NIMS Core Job Planning Skills 221

accuracy

The difference between a measurement reading and the true value of that measurement. The less error present in the measurement, the more accurate the results.

adhesive

A chemical material used to bond two objects together. Adhesives are often used to join nonmetallic and metallic materials.

allowance

The difference between the smallest permissible hole and the largest permissible shaft. An allowance creates a certain kind of fit between mating parts.

ANSI

American National Standards Institute. A private, nonprofit organization that administers and coordinates voluntary standards and systems. ANSI provides a tool classification system that details characteristics such as size, shape, and tolerance.

assembler

The person who assembles parts. Assemblers can also work on designing the product and finishing the product.

assembly

The process of joining objects. Assembly can include use of fasteners, adhesives, or welding.

assembly line

A production process in which products are mass-produced in stages. Assembly lines are a linear method of manufacturing in which the object being produced passes through different work stations until it is complete.

bar stock

Raw material purchased from metal manufacturers in the form of solid, long bars. Bar stock may be round, square, rectangular, or hexagonal.

base

The foundation of a machine that supports all the other machine components. Bases provide both stability and rigidity.

bastard cut

A file cut in which there are roughly 30 teeth per inch that is between a middle cut and a second cut. Bastard cut is the third-coarsest cut overall, but is the coarsest cut widely used by machinists.

bill of materials

BOM. A report that lists the materials required to make a particular product and the cost of each individual component. A bill of materials includes all project materials, including any accessories and fasteners.

blade

The long flat part of a file that contains the cutting surface. The blade can be blunt or tapered.

blunt

Having sides that remain parallel in both width and thickness. A blunt file has a cross section that remains the same in size along its entire length.

bolts

An externally threaded, cylindrical fastener with a head at one end and a threaded blunt end at the other. Bolts are designed to fit into nonthreaded holes to join parts and are assembled with a nut.

bonded abrasive wheel

A grinding tool made of grits that are held together with chemical bonding into a circular shape. A bonded abrasive wheel rotates along the surface of a part to remove material.

brace

A U-shaped hand drill with increased torque that allows it to drill wider and deeper holes. A brace uses the U-shape of its frame as a crank to rotate the drill chuck and bit and perform drilling operations.

chips

A piece of metal that is removed form a workpiece during cutting or grinding. Chips are tiny curls, shards, fragments, shavings, or particles of metal.

circularity

A two-dimensional form tolerance that describes the allowable variability in the shape and appearance of a circle. Also known as roundness, circularity is an individual tolerance.

clearance

A fit that allows intentional space to exist between a hole and the shaft inserted into it. For a clearance fit, the shaft diameter is designed to be slightly smaller than the hole.

coatings

A finish used for protective and decorative purposes. Coatings like paint or varnish are applied to products at the end of the part creation process.

column

The rigid, vertical support section of the machine. Columns suspend components and tools over the workpiece and also support components.

concentricity

A three-dimensional locational tolerance that describes the location of opposing points in cylindrical features with respect to a datum reference. Concentricity is a related tolerance.

countersinking

The cutting of a beveled edge at the end of a hole. Countersinking allows the head of a screw to rest level with the workpiece surface.

cranking handle

A shaft that transfers the rotational motion produced by an operator to a drive gear on a hand drill. A cranking handle's rotation is transferred from the drive gear to the pinion gear and then to the drill bit.

cross section

A section of a feature that is formed by an intersecting imaginary plane. Any two-dimensional cross section of a feature should remain within two imaginary concentric circles to have circularity.

cross section

A surface or shape that is exposed or would be exposed by making a cut at a right angle to the object's axis. The cross section of a bar stock piece may be rectangular, square, hexagonal, or round.

curved cut

A file cut in which the rows of teeth are parallel to each other but form curved rather than straight lines. Curved-cut files are often used to shape and smooth body panels in the automotive industry.

cuts

The patterned size and shape of a file's teeth. The three main cuts of a file are bastard, second cut, and smooth.

cylindricity

A three-dimensional form tolerance that describes the allowable variability in the shape and appearance of a cylinder. Cylindricity is an individual tolerance.

dead-smooth cut

A file cut in which there are roughly 100 teeth per inch. Dead-smooth cut is the smoothest file cut.

dial indicator

A measuring instrument with a contact point attached to a spindle and gears that move a pointer on the dial. Two opposing dial indicators can be used to measure the concentricity of a cylindrical feature.

diameters

The distance measuring from one side of an object to the other that passed through its center. Standard bar stock diameters are usually available in 1/8-in or every-2-mm increments.

disassembled

To take apart by design, often with the intention of reassembly. Assemblies joined with fasteners can be disassembled.

