Surface Grinder Operation 251

The class "Surface Grinder Operation" provides step-by-step guidelines on how to grind a rectangular workpiece. Grinding each side of a workpiece requires wheel dressing and other preparatory steps, and then roughing and finishing passes. Workpiece sides are numbered from 1 to 6 in order to track which sides must be ground perpendicular or parallel to one another. Some workpieces require special considerations, such as mounting on an angle plate or grinding at an angle.

In order to perform successful surface grinding operations, operators must have a solid foundational knowledge of proper grinding methods. This class provides the practical steps and considerations for surface grinding a part from start to finish, which gives operators an understanding of grinding before ever turning on the machine. This will speed up the time it takes for new operators to learn surface grinding, and reduce user errors.

Class Details

Class Name:
Surface Grinder Operation 251
Version:
2.0
Difficulty:
Intermediate
Number of Lessons:
15
Related 1.0 Class:
Surface Grinder Operation 240

Class Outline

  • Surface Grinding
  • Surface Grinding Machines
  • HSRT Surface Grinding Machine Components
  • Surface Grinding Review
  • Grinding a Square or Rectangular Workpiece
  • The Six Sides and Their Uses
  • Review: Grinding a Square or Rectangular Workpiece
  • Before Roughing
  • Roughing
  • Grinding Parallel Surfaces
  • Grinding Perpendicular Surfaces
  • Review: Roughing Parallel and Perpendicular Surfaces
  • Finishing
  • Grinding Flat Surfaces at Different Angles
  • Review: Finishing, Grinding Flat Surfaces at Different Angles

Objectives

  • Describe surface grinding.
  • Describe basic surface grinding machines.
  • Identify the essential components of the HSRT surface grinding machine.
  • Describe the basic process of grinding a square or rectangular workpiece.
  • Describe the relationship between the sides of a square or rectangular workpiece.
  • Describe preparations for roughing a workpiece.
  • Describe roughing a flat surface of a square or rectangular workpiece.
  • Describe grinding parallel surfaces of a workpiece.
  • Describe grinding perpendicular surfaces of a workpiece.
  • Describe finishing a square or rectangular workpiece.
  • Describe grinding flat surfaces at different angles.

