Grinding Wheel Selection 351

"Grinding Wheel Selection" provides a guide on selecting the ideal grinding wheel from a grinding wheel manufacturer's catalog. Grinding wheel manufacturers list various specifications for grinding wheels, including workpiece compatibility, wheel type, wheel dimensions, abrasive material, bond material, grade, grain size, and maximum safe wheel speed. Some specifications, such as wheel type, are selected according to the grinding process. Other aspects of a grinding wheel, such as grain size and wheel structure, depend on workpiece material and the desired grinding results, including tolerance and surface finish.

Selecting the most effective and economical grinding wheel requires a detailed knowledge of each aspect of the wheel and an understanding of the specifications needed to meet the requirements of a grinding operation. An incorrect or incompatible grinding wheel can lead to scrapped parts, damaged wheels or machines, and wasted time and money.

Class Details

Class Name:
Grinding Wheel Selection 351
Version:
2.0
Difficulty:
Advanced
Number of Lessons:
24

Class Outline

  • Grinding Wheel Catalogs
  • Wheel Dimensions
  • Wheel Types
  • Common Grinding Wheel Types
  • Surface Grinding Segments
  • Grinding Wheel Types in Use
  • Reviewing Wheel Types
  • Profile and Gear-Grinding Wheels
  • Inside-Diameter Grinding Wheels
  • Specialty Abrasive Products
  • Selecting an Abrasive Material
  • Wheel Color
  • Variations in Wheel Color
  • Specialty Wheels and Abrasives Review
  • Grain Size
  • Determining Grain Size
  • Bond Material
  • Wheel Grade and Grain Fracturing
  • Reviewing Wheel Materials
  • Maximum Speed Settings
  • Superabrasive Wheels
  • Wheel Economy
  • Interactive Catalog
  • Final Review

Objectives

  • Describe the main considerations when selecting a grinding wheel from a grinding wheel catalog.
  • Describe grinding wheel dimensions listed in grinding wheel catalogs.
  • Describe wheel types listed in grinding wheel catalogs.
  • Distinguish between common grinding wheel types.
  • Describe surface grinding segments.
  • Describe grinding wheels used in profile grinding.
  • Describe inside-diameter grinding wheel structure and selection.
  • Describe coated abrasives.
  • Describe common abrasive materials available in grinding wheel catalogs.
  • Explain the characteristics of different colors in grinding wheels.
  • Explain how grain size relates to wheel selection.
  • Explain how grain size is determined.
  • Distinguish between the bond materials available in grinding wheel catalogs.
  • Explain how to select a wheel grade. Explain how wheel grade affects grain fracturing.
  • Explain the importance of maximum safe operating speed.
  • Describe considerations involved in selecting a superabrasive wheel.
  • Explain how to select the most economical wheel for a grinding operation.

