Advanced Tool Materials 345

abrasive

A material with hard particles or components that wear away other materials. Abrasive materials must be cut with hard tools that can resist wear.

abrasive wear

The process of an object losing material over time due to friction caused by rubbing against another object. Abrasive wear always occurs during metal-cutting operations but it can be controlled through using coated tools.

adaptation

The device used to connect the milling cutter to the spindle. Adapations come in a variety of shapes, some of which, such as tapered adaptations, provide better rigidity.

additves

An element added, usually in small amounts, to a component to improve or change its properties. Additives for oxide ceramic inserts include cerium oxide (CeO₂) and magnesium oxide (MgO) to improve fracture toughness.

aerospace

The industry that involves machines or vehicles of flight. Aerospace components, such as gas turbines and combustors, are often made of superalloys capable of withstanding large amounts of heat, pressure, and other extreme conditions.

Al₂O₃

Aluminum oxide. A common ceramic used as a coating material on cutting tools and in cermet and ceramic cutting tools. Al2O3, also known as alumina, has excellent thermal and chemical-degradation resistance.

alloyed

Intentionally combined with other materials to improve overall performance. Most cutting tools are alloyed with small amounts of other materials that improve properties such as hardness, heat resistance, and wear resistance.

alloys

A metal with purposefully added elements to enhance its mechanical and physical properties. Alloys can also refer to elements added to metal.

alphanumeric

Containing both letters and numbers. Alphanumeric labels are used by both ANSI and ISO to categorize cutting tools.

alumina

Al₂0₃. A common ceramic used as a coating material on cutting tools and in cermet and ceramic cutting tools. Alumina, or aluminum oxide, has excellent thermal and chemical-degradation resistance.

aluminum

A silver-white metal that is soft, light, and thermally conductive. Aluminum is ductile and can deform from cutting pressure.

aluminum oxide

Al₂0₃. A common ceramic used as a coating material on cutting tools and in cermet and ceramic cutting tools. Aluminum oxide, also known as alumina, has excellent thermal and chemical-degradation resistance.

American National Standards Institute

ANSI. A private, nonprofit organization that administers and coordinates voluntary standards and systems. The American National Standards Institute provides a classification system for cutting tools describing them by using the letter "C" followed by a number usually in the range 1 through 8.

binder

A material that holds the particles of a sintered part together. Common binders used for tools made from advanced materials include cobalt, nickel, and molybdenum.

blocks

A rectangular piece of stiff material, such as metal, used to reinforce a workholding setup. Blocks are often used with vises to hold milling workpieces more rigidly.

boring bar

A cylindrical toolholder used to position cutting tools for operations where material will be removed from the interior of a workpiece. Boring bars that are thicker provide more rigid support.

braze

To join materials at a high temperature but below the melting point of the materials using a filler metal. Manufacturers braze small portions of cubic boron nitride (CBN) and diamond tools to carbide inserts to create cheaper CBN and diamond tools.

brittleness

A material's resistance to being stretched, formed, or drawn. An increase in brittleness accompanies an increase in hardness and an increased tendency to fracture.

BUE

Built-up edges. An unwanted rough edge on a cutting tool created when pieces of the workpiece weld onto the cutting tool during cutting. BUE are less common with advanced tool materials, which are harder and cut more cleanly.

built-up edge

BUE. An unwanted rough edge on a cutting tool created when pieces of the workpiece weld onto the cutting tool during cutting. Built-up edges are less common with advanced tool materials, which are harder and cut more cleanly.

carbide

A common cutting tool material created by combining carbon with a hard metal, such as titanium or tungsten. Carbide tools are the most commonly used tools in the metal-cutting industry.

cast aluminum alloys

An aluminum alloy that is poured as a liquid into a mold and cooled into a solid shape. Cast aluminum alloys contain large amounts of silicon fibers, which make them very abrasive.

cast cobalt alloys

A cutting tool material that is an alloy made of cobalt, chromium, and tungsten and designed to resist wear. Cast cobalt alloys, also known as stellites, are nonmagnetic, corrosion resistant, and extremely tough and hard.

