Variable radius gash

A variable radius gash geometry may be provided on a variety of rotary cutting tools. The rotary cutting tools extend along a longitudinal axis, from a shank towards a cutting face that engages a material to be cut during a plunge or ramp operation, and a plurality of gashes may be provided in the cutting face of the rotary cutting tool. The gashes may each be a full radius gash, and the radius defining each of the gashes may be unique or different from one another and tangent to an axial rake face and clearance face surrounding the gash.

BACKGROUND

High-performance rotary cutting tools, such as end mills, may incorporate various geometrical designs, including symmetrical (or equal) geometry designs and variable (or unequal) geometry designs. Symmetrical, equal geometry designs may resonate at natural frequencies during use, and thus vibrate, known as “chatter” in machining terms and which can cause damage to the tool and unacceptable surface finish to the work piece. To control chatter in such standard, non-variable geometry cutting tools, cutting rates need to be reduced, sometimes significantly, thus hindering productivity.

Thus, modern high-performance rotary cutting tools may incorporate variable or unequal geometry designs. Exemplary variable geometry designs include, but are not limited to, unequal flute indexing, variable helix, variable rake, variable edge treatment, etc., and high-performance cutting tools may include one or more of these variable design features. By disrupting the natural frequencies that occur with equal, symmetrical geometry designs, the variable or unequal geometry designs reduce or eliminate “chatter” which can cause improve tool life and surface finish. However, variable geometry designs may subject the tool to varying chip loads, which may result in irregular wear of the cutting edges of the cutting tool.

SUMMARY

In accordance with the present disclosure, a variable radius gash geometry is provided. The variable radius gash geometry may be utilized in a variety of rotary cutting tools having cutting faces at an axial end of the rotary cutting tool. In some examples, the variable radius gash geometry may include a plurality of gash grinds each associated with an end cutting edge, wherein each of the gash grinds is defined by a unique radius such that the end cutting edges have equal length. In some of these examples, each of the gash grinds may be a full radius gash grind that is tangent to an axial rake face and a clearance face; and in some of these examples, the axial rake face and the clearance face associated with each of the plurality of gash grinds may be formed via the gash grind associated therewith. In some examples, the end cutting edges are each formed via the gash grind associated therewith. In some examples, each of the end cutting edges is associated with a flute, the flutes having an unequal flute indexing arrangement.

Also disclosed herein is a variable radius gash geometry for a rotary cutting tool. In some examples, the variable radius gash geometry may include a plurality of gash grinds each associated with an end cutting edge and each tangent to an axial rake face and a clearance face, wherein each of the gash grinds develops the end cutting edge associated therewith with a length equal to the other end cutting edges. In some of these examples, each of the gash grinds may be defined by a unique radius that is different from the other gash grinds. In some examples, the axial rake face and the clearance face associated with each of the plurality of gash grinds may be formed via the gash grind associated therewith. In some examples, the end cutting edges may each be formed via the gash grind associated therewith. In some examples, each of the end cutting edges is associated with a flute, and the flutes may have an unequal flute indexing arrangement. In some examples, each of the gash grinds defines a full radius providing a gash surface having continuous curvature equal to the full radius.

Also disclosed herein is a rotary cutting tool. In these examples, the rotary cutting tool includes a cylindrical body having a cutting portion that extends longitudinally along an axis of the cylindrical body towards an axial end of the cylindrical body; and a cutting face provided at the axial end, the cutting face having a plurality of end cutting edges that are each developed by a gash grind in the cutting face, wherein each gash grind is defined by a different radius that equalizes length of the end cutting edges.

Also disclosed herein is a method of providing a variable radius gash geometry on a cutting face of a rotary cutting tool. This method may include plunging a plurality of grinding wheels into the cutting face, wherein each grinding wheel has a different radius; and grinding a gash into the cutting face with each of the grinding wheels, wherein each of the gashes is defined by a unique radius that corresponds to the different radius of the grinding wheel associated therewith and that develops an associated end cutting edge such that each of the associated end cutting edges have equal length. In some examples, this method may include forming a full radius gash into the cutting face with each of the grinding wheels, wherein each full radius gash is tangent to an axial rake face and a clearance face associated with the full radius gash. In some examples, the method is a method of radius gash grinding that provides an axial rake face and a clearance face tangent to a radius of a gash interposing the axial rake face and clearance face.