Job Roles

Certifications

NIMS
  • Grinding I

Glossary

Vocabulary Term Definition
abrasive belts A type of coated abrasive that is shaped like a wide, flat band. Abrasive belts are fitted around powered rollers that propel the abrasive material past the workpiece surface.
abrasive depth The thickness of the layer of superabrasive material on the grinding edge of a vitrified- or resin-bonded grinding wheel. Abrasive depth is typically a fraction of an inch.
abrasive discs A type of coated abrasive that is flat and circular in shape. Abrasive discs are often used for polishing or blending various surface finishes.
abrasive grain A small, hard particle that forms chips during grinding. Abrasive grains are held together by bond material to create grinding wheels and other abrasive tools.
additives A substance that is added to a material during manufacturing in order to improve or alter the material's properties. Additives can provide increased strength.
air sorting A sizing method for super-fine abrasive grains that involves using a vortex of air to spin the abrasive particles. In an air sorting process, the finer particles move to the outside of the vortex while the larger grains move closer to the center.
aluminum oxide A chemical compound of aluminum and oxygen in the form of white powder or clear crystals. Aluminum oxide, also known as alumina, is a conventional abrasive commonly used to grind plain or alloyed steel.
American National Standards Institute ANSI. A private, nonprofit organization that administers and coordinates voluntary standards and systems for products, services, and systems in the United States. American National Standards Institute designations on grinding wheels indicate bond grade, material type, and other identifying information for the wheel.
ANSI American National Standards Institute. A private, nonprofit organization that administers and coordinates voluntary standards and systems for products, services, and systems in the United States. ANSI designations on grinding wheels indicate bond grade, material type, and other identifying information for the wheel.
ANSI B7.1 A standards document published by the American National Standards Institute, or ANSI, that establishes guidelines regarding the safe use and care of grinding wheels and grinding machines. ANSI B7.1 includes guidelines on machine safety guards, wheel mounting, and wheel speed.
ANSI B74.2 A document published by the American National Standards Institute that specifies shapes and sizes for grinding wheels and mounted point wheels. The ANSI B74.2 standard lists a size range for each wheel type.
arbor The metal stalk or post on which some inside-diameter grinding wheels are mounted. Arbors allow inside-diameter grinding wheels to extend into a workpiece hole or feature.
arc of contact The portion of the grinding wheel's operating surface that is in contact with the workpiece at any point. A smaller arc of contact requires a harder-grade grinding wheel.
batch size A specific quantity of a part to be produced. Batch size should be taken into consideration when selecting a grinding wheel.
bauxite ore An aluminum ore from which aluminum is extracted. Bauxite ore is a major source of aluminum.
Blanchard grinder A type of surface grinder with a vertical spindle and a rotary worktable. Blanchard grinders can be large and typically use grinding segments or side wheels rather than the more common Type 1 grinding wheels.
bond material The adhesive substance in a grinding wheel that holds the abrasive grains together. Bond materials include vitrified, organic, metal, and electroplated.
bond material The adhesive substance in a grinding wheel that holds the abrasive grains together. The bond material determines the hardness of a grinding wheel.
bond posts A structural beam of bond material that connects abrasive grains in a grinding wheel. Bond post thickness helps to determine a wheel's grade.
bonded abrasive A grinding tool made from the combination of abrasive grains and bond material. Bonded abrasives are typically in the form of grinding wheels but also include surface grinding segments.
bonding agent The adhesive material that holds abrasive grains together in a grinding tool. Bonding agents for coated abrasives are usually animal glue or synthetic plastic resins.
bores The interior diameter of a hollow cylindrical workpiece. Bores are finished or enlarged by inside-diameter grinding.
CBN Cubic boron nitride. A manufactured superabrasive with hardness that is second only to diamond. CBN is chemically resistant but will wear quickly in the presence of water at high temperatures.
centerless grinding A type of cylindrical grinding in which a cylindrical workpiece is supported without centers or a chuck. Centerless grinding supports the workpiece on a work rest blade and guides it between a grinding wheel and a regulating wheel.
ceramic aluminum oxide A tough but sharp conventional abrasive made from crushed and dried alumina gel. Ceramic aluminum oxide grains require very high forces in order to fracture and self-sharpen.
ceramics A hard, brittle material that can withstand high temperatures and resist corrosion. Ceramics can be ground using diamond grinding wheels.
cermets A composite material made from ceramic and sintered metal. Cermets have high temperature resistance and high hardness.
chip An unwanted piece of material that is removed from a workpiece during grinding. Chips form when an abrasive grinding wheel grinds a workpiece.
chuck A device that holds a workpiece or grinding tool in place as it rotates. A chuck commonly has three or four jaws that adjust to hold various dimensions.
