The Geometry Difference
Both Type 27 and Type 28 are depressed centre wheels - the hub is recessed to allow the flange nut to sit below the grinding face. The difference is in the profile of the grinding disc:
Type 27 - Flat disc profile. The grinding face is parallel to the wheel axis. Designed for surface grinding at a 5-15 degree angle to the workpiece.
Type 28 - Saucer/convex profile. The disc curves slightly upward from centre to periphery. Designed for more aggressive grinding at a lower (flatter) angle to the workpiece.
Performance Difference
| Parameter | Type 27 | Type 28 |
|---|---|---|
| Grinding angle | 5-15 degrees | 0-10 degrees |
| Material removal rate | Moderate | High |
| Aggressiveness | Standard | High |
| Edge access | Good | Limited |
| Operator fatigue | Lower | Higher |
| Finish quality | Smoother | Coarser |
When to Use Type 27
Type 27 is the standard choice for:
- Weld bead grinding - The flat face allows controlled removal of weld reinforcement
- Surface finishing after cutting - Blending and cleaning cut edges
- Edge chamfering - The flat profile gives better control at edges
- General fabrication grinding - Most angle grinder work in steel fabrication
- Stainless steel grinding - Where finish quality matters
When to Use Type 28
Type 28 is specified for:
- Heavy stock removal - The saucer profile concentrates pressure at a smaller contact area, increasing aggressiveness
- Foundry work - Removing gates, risers, and flash from castings where material removal rate is more important than finish
- Rough grinding before finishing - First pass on heavily scaled or pitted surfaces
- Cast iron - Where the aggressive cut is beneficial
Brands Available
Apidor supplies both Type 27 and Type 28 in multiple brand grades:
- HIFY / FYTER - Economy grade for general fabrication, high volume low-cost requirement
- SUPER FAST / METAFLEX - Mid-premium, good all-round performance
- ZEN PLUS / ZENGOLD - Premium grade, longer life, better finish
- ZIRCOTECH - Zirconia grain for heavy stock removal, foundry work
- ULTRA - Premium long-life for demanding continuous production environments
Contact us with your application details for a specific brand recommendation.