Originators and Designers of Specialty Reamers and Cutting Tools Since 1918

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Nomenclature of Reamers

Technical Support

 

I.          Definition

Reamer - A rotary cutting tool with one or more cutting elements, used for enlarging to size and contour a previously formed hole. Its principal support during the cutting action is obtained from the workpiece

II.         General Classifications

A - Classification Based on Construction

1.         Solid Reamers - Those made of one piece of tool material

2.         Tipped Solid Reamers - Those which have a body of one material with cutting edges of another material brazed or otherwise bonded in place

3.         Inserted Blade Reamers - Those which have replaceable mechanically retained blades. These blades may be solid or tipped and are usually adjustable

4.         Expansion Reamers - Those whose size may be increased by deflecting or bending segments of the reamer body

5.         Adjustable Reamers - Those whose size may changed by sliding, or otherwise moving, the blades toward or away from the reamer axis

B - Classification Based on Method of Holding, or Driving

III.       Explanation of the “Hand” of Reamers

*The terms “right hand” and “left hand” are used to describe both direction of rotation and direction or flute helix or reamers.

A - Hand of Rotation (or Hand of Cut)

1.         Right Hand Rotation (or Right Hand Cut) - the counterclockwise rotation of a reamer revolving so as to make a cut when viewed from the cutting end

2.         Left Hand Rotation (or Left Hand Cut) - the clockwise rotation of a reamer revolving so as to make a cut when viewed from the cutting end

*Special case - pull reamers are considered to be right hand cut if, when viewed from the cutting end, they must be rotated in a clockwise direction to cut

B - Hand of Flute Helix

*Reamers with their cutting edges in planes parallel to the reamer axes are described as having “Straight Flutes”

* Reamers with every other flute of opposite (right and left hand) helix are called “Alternate Helix Reamers”

*Reamers with flute helix in one direction only are described as having right hand or left hand helix

1.         A reamer has a Right Hand helix when the flutes twist away from the observer in a clockwise direction when viewed from either end of the reamer

2.         A reamer has a Left Hand helix when the flutes twist away from the observer in a

counterclockwise direction when viewed from either end of the reamer

IV.        Nomenclature of Reamer Elements and Other Terms Relating to Reaming

Actual Size - The actual measured diameter of a reamer, usually slightly larger than the nominal size to allow for wear

Alternate - Reamer features which differ from each other in turn in a regular sequence such as cutting edges, chip breakers, chamfers, or flutes

Angle of Taper - The included angle of taper on a taper tool or taper shank

Angular Flute - See Flutes

Arbor Hole - The central mounting hole in a Shell Reamer

Axis - The imaginary straight line which forms the longitudinal centerline of a reamer, usually established by rotating the reamer between centers

Back Taper - A slight decrease in diameter, from front to back in the flute length of reamers

Barrel - See preferred term Body

Bell Mouth Hole - A hole which is larger in diameter at the start of the hole than at some distance beyond

Bevel - An unrelieved angular surface of revolution (not to be confused with chamfer) Blade - A tooth or cutting element inserted in a reamer body; it may be adjustable and/or replaceable

Blending Radius - A relieved radius joining the chamfer and the periphery

Body-

1)        The fluted full diameter portion of a reamer, inclusive of the chamfer, starting taper and bevel

2)        The principal supporting member for a set of reamer blades, usually including the shank Burnishing Reamer - A finishing reamer intended to take a light scraping cut and impart a fine finish

Chambering Reamer - A reamer (usually one of a series) for forming a shell chamber, etc. Chamfer - The angular cutting portion at the entering end of a reamer (see also Secondary Chamfer)

Chamfer Angle - The angle between the axis and the cutting edge of the chamfer measured in an axial plane at the cutting edge

Chamfer Length - The length of the chamfer measured parallel to the axis at the cutting edge

Chamfer Relief Angle - See Relief

Chamfer Relief - See Relief

Chip Breakers - Notches or grooves in the cutting edge of some taper reamers designed to break the continuity of the chips

Chucking Reamer - A type of machine reamer with relatively short straight or helical flutes on which the peripheral lands are relieved. They have a relatively small amount of back taper and have either straight or taper shanks.