clearance An intentional amount of space left between two components. Clearance provided by a recessed grinding wheel allows space for a flange when mounting the wheel on the machine spindle.
coal A naturally occurring, carbon-based, and combustible mineral. Coal is often burned as a source of fuel.
coarse Large abrasive grains. Coarse grains produce a rough surface finish.
coated abrasives An abrasive tool composed of abrasive grains adhered to a flexible backing material, such as paper, plastic, or cloth. Coated abrasive tools are often used for finishing operations.
concentration A ratio of the superabrasive grains' weight and the volume of the resin- or vitrified-bonded superabrasive layer around the rim of a grinding wheel. Concentration is an optional designation on an ANSI superabrasive wheel label.
conventional abrasive The category of abrasive materials that includes the most commonly used, inexpensive abrasives. Conventional abrasives are refractory materials and include aluminum oxide and silicon carbide.
conventional abrasives The category of abrasive materials that includes the most commonly used, inexpensive abrasives. Conventional abrasives are refractory materials and include aluminum oxide and silicon carbide.
crush roll A very hard and formed wheel made from hardened steel or carbide. A crush roll feeds slowly and radially into a rotating grinding wheel to create the desired form onto the grinding wheel.
cubic boron nitride CBN. A manufactured superabrasive with hardness that is second only to diamond. Cubic boron nitride is chemically resistant but will wear quickly in the presence of water at high temperatures.
cup wheels A grinding wheel that is shaped like a cup or bow with straight or flared sides. Cup wheels may be side or peripheral grinding wheels.
cylinder wheels A Type 2 abrasive wheel that is designed for side grinding and has a large central mounting hole. Cylinder wheels can be used on surface grinders with vertical machine spindles.
cylindrical grinding A common grinding process in which a cylindrical workpiece is held on one or both ends during grinding. Cylindrical grinding rotates both the workpiece and grinding wheel in order to finish a part.
deburring Removing sharp chips left on a workpiece after a machining or grinding operation. Deburring is often done by hand or by robot using coated abrasives.
deflection The misalignment of components caused by excessive force or vibration. Deflection of a grinding wheel can cause serious injury.
diamond The hardest known substance. Diamond is both a naturally occurring and a manufactured superabrasive.
diamond roll A very hard and formed wheel with diamond grains. Diamond rolls are used to dress grinding wheels for profile grinding.
dressed A grinding wheel that has an angle or profile created on its operating face. Dressing a form or shape on the periphery of a grinding wheel allows the mirror image to be created on the workpiece.
dressing Removing swarf and dull grains from the periphery of the grinding wheel by fracturing away the wheel surface. Dressing also sharpens the grinding wheel so that it can achieve proper surface finish on a workpiece.
dyes A liquid coloring agent that is mixed with raw material during manufacturing. Dyes are an additive used to color a grinding wheel throughout.
electroplated bonds A superabrasive bond type created by immersing a metal wheel in an electrically charged chemical bath containing metal particles. Electroplated-bonded wheels have a single layer of superabrasive grains.
fiberglass A lightweight and strong material composed of a matrix of fine glass fibers weaved into a mesh. Sheets of fiberglass mesh are used as reinforcement in grinding wheels with resinoid bonds designed for handheld operations.
finishing A grinding process that achieves the required size and surface finish of the part. Finishing operations often require faster speeds and a lighter depth of cut.
flange A thick, flat metal ring that is used when mounting a grinding wheel on the grinding machine spindle. Flanges can hold moveable weights to help balance a grinding wheel.
flap discs A type of coated abrasive consisting of many segments of abrasive material extending from the edge of a disc. Flap discs are often used in handheld grinding operations.
flour The finest grain size offered in abrasive materials. Flour grains are used more for polishing operations than for grinding.
fluid suspension A sizing method for super-fine abrasive grains that involves thoroughly mixing the grains in a fluid. In a fluid suspension process, the larger grains settle at the bottom and the smaller grains move to the top.
friability An abrasive grain's ability to fracture and self-sharpen under stress. Friable grains grind cooler because of their self-sharpening effect.
gear A round or cylindrical mechanical component with raised and recessed portions. Gears are designed to intersect with one another and can alter the speed, torque, or direction of mechanical energy.
glazed wheel A smooth formation on the operating surface of a grinding wheel. A glazed wheel generates excessive friction and heat that can damage the workpiece.
grade The hardness of the bond in an abrasive wheel. Wheel grade can be the same for wheels with different structures.
grade The hardness of the bond in an abrasive wheel. Wheel grade can be the same regardless of wheel structure.
grain size The size of the individual abrasive grains that compose a grinding wheel. Grain size is also known as mesh size.
grindability The ease or difficulty with which a workpiece can be ground. Grindability is an important factor in grinding wheel selection.
grinding face The portion of the grinding wheel that contacts the workpiece. The grinding face may also be called the operating surface.
