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BLR’s Safety Training Presentations. Abrasive Grinding Wheels 29 CFR 1910.215, 29 CFR 1910.243. Goals. Types of grinders, OSHA standards, hazards PPE, inspections, safe work practices Quiz. Types of Grinders. Bench or pedestal grinders Portable grinders
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BLR’s Safety Training Presentations Abrasive Grinding Wheels29 CFR 1910.215, 29 CFR 1910.243
Goals • Types of grinders, OSHA standards, hazards • PPE, inspections, safe work practices • Quiz
Types of Grinders • Bench or pedestal grinders • Portable grinders • Edge or circumference used for grinding • Flat side of wheel used for grinding
Types of Wheels • Cutting off wheel • Abrasive wheel • Organic wheel • Inorganic wheel • Vitrified wheel • Wire brush and buffing wheels
Wheel Speed • SFPM • 0.262 X (diameter in inches) X (RPM) • 12” wheel at 1,000 RPM = 3,144 SFPM • 24” wheel at 1,000 RPM = 6,288 SFPM
OSHA Standards • Design specifications for wheels and guards • Proper guarding • Safe operations • Repairs and maintenance • Inspection of equipment
OSHA Violations • Ranks high among most frequently violated standards • Abrasive wheel exposure adjustments • Abrasive wheel machinery work rests
Grinding Wheel Hazards • Hand injuries from the moving wheel • Eye injuries from flying chips • Hearing damage from noise • Breathing hazard from dusts and fumes
Typical Guarding • Heavy metal enclosure • Cover spindle, nut, and flange • Side guards cover 75 percent of wheel diameter • Adjustable tongue guard within 1/4”
Band-Type Guards • Flat side of wheel is used to grind • Back of wheel is guarded • Guard surrounds edge of wheel • Inside of band is free of projections • Inside edge is < 1” from edge of wheel • Wheel protrudes slightly beyond guard
Flanges • Used to mount most abrasive wheels • Transmit torque from spindle to wheel • At least 1/3 wheel diameter • Made of strong and rigid material • Replace when bearing surface becomes worn, warped, or damaged
Blotters • Are compressible washers • Are used between flanges and wheel surface • Ensure uniform distribution of flange pressure • Cover entire contact area of flange
Work Rest • Supports material being worked on • Is adjustable for wheel wear • Must be < 1/8” away from wheel • Large gap could cause jamming
Work Rest (cont.) • Positioned just below wheel’s center • Secured in position • Replaced when worn or damaged
Goals • Types of grinders, OSHA standards, hazards • PPE, inspections, safe work practices • Quiz
PPE • Glasses and face shield • Dust mask • Hearing protection • Gloves
No Loose Clothing, Jewelry, and Long Hair • Oversized shirts or sweatshirts • Unzipped shirts, sweaters, or coats • Long sleeves with unbuttoned cuffs • Dangling jewelry • Long hair
Replacing Grinding Wheels • Disconnect power source • Be sure wheel speed is greater than machine’s maximum speed • Handle wheels carefully • Inspect wheel for cracks or damage
Ring Test • Check for hidden wheel cracks • Use light, nonmetallic tool • Gently tap dry, clean wheel • Metallic “ping” means wheel is OK • Dull thud means wheel is cracked
Inspect the Grinder • Grinder is securely mounted • Wheel is mounted securely • Guards are in place • Power transmission motor is covered • Work rest is positioned correctly
Inspect the Grinder (cont.) • Wheel is evenly worn • Wheel has no nicks, cuts, or cracks • Work area is clear of combustibles • Electrical connections are in good condition • Dust collection system is working
Using the Grinder • Turn on the wheel while standing off to the side • Allow the grinder to come to full speed • Stand in a balanced position • Keep firm control of the grinder or material • Do not extend yourself or overreach
Goals • Types of grinders, OSHA standards, hazards • PPE, inspections, safe work practices • Quiz
Summary • Understand grinding hazards • Adjust tongue guard • Adjust work rest • Inspect grinder and wheel • Wear PPE
Quiz 1. What are the four primary hazards associated with grinders? 2. Name one of the items that frequently violates OSHA standards. 3. When is it safe to wear gloves when using a grinder? 4. How close must the tongue guard be to the wheel? 5. How close must the work rest be to the wheel?
Quiz (cont.) 6. What should you do before performing any maintenance on a grinder? 7. The wheel’s rated speed must be greater than the spindle’s max speed. True or False 8. Describe how to do the “ring test.” 9. How should you test the wheel before using the grinder? 10. What should flanges be inspected for?
Quiz Answers 1. Eyes hit by particles, hands touching grinder, breathing dust, noise 2. Work rest not adjusted right, wheel exposure not adjusted right 3. Only when hands are positioned far away from grinding wheel 4. Within 1/4” 5. Within 1/8”
Quiz Answers (cont.) 6. Disconnect the power source 7. True 8. Tap clean wheel with nonmetallic tool, listen for “ping” sound 9. Stand to the side and turn the wheel on 10. Warping of the bearing surface