Circular Land - See preferred term Margin

Clearance - The space created by the relief behind the cutting edge or margin of a reamer Concentric/Concentricity - See preferred terms Total Indicator Variation and Relative Eccentricity to describe lack of concentricity between two or more reamer elements

Core - The central portion of a reamer below the flutes which joins the lands

Core Diameter - The diameter at a given point along the axis of the largest circle which does not project into the flutes

Core Reamer - A roughening reamer with deep wide flutes to provide ample room for chips in reaming cored holes

Cutter Sweep - The section removed by the milling cutter or grinding wheel in entering or leaving a flute

Cutting Edge - The leading edge of the land in the direction of rotation for cutting

Cutting Face - The leading side of the land in the direction of rotation for cutting on which the chip impinges

Cutting Speed - The peripheral lineal speed resulting from rotation, usually expressed as surface feet per minute (sfm)

Drift - A flat tapered bar for forcing a taper shank out of its socket

Drift Slot - A slot through a socket at the small end of the tapered hole to receive a drift for forcing a taper shank out of the socket

Duplex Lead Reamer - A reamer with one or more flutes having a different lead than the other flutes. This produces a continuous change in flute spacing

Eccentricity (with respect to the reamer axis) - One half the Total Indicator Variation (tiv). See Relative Eccentricity.

End Cutting - A general term describing the extent to which a reamer cuts on the end. Four types are recognized:

1)        End Cutting on the chamfers only

2)        180 degrees End Cutting to the bottom of the flutes (Core Diameter)

3)        180 degrees End Cutting to the center hole or a specified diameter of circle

4)        180 degrees End Cutting to the center of reamer

External Center - The pointed end of a reamer; the included angle varies with manufacturing practice

Feed - The axial advance in inches per revolution of the reamer with respect to the workpiece Flutes - Longitudinal channels formed in the body of the reamer to provide cutting edges, permit passage of chips and allow cutting fluid to reach the cutting edge

Angular Flute - A flute which forms a cutting face lying in a plane intersecting the reamer axis at an angle. It is unlike a helical flute in that it forms a cutting face which lies in a single plane Helical Flute - (sometimes called a “spiral flute”) A flute which is formed in a helical path around the axis of a reamer Spiral Flute - 1) On a taper reamer a flute of constant lead

2) In reference to a straight reamer, see preferred term Helical Flute Straight Flute - A flute which forms a cutting edge lying in an axial plane Fluted Chucking Reamer - See preferred term Chucking Reamer  Flute Length - The length of the flutes not including the cutter sweep

Full Indicator Reading (fir) - See preferred term Total Indicator Variation (tiv)

Gage Line - The axial position on a taper where the diameter is equal to the basic large end diameter of the specified taper

Grinding Recess - A clearance for the edge or corner of a grinding wheel, usually necessary at a change of diameter

Guide - A cylindrical portion following the flutes of a reamer to maintain alignment

Half-Round Reamer - A reamer with a transverse cross-section of approximately half a circle and having one cutting edge

Heel - The trailing edge of the land in direction of rotation for cutting

Helix Angle - The angle which a helical cutting edge at a given point makes with an axial plane through the same point

Hook - See definition under Rake

Internal Center - A 60 degree countersink with clearance at the bottom, in one or both ends of a tool, which establishes the tool axis

Irregular Spacing - A deliberate variation from uniform spacing of the reamer cutting edges

Land - The section of the reamer between adjacent flutes

Land Width - The distance between the leading edge of the land and the heel measured at a right angle to the leading edge

Lead - See preferred term Starting Taper

Lead of Flute - The axial advance of a helical or spiral cutting edge in one turn around the reamer axis

Length - The dimension of any reamer element measured parallel to the reamer axis

Limits - The maximum and minimum values designated for a specific element

Line Reamer - A reamer used to ream two or more separated holes on the same axis Margin - The unrelieved part of the periphery of the land adjacent to the cutting edge Multiple Diameter Reamer - A reamer with two or more cutting diameters

Neck - A section of reduced diameter connecting shank to body, or connecting other portions of the reamer

Nominal Size - The designated basic size of a reamer

Notches - See preferred term Chip Breakers

Oil Grooves - Longitudinal straight or helical grooves in shank, guide, or pilot for lubrication or to carry cutting fluid to the cutting edges

Oil Holes - Holes through which a cutting fluid is fed to the cutting edges of a reamer

Overall Length - The extreme length of the complete reamer from end to end, but not including external centers or expansion screws

Periphery - The outside circumference of a reamer

Pilot - A cylindrical portion preceding the entering end of the reamer body to maintain alignment Pull Reamer - Reamers which are designed to be pulled through long holes (such as gun barrels) while reamer or workpiece is rotated

