Basics of the Surface Grinder 231

The class "Basics of the Surface Grinder" provides an overview of the components, considerations, and varieties of the surface grinding machine. Surface grinders are classified by their table types and spindle orientations, and vary in levels of automation. Wheels, workholding devices, and coolant also vary based on the workpiece and grinding operation.

Surface grinding is a common operation and is performed when very tight tolerances and surface finishes are required. A surface grinder operator must be familiar with the machine itself, as well as how to select and utilize wheels, workholding, and coolant, in order for the grinding operation to be successful. This foundational knowledge is necessary to reduce scrap, increase quality and production rates, and lower costs.

Class Details

Class Name:
Basics of the Surface Grinder 231
Version:
2.0
Difficulty:
Intermediate
Number of Lessons:
22

Class Outline

  • Surface Grinding
  • The Surface Grinding Process
  • The Surface Grinding Machine
  • Reciprocating vs. Rotary Tables
  • Horizontal vs. Vertical Spindles
  • Spindle and Table Orientations
  • Table and Spindle Review
  • Manual Machines and Machine Automation
  • Double Column Machines
  • Profile Surface Grinders
  • Surface Grinding Machines Review
  • Grinding Variables for the Surface Grinder
  • Creep Feed Grinding
  • Grinding Variables Review
  • Surface Grinding Wheel Shapes
  • Wheel Maintenance
  • Surface Grinder Coolant
  • Wheel Shapes and Maintenance Review
  • Basic Workholding Devices
  • Surface Grinder Workholding Fixtures
  • Workholding Operation
  • Final Review

Objectives

  • Describe grinding. Define surface grinding.
  • Describe the surface grinding process.
  • Identify the structural components of the surface grinding machine.
  • Distinguish between reciprocating and rotary tables.
  • Distinguish between vertical and horizontal spindles.
  • Describe the effects of different table and spindle orientations.
  • Describe the differences in operation between manual and CNC grinders.
  • Describe the structure and function of a double column surface grinding machine.
  • Describe the structure and function of profile surface grinding machines.
  • Describe grinding variables.
  • Describe the creep feed grinding process.
  • Identify the basic wheel shapes.
  • Define "dressing" and "truing."
  • Describe the setup and purpose of coolant on the surface grinding machine.
  • Describe common workholding devices used on the surface grinding machine.
  • Describe common workholding fixtures used on the surface grinding machine.
  • Describe the operation of various surface grinder workholding devices.

