Metalworking
Shear Blades for Guillotine and Swing-Beam Cutting
Mild steel, stainless and aluminium plate up to 12 mm. HRC 58–62 working hardness, ground and polished to ≤ Ra 0.4 µm. 4-edge indexable designs available to maximise cutting length per blade.
Cutting mechanics
How a shear blade cuts clean at 12 mm plate
Plate shearing is not a slicing action. The blade pair drives a controlled fracture through the plate thickness, and the fracture path is governed by clearance and rake angle.
A shear blade pair drives a fracture through the plate. The upper blade pushes the plate into the lower blade at an angle set by rake, and the gap between the two blades controls how the fracture travels through the remaining thickness. Too tight and the plate binds; too loose and the fracture deflects, leaving burr.
The two failure modes we see most often — chipping on the cutting edge and progressive burr growth — both trace back to the same root cause: clearance was specified for the wrong plate thickness, or the rake angle was outside the OEM window.
Clearance as a percentage of thickness
Clearance per OEM recommendation, typically 5–10 % of plate thickness. Tight clearance (5–7 %) for stainless to minimise burr; wider clearance (8–10 %) for mild to prevent binding.
Rake and bevel angle
Bevel angle 1°–3° on lower blade, 1°–2° on upper blade. Four-edge indexable designs available to maximise cutting length per blade before re-sharpening.
Edge flatness across length
Cutting edge flatness ≤ 0.02 mm across the blade length. Edge radius 0.05–0.20 mm depending on material and burr-tolerance target. Profilometer-verified before dispatch.
Engineering scope
Six specification levers for metalworking shears
A shear blade is a wear part with a precision edge. The variables below determine burr, twist and edge life — each specified against an international standard, not a guess.
Shear machine types
Guillotine shears (hydraulic and mechanical), swing-beam shears, plate shears, scrap metal shears, and crop-and-square shears for billet. Blade geometry, clearance and rake angle selected per machine class and material being cut.
Plate thickness envelope
Production-validated on mild steel up to 12 mm, stainless steel up to 8 mm, aluminium up to 12 mm. Heavier gauges (> 12 mm) supplied as custom build against drawing. Shear clearance per OEM recommendation, typically 5–10 % of plate thickness.
Material grades
Cold-work tool steel D2 (DIN 1.2379, JIS SKD11), 1.2379 modified grades, and high-chromium tool steel (1.2080, 1.2436) for abrasive cutting. Hardness HRC 58–62 working, tempered and stress-relieved for plate-thickness application.
Edge geometry
Single-bevel and four-edge indexable designs. Bevel angle 1°–3° on lower blade, 1°–2° on upper blade. Cutting edge flatness ≤ 0.02 mm across the blade length, edge radius 0.05–0.20 mm depending on material and burr-tolerance target.
Surface finish
Ground and polished to ≤ Ra 0.4 µm on the cutting edge, ≤ Ra 0.8 µm on the body. Lower-friction finish options available for sticky stainless or coated plate. Surface integrity verified on profilometer before dispatch.
Regrind and indexing
Four-edge indexable blades supplied with up to 4 regrinds before geometry falls below OEM clearance. Single-use lower blades typically reground 2–3 times. Regrind service available in-house with optical comparator verification.
Need shear blades for plate or billet cutting?
Send the OEM machine, plate thickness range, material mix (mild / stainless / aluminium) and target edge life. We will return a written quote with steel grade, hardness, bevel geometry and regrind plan within one business day.