Prints for Metal Cutting Operations 241

angles

A shape formed by two lines that intersect or two rays or line segments sharing a common endpoint. Angles are formed when a section of a part feature has one vertex and two sides.

assembly

The process of fitting components together into a larger or completed part. Assembly includes combining compatibly designed parts, inserting components into a final part, or mechanically joining components together.

auxiliary views

A print view that presents illustrations showing a part at various angles other than a straight-on perspective. Auxiliary views provide a fuller picture of an angled side that cannot be fully represented with a basic orthographic view.

average roughness

Ra. The average distance between the peaks and valleys that characterize a particular surface. Average roughness describes the quality of a surface but does not detect waviness or flaws.

bilateral tolerances

A tolerancing method using a plus and minus deviation from the given dimension. Bilateral tolerances are preferred if deviation in either direction risks exceeding the given dimension and can be equal or unequal.

blind holes

A hole that begins on one side of the workpiece and terminates inside the workpiece. Blind holes have only one opening.

bolt

A cylindrical threaded device used for fastening parts. Bolts usually have flat heads that fit into the recess created by a counterbore or spotface.

boring

A cutting operation in which an existing hole is enlarged. Boring can be done on either a lathe or a mill.

break lines

A wavy or irregular line. Break lines on a print define the boundary of an imaginary, broken-out section of a print or shorten dimensions that are very long.

burr

A rough edge on a metal part created as a result of cutting or machining. Burrs often need to be removed by grinding or creating a chamfer.

callouts

Information on a print that refers to a specific part feature rather than the whole part. Callouts, or local notes, communicate specifications such as chamfer angle and hole diameter.

cavities

A hollow area in a solid part or component. Cavities provide space for another component or part to fit in the part.

center lines

A line made up of alternating long and short dashes. Center lines on a print define the center, or middle, of a symmetrical part.

chamfer

A small, angled surface added to an edge of a workpiece. A chamfer removes the sharp edge and helps eliminate burrs.

chamfers

A small, angled surface added to an edge of a workpiece. A chamfer removes the sharp edge and helps eliminate burrs.

channels

A long, narrow recess in a part. Channels allow space for another component or part to slide into the part.

class

A number designation in the Unified Thread Standard (UTS) that indicates the allowable tolerance and fit for threads. The class of the thread will range from 1 to 3, with 1 being close tolerance and 3 being loose tolerance.

coarse

A pitch where individual threads are spaced apart from one another. Coarse threads are easier to machine but provide less secure fastening.

contours

A curved surface or dimension cut into a workpiece. Contours are cut before machining other part features or cut after every other feature is created.

coordinate measuring machine

CMM. An electronic measuring instrument with a flat polished table that inspects parts in three-dimensional space. Coordinate measuring machines use contact or non-contact probes to make measurements.

counterbore

A flat-bottomed recess added to the opening of a hole. Counterbores provide a space for the head of a flat-faced fastener to rest.

countersink

A cone-shaped recess that is added to the beginning of a hole. Countersinks allow screws to sit flush with a workpiece surface.

crest

The highest point on a thread. The crest size helps determine important thread measurements, such as pitch and diameter.

cross-section

The interior of a surface that is exposed when the part is cut. Cross-section views in prints provide clearer views of interior features, features with depth, and the workpiece material.

cutting-plane lines

A thick line, often dotted or dashed, with arrows at both ends. Cutting-plane lines on a print represent the path and position of an imaginary cut and are used with sectional views of parts.

cylindrical

A three-dimensional (3D) shape that has a circular base and top connected by walls. Cylindrical parts may have parallel or tapered walls and sometimes have grooves, which are slots that curve with the part surface.

decimal

A system of representing parts of a number using a period after a whole number. Decimal numbers grow increasingly smaller moving from left to right after the period.

depth

The top-to-bottom measurement of a hole, recess, or relief. Depth for a feature on a print is often specified in a callout.

designators

A letter used in a thread system to indicate important information about that thread. Designators in thread systems indicate the thread's series, class, and type.

