MAX Depressed Centre Metal Grinding Disc - Type 27 Heavy Duty Wheel

MAX Depressed Centre Metal Grinding Disc - Type 27 Heavy Duty Wheel

The MAX Depressed Centre Metal Grinding Disc is a Type F27 grinding wheel designed for heavy duty material removal on structural steel, mild steel, sheet steel, high-grade steel, and steel pipe. At 6mm thick with an A24RBF aluminium oxide abrasive and 2.5A fibreglass reinforcement, it is built for sustained grinding work where a standard 4mm disc would wear through quickly or flex under load. For fabricators, structural steelwork contractors, and general construction trades who need reliable, aggressive grinding performance across a full working shift, this disc delivers consistent material removal without glazing or loading.

Why Choose the MAX Depressed Centre Metal Grinding Disc

• A24RBF abrasive grade: the A24 coarse aluminium oxide grain delivers an aggressive cut rate on steel, removing weld spatter, mill scale, and excess material faster than finer-grade discs without loading the bond.

• 6mm grinding thickness: at 6mm, this disc has significantly more abrasive material available than a standard 4mm grinding disc, which translates directly into longer disc life and fewer disc changes per shift on heavy grinding work.

• 2.5A fibreglass reinforcement: the additional reinforcement layer compared to the 2A used in standard cutting discs gives the grinding wheel greater lateral stiffness under the side-loading forces generated during grinding operations.

• Depressed centre Type F27 profile: the recessed centre allows the disc to sit flush against flat surfaces and into corner joints, giving the operator full grinding contact without the guard or flange fouling the workpiece.

• Four size variants from 100mm to 230mm: the range covers hand-held angle grinder work on detail joints up to heavy surface grinding on large structural sections, with bore sizes matched to standard professional tool fitments.

• 80 m/s rated across all variants: consistent peripheral speed rating across the range simplifies tool and disc matching on sites where multiple grinder sizes are in use simultaneously.

• EN 12413 manufacture with ISO-controlled quality: unbalance tested to ISO 6103 and run-out controlled to ISO 13942, meeting the dimensional and rotational accuracy standards required for safe professional grinding operations.

What's Included

• One MAX Depressed Centre Metal Grinding Disc in the selected size variant (100mm, 115mm, 125mm, or 230mm)

 Specifications

Size& Performance

 Compatibility

Who Is This For?

The MAX Depressed Centre Metal Grinding Disc is aimed at structural steelwork contractors, fabricators, welders, and general construction trades who carry out heavy grinding, weld dressing, and surface preparation on steel sections, pipe, and plate. It suits both the site operative running a 115mm or 125mm angle grinder for detail grinding on joints and connections, and the contractor using a 230mm grinder for surface preparation on large structural sections. This is a professional specification disc for sustained, high-load grinding work, not for occasional light dressing.

Typical Applications

• Removing weld spatter and dressing weld beads on structural steel fabrications

• Grinding mill scale and surface rust from steel sections before painting or coating

• Removing excess material and sharp edges from flame-cut or plasma-cut steel plate

• Surface preparation of steel pipe and tube before welding or mechanical joining

• Grinding back proud welds and fillet welds on steel frames and structural connections

• Removing corrosion and surface contamination from steel reinforcement bar before concrete pours

• Heavy material removal on steel castings and forgings in workshop environments

How to Use

1. Select the correct disc variant for your angle grinder, confirming the bore size matches your tool's arbor and the tool's maximum RPM does not exceed the disc's rated operating speed for the selected variant.

2. Fit the disc with the depressed centre facing away from the tool body, with the correct Type 27 guard in place. Ensure the flanges seat correctly against the disc face and the locking nut is tightened to the tool manufacturer's specification.

3. Inspect the disc visually before use for chips, cracks, or delamination. Do not use a disc showing any sign of damage.

4. Run the disc at full operating speed for at least 30 seconds before making contact with the workpiece, observing from the side.

5. Apply the disc to the workpiece at a grinding angle of 15 to 30 degrees from the surface. This angle maximises material removal and disc life whilst maintaining operator control.

6. Use consistent, overlapping strokes across the surface. Avoid dwelling in one spot, which concentrates heat and can cause surface hardening on the workpiece.

7. Allow the disc to cool periodically on extended grinding operations. Do not quench a hot disc with water.

8. After use, remove the disc from the tool and store flat in a dry environment away from impact risk.

Safety and Maintenance

Safety during use:

• Eye protection is mandatory: use approved safety goggles or a full face shield to EN 166. Heavy grinding generates high-velocity sparks and abrasive particles across a wide arc.

• Wear cut-resistant gloves to EN 388. Grinding disc edges are sharp and the workpiece surface temperature rises rapidly during heavy material removal.