cast iron

An alloy of iron, carbon, and silicon that contains at least 2.0% carbon. Cast irons are hard due to their carbon content and abrasive due to their silicon content, making them hard to cut with common tool materials.

casting

A manufacturing process that involves pouring a liquid material into a hollow mold until the material cools into a solidified shape. Casting is used to produce cutting tools and other manufacturing parts and products.

catastrophic failure

The sudden and complete breakdown of a tool. Catastrophic failure can be the result of gradual wear or occur suddenly.

CBN

Cubic boron nitride. An extremely hard material that resists chemical wear and retains its hardness even at high heat. CBN tools are effective at machining most steels and cast irons but are very expensive.

ceramic

An inorganic material made of metallic and nonmetallic particles that is hard and brittle and resists heat. Ceramic cutting tools can be used with high cutting speeds but require rigid machine setups.

cermet

A cutting tool material created by binding ceramic with a metal. Cermet tools possess a balance of metal and ceramic tool properties.

chatter

Vibrations of the cutting tool that cause surface imperfections on the workpiece and can damage the tool. Chatter can be reduced by using machines with rigid setups and tools set at positive rake angles.

chemical processing

An operation that creates substances by combining raw materials or that applies a substance to a part. Chemical processing applications include creating solvents and putting lubrication on components.

chemical vapor deposition

CVD. A process that uses chemical reactions at high temperatures to coat a cutting tool with thick, well-bonded coating layers. Chemical vapor deposition is best suited for coating tools that will be used for removing more material with less precision.

chemical wear

Tool degradation due to interactions between two substances that change the makeup of the substances. Chemical wear of tools can be controlled by using coated tools.

chuck

A device that holds a workpiece in place as it rotates. The chuck commonly has three or four jaws that can be adjusted to fit various part sizes.

clamps

A device that holds objects together by applying downward pressure. Clamps can be used to hold a cutting insert in place on a toolholder.

coatings

A thin layer of material added to a component to improve its properties. Coatings for cutting tools increase heat resistance and wear resistance, among other benefits.

cobalt

A hard, gray metal that is highly magnetic. Cobalt is often used as a binder for cutting tools because of its superior coating and adhesion characteristics.

continuous cutting

A metal removal operation where the cutting edge of the tool remains in contact with the workpiece through the operation or for most of the operation. Continuous cutting can create more heat during cutting but has reduced thermal and impact shock.

coolant

A fluid used to cool or lubricate a metal-cutting process. Coolants, also known as cutting fluids, can be oil- or water-based liquid or gas.

copper

A reddish metal that is very ductile, thermally and electrically conductive, and corrosion resistant. Copper should be cut with hard materials to limit deformation.

coronite

A tool material made of titanium nitride (TiN) suspended in high-speed steel (HSS). Coronite is a balance of the toughness of HSS and the hardness of carbide tools.

C-system

The ANSI insert classification standard. The C-system uses the letter "C" followed by a number, usually ranging from 1 to 8, to describe tool grades.

cubic boron nitride

CBN. An extremely hard material that resists chemical wear and retains its hardness even at high heat. Tools made of cubic boron nitride, also called polycrystalline cubic boron nitride (PCBN), are effective at machining most steels and cast irons but are very expensive.

cutting fluid

A fluid used to cool or lubricate a metal-cutting process. Cutting fluids, also known as coolants, can be oil- or water-based liquid or gas.

cutting speeds

The rate at which the surface of the workpiece rotates past the cutting edge of the tool or the rate of movement of the cutting tool in relation to the workpiece surface. Cutting speeds are measured in workpiece revolutions per minute (rpm) for turning, tool rpm for milling, and surface feet per minute (sfm), or surface meters per minute (m/min) in metric, for drilling.

cutting tool

A device made of hard, tough material that is used to remove metal by creating chips. Cutting tools can be made of a range of materials, including high-speed steel (HSS), carbide, cermet, ceramic, and diamond, among others.

