Grinding Ferrous Metals 311

"Grinding Ferrous Metals" provides an in-depth overview of the considerations involved with grinding various ferrous metal workpiece materials. Ferrous metals’ properties vary widely. This class discusses the properties of cast irons, carbon steel, alloy steels, stainless steels, tool steels, and superalloys, and how those properties affect decisions such as abrasive wheel material, coolant usage, and grinding variables.

Ferrous metals are the most commonly ground workpiece material. It is crucial for operators to be familiar not only with the properties of the metals themselves but also with how those properties affect a grinding operation. This class provides operators with knowledge of how to grind ferrous metals successfully, and what potential problems to anticipate and check for within the grinding operation.

Class Details

Class Name:
Grinding Ferrous Metals 311
Description:
"Grinding Ferrous Metals" provides an in-depth overview of the considerations involved with grinding various ferrous metal workpiece materials. Ferrous metals’ properties vary widely. This class discusses the properties of cast irons, carbon steel, alloy steels, stainless steels, tool steels, and superalloys, and how those properties affect decisions such as abrasive wheel material, coolant usage, and grinding variables.

Ferrous metals are the most commonly ground workpiece material. It is crucial for operators to be familiar not only with the properties of the metals themselves but also with how those properties affect a grinding operation. This class provides operators with knowledge of how to grind ferrous metals successfully, and what potential problems to anticipate and check for within the grinding operation.
Version:
2.0
Difficulty:
Advanced
Number of Lessons:
15

Class Outline

  • Grinding Ferrous Metals
  • Workpiece Material Properties
  • Grinding Wheel Materials
  • Grinding Wheel Interactions
  • Chip Formation
  • Review: Workpiece and Wheel Properties
  • Grinding Cast Irons
  • Carbon Steel
  • Alloy Steels
  • Stainless Steel
  • Tool Steels
  • Review: Grinding Irons and Steels
  • Superalloys
  • Superalloy Grinding Methods
  • Review: Superalloys

Objectives

  • Describe how the basic properties of ferrous metals affect grinding.
  • Describe key properties of workpiece materials.
  • Describe how properties of grinding wheel materials affect grinding.
  • Describe the possible chemical reactivity of diamond abrasives on ferrous workpieces.
  • Explain how the properties of a metal affect chip formation during grinding.
  • Describe the properties of different types of cast iron.
  • Describe the properties of carbon steel.
  • Describe the properties of alloy steels.
  • Describe the properties of stainless steel.
  • Describe the properties of tool steels.
  • Describe the properties of superalloys.

