Punching Knives

Creating a functional roof tile requires more than just a cross-cut; it requires surgical internal surgery. Whether you are producing ventilation tiles or specialized technical fittings, the WELSCH punching knives are engineered to create precise apertures without disturbing the structural integrity of the green concrete ribbon.

Our spring-steel punching knives are specifically designed for the rapid plunge-and-retract cycles of modern automated fitting lines. They provide the clean, vertical shear required for high-speed automation, whether executing standard circular punch-outs or complex rectangular ventilation profiles. With a profile as thin as 0.8 mm (21-gauge), these knives slice through concrete with minimal displacement, preventing the cratering effect around the edge of the hole. Hardened and tempered to absorb the mechanical shock of the strike, the spring effect ensures the knife does not deform even if it encounters a slightly larger piece of aggregate.

When the aperture shape is complex or the sand is abrasive, our tool steel punching knives are the premium choice. Through-hardened in a vacuum to 60+ HRC, these knives maintain a razor-sharp perimeter that will not roll or dull even after hundreds of thousands of strikes. They provide a perfectly vertical sidewall within the aperture, essential for the subsequent fitment of plastic or metal vent inserts.

The biggest challenge in punching wet concrete is slug retention. We precision-grind and lap the internal surfaces of our punching knives to a sub-micron finish, ensuring the waste concrete slug releases instantly. Our knives feature a strategic internal taper, allowing the cut material to clear the blade effortlessly during the retraction stroke.