double cut

A file cut in which there are two sets of parallel rows of teeth that intersect at an angle, resulting in diamond-shaped cutting teeth along the file blade. Double-cut files are best for removing larger quantities of material in a single pass.

draw filing

A type of filing in which the machinist pulls the file across the workpiece toward their body. Drawing filing is most often used for finishing.

drill

A multi-point cutting tool used to make round holes. In drilling, either the workpiece is held stationary while the drill rotates to cut a hole to a certain depth, or the drill is held stationary while the workpiece rotates.

drill bit

A multi-point cutting tool used to machine round holes into workpieces. Drill bits have spiral cutting edges and are usually mounted in drill presses.

drill chuck

A type of toolholder that holds drill bits in a machine or manual tool. A drill chuck has jaws and a collar that are tightened to grip a drill bit.

drill press

A machine tool that is used for a variety of holemaking operations. Drill presses use rotating multi-point cutting tools.

drilling

The use of a multi-point tool to machine a new round hole into the surface of a workpiece. Drilling is a type of holemaking operation.

drive gear

The gear that receives energy from a power source via an input shaft. The drive gear in a hand drill transmits power to the pinion gear so that it can rotate the drill bit.

edges

The line along which two surfaces intersect. The edge of a file blade occurs where its two faces meet.

equilateral triangle

A triangle with three equal sides and three equal interior angles. The cross section of a three square file may be either an equilateral triangle or an isosceles triangle.

faces

The flat surface of a file blade. The face contains the teeth of the file, though one face of a file can be smooth and free of teeth.

fasteners

A device that holds objects together or locates them in relation to one another. Common fasteners include screws, bolts, and rivets.

feed handle

A handle attached to a machine that controls the movement of the cutting tool. On an upright drill press, the feed wheel is located on the head.

feeds

The rate at which the cutting tool and the workpiece move in relation to one another. Feed is typically a linear movement.

ferrule

A metal ring on the end of a file handle. A ferrule strengthens the area where the handle meets the file.

file card

A wire brush with short bristles that is used to remove chips from file teeth. Using file cards helps prevent chips caught in a file from scratching a workpiece surface.

file cleaner brush

A stiff-, short-bristled brush used to aid in the removal of chips from a file. Using file cleaner brushes helps prevent chips caught in a file from scratching a workpiece surface.

files

A flat metal cutting tool with a large number of very small teeth. Files wear away workpiece material through abrasion.

filing

A type of benchwork operation that involves manually removing small amounts of workpiece material with a tool that has small, sharp teeth. Filing can smooth workpiece surfaces, remove sharp edges, and add a chamfer.

finishing

A cutting pass that emphasizes tight tolerances and smooth surface finish. Finishing is usually the last step in the machining process.

finishing

A metal-cutting process in which a small amount of material is removed to achieve tight tolerance and good surface finish. Finishing is usually achieved with second-cut to dead-smooth-cut and single-cut files.

fit

A designation of how much space or lack thereof is allowed between mating components. There are three main types of fit: clearance, transition, and interference.

flat file

A type of file with a rectangular cross section that is blunt or lightly tapered and either single or double cut. A flat file is used to file flat surfaces.

force fits

FN. A type of fit in which pressure must exist between the parts. Force fits are a type of interference fit.

frame

The U-shaped body of a brace that is used as a crank to rotate the drill bit. A brace frame has a handle in the center of the U and is manually rotated by the operator.

geometric dimensioning and tolerancing

GD&T. An international standard for communicating instructions about the design and manufacturing of parts. GD&T uses universal symbols and emphasizes the function of the part.

grinding

The use of an abrasive tool to remove material from a workpiece. Grinding operations commonly use abrasive grains bonded into a wheel shape.

half round file

A type of file with a semi-circular cross section that is either blunt or tapered. A half round file is used to file contoured workpiece surfaces.

hand drill

A hand-held tool used to create holes or drive screws. An operator uses a hand drill by turning the drive gear that turns the pinion gear, which then causes the drill bit to rotate and perform drilling operations.

hand file

A type of file with a rectangular cross section that is parallel in width and tapered in thickness with one smooth face and one cutting face. Hand files are used to cut a surface without cutting any adjacent surfaces.

head

The part of a drill press that contains the spindle and the motor. The head of an upright drill press is located at the top of the column and extends over the worktable.

heel

The smooth part of the file located on the blade where the blade meets the tang. The heel does not contain any cutting teeth.

hexagonal

Six-sided. Hexagonal is a standard bar stock shape.

high-speed steel

HSS. 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.

idler gear

A gear that is used to keep the direction of motion consistent between a drive gear and a driven gear. Idler gears only influence direction and do not alter speed and torque between drive and driven gears.

inspection

The examination of a part during or after its creation to confirm that it adheres to specifications. During inspection, defects may be identified and corrected.

interference

A tight fit designed where the smallest permissible shaft is larger than the largest permissible hole. Force is required to assemble parts with an interference fit.

isosceles triangle

A triangle with two equal long sides and one shorter side. The cross section of a three square file may be an isosceles triangle or an equilateral triangle.

joint

The meeting point where two materials are welded together. Welding creates a permanent joint.

knurling

A machining operation that displaces material rather than cutting it. Knurling embeds a textured, rough pattern into a part's surface.

lathe

A machine tool that holds and supports a cylindrical workpiece at one or both ends and rotates it while a single-point cutting tool removes material. Lathes are commonly used to perform turning operations.

lathe filing

A type of filing in which the machinist pushes a file against a workpiece as it rotates on a lathe. Lathe filing can be used for roughing and finishing.

length

The measurement of a component from end to end, rather than along its side. The length of a file runs parallel to its edges and perpendicular to its point.

lobing

Deviation from workpiece roundness. Circularity, cylindricity, and runout all restrict lobing on a cylindrical part.

locational clearance fits

LC. A type of fit in which the parts in an assembly are not meant to move relative to each other. Location clearance fits are loose compared to locational interference and locational transition fits.

locational interference fits

LN. A type of fit that requires assembly components to lightly or heavily press against each other. Locational interference fits are tight compared to locational clearance and locational transition fits.

locational transition fit

LT. A type of fit in which the parts in an assembly are not meant to move relative to each other and require a slight pressure between them. Locational transition fits are tight compared to locational clearance fits and loose compared to locational interference fits.

machine tools

A power-driven machine that uses a cutting tool to remove metal from a workpiece. Common examples of machine tools include the drill press, the lathe, and the mill.

machining

The process of removing material to form an object. Machining methods include milling, turning, and drilling.

manufacturer’s technical data references

Documents provided by a manufacturer that offer specific information about the products they manufacture. Machinists use manufacturer's technical data references to help them select the proper cutting tool for a given operation.

maximum material condition

MMC. The point at which a feature contains the greatest amount of material within its acceptable size limit. The smallest acceptable hole and the largest acceptable shaft are examples of maximum material condition.

mechanical fastening

A process that joins two materials using a clamping force. Examples of mechanical fasteners include screws, bolts, and nails.

middle cut

A file cut in which there are roughly 25 teeth per inch. Middle cut is the second coarsest cut after rough cut.

mill file

A type of file with a rectangular cross section that is blunt or lightly tapered and always single cut. A mill file is used to sharpen tools or finish surfaces.

nails

A thin, pointed type of fastener that is fastened into an object with a hammer. Nails are typically used with nonmetallic materials.

nuts

A fastening device containing a hole with internal threads that mates with a screw or bolt. Most nuts are square or hexagonal.

out-of-round

An irregularly shaped circle that is not totally round. Out-of-round workpieces can occur during lathe filing if the workpiece is over-filed.

pining

The process of a file's teeth becoming clogged with chips from a workpiece. Pining can be prevented by covering the teeth in chalk.

pinion gear

A small circular gear that is driven by a larger circular gear to convey motion. A pinion gear rotates the drill bit on a hand drill.

point

The end of the blade of a file. The point is opposite the tang and is usually squared rather than pointed.

position

A three-dimensional geometric tolerance that controls how much the location of a feature can deviate from its true position. Position is a related tolerance.

rasp cut

A file cut in which the teeth are formed into individual, raised triangular shapes along the surface of the file blade. Rasp-cut files are used on wood and other soft materials.

reaming

The use of a multi-point cutting tool to smooth or enlarge a previously drilled hole. Reaming tools have straight cutting edges.

regardless of feature size

RFS. A modifier indicating that the stated tolerance for a feature applies regardless of its actual size within an acceptable size limit. If RFS controls a location being inspected for position, that location should be inspected with a variable gage.

rough cut

A file cut in which there are roughly 20 teeth per inch. Rough cut is the coarsest file cut.

roughing

A cutting pass that removes material without regard to surface finish. Roughing is often used to separate part pieces from a single sheet of material.

roughing

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

round file

A type of file with a circular cross section that tapers toward the file point. Rounds files are used to enlarge or finish holes, round slots, and curves.

roundness machine

A sophisticated inspection device with a precision spindle that measures various circular and cylindrical features. A roundness machine is necessary for inspecting such tolerances as circularity, cylindricity, circular runout, and total runout.

running and sliding clearance fits

RC. A type of fit in which the part is meant to move in the assembly. Running and sliding clearance fits are abbreviated as RC for running clearance.

