Steel cutting blades do one of the hardest jobs in a plant. They cut a material that is almost as tough as they are. A blade that is slightly wrong for the job leaves burrs, twists the cut piece, and wears out long before it should.
There is no single best blade for cutting steel. The right choice depends on what you cut, how thick it is, and which machine you run. This guide covers the main types of steel cutting blades, how shearing works, the settings that matter, and the blade steels that hold up.
What Are Steel Cutting Blades?
Steel cutting blades are industrial blades made to cut steel sheet, plate, coil, bar, and scrap. They fall into two families.
- Shearing blades: Two blades pass each other and split the steel between them. No chips are made. Shear blades and slitter knives work this way.
- Sawing and abrasive blades: Teeth or abrasive grains remove a thin line of material. Cold saws, band saws, and cut-off wheels work this way.
Shearing is faster and wastes no material. Sawing handles thick sections and shapes that a shear cannot.
Main Types of Steel Cutting Blades
| Blade type | How it cuts | Typical job |
|---|---|---|
| Shear blades | A long upper blade passes a fixed lower blade | Straight cuts in sheet and plate |
| Rotary slitting knives | Pairs of circular knives cut a moving strip | Slitting coil into narrower strips |
| Scrap shear blades | Heavy blades close like jaws or a guillotine | Cutting scrap, bar, and structural sections |
| Cold saw blades | A toothed circular blade cuts at low speed | Bar, tube, and profiles with a clean finish |
| Band saw blades | A toothed steel band runs in a loop | Thick bar stock and structural steel |
| Abrasive cut-off wheels | Abrasive grains grind through the steel | Fast, rough cuts and very hard steel |
Most production cutting of sheet and coil is done by shearing. The rest of this guide focuses on those blades.
How Shear Blades Cut Steel
A shear has an upper blade and a lower blade. One moves and one stays fixed. The steel sits between them.
The cut happens in three stages:
- Deformation: The blade presses into the steel and the edge rolls over slightly.
- Penetration: The blade cuts partway through and leaves a smooth, bright band.
- Fracture: The remaining steel breaks along a line between the two blade edges.
A good cut has a small rolled edge, a clean bright band, a short fracture zone, and very little burr. Three things control that result: blade clearance, rake angle, and blade sharpness.
Blade Clearance: The Setting That Matters Most
Blade clearance is the small gap between the upper and lower blades. It lets the steel fracture cleanly.
A widely used rule of thumb for mild steel is:
- Up to 10 mm thick: Set the clearance to 0.06 mm for each millimeter of thickness.
- Over 10 mm thick: Set the clearance to 0.04 mm for each millimeter of thickness.
| Mild steel thickness | Approximate blade clearance |
|---|---|
| 2 mm | 0.12 mm |
| 6 mm | 0.36 mm |
| 10 mm | 0.60 mm |
| 16 mm | 0.64 mm |
Across different materials and shearing methods, clearance generally falls between 2 and 10 percent of the material thickness. Always check the chart from your machine maker, because stainless and high-strength steels need their own settings.
The wrong clearance damages both the cut and the blade.
- Too little clearance: The cutting force rises, and the blades wear faster.
- Too much clearance: The steel is pulled down between the blades. The edge comes out tapered, rounded, and heavily burred.
Rake Angle
Rake angle is the slope of the upper blade from one end to the other. Because of this slope, the blade cuts across the sheet a little at a time.
| Rake angle | Effect on force | Effect on the cut |
|---|---|---|
| Low | More force needed | Better cut quality, less twist and bow |
| High | Less force needed | More distortion in the cut piece |
If narrow strips come off the shear twisted, a lower rake angle usually helps.
Four-Edge and Two-Edge Blades
Shear blades come in two common designs.
- Four-edge blades: The blade has a square, 90-degree profile. When one edge is dull, you turn the blade and use the next. You get four edges before a regrind.
- Two-edge blades: The upper blade is ground at a slight angle. It cuts with less force, but only two edges can be used.
Four-edge shear blades are popular with fabricators because they cut downtime and grinding costs.
