Cutting & Grinding Discs and Blades: Which One for Which Material?
The right disc or blade depends on two things: the material you are working on and the tool you are using. Use a thin cutting disc to cut metal and a thicker grinding or flap disc to remove it. Use diamond for masonry, tile and composites, and a matched blade for jigsaws, multi-tools and air saws. This guide covers each type, which materials it suits, the sizes that fit common tools, and the safety points that matter.
Quick answer: what to use for each material
| Material | Cutting | Grinding and finishing |
|---|---|---|
| Mild steel | Thin aluminium oxide cutting disc | Depressed-centre grinding disc or zirconia flap disc |
| Stainless steel | Inox (contamination-free) cutting disc | Inox grinding disc or zirconia/ceramic flap disc |
| Aluminium and non-ferrous | Aluminium cutting disc | Aluminium grinding disc that resists clogging |
| Carbon fibre, GRP and composites | Diamond-grit disc or carbide-grit blade | Diamond or fine abrasive disc, with dust extraction |
| Masonry, concrete and stone | Segmented or turbo diamond blade | Diamond cup wheel |
| Tile and ceramics | Continuous-rim diamond blade | – |
| Wood and plastics | Jigsaw or multi-tool blade (HCS) | Sanding disc (see our sanding discs guide) |
Cutting discs
Cutting discs (also called cut-off wheels or slitting discs) are thin, usually 1 to 3 mm, and cut with their edge. Thinner discs cut faster with less heat and burr; thicker discs last longer and suit heavier sections.
Most are flat (Type 41) or have a slightly depressed centre (Type 42) for clearance. Never grind with the side of a cutting disc: it is not built for side loads and can shatter.
Browse cutting discs.
Grinding discs
Grinding discs are thicker, typically around 6 mm, with a depressed centre (Type 27). They remove material quickly: weld seams, bevels, burrs and heavy rust. They leave a rough finish, so most jobs follow up with a flap disc.
Work at a 15 to 30 degree angle to the surface and let the disc do the work. Pressing harder only adds heat and wears the disc faster.
For aluminium, use grinding discs for aluminium. Standard discs clog quickly on soft metals. For steel, see our grinding discs.
Flap discs
Flap discs are made of overlapping abrasive flaps, so they grind and finish in one step. They run cooler than grinding discs and give a smoother surface. That makes them the better choice for blending welds and preparing metal for paint.
| Grain | Best for |
|---|---|
| Aluminium oxide | General-purpose work on mild steel and wood |
| Zirconia | Steel and stainless; longer life under pressure |
| Ceramic | Hard alloys and high-pressure stock removal; fastest cut |
Grit guide: 40 for heavy removal, 60 for general grinding, 80 for blending, 120 for a fine finish before paint.
Diamond discs and blades
Diamond blades cut by abrasion rather than with teeth, so they handle hard and brittle materials that destroy ordinary discs.
| Rim type | Use it for |
|---|---|
| Segmented | Fast, rough dry cuts in concrete, brick and stone |
| Turbo | Faster cuts with a cleaner edge in masonry and stone |
| Continuous rim | Chip-free cuts in tile and ceramics, often wet |
| Diamond-grit (electroplated) | Carbon fibre, GRP, fibreglass and composites |
Shop diamond cutting discs. For detail work with a rotary tool, the Dremel EZ SpeedClic diamond cutting disc fits the Dremel 8200.
Choosing by material
Stainless steel. Use discs marked Inox, or iron, sulphur and chlorine free. Ordinary discs leave iron particles that cause rust spots. Never use a disc on stainless that has already been used on mild steel.
Aluminium and non-ferrous metals. Soft metals load (clog) standard discs, which then overheat and stop cutting. Use discs made for aluminium and keep them for aluminium only.
Carbon fibre and composites. Abrasive discs wear fast on composites and fray the edge. Diamond-grit discs give a clean cut and last far longer. See our guide on how to cut, trim and shape carbon fibre.
Disc sizes and fitting your grinder
The most common angle grinder sizes in the UK are 115 mm (4.5 inch) and 125 mm (5 inch). Larger 230 mm (9 inch) grinders are for heavy cutting. Most discs have a 22.23 mm bore to fit standard grinder spindles.
