A complete lifecycle guide to safe grinding — from CUMI’s manufacturing floor to your workshop. Covering all three customer safety stages: receiving, storing, and usage.
WATCH THE OFFICIAL VIDEO
https://www.youtube.com/watch?v=EwxIenhieUk
Channel: CUMI – Carborundum Universal Limited
Every year, workshop accidents involving abrasive wheels are traced back to a handful of preventable causes — improper storage, wrong mounting, expired wheels, or machines running beyond rated speed. CUMI (Carborundum Universal Limited), one of India’s pioneer abrasive manufacturers since 1954, produced this video guide to address each of these risks head-on.
The video covers the complete safety lifecycle of an abrasive wheel: how CUMI builds safety into manufacturing itself, what to check when a delivery arrives, how to store and ring-test wheels, and the exact procedures for safe mounting and operation.
01—The Abrasive Wheel Safety Practices
CUMI organizes customer safety responsibilities into three sequential stages. A failure at any one can result in wheel breakage, injury, or downtime.
Inspect packaging for tampering before accepting. Confirm all wheels are dry and undamaged. Never use a wheel from a compromised or wet package. |
Keep wheels in a designated rack. Store away from water, solvents, and chemicals. A damaged wheel can look intact but shatter under load. |
Ring-test before every use. Match RPM ratings. Mount correctly with proper flanges and guards. Wear PPE. Run idle for one minute. Use the right wheel for the right material. |
Stage 1: Receiving
Stage 2: Storing
Stage 3: Usage02 — What To Do — And What Not To
Follow these practices every time:
✓ Perform the ring test—tap at 45° on both sides and listen for a clear bell sound before every use.
✓ Match the wheel’s rated RPM to your machine’s RPM—verify both before mounting.
✓ Use equal-width, clean, undamaged flanges covering at least ⅓ of the wheel label.
✓ Ensure side guards cover the spindle, nut, flange, and at least 75% of the wheel diameter.
✓ Wear full PPE — eye protection, face shield, gloves, and hearing protection — before switching on.
✓ Run the wheel idle for at least one full minute before starting actual grinding.
✓ Use angle grinders at 15°–30° for grinding; switch to 90° only for cutting operations.
✓ Store wheels in a dry, designated rack—away from water, solvents, and chemicals.
✓ Match specific wheel grades to the correct job material for performance and safety.
Never do any of the following:
✗ Never use an expired resinoid wheel—organic bonds degrade over time.
✗ Never exceed the RPM limit marked on the wheel label—overspeed causes wheel failure.
✗ Never force a wheel onto a spindle or alter the bore size to make it fit.
✗ Never use a DC wheel or cutting wheel for face grinding.
✗ Never use a damaged, cracked, or wet wheel under any circumstances.
✗ Never use damaged or contaminated mounting flanges—inspect before each use.
→ Ring Test: Tap at 45° on both sides — clear bell sound = safe to use. → RPM: Never exceed the RPM limit on the wheel label. → Flanges: Equal-width, clean flanges covering at least ⅓ of the wheel label. → Guards: Cover the spindle, nut, flange, and 75% of wheel diameter. → Run-in: Always idle the wheel for at least 1 minute before grinding. → Angle: 15°–30° for grinding; 90° for cutting. Never face grind with DC wheels. |
KEY SAFETY RULES AT A GLANCE03 — Products Featured in This Video
The video specifically features CUMI’s Resinoid, Depressed Center (DC), and Vitrified wheels—all manufactured and tested to EN 12413. The two product ranges referenced in the YouTube description:
Product Range 01 Bonded Abrasives CUMI’s vitrified and resinoid-bonded abrasive wheels are precision-engineered for grinding across metal fabrication, automotive, aerospace, steel, and heavy industry. Every wheel is balanced, tested to EN 12413, and marked with Mount-Up guidance. | Product Range 02 Cutting & Grinding Wheels (DC) CUMI’s Depressed Center (DC) grinding and cutting wheels, built for angle grinder use—high material removal rates with built-in safety features. Produced to both EN 12413 and ANSI B7.1 with stringent process controls. |
04—About CUMI
Founded in 1954 as part of the Murugappa Group, CUMI (Carborundum Universal Limited) pioneered the manufacture of bonded and coated abrasives in India. With over 70 years of manufacturing expertise, CUMI has a global presence spanning India, Russia, China, North America, Europe, and Australia.
CUMI manufactures a complete range of bonded abrasives, coated abrasives, cutting blades, nonwoven products, power tools, and metalworking fluids—serving industries from aerospace and automotive to construction, steel, leather, and precision engineering.
