Metal Grinding

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Metal Grinding
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Terminology
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Grinding Wheels

• A grinding wheel is an expendable wheel that is
  composed of an abrasive compound used for various
  grinding and abrasive machining operations.

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Grinding Wheels

• Many different styles available
• Choose correct type grit of wheel
• Replace once when wheel reaches ½ of its original
  diameter.

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Ring Test

• Good Ring
• Bad Thud
• ALWAYS TEST WHEELS BEFORE INSTALATION

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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

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COURSE GRIT WHEELS

• Deeper cuts
• More aggressive
• 0-24

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FINE GRIT WHEELS

• Sharpening
• Finishing
• Less aggressive cuts
• 80-120 grit

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WIRE WHEELS

• Watch out for flying wires!
• Removes rust paint
• Rough Polishing

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Polishing Buffing

• 150 grit and higher
• Cotton

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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

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Dont 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

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Safety Rules

• Adjust tool rest to 1/16 MAX from wheel

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NEVER GRIND ON THE SIDE!

• They are not even
• The sides are not trued during manufacturing
• Not designed to handle heavy loads.
• May shatter leading to a very nasty result.

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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

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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

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Portable Disc GrinderAngle Grinder Hand Grinder
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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!

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Standard Discs

• Used for grinding, de-scaling, polishing,
  blending, and finishing.
• Semi-flexible backing
• Fits curved rough surfaces
• Leaves a smooth swirl-free finish.

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Raised Hub / Type 27

• Hub is raised in the center
• 1/8 thick
• Light Grinding
• Cutting off
• Notching
• ¼ thick
• Heavy duty grinding only

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Saucer Shaped / Type 28

• Identified by saucer shape.
• Easier to use than raised-hub discs
• Designed to be held at shallow angles

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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!

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Can be a workout

• Using the portable disc grinder is hard work
• Rest frequently to avoid fatigue

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Fighting Fatigue Handle Attachment

• Reduces stress on hands and arms
• Necessary for deep cuts
• Makes it easier for disc change-over

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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

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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
  

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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