Also disclosed herein is a method of equalizing length of end cutting edges on a cutting face of a rotary cutting tool having variable flute indexing. This method may include plunging a plurality of grinding wheels into the cutting face, wherein each grinding wheel has a different radius; and grinding gash grinds that each have a unique radius corresponding with the different radius of the grinding wheel utilized to form the gash grind, wherein the gash grinds develop the end cutting edges having equal lengths.

DETAILED DESCRIPTION

The present disclosure is related to rotary cutting tools having variable radius geometries and, more particularly, to rotary cutting tools with variable radius gash geometries.

The embodiments described herein provide variable radius gash geometry for rotary cutting tools, such as end mills, that reduce or eliminate uneven wear of the cutting edges.

FIG.1is a side view of an example rotary cutting tool100(hereinafter, the “cutting tool100”) that may be modified to incorporate the principles of the present disclosure. The depicted cutting tool100is just one example cutting tool that can suitably incorporate the principles of the present disclosure. Indeed, many alternative designs and configurations of the cutting tool100may be employed, without departing from the scope of this disclosure. For example, the principles of the present disclosure may be incorporated with various types of rotary cutting tools, such as end mills, drills, countersinks, counter bores, taps and dies, reamers, routers, etc. Thus, while the cutting tool100is illustrated and described as an end mill, it will nevertheless be appreciated that chip breaking features disclosed herein may be incorporated onto other types of rotary cutting tools without departing from the present disclosure. In the illustrated example, the cutting tool100is configured as an end mill having five (5) flutes and may be used to mill a variety of materials including ferrous type work piece materials such as steel, stainless steel, titanium, etc. However, the cutting tool100may be differently configured with more or less flutes, for example, a multi-flute router, used for routing CFRP and plastic type materials. In some examples, the cutting tool100may include seven (7) flutes or any other flute counts. Regardless, embodiments described herein may be utilized with any number of cutting tools, regardless of their flute count. Thus, embodiments described herein are not limited by the flute count of the cutting tool on which it is disposed.

As illustrated, the cutting tool100generally includes a cylindrical body102that extends longitudinally along an axis A1of the cylindrical body102. Here, the cylindrical body102includes a shank portion104and a cutting portion106that generally defines the length of cut of the cutting tool100, and the cutting portion106extends longitudinally along the axis A1to an axial face or axial end108of the cutting tool100. The cutting portion106is illustrated as having a generally cylindrical shaped periphery, but it may be configured with various other geometries without departing from the present disclosure, including but not limited to a frusto-conical shape or ball nose shape.

The cutting portion106includes a plurality of blades110that are separated by a plurality of flutes112. Each of the blades110has a leading face surface114, a trailing face surface116, and at least one radial relief surface118that bridge the leading face surface114and trailing face surface116. As to each of the blades110, a cutting edge (or lateral or side cutting edge)120is formed at the intersection between the leading face surface114and the radial relief surface118. Here, the blades110and flutes112extend along the cutting portion106, helically about the axis A1. The blades110may be oriented at various helix angles that are measured with respect to the axis A1, and in other non-illustrated embodiments, the blades110and the flutes112may even be oriented parallel to the axis A1. During operation, the cutting tool100rotates in a direction R about the axis A1, and chips are removed from the work piece upward through the flutes112and towards the shank portion104.

The radial relief surface118may have various configurations. For example, the radial relief surface118may exhibit a generally cylindrical configuration, a generally planar configuration, a not-concave configuration, a faceted configuration, or an eccentric configuration when evaluated in cross section. Also, the radial relief surface118may include one or more relief surfaces that are oriented at one or more corresponding relief angles. For example, the radial relief surface118may include a primary relief surface disposed contiguous with the cutting edge120extending at a first relief angle relative to a tangential line drawn at the cutting edge120. In other examples, the radial relief surface118may include a secondary relief surface that is disposed on a side of the primary relief surface opposite of the cutting edge120at a second relief angle relative to the previously mentioned tangential line, where the magnitude of the second relief angle is greater than the magnitude of the first relief angle. In even other examples, the radial relief surface118may include additional relief surfaces, such as a tertiary portion disposed on a side of the second relief surface that is opposite of the first relief surface. These relief surfaces may be provided linearly, or may extend arcuately to blend into each other and/or the trailing face surface116.

