Manual Milling

T-Slots

A T-shaped opening running the length of a machine worktable. T-slots allow operators to use workholding devices during machining processes.

Tolerances

A blueprint specification indicating an unwanted but acceptable deviation from a given dimension. Tolerances state the allowable difference between a part and its intended design.

Cemented Carbide

A common cutting tool material that is pressed and sintered to make both indexable inserts and solid cutting tools. Cemented carbide provides a cutting edge that is very hard and wear resistant.

High-Speed Steel

A common cutting tool material that is relatively inexpensive and offers excellent toughness. High-speed steel tools are often heat treated and coated.

Vise Jaw

A component on a vise that grips and holds the workpiece in place. A vise has one fixed jaw and one moveable jaw.

Mist Cooling

A coolant-delivery method that uses a high-velocity stream of air to disperse a small amount of cutting fluid over the cutting area. Mist cooling reduces the overall amount of coolant needed in a cutting operation.

Multi-Point Tool

A cutting tool that has more than one cutting edge. Multi-point tools include mills and drills.

Inserts

A cutting tool that has multiple usable cutting edges. Inserts are typically very hard and wear resistant.

Alignment Pins

A cylindrical metal fastener that secures a workpiece or workholding device into position. Alignment pins inserted in a worktable's T-slots can securely hold a vise.

Clamp Bolts

A cylindrically shaped, threaded device for fastening parts. Clamp bolts hold the mill head and other components securely in a rigid position until the bolts are loosened.

Encoders

A device that translates mechanical motion into a digital signal. Encoders send locations to display panels on manual mills.

Workholding Devices

A device used to support, locate, and hold a workpiece. Workholding secures the workpiece on the worktable in milling.

Cutting Tool

A device with one or more edges used to create chips and remove material. Cutting tools are either single-point or multi-point tools.

Blueprint

A document containing all the instructions necessary to manufacture a part. A blueprint includes a part drawing, dimensions, and notes.

Finishing Cuts

A final pass of the cutting tool that emphasizes accuracy, tolerance, and surface finish. Finishing cuts often require faster speeds and a lighter depth of cut.

Face Mills

A flat mill cutter with multiple cutting teeth surrounding the bottom edge. The face mill is often used to remove a large amount of material to create flat surfaces.

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.

Feed Handles

A handle attached to a machine that controls the movement of a component. Feed handles, or handwheels, on the milling machine move the table side to side and forward and backward.

Knee Crank

A handle that raises and lowers the knee and worktable of a manual milling machine. Knee cranks allow operators to adjust the feed rate incrementally.

Fixture Plate

A large flat piece of stock clamped to the worktable. Fixture plates provide a flat surface for workholding without interference from the worktable's T-slots.

Speed Range

A limited set of possible speeds at which a machine is capable of running. Speed ranges for a manual mill include high and low range.

Tool Center

A line or point of a cylindrical tool that is equally distant from all other points located on the tool's circumference. Tool centers are located by subtracting the tool's radius from any point on its circumference.

Leadscrew

A long, threaded device that controls the precise movement of machine tool components. The leadscrew controls worktable movement on the mill.

Milling Machine

A machine that uses a rotating, multi-point cutting tool to remove material from a workpiece. Milling machines, or mills, may be manually operated or automated.

Mill

A machine that uses a rotating, multi-point cutting tool to remove material from a workpiece. Mills, or milling machines, may be manually operated or automated.

Metal Cutting

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

Drip Method

A manual coolant-delivery method in which an operator uses a brush to apply fluid on the workpiece surface. The drip method is often used with oil-based cutting fluids.

Spray Bottle Method

A manual coolant-delivery method in which an operator uses a squeezable bottle to spray fluid on the cutting area. The spray bottle method is most often used with water-based cutting fluids.

Knee

A manual mill component that supports the saddle. Knees can also be used to adjust a mill's worktable to different heights.

Vertical Column And Knee Milling Machine

A manual milling machine whose spindle is perpendicular to the floor and machine worktable. Vertical column and knee milling machines are more common than horizontal mills.