Job Roles

Certifications

NIMS
  • Grinding I
  • Grinding Skills-FastTrack

Glossary

Vocabulary Term Definition
aluminum oxide A compound made from bauxite and other additives that is commonly used as an abrasive material. Aluminum oxide is also referred to as alumina.
angle plate A workholding device used in grinding that holds the workpiece to a 90° vertical surface using clamps. Angle plates are used to grind edges.
automatic feed The method of advancing a workpiece into a machine automatically. Automatic feed, also called autofeed, is typically controlled by an on-off lever.
axis The imaginary line around which a part rotates as it is turned. The axis of the machine spindle on a surface grinder indicates the orientation of the wheel.
balance To ensure that a grinding wheel has equal weight across the wheel. A wheel that is out of balance negatively affects grinding operations.
base The foundation of a machine that supports all the other machine components. The base of a surface grinding machine is the bottom portion of the machine.
Blanchard grinders A type of surface grinder that has a vertical spindle and rotary machine table. Blanchard grinders’ spindle and table configuration allows for grinding multiple workpieces uniformly and continuously.
cast iron A metal consisting of iron, over 2.11% carbon, and 1% to 3% silicon. Cast irons will normally contain trace amounts of other elements.
clamps A device used to hold a workpiece in place. Clamps are often used in surface grinding to hold a workpiece against another workholding device, such as an angle plate, for positioning.
column A component at the top of the grinding machine that supports the spindle and vertical ways and controls vertical motion of the grinding wheel. Columns may be fixed or movable.
compound angle An angle that is cut, machined, or ground into a workpiece that passes through two perpendicular planes. Grinding compound angles requires specialized workholding devices.
compound sine plate A magnetic workholding device used in surface grinding to hold workpieces at precise compound angles. Compound sine plates are essentially two sine plates joined into one device.
computer numerical control CNC. A self-contained system of computers and precise motors that executes program instructions to guide machine tool components. Computer numerical control allows operators to program sequences of machining operations.
coolant A liquid substance, often water and oil, used to reduce or maintain the temperature of a part being ground. Coolant is often referred to as grinding fluid in grinding operations.
crossfeed Feed of the workpiece across the wheel. Crossfeed movement toward and away from the column is controlled by the crossfeed handwheel on a surface grinder.
crossfeed handwheel A grinding machine component that controls movement along the saddle ways. The crossfeed handwheel controls side to side table movement toward and away from the column.
deburr Removal of sharp projections left by a tool on a workpiece. Deburring ensures that a workpiece surface is smooth and flat enough to be positioned face down when grinding the opposite surface.
dial indicator An instrument with a contact point attached to a spindle and gears that move a pointer on the dial to measure small distances and angles. Dial indicators are used to check alignment of various machine components or workpiece dimensions.
diamond dresser A tool, containing one or more diamonds, that is used to remove material from the surface of a grinding wheel. Diamond dressers are used for both dressing and truing.
dress To remove swarf, dull grains, and bonding material from a grinding wheel by fracturing away the wheel surface. Dressing can produce a dull or sharp wheel surface according to the desired surface finish.
finishing The final machining operation that produces the complete part. Finishing is performed to obtain the required tolerance and surface finish in surface grinding.
fixture A customized workholding device that is used to position a workpiece. Fixtures may require additional workholding devices to hold the workpiece securely in place.
grains A small, hard particle or crystal of abrasive material. Abrasive grains are bonded together to create grinding wheels and other abrasive tools.
horizontal spindle A grinding spindle with an axis that is parallel to the table. A horizontal spindle on a surface grinder is the most common orientation.
HSRT Horizontal spindle, reciprocating table. A machine configuration with a spindle parallel to a table that moves back and forth. HSRT grinders are the most common surface grinding machines.
locating The accurate positioning of a workpiece in relation to other known surfaces or distances. Locating references the relative location of the tool and workpiece.
magnetic chuck A workholding device that is used to hold workpieces during grinding. Magnetic chucks can be permanent or electromagnetic.
magnetic sine plate A workholding device used in surface grinding to hold workpieces at precise angles. Magnetic sine plates have permanent magnets inside the plate for securing workpieces at an incline.
magnetic V-block A magnetic workholding component with a V-shaped groove down the middle of its body that can be changed and set to various angles. Magnetic V-blocks are designed to hold round, square, or rectangular workpieces.
manual machines A machine tool that is operated by the actions of the machine operator, rather than by automated or computerized actions. Manual machines are less expensive than CNC machines.
micrometer A U-shaped measuring instrument with a threaded spindle that slowly advances toward a small anvil. Micrometers are available in numerous types for measuring assorted dimensions and features.
parallel Two lines or planes that never intersect, regardless of how far they may extend. Parallel surfaces are the same distance apart at any given point.
periphery The perimeter, or the outer edge, of an object, such as a tool or workpiece. Many surface grinders use wheels that cut with their periphery.
perpendicular Two lines or planes that intersect at a 90˚ angle. Perpendicular surfaces of a square or rectangular workpiece are any two surfaces that share an edge.
precision gage blocks A hardened steel block that is manufactured with highly accurate dimensions. Gage blocks are available in a set of standardized lengths.
profile A cross-sectional shape or form of a workpiece created by a specialized grinding wheel. Profile surface grinding is often performed by automated machines capable of precise movements.
reciprocating table The grinding machine component that supports and moves the workpiece side to side. The reciprocating table’s motion is parallel to a wheel mounted on a horizontal spindle.
rotary table The grinding machine component that supports and rotates the workpiece. Rotary tables are cylindrical in shape and often hold multiple workpieces for surface grinding.
roughing The initial machining operation that removes stock rapidly without regard to surface finish. Roughing achieves the basic workpiece shape and dimensions in surface grinding.
saddle The component of a grinding machine that is attached to the ways of the base and supports the table. Through its own ways, the saddle allows motion along a third axis.
semi-automatic machines A machine that performs a grinding cycle independently, but requires an operator to set and start the process. Semi-automatic machines closely resemble manual machines.
setup All the necessary preparation of tooling and fixturing that occurs on a machine before an operation can be executed. Setup includes preparing machines, tools, and materials.
silicon carbide A hard, brittle material used as a conventional abrasive. Silicon carbide grinding wheels are hard and sharp, and the grains break away easily.
spindle A rotating component of a machine tool that can hold and rotate tools. The spindle rotates a mounted grinding wheel in surface grinding, providing power to the grinding process.
steel A ferrous metal consisting of iron and carbon, usually with small amounts of manganese, phosphors, sulphur, and silicon. Steels are the most common metals used in manufacturing.
straight wheel A common type of abrasive tool used in grinding and cutoff operations. Straight wheels generally appear as flat discs.
surface finish The smoothness of a surface after it has been ground. Surface finish is the complete, desired surface.
surface grinding A common grinding process that uses a rotating grinding wheel to remove precise amounts of a material from a workpiece. Surface grinding is capable of producing a variety of workpiece features and designs but is most commonly used to grind flat surfaces.
swarf A gritty combination of chips, abrasive grains, and worn bonding material that is produced during grinding. Swarf can clog a grinding wheel and cause it to function improperly.
table feed The feed of the workpiece past the grinding wheel, which is based on the worktable's rate of movement. Table feed is also known as work feed.
table handwheel A grinding machine component that controls motion of the table along the base ways. The table handwheel controls back and forth table movement.
table reverse dogs A control component of a grinding machine that reverses the direction of table movement at the end of a stroke. Table reverse dogs control table reciprocation and are also called table stroke trip dogs.
table stroke trip dogs A control component of a grinding machine that reverses the direction of table movement at the end of a stroke. Table stroke trip dogs control table reciprocation and are also called table reverse dogs.
taper An angular surface cut into a workpiece. Tapers on flat or rectangular workpieces are gradual changes from a larger height to a smaller height at a constant slope or incline.
tolerances An acceptable deviation from a given dimension or geometry. Tolerances indicate the allowable differences between a workpiece and its intended design in surface grinding.
true To restore a grinding wheel to its round, even shape. Truing can also often restore the wheel balance.
vertical spindle Oriented in an up-and-down direction, or perpendicular to the floor. Vertical spindles are less common than horizontal spindles in surface grinding.
ways Two precisely measured, parallel tracks that support and guide the movement of grinding machine components. Most surface grinders have three sets of ways.
wheel feed handwheel A grinding machine component that controls the incremental vertical motion of the wheelhead along the column ways. The wheel feed handwheel moves the grinding wheel down towards and up away from the workpiece.
wheel guard A protective cover secured over a grinding wheel to protect workers from broken wheels or debris.
wheel segments A smaller section or portion of a whole wheel. Wheel segments are typically used on surface grinders with rotary tables and vertical spindles, such as Blanchard grinders.
wheelhead A grinding machine component that is attached to the column ways. The wheelhead contains the spindle housing.
work feed The feed of the workpiece past the grinding wheel, which is based on the worktable's rate of movement. Work feed is also known as table feed.
workholding A device used to support, locate, and hold a workpiece. The magnetic chuck is a common workholding device on the surface grinder.
worktable The part of the grinding machine that directly or indirectly supports and moves the workpiece. Worktable is another term for table, or machine table.