Sophisticated punches and dies indent metal surfaces with clearly detailed outlines. The marks are precise, easy to identify, and they repeatedly stamp out identical tags. It seems like these hardened alloy tools will last forever. Regrettably, nothing lasts forever, not even a super-toughened punch. The punch press is making more noise than it should, and that formerly sharp-edged indent mark is looking dull. Are there any other telltales showing?
Burr and Rollover Telltales
A newly minted mechanical punch drops down like a hammer. The sheet metal gains a row of tightly arrayed indents in seconds, with the machinery issuing a metallic echo that resembles the output of a machine-gun. Only, the perforating mark is ragged and distorted. On closer inspection, the metal surface around the mark has sunken. In this case, the correct indent pressure has been applied, but the leading edge of the punch has become dulled. This is indent rollover. The ductility of the metal plays a role here, as does the dulled state of the punch cutting edge. Burrs are another problem entirely, but the cause can be traced back to the same dulled edges. Instead of an unbowed, sharply defined indent, the metal distorts and the mark spreads until the punch mark creates a sharpened extrusion of edge-metal.
Tracking Stamp Die Wear
A formidable sheet of steel slides along a production line. It slots into the die stamping anvil, the die drops hard, and a geometrically intricate element drops free. Again, that parts dulling problem is responsible, but the signs are harder to detect. Sure, rollover issues are a problem, but this is a subtractive process, so the flaw isn’t quite as easy to discern. No, look for a lack of dimensional precision between two or more axial contact points. A fully operational stamp die cuts sharp corners and detailed angular arcs. Over at the machine with the dulled and worn die, the cut corners are blunt, the angled edges are laced with burrs, and the overall shape loses its nuanced subtractive outlines.
These are the self-evident product flaws that roll off the equipment line. During the actual production cycle, there are other signs that indicate a punch or die replacement is on the cards. The machinery works harder, it’s noisier, and there are heating problems noted in the maintenance log. An uptake in cooling oil helps reduce the thermal losses, but the problems aren’t going away. The cutting edges are fracturing, wearing, and working their way loose. Replace the business end, the actual cutting punches and dies, before the equipment experiences catastrophic damage.