M2 offers a practical balance of wear resistance, toughness, grindability and cost for many general production applications. It can suit stable piercing when point support, clearance, alignment and heat treatment are correct. High load, abrasive material or extreme volume may justify a different grade or construction.
M35 or M42 may be considered where hot hardness and wear demands exceed those of general-purpose M2. Their higher wear potential does not replace the need for toughness, support and correct clearance. Select them from actual material, thickness, speed, lubrication and observed wear or chipping.
That broad range covers very delicate micro-piercing pins up to heavy-duty punches. Slender micro-punches require quill or guide bush support, while large punches require rigid shanks and high press tonnage. Feasibility must be verified against actual sheet thickness and point length.
The live page states 64 ± 2 HRC. This represents standard cutting-point hardness for HSS tooling. Heavy-duty applications subject to high impact may require a slightly lower hardness or differential tempering (tougher head/shank and hard point) to avoid brittle failure.
That range indicates Ra surface roughness in micrometres. Precision ground and superfinished punch lands reduce sliding friction against sheet edges, prevent material galling, lower stripping forces and extend time between sharpenings.
Common mounting styles include headed/shoulder-retained shanks, straight shanks in split collets/quills, ball-lock retainers for quick exchange, and flange-bolted heavy-duty block assemblies.
A rigid punch retainer plate prevents angular deflection, maintains true vertical alignment, seats the punch head flatly against a hardened backing plate, and absorbs high stripping tension during upward withdrawal.
Yes. A piercing punch works as a matched shear pair with a hardened die button or matrix. The die hole must precisely replicate the punch shape plus the specified per-side cutting clearance.
Total clearance is calculated as a percentage of stock thickness per side (typically 5% to 12% per side depending on sheet shear strength, hardness and desired sheared-band ratio).
Excessive secondary shearing occurs, cutting tonnage spikes, severe heat is generated, stripping friction rises rapidly, and punch edges chip or gall prematurely.
Large burrs form on the slug and hole edge, hole rollover increases, dimensions distort, and slugs tend to pull back out of the die with the retreating punch.
The punch itself can pierce different gauges if its diameter/length can handle the load, but the die button must be changed to maintain the correct percentage clearance for each thickness.
High-strength steel increases cutting forces, snap-through shock and stripping drag. Tooling requires tougher HSS/PM grades, wider clearance (10–14%), shear angles, guided stripper support and PVD coatings.
Yes, but stainless steel work-hardens rapidly and tends to gall. Use cobalt HSS (M35/M42), generous clearance (9–12%), high-pressure stamping lubricant, and TiCN or TiAlN coated punch tips.
Yes. Non-ferrous alloys shear cleanly, but soft metals adhere to punch walls under friction. Highly polished lands, back-taper relief, and lubricated or DLC-coated punches prevent material pickup.
Punching Force = Cut Perimeter (π × d for round) × Stock Thickness × Material Shear Strength. Add a 20–30% safety factor to account for dulling and stripping resistance.
Yes. Rooftop, concave or single-bevel shear angles ground onto the punch face spread cutting engagement through the stroke, reducing peak tonnage and press snap-through shock by up to 30–50%.
Depth of entry should be minimal—typically 1.0 mm to 2.5 mm past the die cutting edge. Excessive penetration causes unnecessary wall wear, heat buildup, and accelerated punch fatigue.
Stripping pulls on the punch in tension during withdrawal (typically 5–20% of piercing force). Inadequate stripping force or unguided stripper plates cause punch buckling, head pull-off or sheet jamming.
Vacuum suction between a flat punch face and slug, excessive die clearance, or heavy oil surface tension pulls slugs up. Use spring-loaded ejector pins, rooftop shear or slug-retention die buttons.
Insufficient die relief angle, lack of exit clearance, burred die lands, or slug stacking beyond die land length cause slugs to pack tightly and burst the die button or snap the punch.
Excessive burr indicates dull cutting edges on the punch or die, excessive clearance, press ram tipping, or improper punch entry depth.
Tapered holes result from excessive die clearance, lack of stock clamping pressure by the stripper, or punch point deflection during penetration.
Breakage is caused by feed misalignment, double blanking, press gib deflection, unguided lateral thrust, sharp shoulder radii, excessive hardness, or loose retainer clamping.
Chipping results from insufficient die clearance, hard inclusion spots in the sheet stock, shock vibration during break-through, micro-cracks from abusive regrinding, or over-hardening.
Bending occurs when compressive load exceeds the buckling limit of slender points. Use stepped punches with thick shanks, quill sleeves or guided stripper bushings to support the point.
Uneven wear indicates non-concentric alignment between punch and die, one-sided stripper clamping, unbalanced shear angles, or tilted press ram movement.
Dry sliding contact, poor land surface finish, tight clearance and adhesive sheet metals cause metal pickup. Polish punch lands, apply PVD coatings (TiCN/DLC) and use extreme-pressure lubricants.
Proper lubrication reduces friction, dissipates heat, lowers stripping force by up to 50%, prevents galling, and dramatically extends cutting-edge life between sharpenings.
High cycle speeds generate significant frictional heat. Tooling requires cobalt HSS or PM grades with high hot hardness, PVD coatings, pressurized mist lubrication, and short entry depths.
Regrind as soon as an edge wear radius of 0.05–0.10 mm or a burr increase appears. Regular maintenance requires minimal stock removal and prevents catastrophic edge breakdown.
Grind the top face using a sharp CBN wheel with copious flood coolant. Remove small increments (0.005–0.01 mm per pass), demagnetize after grinding, and deburr the edge lightly.