cutting variables

An adjustable factor of a metal-cutting operation. Cutting variables include tool geometry, tool material, and speed and feed.

deformation

An unwanted change in a material's shape. Deformation of a tool often renders it unusable for future machining operations.

degrade

Deteriorates. When machining, tool material degrades due to friction, heat, and chemical reactions between the tool material and workpiece.

density

The amount of mass within a specific volume. Tools with greater density, more mass within their volume, have longer service lives and perform better.

depths of cut

The measurement of how far a cutting tool penetrates the workpiece. Depth of cut is the distance from the uncut surface to the machined surface.

diameters

A line going from one side of a circle to the other that travels through the center point. Diameter is used to describe the size of some milling cutters.

diamond

A naturally occurring or manufactured stone made of crystalline carbon that is used as an abrasive because of its extreme hardness. Diamond tools are the hardest cutting tools available.

dies

A reusable mold that is used to shape and compress powder into a rough part. Dies are used in the powdered metallurgy processes that create metal-cutting tools.

diffuses

Spreads from an area of high concentration to an area of low concentration. The silicon in silicon nitrite ceramics diffuses into most metals during cutting.

drill body

The area of the drill that extends from the toolholder. The drill body makes up the majority of the drill and provides the tool with its rigidity.

drilling

The process of using a multipoint tool to produce a hole in a workpiece. Drilling is often the first step in a series of holemaking operations.

ductile

A material's ability to be drawn, stretched, or formed without breaking. Ductile materials usually lack hardness, though present their own challenges when cutting, such as deformation.

ductile cast iron

A metal created by adding magnesium or cerium to gray cast iron to change the graphite from flakes to spheres. Ductile cast iron, sometimes called nodular cast iron, has good tensile strength, impact resistance, and ductility.

engine blocks

A casing that holds various moving parts in an automotive engine and provides channels for fluids to flow. Engine blocks are usually made of cast iron and require precise finishing in order to function properly.

features

A defining characteristic. Features for cutting inserts include tool shape, thickness, nose radius, and size, among others.

feed

The rate at which the cutting tool or workpiece moves in relationship to one another. Feed is often measured in inches per minute (ipm) or millimeters per minute (mm/min).

ferrite

A form of iron with a crystalline structure that gives it magnetic properties. Ferrite can stick to cubic boron nitride (CBN) tools and cause rapid wear and poor surface finish.

ferrous

A material in which iron is the main ingredient. The most common ferrous metals are steel and cast iron.

fibers

A thin thread of material. Fibers are often added to a component or material to improve its strength and toughness.

finishing

A metal-cutting process where a small amount of material is removed to achieve tight tolerance and good surface finish. Finishing depth of cut can vary, but is usually under 0.05 in. (1.27 mm).

finishing

A metal-cutting process where a small amount of material is removed to achieve tight tolerance and good surface finish. Finishing operations prioritize improving part quality over removing material.

fracture

The catastrophic failure of a tool due to a large section of the tool suddenly breaking off. Fracture can occur spontaneously or as the result of other forms of wear.

friction

A force that resists the movement of two objects sliding against each other. Friction is one of the primary causes of tool degradation.

gas turbines

A complex component that uses combustion to transform a gas into movement and energy. Gas turbines must be able to withstand high temperatures and constant, rapid movement.

gear shafts

A cylindrical component that provides a rotational axis for toothed gears. Gear shafts have a number of gaps in their shape, which creates intermittent cutting scenarios on the lathe.

grade H

An ISO category that includes cutting tools best suited for machining hardened metals. Cutting tools with H grades are usually marked with gray on manufacturer specifications.

grade K

An ISO category that includes cutting tools best suited for machining cast iron. Cutting tools with K grades are usually marked with red on manufacturer specifications.

grade M

An ISO category that includes cutting tools best suited for machining stainless steels. Cutting tools with M grades are usually marked with yellow on manufacturer specifications.