grinding fluid A liquid used during grinding to control temperature and lubricate the grinding wheel and workpiece. Grinding fluids are generally water-based or straight oils.
grinding forces An influence that produces a change in an object's motion or state of rest. Grinding forces affect the performance of the grinding wheel.
grinding wheel A wheel made of bonded abrasives that removes material from a workpiece to achieve a precise size and surface finish. Grinding wheels are available in a range of sizes and material combinations.
handheld grinders A handheld tool used to smooth weld beads and cutting materials. Handheld grinders often use abrasive discs or Type 27 or 28 cut-off wheels.
hardness A material's ability to resist penetration, indentation, or scratching. Hardness in a grinding wheel indicates how tightly the bond material holds the abrasives.
hole size The measurement of the distance from edge to edge of the central mounting hole in a grinding wheel. Hole size is also referred to as the mounting diameter.
ID grinding Inside-diameter grinding. Finishing the interior of a workpiece bore. ID grinding requires plain or formed wheels that are generally smaller than outside-diameter grinding wheels.
inside-diameter grinding ID grinding. Finishing the interior of a workpiece bore. Inside-diameter grinding requires plain or formed wheels that are often smaller than outside-diameter grinding wheels.
iron A naturally abundant, commonly used metal. Iron is the main ingredient in steel.
jig grinder A machine used for grinding complex shapes and holes when high degrees of accuracy and surface integrity are required. Jig grinders can use ID wheels to contour around the inside or outside edges of a workpiece.
linear inch A unit of measurement that corresponds to one-twelfth of a foot. A linear inch is a one-dimensional measurement while a square inch is a two-dimensional measurement.
material removal rate The amount of material removed from a workpiece in cubic inches per minute or cubic millimeters per second. Material removal rates fluctuate depending on the type of abrasive in the grinding wheel, wheel speed, and other factors.
maximum operating speed MOS. The highest peripheral speed at which a grinding wheel can safely operate. Maximum operating speed is required by law to be listed on a grinding wheel for the life of the grinding wheel.
mesh size The size of the individual abrasive grains that compose a grinding wheel. Mesh size is also known as grain size.
metal bonds A superabrasive bond type made from cast iron and bronze alloys. Metal bonds are the strongest type of bond material.
meters per second m/s. A measurement of speed that specifies the number of meters that a location on a rotating or reciprocating component travels in one second. Meters per second is used to measure grinding wheel speed.
mounted point wheels A small inside-diameter grinding wheel mounted onto a mandrel. Mounted point wheels are used with jig grinders and for deburring applications.
mounting diameter The measurement of the distance from edge to edge of the central mounting hole in a grinding wheel. Mounting diameter is also referred to as the hole size.
Occupational Safety and Health Administration OSHA. The federal agency that enforces workplace safety and health legislation in the United States. The Occupational Safety and Health Administration helps employers reduce injuries, illnesses, and deaths in the workplace.
OD grinding Outside-diameter grinding. Finishing the exterior surface of a cylindrical workpiece. OD grinding commonly uses a plain or formed grinding wheel.
operating surface The portion of the grinding wheel that contacts the workpiece. The operating surface may also be called the grinding face.
organic bonds A bond type that contains carbon compounds. Organic bonds have much more flexibility than vitrified bonds and can help to decrease vibration.
outside-diameter grinding OD grinding. Finishing the exterior surface of a cylindrical workpiece. Outside-diameter grinding commonly uses a plain or formed grinding wheel.
overhang The distance between the base of an inside-diameter grinding wheel and the chuck. Overhang measures the amount of the arbor that is exposed during grinding.
peripheral speed The distance that a given point on the perimeter of a rotating circular object travels, expressed in surface feet per minute or meters per second. Peripheral speed is used to describe a grinding wheel's operating speed.
peripheral wheel A grinding wheel in which the outer edge is in contact with the workpiece. Peripheral wheels include Type 1 straight wheels.
plugs An inside-diameter grinding wheel in the shape of a cylinder. Plugs are used for very precise grinding operations.
polishing An abrasive finishing process. Polishing results in a part with a smooth, refined, and high-luster surface finish.
porosity The relative number of openings or voids in a material. High porosity generally indicates an open structure wheel.
porous Full of openings and spaces that allow the material to absorb liquids. Porous grinding wheels allow for chip clearance.
profile grinding Creating a unique, nonstandard part feature using a specialized grinding wheel. Profile grinding creates gears and other contoured shapes.
profiles A contoured feature on a workpiece. Profiles include tapers, angles, or steps.
recessed wheels An abrasive wheel that resembles a flat disc with an inner depressed area surrounding the wheel center on one or both sides. Recessed wheels include types 20 to 26.
refractory A material that retains strength at high temperatures due to its low thermal conductivity. Refractory materials include conventional abrasives such as aluminum oxide and silicon carbide.