sanding

A form of grinding that uses a fine grain abrasive to remove small amounts of surface material. Sanding improves the finish of a surface.

screws

An externally threaded, cylindrical fastener with a head and a threaded flat or pointed end opposite the head. Screws are designed either to fit into a threaded hole or form threads into material.

second cut

A file cut in which there are roughly 40 teeth per inch. Second cut is the third-smoothest cut overall, but is considered the middle-grade between bastard and smooth cut, the coarsest and smoothest cuts widely used by machinists.

shrink fits

FN. A type of fit in which one part in the assembly is heated to expand and fit onto another, where it cools and shrinks to create a pressured fit. Shrink fits are a type of interference fit.

single cut

A file cut in which there are parallel rows of teeth set at an angle from the centerline of the file blade. Single-cut files are best for sharpening and finishing a workpiece surface.

smooth cut

A file cut in which there are roughly 60 teeth per inch. Smooth cut is the second smoothest cut overall, but it is the smoothest cut widely used by machinists.

specifications

The design parameters that set the limits of acceptable deviation for a part's intended application. Specifications are established in a blueprint.

speeds

The rate at which the workpiece passes the cutting tool at the point of contact. Surface speed has the greatest effect on tool life.

spindle

The part of the machine tool that spins or rotates. On the drill press, the spindle holds the cutting tool.

square file

A type of file with a square cross section that gradually tapers. Square files are used to enlarge and finish rectangular holes, slots, and angles.

straight filing

A type of filing in which the machinist pushes the file across the length of a workpiece on a straight or slightly diagonal path. Straight filing can be used for roughing or finishing.

surface finish

The degree of roughness and variation on the surface of a part after it has been manufactured. The surface finish of a part may need to be smooth or intentionally rough.

surface finish

The measured surface profile characteristics of a completed workpiece. Surface finish can be improved with filing.

tang

A tapered extension at the end of a file opposite the point. Tangs are the part of the file onto which a handle is secured.

tapered

Gradually decreasing in size from one end of the object to the other. A tapered file has a width, thickness, or both that decreases in size along its entire length.

tapping

The process of cutting internal threads in a workpiece. Tapping uses a rotating multi-point tool.

teeth

The cutting points of a tool. Teeth can either be molded or cut into a tool.

thickness

The measurement of a component from top to bottom. The thickness of a file measures the distance between its two faces and runs perpendicular to both the point and blade edges.

three square file

A type of file with a triangular cross section that tapers toward the file point. A three square file, or triangular file, is used to finish corners and angles.

tolerance zone

An imaginary zone in which a part feature must be completely contained for the part to pass inspection. The tolerance zone contains the dimensions between the maximum and minimum limits of a feature's location.

tolerances

The acceptable variation from a specific dimension. Tolerances represent the amount a part can deviate from its specifications while still performing its desired function.

torque

A force that attempts to twist or rotate a material. Torque is used to turn a screw or other threaded fastener.

total indicator reading

TIR. The absolute value of the total deviation of a dial indicator's movement. TIR is calculated to inspect the total runout of a cylindrical part or the flatness of a prismatic part.

total runout

A three-dimensional geometric tolerance that controls the form, orientation, and location of the entire length of a cylindrical part as it rotates. Total runout is a related tolerance.

transition

A fit toleranced for an allowance that permits both a clearance and an interference fit. For a transition fit, a clearance fit occurs with the smallest shaft diameter and the largest hole diameter, but an inference fit occurs with the largest shaft diameter and the smallest hole diameter.

triangular file

A type of file with a triangular cross section tapers toward the file point. A triangular file, or three square file, is used to finish corners and angles.

upright drill press

A type of drill press on which the head extends over the worktable. On an upright drill press, the column supports both the head and the worktable.

vise

A workholding device with two jaws, usually one fixed and one movable, that grip and hold a workpiece in place. Vises hold a workpiece in place during filing operations.

wear

The erosion of material as a result of friction. Wear occurs to the teeth of a file if excessive force is used on the tool.

welding

A joining process that uses heat, pressure, friction, or a combination of methods to fuse two materials together permanently. Welding is used in a variety of industries from auto manufacturing to aerospace engineering.

width

The measurement of a component along its side, rather than from end to end. The width on a file occurs parallel to the point and perpendicular to the length.

workholding

A method or device for securing a workpiece for a machining operation. Workholding can include chucks, vises, and bolts.

worktable

A machine component that supports the workpiece and any workholding devices. The worktable on an upright drill press is supported by the column.

wrench

A type of hand tool that tightens and turns bolts and nuts. Wrenches contain fixed or moving jaws or a round attachment that grips the nuts or bolts.