grade P

An ISO category that includes cutting tools best suited for machining a variety of steels. Cutting tools with P grades are usually marked with blue on manufacturer specifications.

grade S

An ISO category that includes cutting tools best suited for machining high-temperature alloys. Cutting tools with S grades are usually marked with orange on manufacturer specifications.

grades

A letter and/or number designation that describes the specific chemical and material composition for a particular tool or that indicates how that tool should be used. Grade is highly variable between manufacturers and any broad classification system can only be used as a general guideline.

grain

An arrangement of microscopic crystals in a material. Grain structures can be fine or coarse, which have different impacts on cutting tool material.

graphite

A soft, black form of carbon. Graphite is naturally lubricated and becomes very hard at high temperatures, making it an ideal material for hot press dies.

gray cast iron

An iron alloy with at least 2.0% carbon in which graphite flakes are dispersed throughout the metal. Gray cast iron is the most common form of cast iron.

grinding

Using an abrasive to wear away a workpiece surface and achieve highly accurate dimensions and geometry. Grinding operators commonly use abrasive grains bonded into a wheel.

grinding wheels

A tool made by bonding abrasive grits together and forming them into a circular shape. Grinding wheels can be made of advanced materials including ceramic, cubic boron nitride (CBN), and diamond.

grooving

A machining operation where the tool cuts a narrow channel into a workpiece. Grooving on a lathe involves putting pressure on three sides of the cutting tool, requiring a tool with greater toughness.

hardened

A metal that has been subjected to a manufacturing process, such as heating and quenching, to improve its hardness. Hardened metals can be more efficiently machined with harder tool material, such as ceramic or cermet.

hardness

A material's ability to resist indentation or scratching. An increase in hardness generally leads to a decrease in toughness, or ability to withstand fracture.

heat exchangers

A device that circulates a contained cool fluid through a component or other fluid to keep the temperature low. Heat exchangers are often made of aluminum alloy bodies with copper alloy pipes.

heat wear

Tool degradation or a change in tool shape that occurs when when a material is exposed to heat. Heat wear in cutting tools keeps them from maintaining a sharp, strong edge during cutting.

high-speed steel

HSS. A metal used to create cutting tools in order to machine other metals. High-speed steel is tougher than carbide but offers less hardness and wear resistance.

high-temperature alloys

One of a group of metals based on iron, cobalt, or nickel that exhibits excellent mechanical properties, such as hardness or corrosion resistance, at elevated temperatures. High-temperature alloys are difficult to cut because they are often hard and resist deforming even at elevated temperatures.

hot hardness

The ability of a material to retain its hardness at high temperatures. Hot hardness is found in many of the advanced tool materials, such as ceramic and cermets.

hot pressing

A sintering process where the tool powder is compressed into shape and heated to strengthen it at the same time. Hot pressing creates tools with improved density and grain size over conventional sintering methods.

HSS

High-speed steel. A metal used to create cutting tools in order to machine other metals. HSS is tougher than carbide but offers less hardness and wear resistance.

impact shock

The sudden force generated when a cutting tool initially engages or reengages with a workpiece. Impact shock is most common in milling because milling involves intermittent cutting where the tools constantly enter and exit the workpiece.

inclusions

A substance that is unintentionally present in a metal and that often has undesirable properties. Inclusions, such as oxides and sulfides, can damage cutting tools that do not possess the correct balance of hardness and toughness.

indexable inserts

A cutting tool with multiple cutting edges. Indexable inserts are rotated to expose a fresh cutting edge when one edge becomes excessively worn.

insert numbers

A series of numbers and/or letters used to describe a cutting tool insert. The insert number, also known as a part number or product number, usually refers to the ANSI insert identification number, but it can also refer to the ISO insert identification number.

intermittent cutting

A metal removal process during which one or more cutting edges repeatedly enter and exit the workpiece surface. Intermittent cutting, sometimes called interrupted cutting, causes temperature fluctuations that can lead to thermal cracking, particularly in hard materials.

intermittent cutting

A metal-removal process in which one or more edges of the cutting tool repeatedly enter and exit the workpiece surface. Intermittent cutting, or interrupted cutting, causes temperature fluctuations and continual impacts that can lead to tool fracture.