dial indicator

A measuring instrument with a contact point attached to a spindle and gears that move a pointer on the dial to measure small distances and angles. Two opposing dial indicators can be used to measure the angularity of a part feature, such as a chamfer, and a single dial indicator can be used to check the alignment of various machine components or workpiece dimensions.

diameter

A line measuring the distance from one edge of a circle to the opposite edge that passes through the center. Diameter for various holes on a print are often specified in callouts.

dimension lines

A thick, solid line with arrows at both ends and a dimension in the center. Dimension lines on a print define the measurement of a part feature.

dimensions

The desired measurement of a part or part feature. Dimensions include the desired length, width, and height of a part or feature.

drawings

A document that contains detailed instructions to make a part. Drawings, or prints, contain dimensions, directions, and details to guide employees in metal cutting operations to machine a part and its features.

drill press

A machining tool that uses a drill to penetrate the surface of a workpiece and make a round hole. Drill presses can be used for a variety of holemaking operations including drilling, boring, reaming, tapping, counterboring, and countersinking.

drilling

A machining process that machines round holes into the surface of a workpiece. Drilling can be done on a drill press, lathe, or mill.

engineers

A person responsible for designing parts, machines, and manufacturing operations. Engineers are responsible for drawing accurate and usable prints in metal cutting.

English System

A standard system of measurements based on the inch, second, pound, and Fahrenheit degrees. English measurements are primarily used in the United States and England.

extension lines

A thin, solid line that is perpendicular to a dimension line and placed at the end of a dimension line's arrow. Extension lines on a print connect the ends of a dimension line to the relevant part feature.

face milling

A milling operation in which the surface of the workpiece is perpendicular to the spindle axis. Face milling is useful for creating recessed indentations with flat bottoms, such as pockets, slots, and grooves.

FAO

Finish all over. An abbreviation on a print that indicates a part requires finishing on every surface. FAO indicates to an employee that the same surface finish needs to be applied to all surfaces of the part being machined.

fasteners

A device that holds two or more objects together. Common fasteners include screws, bolts, and rivets.

features

A distinguishing characteristic that performs a function on a part. Features include grooves, pockets, and holes.

fillet-and-radius gage

A measuring tool with a series of rounded tabs of differing sizes. Fillet-and-radius gages are used to measure rounded or circular features.

fillets

A rounded surface on the edge of a part. Fillets eliminate sharp edges and improve part strength by spreading stress at the edge over more of the part.

fine

A pitch where individual threads are grouped closely together. Fine threads are harder to machine but provide very secure fastening.

finishing processes

A final manufacturing operation that smooths the surfaces of a part to specification. Finishing processes include grinding, milling, shot peening, and plating.

flat-faced fastener

A threaded fastening device with symmetrical head that ends with a smooth, even surface. The most common flat-faced fastener is a screw.

flush

In line and level with another surface. Countersinks allow screws to sit flush with the face of a cutting tool.

fractions

A numerical expression with two numbers placed above and below a division line with the top number indicating how many parts of the bottom number are present in a measurement. Fractions can be just the fraction or appear with a whole number.

friction

The resistance that occurs when two surfaces attempt to slide by one another. Friction can be reduced by creating parts with smoother surface finishes.

gage blocks

A cube-shaped measurement device made of metal or ceramic that can be placed in a recessed area to assess its length, depth, and width. Gage blocks come in sets and are used together to determine precise measurements.

general notes

Any information that applies to the entire part on a print. General notes are usually located next to the title block and contain information such as required testing and surface finish.

go/no-go gages

A measurement tool that is set so that a properly machined part will fit into it easily and an improperly machined part will not. A go/no-go gage can be used to quickly check a part's threads for accuracy.

grid

The setup and structure of a print. Grids use letters and numbers positioned on the outer edges of a print to mark specific part locations.

grooves

A channel cut into a cylindrical workpiece. Grooves are often produced through turning on a lathe.

height gages

A type of measuring instrument with a precision finished base, a beam that is at a right angle to the base, and an indicator. Height gages are used to measure gage pin height to assess various workpiece dimensions.