In some examples, the cutting tool100has at least one end cutting edge extending beyond half a diameter of the cutting tool100, thereby allowing cutting across the entire diameter of the cutting tool. This is referred to as center-cutting end design, andFIG.2illustrates an exemplary center cutting end design200, according to one or more embodiments. Here, the center cutting end design200includes two (2) flutes202that extend to (or beyond) a center204of a cutting diameter D of the tool, to thereby define center cutting edges206extending across the center204. Here, a pair of end cutting edges208that do not extend to (or stop short of) the center204of the cutting diameter D and are thus shorter than the center cutting edges206. The center cutting end design200enables the cutting tool100to do a direct plunge (axially) into a material to cut similar to a drilling operation.FIG.3illustrates a plunge operation of a cutting tool having the center cutting end design200ofFIG.2. This results in a hole in the material from which the cutting tool100may then mill radially. Drill design, however, is more effective than end mill design for entering material axially to make a hole. And, although plunge milling with the cutting tool100having a center-cutting end design (e.g., such as the center cutting end design200ofFIGS.2-3) is an effective operation, it is limited in use due to its aggressiveness, especially in difficult to machine materials.

In other examples, however, the cutting tool100may have a non-center-cutting end design.FIG.4illustrates an exemplary non-center-cutting end design400, according to one or more examples. Here, the non-center cutting end design400includes five (5) flutes402that do not extend to a center404of the tool's cutting diameter D. While the non-center-cutting end design400may inhibit direct axial plunging due to its open design where the flutes402do not extend to or past the center404, the non-center-cutting end design400is effective at aggressively ramping into the material. In particular, the open design of the non-center-cutting end design400provides extra room for material or chip evacuation, thereby making the non-center-cutting end design400effective and/or efficient at ramping into a material.FIG.5illustrates a ramping operation of a cutting tool having the non-center-cutting design ofFIG.4. The non-center-cutting end design400provides flexibility as the cutting tool100having such design may be manufactured from a carbide blank with a central hole that permits the cutting tool100to be utilized with a through the spindle coolant delivery system.

The cutting tool100also includes a gash (or gash relief or gash grind)600formed into the axial end108of the cutting tool100. The configuration of the gash600may determine whether the cutting tool100incorporates a center cutting end design or a non-center cutting end design, and may thus determine the axial feed capabilities of the cutting tool100(i.e., whether it may plunge into the material, and parameters at which it may plunge there-into, or whether it may ramp into the material, and the parameters at which it may ramp there-into). The gash600is more clearly illustrated inFIGS.6-7, which are isometric and detailed side views of the cutting tool100ofFIG.1, respectively. The cutting tool100includes a cutting face602at the axial end108of the cutting tool100that engages and cuts the material when plunging or ramping into the material. The gash600is a notch or clearance that is ground or otherwise arranged on the cutting face602, between an axial rake face604and a clearance face606, so as to provide room for chip evacuation as the cutting tool100is plunging or ramping into the material. As more fully described herein, the axial rake face604and the clearance face606may be formed when grinding the gash600, for example, the axial rake face604and the clearance face606may be formed during radius gash grinding. The gash600is a grind that helps form or develop an end cutting edge608of the cutting tool100that engages material when feeding the cutting tool100into material in an axial direction along the axis A1. Thus, the end design of the cutting tool100may depend on the configuration of the gash600.

Various parameters define the gash600. For example, the gash600may be arranged at a gash angle702(seeFIG.7), which is the relief angle of the gash600. The gash angle702is measured from a gash surface610(i.e., a bottom surface610of the gash600) to a cutting diameter D (i.e., margin to margin) of the cutting face602. As exemplified inFIG.7, to measure the gash angle702, the axial or end cutting edge608is rotated to a centerline of the cutting tool100(i.e., the axis A1), and the gash angle702is measured parallel to the centerline (i.e., axis A1) of the cutting tool100. In addition, the gash600may have a depth parameter and a radius parameter. The gash angle, depth, and radius of the gash600may be designed and closely controlled to balance strength with efficient cutting of the cutting tool100. In some examples where the cutting tool100includes a plurality of gashes600, each of the gashes600may include the same gash angle, the same gash depth parameter, and the same gash radius parameter; however, in some examples, one or more of the gashes600may have one or more parameters different from one or more of the other gashes600.