International Organization for Standardization

ISO. An international organization that establishes standards and guidelines for various products and processes. The International Organization for Standardization provides a classification system for cutting tools, categorizing them by grade and other important identifying features and characteristics.

interrupted cutting

A metal removal process in which one or more edges of the cutting tool repeatedly enter and exit the workpiece surface. Interrupted cutting, or intermittent cutting, causes temperature fluctuations and continual impacts that can lead to tool fracture.

jaws

A holding device on a chuck that clamps down on the workpiece. More jaws provide more workpiece stability and rigidity.

lathe

A machine tool that is used to produce a range of parts from cylindrical workpieces. On a basic lathe, the workpiece is rotated by the spindle while the cutting tool is guided along the workpiece to create a finished part.

lubricated

Covered in a substance that reduces friction. A lubricated moving component will move smoothly.

metal-cutting

A machining process that uses a tool to remove metal from a workpiece. Metal-cutting processes include turning, milling, and drilling.

meters per minute

m/min. A metric measurement of speed describing the distance that the tool tip travels in one minute. Meters per minute is used in turning operations on the lathe.

milling

A cutting operation in which a rotating multipoint cutting tool is fed along the surface of a part to remove material. Milling operations are generally used on flat or rectangular workpieces.

milling cutter

A multipoint cutting tool that has a number of teeth, or cutting edges, around its cutting surface. Milling cutters can cut with their face, in face milling, or their side, in end milling.

milling cutters

A multipoint cutting tool that has teeth around its cutting surface. Milling cutters include face mills and end mills.

mixed ceramics

A ceramic cutting tool material made of aluminum oxide and titanium carbide. Mixed ceramics are harder than oxide ceramics but still have limited fracture resistance.

molybdenum

A metal that increases toughness and wear resistance. Molybdenum is often used as a cutting tool binder or alloy to improve the toughness, and therefore fracture resistance, of a tool.

molybdenum carbide

MoC. A hard ceramic made from combining molybdenum and carbon. Molybdenum carbide is used to make cermet and ceramic tools.

nickel

A hard, ductile, silvery-white metal. Nickel is difficult to cut with common tool materials because of its hardness and impact resistance.

niobium

A platinum-gray, ductile metallic alloying element used as a strengthening agent in tool material. Niobium helps control grain growth to create a tool with uniform properties.

nitriding

A metallurgical surface preparation method by which metal is heated within a nitrogen-rich environment. Nitriding improves the hardness of metals, including cutting tool material.

nitrogen

A colorless, odorless, tasteless gas that naturally exists in the atmosphere. Nitrogen is used in some tool-enhancement procedures, such as nitriding.

nonferrous

Metals that do not contain a significant amount of iron. Common nonferrous metals include aluminum and copper.

nose radius

The degree of roundness at the intersection of cutting edges on a tool. The nose radius is described by the insert number and influences factors such as surface finish and insert strength.

operators

A person trained to run a specific machine. Operators are responsible for helping ensure that a machining process runs properly, efficiently, and safely.

overhang

The amount the shank of the toolholder extends from the secured toolholder base. Increased overhang can lead to an increase in chatter and vibration.

oxide ceramics

A ceramic cutting tool material made of aluminum oxide and zirconium oxide. Oxide ceramics are less hard than other ceramics, but have good resistance to chemical degradation, wear, and heat.

