Portable Grinder Safety - Schools Insurance Program for Employees

Portable Grinder Safety - Schools Insurance Program for Employees
Schools Insurance Program for Employees
Date:
April 16, 2008
To:
District Safety Coordinators and
MOT Directors
From:
Mike Bruffey
Coordinator of Safety – SIPE
Subject:
Portable Grinder Injury
Portable Grinder Safety
In a recent incident at a San Luis Obispo County Public School involving a hand held portable
disc sander, an employee was injured when the cut-off wheel unexpectedly disintegrated,
sending pieces flying across the workshop. The employee received minor injuries to his leg
from one of the flying pieces. Upon inspection of the disc sander and type of wheel being used
at the time, several issues were discovered that led to the accident.
1. The disc sander in question was rated for 23,000 RPM and tested at 19,500.
2. The mounted cut-off wheel had a max RPM rating of 13,580.
3. The cut-off wheel was unknowingly mounted on the arbor (serving as a disc pad) and a
sanding disc was mounted on top of it (see photos at end of report).
4. Disc Sander being used may have been too large to fit into the space being worked on
and the wheel may have hit the metal being sanded in two places at the same time.
These types of incidents involving grinders do not happen often, but when they do, the results
can lead to serious injuries and even death. Besides grinding wheels disintegrating, other types
of incidents involve kickbacks and entanglements with clothing and other materials.
Schools Insurance Program for Employees
7455 Morro Road Atascadero, CA 93422
(805) 460-0280
www.slosipe.org
Inspection
Pre-operation inspections should occur before use and include the following:
•
The guard (when required) should be present and firmly attached. Guards for most of
these types of grinders have a maximum exposure angle of 180° and are located
between the operator and the wheel.
•
Check the wheel for cracks, chips, gouges or other damage.
•
Verify that the rated wheel speed is greater or equal to that of the grinder and the
correct wheel size is used.
•
Flange nuts and flanges must be in good condition and suit the wheel.
•
Look for worn or damaged mounting accessories.
•
Grinding wheel holes should fit the arbor correctly.
•
Ensure the wheel being used is correct for the application, correctly mounted and
tightened before use. Do not over tighten the mounting nut.
•
Inspect the electrical cord or air hose for damage.
•
Inspect the work area for loose objects that might strike the grinder wheel.
General Safety Rules
•
Read the manufacturers operator safety manual before use.
•
Don’t use a grinder if you have not been properly trained.
•
Ensure the grinder/sander being used is suitable for the task.
•
Personal protective equipment such as safety glasses or goggles, face shields, hearing
protection and gloves must be worn at all times. Consider wearing protective clothing
on the arms, legs and feet as well.
•
Never clamp the grinder in a vise.
•
Use clamps or another method to secure the work piece.
•
Never use a grinder without the guard. One exception to this rule is if the wheel is two
inches or less, it is not required to have a guard.
•
Allow the grinder to come up to full speed before applying it to the workpiece.
•
Do not allow anyone to stand in front of a spinning grinding wheel at any time.
•
Make smooth contact with the work piece and avoid bumping action or excessive
pressure.
•
When starting a cold wheel, apply it to the workpiece slowly until the wheel gradually
warms up.
•
Direct sparks away from yourself, others in the workplace and flammable or
combustible materials.
•
Keep coworkers and visitors away from all grinding operations
•
Always keep both hands on the tool.
Schools Insurance Program for Employees
7455 Morro Road Atascadero, CA 93422
(805) 460-0280
www.slosipe.org
•
Do not overreach and maintain firm footing and balance.
•
Position the grinder in a way that the guard provides the maximum protection to the
operator from sparks and/or flying debris.
•
Use caution when grinding in corners because a sudden, sharp movement of the
grinder may occur when the wheel strikes the secondary surface.
•
Maintain an angle of approximately 15° to 30° between the disc and the working
surface.
•
Do not apply side pressure on the grinding or cutting wheel.
•
Never override the ON/OFF switch or secure it in the ON position.
•
Use only replacement parts recommended by the manufacturer.
•
Wet or damp grinding wheels as well as ones that have been dropped should be
discarded.
•
If excessive vibration occurs or it operates roughly upon starting, immediately shut the
tool off and check the grinder and wheel for damage.
•
Newly mounted discs should run freely for at least one minute before cutting or
grinding
•
Never apply pressure to stop a spinning disc.
•
If the disc label is missing or illegible, replace it with a new one.
•
Use grinders with adjustable/moveable guards when working in difficult to reach
places.
•
Use grinders with a safety slip clutch or other electronic clutches that prevent kickback.
•
Grinder speeds should be checked periodically (SIPE will do this).
•
Unplug the grinder before changing discs and wheels.
•
Grinders and grinding wheels should be handled carefully to avoid damage.
•
Pneumatic grinders/sander should be operated at or below the recommended PSI.
Wheel and Ring Test
Ring test: The wheels should be tapped gently with
a light nonmetallic implement, such as the handle of
a screwdriver for light wheels, or a wooden mallet
for heavier wheels. Tap wheels about 45º each side
of the vertical centerline and about 1 or 2 inches
from the periphery as indicated by the spots in the
figures below. Then rotate the wheel 45º and
repeat the test. A sound and undamaged wheel will
give a clear metallic tone. If cracked, there will be a
dead sound and not a clear "ring." The ring test is
subject to interpretation by the inspector and is
primarily applicable to vitrified bonded wheels.
Schools Insurance Program for Employees
7455 Morro Road Atascadero, CA 93422
(805) 460-0280
www.slosipe.org
Please feel free to contact SIPE to conduct an RPM test on all portable and stationary grinders
at your worksite.
Schools Insurance Program for Employees
7455 Morro Road Atascadero, CA 93422
(805) 460-0280
www.slosipe.org
Approximate area
of grinding/sanding
Schools Insurance Program for Employees
7455 Morro Road Atascadero, CA 93422
(805) 460-0280
www.slosipe.org
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising