Types of discs and their purpose
Bakelite abrasive wheels for angle grinders come in three main types:
| Type | Appointment | Features |
|---|---|---|
| Type 27 | Cleaning and grinding | Grinding (off-center), thickness 6+ mm |
| Type 41 | Cutting | Flat cutting, thickness 1-3.2 mm |
| Type 42 | Cutting | Cut-off with offset center, thickness 1-3.2 mm |
Protective cover is mandatory
The type of protective cover depends on the operation:
For grinding (type 27):
- 180 mm and 230 mm discs - casing with closed top protection
- Discs less than 180 mm - standard configuration casing
For cutting (type 41, 42):
- For all diameters - special cutting cover with increased protection zone
EN 12413 marking - what does it mean?
Each certified wheel has a marking according to EN 12413, which contains 11 mandatory elements:
| № | Marking element |
|---|---|
| 1 | Usage restrictions (pictograms) |
| 2 | Maximum speed (rpm) |
| 3 | Maximum operating speed (m/s) |
| 4 | PPE pictograms (mandatory in France) |
| 5 | Dimensions (mm) |
| 6 | Manufacturer / brand |
| 7 | Declaration of Conformity EN 12413 |
| 8 | Expiry date / traceability code |
| 9 | Application type (optional) |
| 10 | Abrasive specification |
| 11 | ISO type/shape (optional) |
12 safety rules: WHAT TO DO and WHAT NOT TO DO
1. Check the EN 12413 marking
✅ CORRECT: Make sure the wheel has the EN 12413 marking and an expiration date.
❌ WRONG: Never use a wheel without the EN 12413 marking.
2. Read the instructions
✅ CORRECT: Always read the safety instructions.
❌ WRONG: Don't throw away the instructions without reading them.
3. Examine the disc
✅ CORRECT: Inspect the wheel for damage, cracks, or unusual spots.
❌ WRONG: Never use a damaged wheel.
4. Check the speed
✅ CORRECT: The speed indicated on the car should not exceed the speed on the disc.
❌ WRONG: Do not use the wheel if its speed is lower than the speed of the car.
5. Correct installation of flanges
✅ CORRECTLY: Install flanges evenly and correctly for each type of wheel.
❌ WRONG: Skewed or incorrectly installed flanges lead to wheel beating and destruction.
6. Protective cover is mandatory
✅ CORRECT: Make sure the protective cover is installed correctly.
❌ WRONG: Never remove the protective cover. This is the most common cause of serious injuries.
7. Secure the workpiece
✅ CORRECT: The workpiece must be securely fastened.
❌ WRONG: Never cut an unstable workpiece - it can jam the wheel.
8. Personal protective equipment
✅ CORRECT: Use a full set of PPE: safety glasses, gloves, headphones, and, if necessary, a respirator.
❌ WRONG: Never work without protective equipment.
9. Cutting wheels - for cutting only
✅ CORRECT: Use type 41 and 42 wheels exclusively for cutting.
❌ WRONG: Never grind with a cutting wheel. Side loading will cause breakage.
10. Grinding wheels - for grinding only
✅ CORRECT: Type 27 wheels are designed for cleaning and grinding.
❌ WRONG: Do not use for cutting unless specifically stated on the disc.
11. Cut straight
✅ CORRECT: Always hold the cutting wheel straight at a 90° angle to the workpiece.
❌ WRONG: Never turn or twist the wheel while cutting - this causes jamming and tearing.
12. Don't push too hard
✅ CORRECT: Let the disc cut itself - hold the tool loosely.
❌ WRONG: Never use excessive force. This will overheat the wheel and may cause it to break.
Summary: 5 main rules
- Check the EN 12413 marking and the best before date
- Do not exceed speed— machine RPM ≤ wheel RPM
- Don't remove the cover - it will save your life.
- Don't grind with a cutting wheel - each type is for its own operation
- Don't push - let the disc work on its own
Frequently asked questions
Can I grind with a cutting disc?
Absolutely not. Cut-off wheels (type 41, 1-3 mm thick) are intended for peripheral cutting only. Lateral loading causes stresses that the wheel is not designed for, which can lead to wheel breakage. For grinding, use grinding wheels (type 27, 6+ mm thick) or flap wheels.
How to determine the type of disc?
The type is indicated on the wheel marking. Type 41— flat cutting (thickness 1-3.2 mm). Type 42— cutting with an offset center. Type 27— grinding with an offset center (thickness 6+ mm). The type is also determined visually: cutting wheels are thin, grinding wheels are thick.
What kind of guard is needed for cutting and grinding?
For cutting (types 41, 42) a special cutting guard with an increased protection zone is required. For grinding (type 27): 180/230 mm wheels - guard with closed protection on top, wheels smaller than 180 mm - standard guard.
Why is it important to check the expiration date?
Bakelite bond absorbs moisture and loses strength over time. After 3 years from the date of manufacture, the wheel may not withstand working loads. Using an expired wheel is one of the main causes of breakage during operation.
Do you need certified abrasives?
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