PCD

Polycrystalline diamond. A synthetic form of diamond with varying sizes of crystal structure. PCD tools better resist fracture than other diamond tools and create better surface finish.

physical vapor deposition

PVD. A process that deposits a thin, even layer of coating on the surface of a tool using ions to attract evaporated coating material. Physical vapor deposition is best suited for coating tools that will be used for more precise shaping operations, such as finishing.

plasma-assisted CVD

PaCVD. A chemical vapor deposition process that uses plasma to assist with vaporization and the reaction of the chemical vapor. Plasma-assisted chemical vapor deposition can be performed at a much lower temperature than traditional chemical vapor deposition.

polishing

An abrasive finishing process used to improve the surface of a part and give it a smooth, shiny appearance. Polishing a cutting tool before using it reduces friction and wear.

polycrystalline cubic boron nitride

PCBN. An extremely hard material that resists chemical wear and retains its hardness even at high heat. Tools made of polycrystalline cubic boron nitride, also called cubic boron nitride (CBN), are effective at machining most steels and cast irons but are very expensive.

polycrystalline diamond

PCD. A synthetic form of diamond with varying sizes of crystal structure. Polycrystalline diamond tools better resist fracture than other diamond tools and create better surface finish.

positive side rake angle

An angle formed between the tool face and the longitudinal centerline of the workpiece when the face is tilted down and away from the workpiece. A positive side rake angle can help improve surface finish.

powder metallurgy

The process of creating parts through compressing and heating granulated metal. Powder metallurgy is used to create parts without metal removal processes and is often used to make cutting tools.

prechamfering

Creating a smooth, beveled edge on a workpiece before it is machined. Prechamfering allows cutting tools to enter the workpiece more easily, reducing friction and pressure.

pressure

The exertion of a mechanical force upon an object. In metal-cutting operations, the amount of pressure is usually related to the feed rate, with high feed rates exerting more pressure.

production rates

The time it takes to build a part or the number of parts that can be made in a set period of time. Production rates are increased when harder tool material allows for faster cutting speeds.

properties

A defining characteristic of a material. Properties are often divided between mechanical properties, which describe how a material responds to external forces, and physical properties, which describe basic qualities of the material.

rigid

Stiff and inflexible. Rigid machine setups help prevent vibration, which can cause a cutting tool to fracture.

Rockwell C Scale of Hardness

HRC. A measure of how well a material resists penetration, indentation, and scratching. The Rockwell C Scale of Hardness testing involves pressing a diamond tool into a material with a great amount of force.

roughing

A metal-cutting process where a large amount of material is removed to shape the workpiece. Roughing depth of cut can vary, but is usually between 0.25 in. (6.35 mm) to 0.15 in. (3.81 mm).

roughing

A metal-cutting process where a large amount of material is removed to shape the workpiece. Roughing operations prioritize removing material over improving part quality.

scale

A flaky film of oxide that forms on heated or rusted metals. Scale on a workpiece can increase tool wear and should be removed with a tool made of a hard and tough material, such as cast cobalt alloys.

screws

A threaded device used for fastening parts or transferring motion. Screws can be used to hold a cutting insert in place on a toolholder.

semifinishing

A metal-cutting process that focuses on shaping the final part, but is not as precise as finishing. Semifinishing depth of cut can vary, but is usually between 0.10 in. (2.54 mm) to 0.05 in. (1.27 mm).

semiroughing

A metal-cutting process that focuses on removing material, but that involves less material removal than roughing. Semiroughing depth of cut can vary, but is usually between 0.15 in. (3.81 mm) to 0.10 in. (2.54 mm).

setups

All the necessary preparation of tooling and fixturing that occurs on a machine before operation begins. Proper machine setup is essential when using harder cutting tool materials to prevent catastrophic failure.

shank

The long, rectangular section of the toolholder that is clamped into the turret or the cylindrical part of a milling cutter held in the spindle. Shanks that are thicker provide more rigid support.

shim seats

The depression in the toolholder that holds the thin component that provides a base for the cutting insert. Damaged shim seats cause the insert to vibrate in the toolholder.

sialon

A ceramic cutting tool material made by combining silicon nitride (Si₃N₄) and aluminum oxide (Al2O3). Sialon inserts have the toughness of silicon nitride ceramic but can be used with a wider range of materials.