When forming the gash600in the cutting tool100, the grinding wheel that produces the gash600enters the cutting face602of the cutting tool100, and “walks” laterally to provide the gash600with a width dimension W. Laterally “walking” the grinding tool to form the gash600in this manner imparts a square (or trapezoidal) shaped geometry on the gash600(i.e., a squarish gashing or trapezoidal gashing), as illustrated inFIG.6andFIG.7. Here, the squarish (or trapezoidal) gashing includes a generally flat gash surface610and the axial rake face604and the clearance face606extend therefrom at respective junctions612,614with the gash surface610(seeFIG.7). Also, radiused corners are ground at the junction612between the gash surface610and the axial rake face604and at the junction614between the gash surface610and the clearance face606, and the radius of such radiused corners is equal to the radius of the grinding wheel (or other tool) utilized to grind the gashes600. In some examples, a single conventional grinding wheel is utilized to grind the gashes600(i.e., to form the gash600grinds). However, such squarish (trapezoidal) gashing creates a weak point (or weakness) that is susceptible to breakage or failure, for example, breakage or chipping a corner616at the axial end108of the cutting tool100. Also, gashes600formed in this manner often have equal widths W (i.e., the width W of the gash surface610is the same for each of the gashes600and flute112associated therewith) but, in examples where the cutting tool100has unequal indexing (or variable indexing), the gashes600formed (or ground) in that manner may result in the end cutting edges608having unequal (or different) lengths.

FIGS.8-9are exemplary end views of cutting tools having unequal (or variable) indexing of the blades110and the flutes112, wherein the end cutting edges608produced by the gash600grinds have unequal lengths. In particular,FIG.8illustrates an example of the cutting face602having unequal flute indexing andFIG.9illustrates how grinding (or forming) the gashes600on the cutting face602ofFIG.8that incorporates unequal flute indexing provides the end cutting edges608with unequal lengths. Here, the cutting tool100incorporates unequal flute indexing such that the flutes112are arranged at different index angles a°, b°, c°, d°, e° (FIG.8), and grinding the gashes600into the cutting face602such that the gashes600each have equal widths W results in the end cutting edges608having unequal lengths a, b, c, d, e (FIG.9). Thus, providing the gashes600with uniform dimensions (i.e., uniform dimensioned gashes600) in a cutting tool100having unequal flute indexing may result in the end cutting edges608having varying (or different) lengths. However, this may result in irregular wear to the end cutting edges608, for example, during aggressive ramping operations, in addition to weakening of the corners616as mentioned above.

In other embodiments, the cutting tool100may include a variable radius gash geometry.FIGS.10-16illustrate an exemplary variable radius gash geometry, according to one or more embodiments of the present disclosure. Variable radius gash geometry includes, or is defined by, a plurality of full radius gashes, each of unique size and each tangent to its neighboring axial rake face and clearance face. Thus, variable radius gash geometry is a grind feature that may include grinding each gash to have a unique or different radius to provide a plurality of variable radius gashes, and each such variable radius gash may be ground with a full radius (i.e., a continuous radius from the axial rake face to the clearance face) such that it is tangent to its associated axial rake face and the clearance face. This may be accomplished with a single angle form wheel utilized to cut gashes of different radii. Here, the single angle form wheel, that may vary in size according to the size of the cutting tool100being made or modified, generates the cutting face (axial rake face), the radius in the bottom of the gash, and the clearance face via multi-axis movements of the single angle form wheel controlled, for example, by a computer numerical control (“CNC”) grinding program. Thus, the axial rake face, the radius of the gash, and clearance face may all be formed during the radius gash grinding. However, in other examples, differently sized grinding wheels (i.e., multiple formed wheels) may be utilized to form the gashes of different radii, and in such latter examples, the differently sized grinding wheels may each cut an individual variable radius gash via an individual plunge grind operation. Accordingly, a gash surface of each such variable radius gash includes a continuous curvature extending between its neighboring axial rake face and clearance face. In addition, variable radius gash geometry described herein may be incorporated into cutting tools having center cutting end designs or a non-center cutting end design.

The dimensions of the different gash radii utilized in the variable radius gash geometry may depend on dimensions of the cutting tool, the flute indexing, and/or the desired length of the resulting end cutting edges. For example, the size of the variable radius gash may be dependent on the flute count and diameter of the particular cutting tool into which the variable radius gash geometry is to be incorporated. In some examples, the variable radius gashes each have the same depth into the cutting face as measured along the longitudinal axis, but in other examples, one or more of them may have a different depth. Also, each of the full radius gashes may have the same gash angle, or one or more of the full radius gashes may have a gash angle that is different from the gash angles of one or more of the other full radius gashes. The gash angle of one or more of the full radius gash grinds may be selected from a range of gash angles, positive or negative, and in some examples the gash angle of one or more of the full radius gash grinds is selected based on the material to be machined. In addition, the gash angle of the various radius gash grind may vary from flute to flute such that, for example, the various radius gash grind in a first flute may oriented a positive gash angle and the gash angle of the various radius gash grind in a second flute may be oriented at a different positive gash angle or at a negative gash angle, etc. In some examples, variable radius gash geometry utilizes full radius gashes oriented at the same or different gash angles. This will allow the cutting tools incorporating variable radius gash geometry to include variable axial rake, similar to how the variable radial rake is provided in the Z-CARB-AP series tools provided by KYOCERA SGS Precision Tools. The diameters of the variable radius gashes depend on the diameter and flute count of each tool and may thus include any number of dimensions depending on those parameters.