hidden lines

A thin line made up of a series of short dashes. Hidden lines on a print define part features that are not visible in that view of the part.

informational blocks

A section of the print that contains background or general information about the print or part. Informational blocks include title and tolerance blocks.

inside diameter threads

ID threads. A uniform, spiraling groove on the interior of a part or hole. Inside diameter threads are usually mated to parts with outside diameter threads.

inside micrometer

An adjustable, handheld contact instrument, which can be either mechanical or electronic, that is used to measure the inside diameter of larger holes. An inside micrometer is often used to measure the accuracy of holes and hole features, such as counterbores and spotfaces.

ISO Metric Thread Standard

A system used to communicate thread specifications based on metric measurements. The International Organization for Standardization (ISO) Metric Thread Standards are signified by an "M" at the start of the measurement specifications in a thread callout.

lay

The direction of the grain of the surface finish. Lays are most commonly required to be parallel or perpendicular to the part surface and specifications are indicated with symbols on prints.

leader lines

A thin line with an arrow pointing at a part feature. Leader lines on a print tie a dimension to a feature, especially when there is limited space on a print.

limit dimensions

A tolerancing method using an absolute maximum and minimum allowable dimension. Limit dimensions specify a range of acceptable measurements instead of target dimensions.

local notes

Information on a print that refers to a specific part feature rather than the whole part. Local notes, or callouts, communicate specifications such as chamfer angle and hole diameter.

machining

Manufacturing a part by removing material from a workpiece in the form of chips. Machining operations include metal cutting, water-jet cutting, and electrical discharge machining (EDM).

machinists

A person responsible for ensuring a machine performs its job correctly, efficiently, and safely. Machinists, or operators, are responsible for interpreting manufacturing prints and implementing the design using various metal-cutting machines.

major diameter

The largest diameter, or circular surface, feature of a workpiece. On a thread, the major diameter is the diameter from crest to crest of an external thread or from root to root of an internal thread.

metal cutting

A group of machining processes that use a single- or multi-point tool to remove metal from a workpiece in the form of chips. Common metal cutting operations include turning, milling, and drilling.

metric

A standard system of measurements based on the meter, second, kilogram, and Celsius degrees. The metric system is internationally recognized.

microinches

µin. One-millionth (.000001) of the English standard inch. Surface roughness is indicated in microinches on prints.

micrometer

A handheld measuring device used to inspect the dimensions of parts. The typical micrometer is accurate within 0.001 in. (0.02 mm).

micrometers

µm. One-millionth of the metric standard meter. Micrometers are the metric standard used when converting from the English unit microinches (µin).

milling

A machining process in which a rotating multi-point cutting tool is fed along a part's surface to remove material. Milling operations typically produce flat surfaces.

minor diameter

The distance from root to root of an external thread or from crest to crest of an internal thread. Minor diameter is the narrowest portion of the threaded part or hole.

notes

An additional instruction or general comment added to a blueprint. Notes can contain information about the material, finish, tooling, tolerances, and other miscellaneous information.

object lines

A thick, solid line. Object lines, or visible lines, on a print represent edges of a part that can be seen from that particular view.

operators

A person responsible for ensuring a machine performs its job correctly, efficiently, and safely. Operators, or machinists, are responsible for interpreting manufacturing prints and implementing the design using various metal-cutting machines.

orthographic views

A print view that presents a series of illustrations that show a part's top and bottom, front and back, and right and left sides. Orthographic views communicate the shape and size of a part as well as clearly depicts all its design elements.

outside diameter threads

OD threads. A uniform, spiraling groove on the exterior of a part or hole. Outside diameter threads are usually inserted into a part with an inside diameter thread.

perspectives

A specific point of view. Different perspectives show different sides and aspects of a part on a print.

pictorial

A type of representation of a part or part feature that is realistically detailed and accurate. Pictorial representations are sometimes used to represent threads on prints.