silicon

A blue-gray, nonmetallic, crystalline material that is hard and brittle. Silicon content increases a material's abrasiveness.

silicon carbide

SiC. A compound of silicon and carbon that contains thin, flexible filaments. Silicon carbide is used to reinforce and improve the toughness in ceramic cutting inserts.

silicon nitride

Si₃N₄. A compound of silicon and nitrogen. Silicon nitride is a hard ceramic.

silicon nitride ceramics

A ceramic cutting tool material made of silicon and nitrogen. Silicon nitride ceramics have improved hot hardness and toughness compared to oxide and mixed ceramics, but degrade when exposed to most workpiece materials.

sintered

Exposed to high heat. Compressed powder metallurgy parts are sintered in order to harden and strengthen them.

solid tools

A cutting implement where the cutting edges and at least part of the shaft are made of one material. Solid tools can be made of a range of materials and include end mills, face mills, and drills.

spindle

A machine component that holds and spins a workpiece or tool. Spindles should be well lubricated to prevent inconsistent motion that could damage the workpiece or tool.

stainless steel

A type of steel that contains more than 11% chromium and exhibits excellent corrosion resistance. Stainless steels often contain nickel, which can cause issues when using cutting tools that have nickel binders.

steel

A metal primarily made of iron with less than 2% carbon, often including other additives. Steel can be cut at higher speeds when using advanced tool materials.

stellites

A cutting tool material that is an alloy made of cobalt, chromium, and tungsten and designed to resist wear. Stellites, also known as cast cobalt alloys, are nonmagnetic, corrosion resistant, and extremely tough and hard.

strength

The ability of a material to resist forces that attempt to break or deform it. Inserts with good strength can operate at higher feed rates and withstand tool wear.

superalloys

An expensive metal with a number of additives to create a metal that has excellent strength and resistance to deformation, heat, and corrosion. Superalloys, including Inconel and Hastelloy, are extremely hard and should be machined with harder cutting tool materials.

surface feet per minute

sfm. An English measurement of speed describing the distance that the tool tip travels in one minute. Surface feet per minute is used in turning operations on the lathe.

surface finish

The measured surface profile characteristics of a completed workpiece. Surface finish can be improved by using harder cutting tools.

tantalum-niobium carbide

TaC-NbC. A hard ceramic material made from tantalum, niobium, and carbon that is ductile and heat resistant. Tantalum-niobium carbide is used to make cermet and ceramic tools that have better toughness than others.

teeth

The cutting edges of a milling cutter. Teeth can either be molded into the tool, as in a solid mill, or they can be indexable cutting inserts.

thermal conductivity

A physical property that indicates how well heat energy transfers through a material. Thermal conductivity is high in cubic boron nitride (CBN) and diamond.

thermal distortion

An unwanted change in the shape of a component due to heat exposure. Thermal distortion can cause workpieces and tool materials to deform if they are exposed to excessive temperatures.

thermal shocks

The stresses formed in a tool as it repeatedly heats and cools in a cycle. Thermal shock creates small fissures in the tool that can eventually cause catastrophic failure.

thickness

The measurement of an insert from the seating surface to the cutting edge. Thickness is described by the cutting insert number.

threading

The process of cutting a long, spiraling groove into a cylindrical workpiece. Threading places a great deal of pressure and heat on the cutting point of a tool, which can cause harder materials to fracture.

TiC

Titanium carbide. A ceramic material used in cermet and ceramic cutting tools. TiC is especially hard and brittle.

TiCN

Titanium carbonitride. A compound of titanium, carbon, and nitrogen often used as coating for cutting tools and in cermet and ceramic cutting tools. TiCN offers good abrasive wear resistance and, in coatings, helps coating layers adhere to the substrate.