Hardness

A material's ability to resist penetration, indentation, or scratching. Increased hardness tends to indicate a material is very strong and resistant to wear.

Properties

A measurable quality or attribute of a specific material. Properties include aspects such as hardness, toughness, and ductility.

Saddle

A mill component that enables the worktable to move side to side and back and forth. Saddles are located between the knee and worktable on a mill.

Horizontal Column And Knee Milling Machine

A milling machine with a spindle that is parallel to the ground and machine worktable. Horizontal column and knee milling machines are less common than vertical column and knee milling machines.

Face Milling

A milling operation that removes large amounts of metal and produces a flat surface. Face milling primarily cuts with the bottom of the cutting tool.

End Milling

A milling operation that uses a narrower mill to cut surfaces parallel or perpendicular to the spindle axis. End milling can create a variety of workpiece features, such as pockets, slots, and contours.

Manual Milling

A milling operation where machine movements are controlled by an operator. Manual milling is most commonly performed on the vertical knee and column mill.

End Mill

A narrow cutting tool that can be used to machine grooves, slots, pockets, and contours into workpieces. End mills have one or more flutes.

Aluminum

A nonferrous, silvery, lightweight, soft, very ductile metal. Aluminum is highly machinable.

Precision-Ground Parallels

A pair of metal support blocks that machinists use to position a workpiece to the desired working height in a vise. Parallels are made using highly accurate precision grinding processes to ensure both blocks have equal thickness.

Workpiece

A part that is subjected to one or more manufacturing procedures. Workpieces for milling operations are most commonly metal materials.

Indicator Pin

A point on the end of the dial indicator. Indicator pins run across two or more surfaces to measure differences in distance.

Edge Finder

A rod-shaped tool that operators use to find the exact edge of a part. Edge finders are commonly used in milling to locate part zero.

Gear

A round or cylindrical mechanical component with teeth that transmits power. Gears mesh with one another and can alter the speed, torque, or direction of mechanical energy.

Parameters

A set of measurable factors or characteristics that define the scope of an operation. Parameters of a milling operation include workpiece tolerances and properties.

Quill

A shaft that moves the spindle in and out of the mill head. The quill controls the spindle's depth.

Collet

A slitted device that expands or contracts to securely hold a cutting tool or workpiece. On the mill, collets hold tools in the spindle.

Three-Dimensional

A space that has length, width, and depth. Three-dimensional space can be represented by the Cartesian coordinate system.

Flute

A spiraling groove or recess around the periphery of a cutter that allows for chip flow away from the cut. Flutes also facilitate the flow of cutting fluid.

Coolant

A substance used to cool or lubricate a metal cutting process. Coolants can be oil- or water-based liquids, gases, or pastes.

Cartesian Coordinate System

A system that describes the location of an object by numerically expressing its distance from a fixed position along three linear axes. Cartesian coordinates are used to direct machine tool movements.

Cutting Fluid

A type of coolant used to cool or lubricate a metal cutting process. Cutting fluids are typically oil- or water-based liquids.

Conventional Milling

A type of milling that feeds the workpiece against the cutting tool rotation. Conventional milling creates chips that become gradually wider during the cut.

Climb Milling

A type of milling that feeds the workpiece in the same direction as the cutting tool rotation. Climb milling creates chips that become gradually narrower during the cut.

Analog Measurement

A type of readout that uses dials with scales inscribed on them to display dimensions on the mill. Analog measurement is less precise than digital readout.

Grade

A type or category of cutting tool material specified for a particular use. Grades indicate different types of cemented carbides used in milling.

Vise

A workholding device with two jaws that grip and hold a workpiece in place. Vises are commonly used for workholding on the mill.

Setup

All the necessary preparation of tooling and fixturing that occurs on a machine before a milling operation can be executed. Setup includes preparing machines, tools, and materials.

Precision Machinist Square

An L-shaped tool that a machine operator can use to align square or linear workpieces. Precision machinist squares are less exact than indicators.

Jump Off

An abrupt, but slight, off-center shift of the edge finder pin. Jump off indicates that an edge finder has located a workpiece edge.