Before fitting a disc, check three things:
- The disc diameter matches the grinder and its guard.
- The maximum speed printed on the disc (rpm or m/s) is equal to or higher than the grinder’s no-load speed.
- The disc is within its expiry date. Resin-bonded discs carry one under EN 12413 and should not be used after it.
Grinders: Makita 115 mm angle grinder, Metabo 125 mm angle grinder and air grinders.
Jigsaw blades
Most modern jigsaws take T-shank blades; some older tools use U-shank. Choose the blade by material, then by tooth count (TPI, teeth per inch).
| Blade material | Use it for | Typical TPI |
|---|---|---|
| HCS (high carbon steel) | Wood, MDF, chipboard, soft plastics | 6–10 for fast cuts, 10–14 for clean cuts |
| HSS (high speed steel) | Sheet steel, aluminium, non-ferrous metals | 14–36 (higher for thinner metal) |
| BIM (bi-metal) | Metal and wood with nails; longer life | 10–24 |
| Carbide (HM or carbide grit) | GRP, fibreglass, tile, abrasive materials | Grit or fine tooth |
Fine-cut wood blades such as the Bosch T101B give a splinter-free edge on laminates and visible faces. For sheet metal, use Bosch metal cutting jigsaw blades. For foam, rubber and soft materials, use Bosch soft materials blades. For fibreglass, use GRP jigsaw blades.
Multi-tool (oscillating) blades
Multi-tool blades make plunge cuts, flush cuts and detail cuts where saws cannot reach. Check the mounting system first: Starlock, OIS or universal (open-fit). A blade that does not match your tool’s fitting will not seat safely.
| Blade | Use it for |
|---|---|
| HCS | Wood, plasterboard, soft plastics |
| BIM (bi-metal) | Wood with nails, thin metal, pipes |
| Carbide | Grout, GRP, fibreglass, hard plastics |
| Diamond | Tile, grout, ceramics |
| Scraper | Removing sealant, adhesive and old coatings |
Shop multi-tool blades for tools such as the Fein multi-tool and the Makita 18V cordless multi-tool.
Air saw blades
Air saws (reciprocating air body saws) are the bodyshop tool for cutting panels, sills and exhaust sections cleanly. Blades are usually bi-metal and come in 18, 24 and 32 TPI. Use 18 TPI for thicker sections and 32 TPI for thin sheet metal. As a rule, keep at least three teeth in the material at once.
See our pneumatic cutting tools.
Safety checklist
Keep the guard fitted and positioned between you and the disc.
Run a new disc at full speed for at least 30 seconds, guard on, pointed away from people, before use.
Wear eye or face protection, gloves and ear defenders. Grinding and cutting are loud enough to need hearing protection.
Composites and carbon fibre create fine, hazardous dust. Use extraction and suitable respiratory protection. Read our dust extraction classes guide and carbon fibre dust safety.
Store discs flat and dry. Discard any disc that is chipped, cracked, damp or out of date.
Frequently asked questions
What is the difference between a cutting disc and a grinding disc?
A cutting disc is thin (1–3 mm) and cuts with its edge. A grinding disc is thicker (around 6 mm) and removes material with its face at an angle. Never use a cutting disc for grinding.
What is the best disc for cutting aluminium?
Use a cutting disc made for aluminium. Its bond and grain resist clogging, which is the main cause of slow, hot cuts in soft metals.
Can I use a cutting disc in a drill?
No. Angle grinder discs must not be fitted to drills. For small cuts, use mandrel-mounted cutting wheels made for rotary tools, such as Dremel accessories.
What disc should I use to cut carbon fibre?
Use a diamond-grit disc or blade. It gives a clean edge without fraying and lasts much longer than an abrasive disc. Always use dust extraction.
Which grit flap disc should I use?
40 grit for heavy stock removal, 60 for general grinding, 80 for blending welds and 120 for finishing before paint.
What size disc fits my angle grinder?
Use the size your grinder and guard are rated for, usually 115 mm or 125 mm. Most discs have a 22.23 mm bore. Check the disc’s maximum speed is at least the grinder’s rpm.
Do cutting discs expire?
Yes. Resin-bonded discs carry an expiry date, normally three years from manufacture, because the bond weakens over time.