TiN

Titanium nitride. A hard, ceramic material used on cutting tools to reduce friction and in cermet and ceramic cutting tools. As a coating, TiN has a characteristic yellow or gold color that makes wear more visible.

titanium

A silver-gray, strong, lightweight metal known for its corrosion resistance and strength-to-weight ratio. Titanium is often used in the aerospace and medical industries.

titanium carbide

TiC. A ceramic material used in cermet and ceramic cutting tools. Titanium carbide is especially hard and brittle.

titanium carbonitride

TiCN. A compound of titanium, carbon, and nitrogen often used as coating for cutting tools and in cermet and ceramic cutting tools. Titanium carbonitride offers good abrasive wear resistance and, in coatings, helps coating layers adhere to the substrate.

titanium nitride

TiN. A ceramic material used on cutting tools to reduce friction and in cermet and ceramic cutting tools. As a coating, titanium nitride has a characteristic yellow or gold color that makes wear more visible.

tolerances

An unwanted but acceptable deviation from a given dimension defined by a manufacturing print. Tolerance that must be exact is best created through the use of harder cutting tools.

tool geometry

The collective angles formed by the dimensions of the cutting tool and the positioning of the tool. Tool geometry is a key factor in tool service life, the surface finish of a part, and machining efficiency.

tool life

The length of time a cutting tool is expected to be operational before it must be replaced. Tool life can be extended through optimized implementation, including having a properly rigid machine setup and using correct tool geometry.

tool steel

A special carbon steel with alloying elements, such as chromium or molybdenum, to improve strength, toughness, and wear resistance. Tool steels are typically made from high-carbon steel, making them hard and difficult to cut.

toolholder

A device used to hold a cutting component in place. Toolholders come in a variety of shapes and sizes, but more rigid ones are required when using hard cutting tools.

toughness

The ability of a material to absorb energy without breaking or fracturing. Tough cutting tools are able to withstand sudden stresses but are less hard.

tungsten

A metal that is very strong at elevated temperatures. Tungsten is often used as a cutting tool binder or alloy to improve heat resistance.

turning

A machining operation where a cylindrical workpiece is rotated while a single-point tool is guided along the length of the part. Turning is a common machining operation performed on the lathe.

UCON

A tool material made from niobium, tungsten, and titanium. UCON is hard and tough, but has limited application because it is prone to chipping.

vises

A workholding device with one fixed jaw and one movable jaw. Vises are often used to hold simple rectangular or cubic workpieces on a mill or machining center.

wear

The erosion of material as a result of friction, temperature changes, chemical degradation, or other issues. Tool wear types include fracture, flank wear, and notch wear.

wear resistance

The ability of a material to resist the gradual wearing away caused by abrasion and friction. Wear resistance is often greater in harder tools.

whisker-reinforced ceramics

An oxide ceramic with the addition of thin fibers of silicon carbide (SiC). Whisker-reinforced ceramics have excellent fracture resistance and can, therefore, be run at more aggressive feed rates than oxide or mixed ceramics.

whiskers

Thin reinforcing fibers. Whiskers of silicon carbide (SiC) in ceramic cutting tools increase fracture resistance and improve performance.

white cast iron

A metal formed by immediately cooling cast iron before the carbon can separate out into graphite. White cast iron is hard, brittle, and difficult to cut.

work hardening

An increase in the hardness of a metal due to plastic deformation caused by a cold working or machining process. Work hardening can occur when the pressure of metal cutting causes the metal to deform and harden.

workholding

A device used to support, locate, and clamp a workpiece for a manufacturing operation. Workholding for operations using advanced tool materials must provide more support than an operation using a common tool material.

workpiece

A part that is subjected to one or more manufacturing procedures, such as metal cutting, welding, or casting. Workpiece material and manufacturing operation help determine the proper cutting tool material to use.

zirconium oxide

ZrO₂. A white crystalline compound of oxygen and zirconium that is used as a coating for cutting tools and in cermet and ceramic cutting tools. Zirconium oxide resists oxidation and corrosion at high temperatures.

ZrO₂

Zirconium oxide. A white crystalline compound of oxygen and zirconium that is used as a coating for cutting tools and in cermet and ceramic cutting tools. ZrO2 resists oxidation and corrosion at high temperatures.