relief A tapered or angled surface behind the operating face of a grinding wheel. Relief prevents rubbing and burnishing of the workpiece from the side of the grinding wheel, particularly when grinding to a shoulder.
relieved wheels An abrasive disc-shaped wheel that gets thinner toward its center on one or both sides. Relieved wheels provide clearance between the side of the grinding wheel and the workpiece shoulder to minimize side grinding.
resinoid bonds A type of organic bond material that offers rapid stock removal and fine surface finishes. Resinoid bonds are made from plastic resins.
revolutions per minute rpm. The number of revolutions that a rotating component completes in one minute. Revolutions per minute is a measurement of speed.
rigid Stiff and uneasily bent. Rigid bond materials result in a higher grade grinding wheel.
rotary table A rotating, circular surface that supports the workpiece and moves it in a circular direction during grinding. Rotary tables are used in combination with the vertical spindle on a Blanchard grinder.
shoulder A 90° angled surface on a workpiece that is created on a lathe and finished on a cylindrical grinder. A shoulder can join two different diameters on a workpiece.
side wheel A grinding wheel in which the front portion, or face, of the wheel is in contact with the workpiece. Side wheels include Type 2 cylinder wheels.
silicon carbide A chemical compound made from silicon and carbon. Silicon carbide is a conventional abrasive with grains that are harder, more friable, and more aggressively shaped than aluminum oxide grains.
spindle A rotating component on a machine. A spindle on a grinding machine wheelhead holds and rotates the grinding wheel.
spindle nut A fastener containing a hole and internal threads that mates with a screw or bolt. Spindle nuts are used to secure the grinding wheel assembly to the machine spindle.
stock Raw material that is used to make a finished part. Stock is available in many standard shapes, including bars, rods, and sheets.
straight wheels A common abrasive wheel used in grinding and some cut-off operations. Straight wheels are simple disc shapes and can also be dressed to create a specific operating surface.
structure The relative amount of grains, bonds, and space in an abrasive grinding tool or wheel. Structure helps to determine a grinding wheel's grade.
superabrasive A group of relatively expensive abrasive materials possessing superior hardness, wear resistance, and thermal conductivity. Superabrasives used for grinding wheels are cubic boron nitride and diamond.
superabrasives A group of relatively expensive but effective materials possessing superior hardness, abrasion resistance, and thermal conductivity. Superabrasives used in grinding wheels are cubic boron nitride and diamond.
surface feet per minute sfm. A measurement of speed that specifies the number of feet that a location on a rotating or reciprocating component travels in one minute. Surface feet per minute is used to measure grinding wheel speed.
surface finish The texture of a part after it has gone through the grinding process. Surface finish is key to the performance of a finished part.
surface grinder A grinding machine used to finish flat workpiece surfaces by removing precise amounts of material. A surface grinder with a vertical spindle may require a cylinder wheel or segmented wheel.
surface grinding A common grinding process that uses a grinding wheel to grind precise amounts of material from a workpiece surface. Surface grinding generally creates flat surfaces but can also create complex 3D surfaces if a formed grinding wheel is used.
surface grinding segment A bonded abrasive designed for use in a Blanchard surface grinder. Surface grinding segments are individually mounted on the vertical machine spindle above the workpiece to collectively form the shape of a grinding wheel.
thermal conductivity A material's ability to transmit heat. The thermal conductivity of superabrasive grinding wheels extracts heat from the grinding operation.
tolerance The allowable deviation from a given dimension that will still allow a finished part to perform its intended function. Tolerances indicate the allowable difference between a physical feature and its intended design.
tungsten carbide A chemical compound containing equal parts tungsten and carbide atoms. Tungsten carbide arbors provide more rigidity than steel arbors.
vertical machine spindle A surface grinder with a wheelhead oriented perpendicular to the floor. Vertical machine spindles require a side wheel or grinding segment.
vitrified bonds A clay or ceramic bond material characterized by strength, rigidity, and resistance to oils, water, and temperature changes. Vitrified bonds have qualities similar to glass.
wheel diameter The distance from one edge of a grinding wheel through the center and to the opposite end. Wheel diameter is measured in inches or millimeters.
wheel speed The rate at which the grinding wheel moves past the workpiece surface at the point of contact. Wheel speed is measured in surface feet per minute (sfm) or meters per second (m/s).
wheel thickness The distance, measured in inches or millimeters, between the top and bottom surfaces of a grinding wheel. A grinding wheel can have thickness measurements for different portions of the wheel.
wheel type A number used to identify a specific grinding wheel shape. Wheel type is used to specify wheel shape in grinding wheel catalogs.
zirconia alumina A tough, large-grain conventional abrasive made from aluminum oxide and zirconium oxide. Zirconia alumina wheels are used in cut-off grinding and in snagging operations.