By grinding a plurality of full radius gashes, each of unique size and tangent to the neighboring axial rake and clearance faces, the lengths of the end cutting edge will be the same. Thus, variable radius gash geometry may be incorporated into cutting tools having unequal flute indexing to equalize the lengths of the end cutting edges formed by the gash grind, and thereby improve ramping ability and overall performance. In addition, because the gashes of the variable radius gash geometry have a full radius (rather than “walking” the grinding wheel to form squarish or trapezoidal gashing), the corners of the cutting tool are significantly strengthened. Indeed, load testing has shown that the variable radius gash geometry may increase the strength of the corners up to three (3) times compared to conventional gash geometry. The increased strength provided by the variable radius gash geometry also stabilizes the cutting tool during heavy milling, which promotes tool life.

The variable radius gash geometry may be provided on various types of rotary cutting tools, such as the cutting tool100described with reference toFIGS.1-9. Thus, the variable radius gash geometry described herein may be incorporated into end mills, drills, countersinks, counter bores, taps and dies, reamers, routers, etc. However, while the variable radius gash geometry is described and illustrated with reference to an end mill, it will nevertheless be appreciated that the variable radius gash geometry disclosed herein may be incorporated onto other types of rotary cutting tools without departing from the present disclosure. In addition, the variable radius gash geometry may be incorporated into cutting tools with unequal flute indexing as mentioned above, but may also be incorporated into cutting tools having other types of flute indexing.

FIG.10is an isometric view of a cutting tool1000incorporating a variable radius gash geometry1002, according to one or more embodiments of the present disclosure. As illustrated, the variable radius gash geometry1002includes a plurality of gashes1004arranged at an axial end1006of the cutting tool1000. A plurality of end cutting edges1008are formed at the axial end1006, with each of the end cutting edges1008corresponding with one of the gashes1004. Also, each gash1004includes a gash surface1016, with an axial rake face1010extending from the end cutting edge1008into a first side of the gash surface1016and a clearance face1012extending from an opposite second side of the gash surface1016, away from the axial rake face1010and towards a neighboring end cutting edge1008. Here, the gash surface1016includes a continuous curvature of constant radius, with the gash surfaces1016of the different gashes1004having unique or different radii. However, one or more of the gash surfaces1016may have a flat portion. Thus, grinding each of the gashes1004into a cutting face at the axial end1006of the cutting tool1000develops a corresponding one of the plurality of end cutting edges1008, as well as the gash surfaces1016and the corresponding axial rake face1010and the corresponding clearance face1012of the gash1004.

FIG.11is detailed side view of the variable radius gash geometry1002ofFIG.10. As illustrated, the gashes1004each include (or, are each defined by) a radius R. In particular, each of the gashes1004is a full radius gash, defined by its radius R, such that the gash1004is tangent to the axial rake face1010and the clearance face1012associated therewith. Grinding the gash1004as a full radius gash adds strength to a corner1014of the cutting tool1000. Also, the radius R for each of the gashes1004is unique or different from the radii of the other gashes1004, thereby providing the cutting tool100with the variable radius gash geometry1002and equalizing the lengths of the end cutting edges1008formed when grinding the gashes1004. In the illustrated examples, the gash surface1016is ground with radius R that is tangent to the axial rake face1010and the clearance face1012surrounding the gash surface1016.

FIGS.12-13illustrate how providing the gashes1004, each with a unique size or radius and tangent to its corresponding axial rake and clearance faces, equalizes the lengths of the end cutting edges1008.FIGS.12and13are end views of the cutting tool1000ofFIGS.10and11configured with unequal indexing, and illustrate how the variable radius gash geometry1002equalizes the lengths of the end cutting edges1008formed by the gash1004grinds. In particular,FIG.12illustrates an example of the cutting tool1000having unequal flute indexing andFIG.13illustrates how grinding (or forming) grinding the variable radius gash geometry1002forms the end cutting edges1008with equal lengths a′, b′, c′, d′, e′. Here, the cutting tool1000incorporates unequal flute indexing such that the flutes are arranged at different index angles a°, b°, c°, d°, e° (FIG.12), and grinding the gashes1004, each with a unique and full radius R that is tangent to the axial rake face1010and the clearance face1012, results in the end cutting edges1008having equal lengths a′, b′, c′, d′, e′ (i.e., a′=b′=c′=d′=e′).