pin gages

A type of gage available in a set and used to measure hole diameter. Pin gages are available in different ranges from .028 to 1.000 inch sizes (7.112 to 25.4 mm) in increments of 0.001 inch (0.025 mm).

pitch

The distance in metric units between the crest, or top-most point, on two threads. Pitch helps describe the regularity of threads from coarse, or few threads, to fine, or many threads.

plating

The process of adding a thin layer of metal to serve as a decorative or protective coating on a part. Plating is sometimes used to improve the surface finish of a part.

pockets

An interior recess that is cut into the surface of a workpiece. Pockets are circular or rectangular.

print views

A representation of a part from a specific point of view created from a range of line types that illustrate a part's shape and design. Print views include orthographic, auxiliary, and section views.

prints

A document that contains detailed instructions to make a part. Prints, or drawings, contain dimensions, directions, and details to guide employees in metal cutting operations to machine a part and its features.

profilometer

An inspection device that uses a stylus to trace along the surface of a part. Profilometers determine the average amount of roughness on a surface.

radius

A line measuring the distance from the center of a circle to any point along its edge. A radius defines circle measurements as well as any feature with a half-circular shape, such as a rounded corner.

reaming

A machining process that enlarges or smooths previously drilled holes using a cutting tool with straight cutting edges. Reaming can tighten the tolerance of a machined hole.

recessed

Set back from the surface. Recessed features on parts created with metal cutting include pockets and slots.

root

The lowest point on a thread. The root size helps determine important thread measurements, such as pitch and diameter.

sampling length

The length of the surface operators must examine to properly assess various roughness measurements. Sampling lengths are generally given in inch (millimeter) measurements.

scale

The relationship between the drawing of the part on the print and the actual finished part. Scale for an illustration will be given on a print, usually in the title block.

schematic

A type of symbol or diagram that is used to represent a part or part feature. Schematics are sometimes used to represent threads on prints.

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.

section lines

Identifies the imaginary cut portion of a part in a section view. Section lines appear as a series of diagonal lines drawn close together.

section views

A print view that presents cross-section illustrations of a part that show its interior. A variety of section views may be contained in a print.

series

A thread designation in the Unified Thread Standard (UTS) that identifies the coarseness or fineness of threads. Thread series are communicated using abbreviations such as UNC, UNF, and 8-UN, among others.

shot peening

A procedure where small spheres of hard material, usually steel, are forced through a nozzle at high rates of speed at the surface of a metal part. Shot peening improves surface finish and increases the material's strength and ability to withstand different types of damage.

sine bar

A measuring device used specifically to precision measure angles. Sine bars are types of taper micrometers and can be used to measure taper angles without removing the workpiece from the machine.

slope

The change in width of a taper. Slopes describe how the width of a part decreases or increases along the length of the taper.

sloped

Rising or lowering at a gradual angle. Sloped surfaces on a part are easiest to see in an auxiliary print view.

slots

A channel or groove that is machined into the surface of a workpiece. Slots are typically narrow and long.

specifications

A description of the essential physical and technical properties of a part. Specifications, sometimes called specs, include information on the shape and tolerance of a part as well as, sometimes, required mechanical and physical properties.

spotface

A shallow flat-bottomed recess added to the opening of a hole. Spotfaces allow the head of a flat-faced fastener to sit flush with a workpiece surface.

standard

An established policy regarding a particular practice, method, or measurement. Standard taper sizes are established by a number of organizations in the United States and internationally, including American Standard and the International Organization for Standardization (ISO).

standardized

Using an established rule or set of expectations. Standardized thread measurements include the Unified Thread Standard, for English measurements, and the International Organization for Standardization (ISO) Metric Thread Standards, for metric measurements.

stress

A force that attempts to deform an object. Stress in a part can be reduced through the use of a fillet, which spreads stress over a greater area of the part.

surface finish

The degree of roughness and variation on the surface of a part. Surface finish is commonly indicated on a print using a checkmark symbol and a required roughness height.

surface finishes

The degree of smoothness of a part's exterior after manufacturing. Surface-finish quality will usually be specified on a manufacturing print.