• Hearing protection to EN 352 is required. Angle grinders operating under grinding load consistently exceed 85dB(A).

• Respiratory protection: grinding steel generates nuisance dust and metallic fume. Wear a minimum FFP2 mask to EN 149 where local exhaust ventilation is not available.

• Never exceed the maximum operating RPM for the selected disc variant.

• Do not use this disc for cutting operations. It is a Type F27 grinding wheel designed for surface grinding only. Using it for cutting puts lateral stress on the disc in a direction it is not designed to resist.

• The Abrasive Wheels Regulations 1970, as incorporated into PUWER 1998, require that abrasive wheels are only mounted and operated by trained and appointed persons.

After use and storage:

• Inspect the disc after each use for chips, cracks, glazing of the abrasive surface, or delamination of the reinforcement layers.

• A glazed grinding surface, where the disc feels smooth and cuts slowly, indicates the bond is not releasing worn grains correctly. This can sometimes be corrected by dressing the disc face on a piece of scrap steel before discarding.

• Store discs flat in a dry, stable-temperature environment away from impact, vibration, and damp conditions.

• Dispose of worn or damaged discs as general factory waste in line with site waste management procedures.

Frequently Asked Questions

Q: What is the difference between a Type F27 depressed centre grinding disc and a Type F41 flat cutting disc?

 A: A Type F27 disc has a recessed centre that raises the grinding face above the mounting hardware, allowing flush contact with flat surfaces and into corner joints. A Type F41 is a flat cut-off wheel designed exclusively for straight cutting. Using a cutting disc for grinding or a grinding disc for cutting are both serious safety risks under the Abrasive Wheels Regulations.

Q: Why is the A24RBF grade used for heavy duty grinding rather than a finer grade?

A: The A24 coarse grain removes material aggressively, which is exactly what heavy grinding work demands. Finer grains cut more slowly and load up faster on heavy steel surfaces. The RBF bond holds the grain firmly enough to resist wear under high grinding pressure whilst still releasing spent grains to expose fresh abrasive.

Q: What does EN 12413 mean and why does it matter on a UK site?

 A: EN 12413 is the harmonised standard for bonded abrasive products covering dimensional accuracy, maximum operating speed, and structural integrity. Specifying EN 12413 certified discs supports compliance with the Abrasive Wheels Regulations under PUWER 1998 and strengthens your risk assessment documentation.

Q: Can this disc be used on stainless steel?

 A: No. The A24RBF bond is not formulated to be free from iron, sulphur, or chlorine, which means it will contaminate stainless steel cut and ground faces, destroying the passive layer and initiating corrosion. For stainless steel grinding, use a dedicated inox grinding disc with a contamination-free bond formulation.

Q: What grinding angle gives the best results with a depressed centre disc?

 A: Apply the disc at 15 to 30 degrees from the workpiece surface. Below 15 degrees reduces material removal rate and increases the risk of the disc edge catching. Above 30 degrees concentrates wear on a narrow band of the disc face and increases operator fatigue on extended grinding work.

Q: How do I know if my grinding disc has glazed and what should I do?

 A: A glazed disc feels smooth against the workpiece, cuts slowly, and generates more heat than usual. Glazing happens when the bond is too hard for the material being ground and worn grains are not releasing. Dress the disc face briefly on a piece of scrap steel to expose fresh abrasive. If glazing recurs quickly, the disc grade may not be matched to your application.

Q: What is the 2.5A reinforcement and why does it matter for grinding versus cutting?

 A: The 2.5A designation indicates a heavier fibreglass reinforcement layer than the 2A used in standard cutting discs. Grinding applies sustained lateral and radial forces to the disc simultaneously, which requires greater structural resistance than straight cutting. The additional reinforcement reduces flex under load and extends disc life on heavy grinding work.

Q: Can I use the 230mm variant on a standard 230mm angle grinder?

 A: Yes, provided your angle grinder is rated for 230mm discs, fitted with the correct Type 27 guard, and the tool's maximum RPM does not exceed 6,600rpm for this variant. Always verify your tool's nameplate specifications before fitting any disc.

Q: Why should I order from CMT Group rather than a general tool merchant?

 A: CMT Group has supplied construction and industrial sites across the UK since 2010, with a fleet of over 100 FORS Silver accredited vehicles covering 90% of the UK mainland. Orders placed online by 7pm qualify for next working day delivery, and a VIP dedicated delivery service is available UK-wide for urgent site requirements, dispatched within 30 minutes. CMT's EDGE procurement portal gives construction buyers agreed contract pricing, spending controls, and live delivery tracking with What3Words integration.