210 Agricultural Mechanics and Technology Systems
Copyright Goodheart-Willcox Co., Inc.
• For portable tools, apply only light pressure and let the tool do the
work. Keep the tool in constant motion to reduce digging in/over-
sanding and heat buildup.
• For stationary tools, ensure that the machine is mounted in a
secure position. Apply even pressure and move the work material
continuously across the face of the stone/sander.
Grinders
Grinders are machines that use high-speed rotation and an abrasive to
smooth and shape metal. They are also used to remove small amounts of
metal from surfaces and edges and to polish metal surfaces. Portable grinders
include angle grinders and die grinders. Stationary models include bench
grinders, pedestal grinders, and surface grinders. The type of grinder chosen
depends on the materials and the type of job.
Grinder Abrasives
Grinders use abrasive materials that are formed
by bonding adhesive particles together to create solid,
usually nonfl exible, synthetic stones. These materials
are sometimes reinforced with fi brous fi llers that
strengthen the stone and extend the working life of
the abrasive consumables. New layers of abrasives are
exposed as the wheel or stone is worn away from use.
Angle Grinders
Angle grinders are essential handheld tools for
grinding and shaping metal parts to be welded. They
are also used for rough sharpening operations and
for cleaning parts. Angle grinders, also called disc
grinders, can be fi tted with an assortment of grinding
stones, wire brushes, sanding attachments, and buffi ng
wheels to meet any number of cleaning and polishing
needs, Figure 8-44. The disc is typically held at an angle
of 15° to 30° to the surface of the material.
In addition to the power tool safety rules and the rules specifi c to grinders
and sanders, observe the rules listed here when working with angle grinders:
• Inspect the disc or attachment for defects before starting the machine.
• Always use both hands to hold the angle grinder by the provided
handles.
• Ensure that sparks and debris are directed in a safe direction and away
from others.
• Always engage the material by gently touching the grinder to the work.
• Avoid free spinning unnecessarily.
• Be cautious of kickback if the grinder is allowed to bind. Binding may
occur when attempting to grind inside of a hole or depression or when
excessive pressure is applied.
KKulikov/Shutterstock.com
Figure 8-44. A typical pneumatic angle grinder.
Many different sizes and types of attachments
are available for disc grinders. Always match the
correct diameter, arbor size, and rated rpm to the
power tool.