Rotary Slitting Knives for Steel Coil
Slitting lines cut wide coil into narrow strips. They use pairs of circular knives mounted on two arbors, with spacers between them to set the strip width.
The same rules apply as in shearing. The gap between the upper and lower knives must suit the thickness and strength of the steel. The knives must also be the same diameter and thickness across the set, or the strip edges will not match.
Edgemills supplies rotary slitting knives ground to tight tolerances for this reason.
Blade Steels for Cutting Steel
The blade must be harder than the steel it cuts. It must also be tough enough to survive the shock of each cut. These two needs pull in opposite directions.
| Blade steel | Strength | Best use |
|---|---|---|
| D2 (high-carbon, high-chromium) | High wear resistance | Thin and medium sheet, and general shearing |
| Shock-resisting tool steels | High toughness | Thick plate and heavy cuts |
| H13 hot-work steel | Holds its strength when hot | Hot shearing and heavy impact |
| M2 high-speed steel | Wear resistance that survives heat | Slitter knives and saw blades |
| Tungsten carbide | The highest wear resistance | High-volume slitting of thin strip |
As a rule, use a harder, more wear-resistant steel for thin material. Use a tougher steel for thick material. Our guide to the best material for metal shear blades covers this choice in more depth.
How to Choose Steel Cutting Blades
| What you cut | Blade choice |
|---|---|
| Mild steel sheet | D2 four-edge shear blades |
| Stainless steel sheet | D2 or a tougher grade. Keep the blades sharp, because stainless work-hardens. |
| High-strength steel | A tougher, shock-resisting grade |
| Thick plate | Shock-resisting steel at a lower hardness |
| Hot steel | H13 |
| Steel coil | Rotary slitting knives in D2, high-speed steel, or carbide |
Give your supplier the full picture: the steel grade, the thickness range, the machine, and how your current blades fail.
Signs Your Steel Cutting Blades Are Worn
- Burrs get taller. This is usually the first sign.
- The cut edge looks rough or torn. The bright band shrinks, and the fracture zone grows.
- Strips twist or bow more than before.
- The machine sounds louder and needs more force.
- Chips appear on the edge. These leave marks on every cut.
When you see these signs, turn the blade to a fresh edge or send it for regrinding. After a regrind, the blade is slightly smaller, so reset the clearance before you cut. The wrong clearance after grinding can chip a freshly sharpened blade.
What to Send When You Order Blades
- Machine make and model
- Blade length, width, and thickness
- Hole positions, sizes, and type
- Number of cutting edges
- The steel you cut and its thickness range
- The blade steel and hardness you want, if you have a preference
Need Steel Cutting Blades Made to Spec?
Edgemills manufactures shear blades, straight knives, and rotary slitting knives for metal fabrication. We work in D2, M2 high-speed steel, tungsten carbide, and CPM grades, to tolerances as tight as ±0.0005 inch.
Shearing only works well when the blades fit the machine and the material. Send us a drawing or a sample and get a quote.
FAQs
What is the best blade for cutting steel?
It depends on the job. Shear blades are best for straight cuts in sheet and plate. Rotary slitting knives are best for coil. Cold saws and band saws suit bar, tube, and thick sections. For shearing, D2 suits thin and medium sheet, and tougher steels suit thick plate.
What clearance should shear blades have for mild steel?
A common rule of thumb is 0.06 mm of clearance for each millimeter of thickness, up to 10 mm. For thicker plate, use 0.04 mm for each millimeter. Check your machine maker’s chart, since other steels need different settings.
Can the same blades cut mild steel and stainless steel?
Often they can, but the settings change. Stainless is stronger and work-hardens as it is cut, so it needs sharp blades, more force, and a clearance set for that material. A shear rated for a given thickness of mild steel can cut only a thinner gauge of stainless.
How often should steel cutting blades be sharpened?
There is no fixed interval. It depends on the steel, the thickness, and the volume. Watch the burr height and the edge quality. When they get worse, turn the blade to a fresh edge or regrind it. Sharpening early removes less steel and extends blade life.