Transcript Metal Grinding - Two Rivers High School

METAL GRINDING
Terminology
Grinding Wheels
• A grinding wheel is an expendable
wheel that is composed of an abrasive
compound used for various grinding
and abrasive machining operations.
Grinding Wheels
• Many different styles available
• Choose correct type & grit of wheel
• Replace once when wheel reaches ½ of its
original diameter.
Ring Test
• Good – Ring
• Bad – Thud
• ALWAYS TEST WHEELS BEFORE
INSTALATION
Wheel Identification
Size:
• 10” x 1.5” x 1.25”
• Wheel Diameter x thickness x arbor size
Grit : How aggressive the wheel will grind
• Higher Grit = Smoother Wheel
RPM : How fast the wheel can spin safely
• Use wheels that meet or exceed the grinder RPM rating!
Color:
• Grey & Brown – workhorse grits, mild steels
• Pink & White – harder steels that require cool grinding
surface
• Ruby Red – Tool steels and sharpening
COURSE GRIT WHEELS
• Deeper cuts
• More aggressive
• 0-24
FINE GRIT WHEELS
• Sharpening
• Finishing
• Less aggressive cuts
• 80-120 grit
WIRE WHEELS
• Watch out for flying wires!
• Removes rust & paint
• Rough Polishing
Polishing & Buffing
• 150 grit and higher
• Cotton
Dressing a Grinding Wheel
• Adjust tool rest to proper
•
•
•
•
•
•
gap for dressing
Turn on grinder
Hook dressing tool on tool
rest
Put light pressure on
wheel while moving back
and forth
Continue until wheel is
smooth
Readjust tool rest to 1/16”
LINK
Don’t grind soft metals!
• Aluminum, copper, brass, etc.
• The metal is too soft
• The heats up and melts into the grain
• It will need to be dressed
Safety Rules:
• Adjust tool rest to 1/16” MAX from wheel
NEVER GRIND ON THE SIDE!
1. They are not even
The sides are not trued during
manufacturing
2. Not designed to handle heavy loads.
May shatter leading to a very
nasty result.
Safety Rules
• PPE – Glasses, shield, dust mask, ears
• NEVER wear gloves!
• Hold the piece with a locking pliers if it gets hot.
• Stand to the side during startup
• Inspect wheel
• Re-Dress uneven or loaded wheels
• Wear a mask
• Keep rest 1/16” from wheel
Safety Rules:
• Hold work by hand or with a clamp or vice grip
• Do not adjust or repair while grinder is running
• DO NOT FORCE IT!
• Keep your work piece on the tool rest at ALL
times
Portable Disc Grinder
Angle Grinder
Hand Grinder
Types of Discs
1. Grinding wheel
• Weld preparation
• Removing slag/unwanted welds
2. Fiber Cut-off Wheel
• Metal cutting
• Use at a 90 degree angle only
3. Flap Disc / Sanding Disc
• Metal finishing
4. Cup brush
• Used for removal of paint
• Weld cleanup
• Hold with EXTRA force!
Standard Discs
• Used for grinding, de-scaling, polishing, blending, and
finishing.
• Semi-flexible backing
• Fits curved & rough surfaces
• Leaves a smooth & swirl-free finish.
Raised Hub / Type 27
• Hub is raised in the center
• 1/8” thick
• Light Grinding
• Cutting off
• Notching
• ¼” thick
• Heavy duty grinding only
Saucer Shaped / Type 28
• Identified by saucer
shape.
• Easier to use than
raised-hub discs
• Designed to be held
at shallow angles
Changing the Discs
• UNPLUG IT!!!!!!!!!!!!
• Engage the spindle lock
• Use the correct size wrench
• Wear gloves and remove wheel
• Snug new wheel with arbor wrench!
Can be a workout
• Using the portable disc grinder is hard work
• Rest frequently to avoid fatigue
Fighting Fatigue – Handle Attachment
• Reduces stress on hands and arms
• Necessary for deep cuts
• Makes it easier for disc change-over
Fighting Fatigue- Speed Lock
• Locks the grinder into full speed
• (Cruise-Control)
• Convenient for heavy grinding
• Several styles
• All are located on the power switch
Safety Rules
• PPE: Eye protection, long sleeve leather
gloves
• face shield is recommended
• Use correct wheel for the application
• Check condition of wheel before each use
• Replace once wheel is half gone
• Do not remove the wheel guards
• Secure your work piece
• Shoot your sparks in a safe direction
• LET THE GRINDER DO THE WORK
• Never set it down on while the disc is
spinning
Pneumatic Grinders
• Use compressed air instead of
electricity
• Better for extended grinding
applications
• Need a good air-compressor to
keep up
• Same attachments available as
electric