Certifications

Glossary

Vocabulary Term Definition
abrasion resistance A material’s ability to resist breaking at the surface caused by contact with another surface. Abrasion-resistant metals tend to have higher hardness.
abrasion resistance A material’s ability to resist grinding or wear by contact with a hard, rough material. Abrasion-resistant metals tend to have higher hardness.
abrasion-resistant A material’s ability to resist grinding or wear by contact with a hard, rough material. Abrasion-resistant metals tend to have higher hardness.
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.
additives A substance that has been intentionally added to a metal to improve its properties. Additives include bismuth and sulfur.
alloy steels A grouping of steels whose contents have been manipulated to achieve specific results. Alloy steels are common workpiece materials.
alloying elements A substance that is intentionally added to a material in order to change its properties. Alloying elements are usually added to a base material in very small amounts.
alloying elements A substance that is intentionally added to a metal in order to change its properties. Alloying elements are usually added to a base metal in very small amounts.
alloys Metals that are combined with various materials, rather than existing as a pure elemental metal. Steel is an alloy of iron and other materials.
alumina A compound made from bauxite and other additives that is commonly used as an abrasive material. Alumina is also referred to as aluminum oxide.
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.
arc of cut The area of contact between the grinding wheel and the workpiece. Arc of cut is also called the cutting zone.
bismuth A white, brittle metal with a pinkish tinge. Bismuth may be added to steel to improve its ability to be cut or ground.
bonding material The adhesive material in grinding wheels that holds the abrasive grains together. Bonding materials can be vitrified, organic, and resinoid.
boron A gray metalloid element. Boron is often added to metals as an alloying element to increase hardness.
brittleness A material’s tendency to break when drawn, stretched, or formed. Brittleness tends to accompany hardness.
carbon A nonmetallic chemical element that combines readily with metallic elements. Carbon is found in steel, carbide, diamond, and other materials.
carbon tool steels A grouping of steels used in various types of cutting tools. Carbon tool steels are inexpensive but not highly resistant to heat.
case-hardened Carburized, or heated within a carbon-rich environment, to increase carbon levels on a metal surface. Case hardening creates a hard, brittle exterior shell.
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.
CBN Cubic boron nitride. A cutting tool material with hardness that is second only to diamond. Cubic boron nitride tools are very effective, but they are also very expensive.
ceramic A very hard, brittle material that contains metallic and nonmetallic elements. Ceramics are often used as cutting and abrasive tools.
ceramic alumina An exceptionally tough, sharp abrasive. Ceramic alumina is also known as ceramic aluminum oxide.
ceramic aluminum oxide An exceptionally hard, strong, sharp abrasive made from a process in which alumina gel is dried and crushed. Ceramic aluminum oxide can grind with greater precision than other conventional abrasives.
chemically react To undergo a change due to contact with another substance. During a chemical reaction, the physical structure of a substance will alter in some way.
chemically-resistant Able to withstand exposure to chemicals. Chemically resistant materials tend not to react with workpieces and other materials.
chips Pieces of metal that are removed from a workpiece when a tool cuts or grinds the metal. During grinding, small chips are formed by the grinding wheel’s abrasive grains.
chromium A hard gray metal often used as an alloying element in steel. Chromium is highly resistant to corrosion and wear.
chromium A hard gray metal that is highly resistant to corrosion and wear. Chromium is typically 15% of stainless steels.
cobalt A common alloying element. Cobalt increases a material’s thermal resistance, and can increase hardness or toughness depending on the material.
continuous dressing A specialized method of dressing a grinding wheel that keeps the dresser in constant contact with the wheel. Continuous dressing is a method developed for grinding superalloys.
conventional abrasives The category of abrasive materials that includes the most commonly used, inexpensive abrasives. Conventional abrasives include aluminum oxide, silicon carbide, zirconia, and tungsten carbide, among others.
coolant A substance used to reduce or maintain the temperature of a part being ground. Coolants are usually liquid, such as grinding fluid.
corrosion resistance The ability of a material to resist destruction or deterioration due to exposure to chemicals or elements. Corrosion resistance is a advantageous property of stainless steels.
corrosive Causing gradual deterioration of another substance by chemical reaction through contact. Corrosive substances can damage or destroy metal workpieces.
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 to remove large amounts of material and produce a good surface finish with one operation.