Useful Links:
Full product range: cumiabrasive.in
Request a consultation: cumiabrasive.in/contact-us
Watch the video: youtube.com/watch?v=EwxIenhieUk
05—Why This Guide Matters
Abrasive wheels spin at thousands of revolutions per minute. A wheel that fails under load does not simply stop — it shatters, sending fragments outward at lethal velocity. The injuries and downtime that follow are preventable in almost every case.
What makes this CUMI video especially useful is its end-to-end perspective. Most safety guides focus only on the operator at the moment of use. This one starts at the manufacturing process so that users understand why each safety rule exists. When you know that CUMI verifies a wheel’s Young’s modulus, runs it through PRO and SRO testing, and speed-certifies it to EN 12413 before it leaves the factory, you understand exactly why skipping the ring test or exceeding RPM is so dangerous.
Whether you are a workshop manager setting safety procedures, a trainer onboarding new operators, or an individual professional working with angle grinders every day—watch the video, share it with your team, and apply each one of these practices consistently.
Frequently Asked Questions
1) What is the ring test for abrasive wheels?
The ring test is a pre-use safety check performed before mounting any abrasive wheel. Hold or suspend the wheel freely and tap it at 45° on either side of the vertical axis using a light, non-metallic object—such as a screwdriver handle or wooden mallet. A crack-free wheel produces a clear, bell-like ringing sound. If you hear a dull thud instead, the wheel has an internal crack and must be discarded immediately. CUMI recommends performing this test every single time before use, not just when a wheel is new.
2) What PPE is required for grinding operations?
Before operating any abrasive wheel, you must wear safety glasses or impact-rated goggles, a full face shield, protective gloves, hearing protection (grinding generates damaging noise levels), and appropriate overalls or protective clothing. Loose clothing, ties, or open sleeves must never be worn near rotating wheels. CUMI’s safety guidance states that all PPE must be fully in place before the machine is switched on—not after the wheel has started spinning.
3) Can I use a DC wheel for face grinding?
No, depressed center (DC) wheels and cutting wheels must never be used for face grinding. This is one of CUMI’s absolute usage restrictions. DC wheels are designed to operate at specific angles—15° to 30° for grinding operations and 90° for cutting. Using a DC or cutting wheel flat against a surface (face grinding) places perpendicular stress on the wheel that it is not designed to withstand, significantly increasing the risk of wheel breakage and serious injury.
4) What does EN 12413 mean on a grinding wheel?
EN 12413 is the European safety standard for bonded abrasive products, including grinding and cutting wheels. A wheel marked EN 12413 has been manufactured and tested to meet strict requirements covering dimensions, balance, structural integrity, and maximum operating speed. CUMI tests every resinoid, DC, and vitrified wheel to EN 12413—including PRO (profile run-out), SRO (side run-out), side load testing, and a speed test to certify the wheel can sustain its rated RPM safely. When you see EN 12413 on a wheel, it means the product has passed a defined set of safety-critical quality checks before leaving the factory.
5) How should abrasive wheels be stored?
Abrasive wheels must be stored in a designated rack specifically designed for the purpose — never stacked loosely on shelves, left on workbenches, or stored in toolboxes where they can shift and chip. The storage area must be dry, with no exposure to water, solvents, or chemical vapors, as moisture and chemical contact can degrade the bonding agent and weaken the wheel’s structure invisibly. Wheels should also be stored away from areas with heavy traffic, crane activity, or excessive vibration. Always keep wheels in their original packaging until use, as the packaging carries critical safety and specification information.
6) How long should a grinding wheel run before use?
According to CUMI’s safety guidelines, every grinding wheel should be run at idle—with no workpiece contact—for a minimum of one full minute before actual grinding begins. This idle run-in period allows any latent defects to manifest before the operator applies pressure and lets the wheel reach thermal and rotational stability. The full guard must be in place, and the operator must stand clear of the wheel’s path during this run-in period.
7) What happens if you exceed a grinding wheel’s RPM limit?
Exceeding a wheel’s rated RPM is one of the most dangerous things an operator can do. As rotational speed increases, the centrifugal stress on the wheel rises exponentially—doubling the speed roughly quadruples the stress. Beyond the rated RPM, the wheel’s bond system can no longer hold the abrasive grains together, and the wheel can shatter without warning, sending high-velocity fragments in all directions. CUMI marks the maximum operating speed clearly on every wheel label. Always verify that the wheel’s rated RPM meets or exceeds your machine’s operating speed before mounting.
8) What is the correct flange setup for mounting a grinding wheel?
Always use a matched pair of equal-width flanges—both flanges must be the same diameter and in undamaged, clean condition. The flanges must cover at least one-third of the wheel’s diameter (as indicated by the wheel label area). The wheel should fit freely onto the spindle without requiring any force—if you need to force the wheel on, or if the bore needs to be altered to fit, do not proceed. Bore misalignment from incorrectly fitting flanges is a leading cause of wheel imbalance and breakage during operation.
