Benefits of Vacuum Heat Treatment in Punches and DiesMarch 20, 2018
Before writing down a compelling argument, one that explains why punches and dies are formed from hardened super-alloys, we should talk a little about vacuum heat treatment. First and foremost, what happens inside the airless furnace? Well, air is sucked out of the heated chamber, then an inert gas replaces the air. But why go to all this trouble? What does the process have to offer?
Super-Hardened Dies and Punches
To bring out the best in these shear-resistant tools, they’re toughened inside a vacuum heat treatment chamber. Let’s explain that initial benefit. Oxygen, a gaseous element that nourishes fire, is present in our atmosphere. If it’s left in a heat treatment furnace, the part will experience a subsequent alteration, a change in its material and mechanical properties. With that said, the heat-induced changes may not be uniform, especially when the air is convecting over the subject workpiece. Vacuum heat treatment equipment offers a degree of process uniformity that can’t be matched by a regular furnace setting. Placed in this argon-charged chamber, every die and every punch is hardened uniformly.
Uniformly Dispersed Work Stress
A punch is an impact tool. Dies, well, they’re exposed to great quantities of shear stress. Applied unevenly, and that’s often the case, a careless mallet strike or die twist incurs stress along a leading edge. The disproportional exertion causes an unevenly heat conditioned tool to fracture. As for the consistently hardened dies and punches loaded in that vacuum heat treatment chamber, they don’t fracture, nor do they crack or split or snap. In this case, the alloy microstructure has assumed an even grain, a dense but very even grain. Additionally, and this applies to the finest tools on the market, quality-fabricated dies and punches should always be manufactured according to the highest engineering tolerances. Imagine that fabrication process in motion. Now, imagine the high-tolerance tungsten carbides entering a standard hardening furnace. The process warps the parts, probably because the air in there is circulating wildly. Vacuum heat treated tools don’t warp, nor do they distort or lose their precisely engineered dimensional forms.
Replaced with ultra-pure argon or nitrogen, the evenly heated inert gas is the secret ingredient inside a vacuum heat treatment furnace. When worked dies and punches are exposed to several thousands of degrees of cooking heat, the dense alloys harden evenly and produce a fine, uniformly distributed micro-grain. Upon leaving the equipment station, the solid chunks of superbly engineered, geometrically precise tools are distortion free and consistently hardened. Also, just as a bonus, the tools will not discolour or oxidise, so no post-cleaning work is required.
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