cubic boron nitride CBN. An abrasive material with hardness that is second only to diamond. Cubic boron nitride tools are very effective, but they are also very expensive.
diamond The hardest known substance. Diamond is both a naturally occurring and manufactured abrasive.
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.
ductile cast iron A type of cast iron containing round nodules of graphite that increase its ductility. Ductile cast iron is similar to malleable cast iron.
ductility A material’s ability to be drawn, stretched, or formed without breaking. Ductility is present in the absence of brittleness.
electroplated A superabrasive bond material created by immersing a metal wheel in an electrically charged chemical bath that contains metal particles. Electroplated bonds help maintain the wheel’s shape for the duration of its use.
end mills A long, thin mill cutter with cutting edges that spiral up the sides, resembling a drill. End mills can create complex features on metal parts.
ferrous metal A metal containing iron, generally as a primary ingredient. Ferrous metals include steels and cast iron.
friability The ability of abrasive grains to fracture and self-sharpen under stress. Abrasive grains with low friability may be too dull to grind effectively.
grains A small, hard particle or crystal of abrasive material. Abrasive grains are bonded together to create grinding wheels and other abrasive tools.
graphite A soft, black formation of carbon. Graphite is brittle and has lubricating properties.
gray cast iron A type of cast iron containing large flakes of graphite. Gray cast iron is the least expensive and most widely used cast iron.
grinding The use of an abrasive to remove material from the surface of a workpiece and change its shape. Grinding operations commonly use abrasive grains bonded into a wheel shape.
grinding fluid A liquid used during grinding to clean, cool, and lubricate. Grinding fluid is also referred to as coolant.
grinding variables The measureable rates of movement of tools and workpieces. Grinding variables include speed, feed, and depth of cut.
hardness A material’s ability to resist penetration, indentation, or scratching. Hard materials tend to be brittle and resistant to wear.
heat treatment Controlled heating and cooling processes used to change the structure of a material and alter its physical and mechanical properties. Heat treatments can harden the surface layer of iron-based alloys.
heat treatment The controlled heating and cooling processes used to change the structure of a material and alter its physical and mechanical properties. Heat treatments can harden the surface layer of iron-based alloys.
high-speed steel HSS. A grouping of tool steels commonly used in cutting tools. High-speed steels typically have excellent toughness.
iron A naturally abundant, commonly used metal. Iron is present in all ferrous metals.
iron carbide A hard, brittle compound made from iron and carbon. Iron carbide is also known as cementite.
loading A building up of swarf in a grinding wheel that clogs the spaces between grains. Loading can be removed by dressing and truing a grinding wheel.
lubricating properties The ability of a substance to reduce friction between two surfaces in relative motion. Lubricating properties can help prevent damage to the workpiece surface and prolong tool life.
magnesium A strong, extremely lightweight metal that also has poor wear resistance and can be very reactive. Magnesium is often used as an alloying element.
malleable Able to be formed or shaped through impacts or pressure. Malleable materials do not break or fracture easily.
malleable cast iron A type of cast iron containing rounded particles of graphite. Malleable cast iron is more ductile and less brittle than gray or white cast iron.
manganese A hard, brittle gray metal that is often used as an alloying element. Manganese is added to stainless and other types of steels.
mechanical forces A force that attempts to deform a material. Mechanical forces may attempt to stretch, compress, bend, dent, scratch, or break a material.
mechanical properties A characteristic that describes how a material reacts when subjected to an impact or energy that attempts to stretch, compress, bend, dent, scratch, or break it. Mechanical properties that influence grinding operations include hardness, toughness, and ductility.
mild steel The most basic type of steel, which consists only of iron and carbon. Mild steel is also known as plain carbon steel.
molybdenum A metal that is used to add toughness, hardness, strength, and wear resistance to steels. Molybdenum may be substituted for tungsten in tool steels.
nickel A silvery metal that is both tough and corrosion resistant. Nickel is often added to metals as an alloying element.
nitrogen A naturally occurring gas that can be used as an alloying element. Nitrogen can promote strength and resistance to pitting in stainless steels.
organic bond An abrasive bonding material derived from a naturally occurring substance. Organic bonds tend to soften when exposed to heat.
personal protective equipment PPE. Safety equipment that workers wear or use to prevent injury in the workplace. Personal protective equipment used commonly in grinding protects workers’ hands, arms, and eyes.
