spiral cutters with either left- or right-hand twist. The choice depends on whether the panel is face-up (left-hand twist) or face-down (right-hand twist).
Machines with relatively low rotational speed but a high peripheral speed (such as spindle moulders) inevitably produce a cutter chatter pattern if fed at high speed. An acceptable finish relies on an optimum balance between machine speed and feed speed.
Edge trimming may be carried out with conventional equipment (fixed or portable routers) or with hand laminate trimmers. With hand trimmers, keep the overhanging laminate to a minimum so that the limited power of the machine copes with faster feed speed.
Bevel trimming at 60° is preferred to 45° as this minimises the width of cut through the stainless steel. Flush trimming at 90° gives the maximum cutter life, as vertical movement produces a number of fresh cutting edges. Remove any slight burrs or cutter marks with a fine file or abrasive paper, cutting on the down stroke.
To achieve the best possible finish on stainless steel, cutters must be sharp and well maintained. Disposable TCT cutters are recommended, wherever possible, for speed and ease of maintenance.
If self-guide cutters are used they should be of the ball bearing and not fixed pin type. Make sure that all bearing guides are free running to avoid marking the surface.
CAUTION
Burrs and metal edges are very sharp: they can cut flesh and electric cables.
|