Radial Rake Angle - See definition under Rake

Radial Runout - The radial variation from a true circle which lies in the diametral plane and is concentric with the reamer axis. See term Total Indicator Variation

Rake - The angular relationship between the cutting face, or a tangent to the cutting face at a given point and a given reference plane or line

Axial Rake - Applies to angular (not helical or spiral) cutting faces. It is the angle between a plane containing the cutting face, or tangent to the cutting face at a given point, and the reamer axis Helical Rake - Applies to helical and spiral cutting faces only, (not angular). It is the angle  between a plane tangent to the cutting face at a given point on the cutting edge, and the reamer axis

Hook - A concave condition of a cutting face. The rake of a hooked cutting face must be determined at a given point

Negative Rake - Describes a cutting face in rotation whose cutting edge lags the surface of the cutting face

Positive Rake - Describes a cutting face in rotation whose cutting edge leads the surface of the cutting face

Radial Rake Angle - The angle in a transverse plane between a straight cutting face and a radial line passing through the cutting edge

Tangential Rake Angle - The angle in a transverse plane between a line tangent to a hooked cutting face at the peripheral cutting edge and a radial line passing through this point of tangency Recess - See preferred term Grinding Recess

Relief - The result of the removal of tool material behind or adjacent to the cutting edge to provide clearance and prevent rubbing (heel dragging)

Axial Relief - The relief measured in the axial direction between a plane perpendicular to the axis and the relieved surface. It can be measured by the amount of indicator drop at a given radius in a given amount of angular rotation

Back-Off - See preferred term Relief

Cam Relief - The relief from the cutting edge to the heel of the land produced by cam action

Chamfer Relief - The axial relief on the chamfer of the reamer

Chamfer Relief Angle - The axial relief angle at the outer corner of the chamfer. It is measured by projection into a plane tangent to the periphery at the outer corner of the chamfer

Eccentric Relief - A convex relieved surface behind the cutting edge

End Relief - See preferred term Axial Relief

Flat Relief - A relieved surface behind the cutting edge which is essentially flat

Primary Relief - The relief immediately behind the cutting edge or margin, properly called Relief Relief Angle - The angle, measured in a transverse plane, between the relieved surface and a plane tangent to the periphery at the cutting edge

Radial Relief - Relief in a radial direction measured in the plane of rotation. It can be measured by the amount of indicator drop at a given radius in a given amount of angular rotation

Secondary Relief - An additional relief behind the primary relief

Relative Eccentricity - The distance between the axis of one portion and the axis of some other portion of a reamer

Rose Reamer - A type of reamer with lands which are not relieved on the periphery. It has a relatively large amount of back taper

Runout - See Radial Runout

Salvage Hole - A central hole in the front end of a reamer of sufficient depth to provide for reconditioning

Secondary Chamfer - A slight relieved chamfer adjacent to and following the initial chamfer on a reamer

Shank - The portion of the reamer by which it is held and driven

Size - See terms Actual Size and Normal Size

Sleeve - A tapered shell designed to fit into a specified socket and to receive a taper shank smaller than the socket

Socket - The tapered hole in a spindle, adaptor or sleeve, designed to receive, hold, and drive a tapered shank

Spiral Flutes - See Flutes

Squared Shank - A cylindrical shank having a driving square on the back end

Staggered Flutes - See preferred term Irregular Spacing

Starting Radius - A relieved radius at the entering end of a reamer in place of a chamfer

Starting Taper - A slight relieved taper on the front end of a reamer

Step Reamer - A multiple diameter reamer with all lands in each step ground to the same diameter

Straight Shank - A cylindrical shank

Straight Flute - see Flutes

Subland Reamer - A type of multiple diameter reamer which has independent sets of lands in the same body section for each diameter

Tang - The flattened end of a taper shank which fits a slot in the socket

Tang Drive - Two opposite parallel driving flats on the extreme end of a straight shank

Taper Per Foot - The difference in diameter between two points 12 inches apart measured along the axis

Taper Shank - A shank made to fit a specified (conical) taper socket Taper Square Shank - A taper shank whose cross section is a square Tongue - See preferred term Tang

Total Indicator Reading (tir) - See preferred term Total Indicator Variation (tiv)

Total Indicator Variation (tiv) - The difference between the maximum and minimum indicator readings obtained during a checking cycle

Undercut - See preferred term Grinding Recess

Web - See preferred term Core Diameter

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