Scale Dials

An analog device that measures linear movement. Scale dials are numbered collars attached to the feed handles and crank on manual mills.

Glass Scale Encoders

An encoder that uses light sensors to detect movement. Glass scale encoders are the most accurate encoders because they are not subject to backlash.

Centerline

An imaginary line that runs through the center of a cylindrical tool. The centerline of an edge finder pin is aligned to the part edge when the pin jumps off.

Axes

An imaginary straight line that is used to measure the location of an object in three-dimensional space. The Cartesian axes are the X, Y, and Z axes.

Roughing Cuts

An initial pass of the cutting tool that emphasizes heavy material removal rates, high feed rates, and a heavy depth of cut. Roughing cuts remove most of the material quickly without regard to surface finish.

Dial Indicator

An instrument capable of measuring small distances and angles. Dial indicators may be used for fine positioning in manual milling.

Tooling

Assorted tools used in various manufacturing processes. Tooling used in milling operations includes face mills, end mills, and holemaking tools.

Heat Treatment

Controlled heating and cooling processes used to change a material's structure and alter its physical and mechanical properties. Heat treatment often adjusts a material's hardness.

Teeth

Cutting edges of a circular cutting tool. Teeth perform the cutting action while flutes clear chips.

Digital Readout

DRO. A type of readout that uses an encoder attached to a machine that transfers information to a digital display. Digital readout is capable of very precise measurements.

Indexable

Having multiple cutting edges that can be repositioned to reveal a fresh cutting edge. Indexable inserts on a face mill can be rotated to a different cutting edge once the original edge has been worn or damaged.

Linear

In a straight line along a single axis. Linear workpieces can be aligned on a mill worktable using a precision machinist square.

Soft

Less able to resist forces that would break, penetrate, or scratch a material's surface. Soft materials are characterized by their lack of hardness.

Perpendicular

Meeting at a 90° angle. On a vertical mill, the spindle is perpendicular to the worktable.

Concentric

Rotating in a perfectly circular motion. Concentric is the opposite of eccentric.

Eccentric

Rotating in an erratic, non-circular motion. Eccentric is the opposite of concentric.

Z Axis

The Cartesian axis representing coordinate positions along a line parallel to the tool spindle and perpendicular to the worktable. The Z axis describes vertical, up-and-down movement.

Y Axis

The Cartesian axis representing coordinate positions along the shortest distance parallel to the worktable. The Y axis describes a mill worktable's forward-and-backward movement.

X Axis

The Cartesian axis representing coordinate positions along the longest distance parallel to the worktable. The X axis describes a mill worktable's side-to-side movement.

Strength

The ability of a material to resist forces that attempt to break or deform it. Increased strength in materials can make them more difficult to machine.

Alignment

The accurate positioning of machine components. Alignment of the mill head to the worktable is an important step of setup for the manual mill.

Arbor

The bar attached to the spindle of a horizontal milling machine. The arbor holds the milling cutter for different types of milling processes.

Surface Finish

The degree of smoothness of a part's surface after it has been manufactured. Surface finish is the result of the surface roughness, waviness, and flaws remaining on the part.

Specifications

The design parameters that set the limits of acceptable deviation for a part's intended application. Specifications are also called specs.

Radius

The distance between a point on a circle's circumference and its center. The radius of an edge finder's pin must be factored into locating an exact workpiece edge.

Diameter

The distance from one edge of a circle to the opposite edge, passing through the center. The diameter of a cutting tool helps determine the cutting speed in milling.

Origin

The fixed central point in the Cartesian coordinate system. The origin has a numerical value of zero at each axis.

Base

The foundation of a machine that supports all other machine components. Bases stabilize mills and provide them with rigidity.

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 using the proper tool geometry or cutting with fluids.

Reference Point

The location of a tool, workpiece, or machine component in an established position. A reference point provides a location from which to accurately measure and create part features in a milling operation.

Worktable

The machine component that supports the workpiece and any workholding devices during machining. Worktables on manual mills move side to side, back and forth, and up and down.

