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Grinding Disc (T27): Uses, Advantages & How It Differs from Cutting Discs
A grinding disc (T27 depressed-center grinding wheel) is a thick (typically 6.0 mm) resin-bonded abrasive wheel for angle grinders. Where a cutting disc slices through material, a grinding disc removes material from the surface — weld beads, rust, burrs, mill scale and uneven edges on steel structures and pipes.
Main Uses
- Weld removal and weld dressing on structural steel
- Deburring and edge chamfering after cutting
- Removing rust, mill scale and old coatings
- Surface preparation before painting or welding
- Heavy-duty grinding in fabrication and repair work
Advantages
- Fast material removal: coarse abrasive and thick section grind aggressively.
- Extended lifespan: 6 mm of abrasive outlasts thin discs many times over on surface work.
- Operator stability: depressed-center design allows a comfortable 15–25° grinding angle.
- Safety: built to withstand side loads that would shatter a cutting disc.
Specifications
| Size (mm) | Size (inch) | Max RPM | Fits grinder |
|---|---|---|---|
| 100 × 6.0 × 16.0 | 4" × 1/4" × 5/8" | 15,200 | 4" angle grinder |
| 115 × 6.0 × 22.2 | 4-1/2" × 1/4" × 7/8" | 13,300 | 4-1/2" angle grinder |
| 125 × 6.0 × 22.2 | 5" × 1/4" × 7/8" | 12,230 | 5" angle grinder |
| 150 × 6.0 × 22.2 | 6" × 1/4" × 7/8" | 10,200 | 6" angle grinder |
| 180 × 6.0 × 22.2 | 7" × 1/4" × 7/8" | 8,500 | 7" angle grinder |
| 230 × 6.0 × 22.2 | 9" × 1/4" × 7/8" | 6,640 | 9" angle grinder |
Grinding Disc vs Cutting Disc — the Critical Difference
- Cutting discs (0.8–2.5 mm) are for straight-in cutting only — never use them for side grinding.
- Grinding discs (6 mm) are for surface grinding at a 15–25° working angle — never use them to cut.
- Mixing the two is the most common cause of disc breakage accidents.
FAQ
What grit is a grinding disc?
Standard grinding discs use coarse grain around 24–30 grit for fast stock removal. For finishing, follow with a flap disc (40–120 grit).
Can a grinding disc be used on stainless steel?
Yes, with an INOX-rated grinding disc to avoid contaminating the surface.
How do I know when to replace a grinding disc?
Replace when the disc wears down toward the label, when grinding rate drops noticeably, or if the disc is chipped, cracked or past its expiry date (resin bonds age — typically 3 years).
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- Cutting Disc Size Guide: 4.5" vs 5" vs 7" vs 9" — Which One Do You Actually Need?
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