Job Roles

Certifications

NIMS
  • Grinding I

Glossary

Vocabulary Term Definition
abrasive A material consisting of hard particles used to wear away or remove workpiece material. Abrasives are bonded in the shape of a wheel for grinding operations.
arc of cut The area of contact between the grinding wheel and the workpiece. Arc of cut is also called the cutting zone.
base The foundation of a grinding machine that supports all the other machine components. The base of a grinder 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.
bonding The adhesive material in grinding wheels that holds the abrasive grains together. Bonds may be vitrified, organic, metal, or electroplated.
chip An unwanted piece of material that is removed from a workpiece. Chips are formed when a tool cuts or grinds material.
CNC Computer numerical control. A self-contained system of computers and precision motors that executes program instructions to guide machine tool components. CNC machines offer increased productivity and flexibility.
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 moveable.
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.
concentric Having or sharing a common center between two circles or round objects, such as the center hole on a grinding wheel and its outside edge. Concentric circles should be both aligned and equally round.
coolant A substance, usually liquid, used to reduce or maintain the temperature of a part being ground. Grinding fluid is a type of coolant.
creep feed grinding A grinding method in which the depth of cut is increased while the feed rate is decreased. Creep feed grinding is used for large amounts of material removal.
crossfeed handwheel A grinding machine component that controls movement along the saddle ways. The crossfeed handwheel controls side-to-side table movement.
cup wheel A grinding wheel that is shaped like a cup or a bowl. A cup wheel may have sides that are either straight or flaring.
depth of cut The amount of penetration a grinding wheel makes, or the distance from the uncut surface to the machined surface. In surface grinding, depth of cut refers to how far a grinding wheel grinds into the workpiece.
diamond A naturally occurring or manufactured stone that is the hardest known substance. Diamond is used as a truing and dressing tool due to its hardness.
double column surface grinding machines A type of surface grinder that has two machine columns and spindles, rather than only one. Double column machines are often designed to accommodate very large workpieces.
dressing Removing swarf, dull grains, and bonding material from a grinding wheel by fracturing away the wheel surface. Dressing also sharpens the wheel.
electromagnetic chucks A workholding device that produces a variable magnetic pull. Electromagnetic chucks are powered by electric current and can hold a variety of workpieces when turned on but are inactive when off.
feedrate The rate at which the cutting tool and the workpiece move in relation to one another. Feedrate refers to the speed at which the workpiece moves past the wheel in surface grinding.
finishing A process that achieves the desired surface finish on a part. Finishing is the last operation performed 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.
fracture The breaking apart of grains in an abrasive wheel during grinding. Fracturing is part of the wheel’s self-sharpening process and essential to producing a good surface finish.
glazing The unwanted formation of a smooth surface on a grinding wheel. Glazing can be caused by loading.
grains A small, hard particle or crystal of abrasive material. Abrasive grains are bonded together to create grinding wheels and other abrasive tools.
grinding Using an abrasive to wear away a workpiece surface and achieve highly accurate dimensions and geometry. Grinding operations commonly use abrasive grains bonded into a wheel shape.
grinding variables The measureable rates of movement of cutting tools and workpieces. Grinding variables for surface grinding include wheel speed, table feed, and depth of cut.
grinding wheel A wheel made of a bonded abrasive used to remove material from the surface of a workpiece. A grinding wheel removes microscopic chips of material from a workpiece and can produce very fine surface finishes.
handwheels A wheel-shaped device that is turned by hand in order to control a machine component. Handwheels are found on manual machine tools.
hardware The physical equipment used in a computer system. Hardware includes a computer screen, keys, and power supply.
horizontal machine spindles Oriented in a sideways direction, or parallel to the floor. Most surface grinder spindles are positioned horizontally.
loading A build-up of swarf in a grinding wheel that clogs the spaces between grains. Dressing and truing a grinding wheel prevents loading.
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.
magna-lock clamps A two-piece magnetic clamping system with flexible fingers designed to hold nonmagnetic or very small workpieces during grinding. Magna-lock clamps are also known as magna-vise clamps.
magna-vise clamps A two-piece magnetic clamping system with flexible fingers designed to hold nonmagnetic or very small workpieces during grinding. Magna-vise clamps are also known as magna-lock clamps.
magnetic adjustable 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 adjustable V-blocks are designed for grinding angles and holding round, square, or rectangular workpieces.
magnetic chuck A device that uses magnetic force to hold metal objects that are susceptible to magnetism. Magnetic chucks are common workholding devices used in surface grinding, and can be permanent or electromagnetic.
magnetic field The area surrounding magnets that contains strong magnetic forces. Magnetic fields produced by magnetic chucks have varying intensity depending on factors like workpiece size and material.
magnetic parallels Blocks set parallel to each other that extend the magnetic field of the magnetic chuck. Magnetic parallels can support projecting or irregular 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.
meters per second m/s. A measurement of speed that is a direct function of the workpiece or tool diameter and its rate of rotation. Meters per second measures the number of meters that a location on a rotating component travels in one second.