plain carbon steel The most basic type of steel, which consists only of iron and carbon. Plain carbon steel is also known as mild steel.
polycrystalline diamond PCD. The manufactured form of a carbon mineral that is the hardest substance known to man. Polycrystalline diamonds are created through a high-heat, high-pressure process.
properties A measurable quality or attribute of a specific material. Properties include aspects such as hardness, toughness, and ductility.
resin An organic bond used in grinding tools that offers rapid stock removal and fine finishes. Resins are similar to the base materials of plastics.
resinoid bond An organic bond used in grinding tools that offers rapid stock removal and fine finishes. Resinoid bonds are made from synthetic materials.
rubber An organic bond used to hold abrasive grains together in grinding wheels. Rubber offers smooth grinding action and fine finishing.
saw blades A multipoint tool used to cut through metal and separate it into pieces. Saw blades may be flexible and constructed from a continuous loop or band of metal.
silicon A common metallic element. Silicon is an alloying element in cast irons.
silicon carbide A hard, brittle material used as an abrasive and as a refractory material. Silicon carbide grinding wheels are hard and sharp, and the grains break away easily.
silicon carbide A mixture that is heated, crystallized, then crushed and used as an abrasive material. Silicon carbide grinding wheels are hard and sharp, and the grains break away easily.
sintered Solid metallic material that is made from powders pressed, then heated, into a desired shape. Sintered metals are very uniform in composition.
stainless steel A grouping of steels that contain large percentages of chromium, as well as nickel, manganese, and/or nitrogen. Stainless steels have very high hardness and corrosion resistance.
steel A ferrous metal consisting of iron and carbon, usually with small amounts of manganese, phosphorus, sulfur, and silicon. Steel is the most common manufacturing metal.
steels A category of metals containing primarily iron and carbon, usually alloyed with small amounts of elements such as manganese, phosphorous, sulfur, and silicon. Steels are the most common manufacturing metals.
strength A metal’s ability to resist stress caused by forces attempting to break or deform the material. Strength may refer to tensile, compression, or shear strength, depending on the direction of the force.
sulfur A pale, yellow, brittle element. Sulfur may be added to steel in order to improve its ability to be cut or ground.
superabrasives A group of highly effective abrasive materials possessing superior hardness and abrasion resistance. Superabrasives include cubic boron nitride and diamond.
superalloys A specialized metal alloy that is designed to exhibit properties such as high strength under extreme temperatures and conditions. Superalloys are very expensive and have very high hardness.
surface finish The quality of a surface after an operation. Surface finishes may be rough, smooth, or wavy, among other conditions, depending on the operation.
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.
tensile strength A material’s ability to resist forces that attempt to pull it apart or stretch it. Tensile strength determines how chips stretch before fracturing.
tensile strength A material’s ability to resist forces that attempt to pull it apart or stretch it. The tensile strength of the workpiece is a factor for selecting the abrasive grain of the grinding wheel.
thermal conductivity A physical property that indicates how well heat energy transfers through a material. Materials with low thermal conductivity make good heat insulators.
thermal resistance A material’s ability to resist degradation when exposed to heat. Thermal resistance is also known as heat resistance.
tolerances An acceptable deviation from a given dimension or geometry. Tolerances indicate the allowable difference between a physical feature and its standard design.
tool steels A grouping of alloy steels designed to be used as cutting tools, dies, punches, and other tools. Tool steels are designed for toughness, hardness, and wear resistance.
toughness The ability of a material to withstand impact without breaking. Toughness is generally higher in softer materials.
tungsten An expensive gray metal that has high strength at elevated temperatures. Tungsten is a component of various cutting tool materials.
vitrified bond A clay or ceramic bond characterized by its strength, rigidity, and resistance to oils, water, and temperature changes. Vitrified bonds have qualities similar to glass.
wear resistance A material’s ability to resist the gradual wearing away caused by abrasion and friction. Wear resistance is a common property of ferrous metals.
wear-resistant The ability of a material to resist the gradual wearing away caused by abrasion and friction. Wear resistance is an important property of cutting tools.
white cast iron A type of cast iron containing carbon in the form of iron carbide. White cast iron has high hardness and wear resistance.
wrought Metal that has been bent, hammered, or otherwise physically formed into a specific shape. Wrought high-speed steels are less hard, tough, and wear resistant than sintered high-speed steels.