symbols

A picture or illustration used to stand in for a specific type of information. Symbols are used in metal-cutting prints to represent information such as hole diameter and depth.

taper

The uniform increase or decrease in the width or diameter of a part or a part feature. Tapers are often manufactured based on industry standards.

taper angles

The entire angle that describes the taper of a surface, cylindrical part, or hole. Taper angles are used with the length of the taper to determine slope.

taper notes

A ratio that indicates how the width of a part should change along the length of a taper. Taper notes will use the same unit of measurement as the other dimensions on the print.

taper per foot

TPF. A unit of measurement for a taper. Taper per foot indicates the change in the width or diameter in inches of the part or part feature for each foot along the length of the taper.

taper ring gage

A circular measuring device used to inspect the size of tapers. Taper ring gages are used for measuring cylindrical tapers.

tapping

A machining process that creates internal threads in a round hole with a multi-point tool. Tapping can be performed on a drill press or lathe.

telescope gages

A handheld, mechanical contact instrument used to measure the size of interior features, such as holes. Telescope gages are extended inside the interior feature until they touch both sides, then they are removed and measured with a micrometer.

thread ring gages

A disk of heavy metal with a central, threaded hole made to match a particular outside diameter thread. Thread ring gages are screwed onto the part being inspected in order to make sure the threaded hole and fastener mate properly.

thread rolling

A metalworking process that uses pressure from two or more cylindrical rollers to impart threads on the surface of a workpiece. Thread rolling is generally used to mass produce uniform fasteners.

threads

A long, spiraling groove on a workpiece or in a hole. Threads are essential for the creation of fasteners.

threads per inch

TPI. The number of threads, each consisting of a crest and root, on a part or in a hole that will fit in an inch. Threads per inch measurements are used to help describe pitch in the Unified Thread Standard (UTS).

through holes

A hole that starts on one side of a workpiece, extends through it, and exits out of the opposite surface of the workpiece. Through holes can be seen from both ends or sides of a part.

title blocks

A portion of a print that contains basic identifying information. Title blocks include information such as the company name, part name, part number, and engineer.

tolerance block

An informational block that details acceptable deviations from given dimensions for an entire part. Tolerance blocks are used when most part features have a similar tolerance range.

tolerances

An acceptable deviation from a specified part measurement. Tolerances usually include deviations that are larger or smaller than the intended design.

turning

A machining process that rotates a cylindrical workpiece while a single-point tool is guided along the length of the part. Turning is performed on a lathe.

type

A thread designator that indicates if the thread is external or internal. The type is usually indicated by a letter in both the Unified Thread Standard (UTS) and the International Organization for Standardization (ISO) Metric Thread Standard.

Unified National Coarse

UNC. A Unified Thread Standard (UTS) indicating that the threads on a part or in a hole will be relatively spread apart. Unified National Coarse measurements will be specified in UTS reference material based on the other measurement information supplied in the callout.

Unified National Fine

UNF. A Unified Thread Standard (UTS) indicating that the threads on a part or in a hole will be relatively close together. Unified National Fine measurements will be specified in UTS reference material based on the other measurement information supplied in the callout.

Unified Thread Standard

UTS. A standard used to communicate thread specifications based on English measurements. The Unified Thread Standard is the main standard system used for threaded parts and holes in the United States and Canada.

unilateral tolerances

A tolerancing method using a deviation in only one direction, either plus or minus, from the specified dimension. Unilateral tolerances are used if variation in only one direction risks exceeding the given dimension.

visible lines

A thick, solid line. Visible lines, or object lines, on a print represent edges of a part that can be seen from that particular view.

waviness height

The measurement of the tallest point of the surface from a straight mean line that averages the highest and lowest points. Maximum waviness height, usually given in inches (millimeters), may be included on a print in the surface finish requirements for a part.

waviness width

The average length of the waves on a part surface from valley to peak to valley. Maximum waviness width, usually provided in inches (millimeters), may be included on a print in the surface finish requirements for a part.