part program A series of alphanumerical instructions that guides the movements of a CNC machine. A part program directs a CNC machine to perform the necessary sequence of operations to machine a specific workpiece.
periphery The perimeter, or the outer edge, of an object, such as a tool or workpiece. Some grinding wheels cut with their periphery.
permanent magnetic chucks A workholding device consisting of a series of long magnetic inserts arranged side-by-side and interconnected within a grid of conductive material. Permanent magnetic chucks are turned on by a lever that moves the magnetic inserts inline with a conductive grid.
precision angle plate A workholding device used in grinding which holds the workpiece to a vertical surface using clamps. Precision angle plates can hold non-magnetic workpieces.
precision gage block A hardened steel block that is manufactured with highly accurate dimensions. Gage blocks are available in a set of standardized lengths.
precision V-block A magnetic workholding component with a fixed, unchangeable V-shaped groove down the middle of its body. Precision V-blocks are designed to hold round, square, or rectangular workpieces.
profile grinder A specialized grinding machine that is designed to conform to a particular grinding operation or part shape. Unlike most surface grinders, profile grinders are not made to grind flat surfaces.
programmable logic controller PLC. A processor-driven device that uses logic-based software to provide electrical control to machines. In grinding, PLCs are the controllers that run computer numerical control (CNC) systems.
recessed wheel An abrasive wheel that resembles a flat disk with a depressed area surrounding the wheel center. Recessed wheels are wider at their periphery than their center.
reciprocating table The grinding machine work surface which supports and moves the workpiece back-and-forth. Workholding devices hold the part on the reciprocating table.
rigidity The condition of a workpiece, machine, or machine setup characterized as stiff and immovable. Rigid components are fixed securely in place.
rotary table A rotating, cylindrical surface which supports and moves the workpiece in a circular direction during grinding. Rotary tables often hold multiple workpieces.
roughing Rapid removal of stock without regard to surface finish. Roughing achieves the basic dimensions of a workpiece and is performed prior to finishing operations in surface grinding.
saddle The component of a grinding machine that is attached to the ways of the base and supports the table. The saddle allows motion in a third axis through its own ways.
sine plate A magnetic workholding device used in surface grinding to hold workpieces at precise angles. Sine plate angles are adjusted using metal rolls and precision gage blocks.
software The coded programs, instructions, formulas, and operations that structure the actions of a computer. Software makes up the non-physical components of a computer.
spindle A rotating component of a machine tool that can hold and rotate tools. Grinding wheels are typically mounted onto a spindle.
straight wheel A common type of abrasive tool used in grinding and cutoff operations. Straight wheels generally appear as flat disks.
superabrasives A group of relatively expensive but effective materials possessing superior hardness. Superabrasives include cubic boron nitride and diamond.
surface feet per minute sfm. A measurement of speed that is a direct function of the workpiece or tool diameter and its rate of rotation. SFPM measures the number of feet that a location on a rotating component travels in one minute.
surface finish The quality of a surface after it has been ground. Surface finishes may be rough, wavy, or smooth, among other conditions, depending on the operation.
surface grinding A common grinding process that uses a rotating grinding wheel to wear away precise amounts of a flat workpiece surface. Surface grinding is often one part of a sequence of machining operations.
swarf The 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 The part of the grinding machine which directly or indirectly supports the workpiece. On a surface grinder, the table may reciprocate or rotate.
table feed The feed of the workpiece past the grinding wheel. In surface grinding, table feed, also known as work feed, is based on the worktable’s rate of movement.
table handwheel A grinding machine component that controls motion of the table along the base ways. The table handwheel controls up-and-down table movement.
toe clamps A clamp with a serrated surface that reaches forward and down to grip the workpiece from the side. Toe clamps leave a workpiece's top surface free for surface grinding.
tolerance An acceptable deviation from a given dimension or geometry. Tolerances indicate the allowable difference between a physical feature and its standard design.
truing To restore a grinding wheel to its original, intended shape. Truing can also often restore the wheel balance.
vacuum chuck A workholding device that holds a workpiece to its surface through air pressure. Vacuum chucks can be used for non-magnetic workpieces during surface grinding.
vertical machine spindles Oriented in an up-and-down direction, or perpendicular to the floor. Vertical machine spindles are less common than horizontal machine 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 wheel component that controls the incremental vertical motion of the wheelhead along the columns ways.
wheel speed The rate at which the grinding wheel rotates at the arc of cut. Wheel speed depends upon the spindle speed and wheel size.
wheelhead A grinding machine component that is attached to the column ways and contains the spindle housing.
work feed The feed of the workpiece past the grinding wheel. In surface grinding, work feed, also known as table feed, is based on the worktable’s rate of movement.
workholding A device used to support, locate, and clamp a workpiece. The magnetic chuck is a common workholding device on the surface grinder.
workholding The process of securely supporting, locating, and clamping a workpiece for a manufacturing operation. The magnetic chuck is a common workholding device for surface grinding.
worktable The part of the grinding machine which directly or indirectly supports the workpiece. Worktable is another term for table, or machine table.