Toughness

The material's ability to withstand forces that attempt to break it. Toughness determines the ability of a cutting tool to withstand a sudden stress.

V-Ram

The moveable component attached to the mill head. The V-ram facilitates the machining of oversized parts or long parts that hang over the edge of the mill table.

Spindle

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

Overarm

The part of the horizontal milling machine that reaches over the workpiece and worktable. The overarm supports the spindle and arbor.

Head

The part of the vertical milling machine that holds the spindle. The head also contains various speed and feed controls for the mill.

Square

The process of machining a workpiece to make the sides parallel and even. Squaring is most often performed by face milling on the manual mill.

Readout

The process of reading information from a machine and displaying it in an understandable form. Readout measures locations and movements on a mill and can be analog or digital.

Rigidity

The property of a workpiece, machine, or machine setup characterized as stiff and immoveable. A mill's rigidity is provided by its base.

Cutting Speed

The rate at which a single cutting edge of a cutting tool rotates in one minute. Cutting speed is measured in surface feet per minute (sfm) or meters per minute (m/min).

Tool Wear

The rate at which the cutting edge of a tool degrades during machining. Tool wear may result from improper speed and feed rates.

Feed

The rate at which the cutting tool and the workpiece move in relation to one another. On the mill, feed often describes a linear movement of the cutting tool into the workpiece to remove material.

Spindle Speed

The rate at which the machine spindle rotates. Spindle speed is typically measured in revolutions per minute.

Machinability

The relative ease with which a machining process, such as milling or turning, can remove workpiece material. Machinability depends on the properties of the workpiece material.

Backlash

The relative movement of interlocked mechanical components due to slack, or extra space, between them. Backlash often occurs when motion is reversed.

Numerical Display Panel

The screen that displays information about a machine for the operator. Numerical display panels indicate the position of the workpiece on a manual milling machine.

Part Zero

The starting point of X, Y, and Z coordinates for a specific workpiece. Part zero acts as a reference point for all part dimensions.

Chip Load Per Tooth

The thickness of a chip, or amount of material, that is removed by one cutting edge of the tool. Chip load per tooth is also known as feed per tooth.

Feed Per Tooth

The thickness of a chip, or amount of material, that is removed by one cutting edge of the tool. Feed per tooth is also known as chip load per tooth.

Depth Of Cut

The thickness of material removed by one pass of the cutting tool. Depth of cut measures how far the cutting tool penetrates the surface of the workpiece during a cut.

Milling

The use of a rotating multi-point cutting tool to remove material from a workpiece. Milling includes a wide range of versatile metal cutting operations.

Column

The vertical support, or backbone, of a milling machine. The column is supported by the machine base.

Locate

To establish a designated location. Locating part zero sets a starting point on the workpiece for a manual milling operation.

Lubricates

To use a fluid to reduce the friction between components. Lubricating a cutting tool typically reduces resistance, heat, and wear.

Parallel

Two lines or axes that are equidistant from each other at all points along their length, and thus never intersect. On a horizontal mill, the spindle is parallel to the worktable.

Helical

Winding in the shape of a spiral or coil. Helical flutes appear on drills and end mills.

Adjusting Screw

a screw that gradually moves a machine component with each turn. The adjusting screw on the manual mill head allows the operator to align the head in the X axis.

Flood Cooling

coolant-delivery method that completely covers the workpiece and the cutting tool with cutting fluid. Flood cooling is the least commonly used fluid delivery system for manual milling.

Meters Per Minute

m/min. A metric system measurement of speed describing the distance in meters that the cutting edge travels in one minute. Meters per minute is dependent on both spindle rpm and cutting tool diameter.

Revolutions Per Minute

rpm. A measurement of speed that indicates how many times the spindle has rotated in one minute. Revolutions per minute is measured from the center of tool or spindle rotation.

Surface Feet Per Minute

sfm. An English system measurement of speed describing the distance in feet that the cutting edge travels in one minute. Surface feet per minute is dependent upon both spindle rpm and the cutting tool diameter.