FIGS.14-15are various perspective views of the cutting tool1000having the variable radius gash geometry1002ofFIGS.10-11, whereasFIG.16is a top view thereof. As illustrated, the gashes1004are each a full radius R, tangent to the axial rake face1010and the clearance face1012, and the full radius R of each of the gashes1004is unique (or different) from the other gashes1004. This results in the end cutting edges1008having equal lengths, which adds strength and durability to the corners1014.

Also disclosed herein are various methods associated with the variable radius gash geometry. For example, this disclosure includes methods for forming a variable radius gash geometry, methods for manufacturing a rotary cutting tool having a variable radius gash geometry on a cutting face of the rotary cutting tool, methods for equalizing end cutting edges of a rotary cutting tool having variable flute indexing, etc. Such methods generally include generating a variable radius form for each of the variable radius gashes via use of a single form grinding wheel. Here, for example, the single form grinding wheel may be plunged into a cutting face (to form one variable radius gash at a time) and then walked along a radius tool path (corresponding with the unique radius of the particular gash being ground) to grind the radius form of each variable radius gash. For example, a CNC grinding program may control the single form grinding wheel to cut with multi-axis movements the cutting face (axial rake face), the radius in the bottom of the gash, and the clearance face. Thus, the axial rake face, the radius of the gash, and clearance face may all be formed during the radius gash grinding However, such methods may instead generally include plunging a plurality of grinding wheels into a cutting face of a rotary cutting tool, one at a time or two or in groups of two or more at the same time, where each grinding wheel has a unique or different radius to form gash grinds having corresponding unique or different radii and to develop end cutting edges having the same length (i.e., to equalize length of the end cutting edges).

In one example, a method includes a step of providing a rotary cutting tool having a cylindrical body that extends along a longitudinal axis towards an axial end, wherein the rotary cutting tool further includes a cutting face at the axial end. This method may also include a step of providing a single form grinding wheel (or other cutting tool). This method may also include a step of plunging the grinding wheel into the cutting face, axially along the longitudinal axis, and then walking the grinding wheel along a first radius path, so as to form a first gash grind having a first unique (or different) radius that is tangent to the axial rake face and the clearance face associated therewith. This method then includes a step of plunging the grinding wheel into the cutting face, axially along the longitudinal axis, and then walking the grinding wheel along a second radius path, so as to form a second gash grind having a second unique (or different) radius that is tangent to the axial rake face and the clearance face associated therewith. It will be appreciated that this step of forming the unique gash grinds may be repeated “n” number of times, where the number “n” corresponds with the number of flutes present on the cutting tool. Thus, for a tool having seven (7) flutes, this method may then include a step of plunging the grinding wheel into the cutting face as described above, so as to form a third gash grind having a third unique radius, a fourth gash grind having a fourth unique radius, a fifth gash grind having a fifth unique radius, a sixth gash grind having a sixth unique radius, and a seventh gash grind having a seventh unique radius. Accordingly, this method may be utilized with rotary cutting tools having any number of flutes. By plunging the grinding wheel into the cutting face when forming each uniquely dimensioned gash grind, the grinding wheel enters the cutting face so as to form or develop a gash grind having a radius that is tangent to the axial rake face and the clearance face, and wherein the grinding wheel follows a unique radius tool path when forming each gash such that the radii of the gash grinds are different from each other (i.e., unique). This method may also include a step of removing or withdrawing each of the plurality of grinding wheels from the cutting face, one at a time or simultaneously.

In this method, the step of plunging the grinding wheel into the cutting face may include forming either the axial face or the clearance face of the gash, and then continuing along the radius tool path to form the gash surface tangent to the previously formed axial face or the clearance face, and then forming the other of the clearance face or axial face of the gash tangent to the unique radius of the radius tool path. Thus, when forming the axial face and the clearance face, the grinding tool may follow a linear tool path either when plunging into the cutting face or when being retracted therefrom. Thus, the method may include forming the gash surface of the gash, together with forming the axial rake race and clearance thereof that are tangent to a radius defining the gash surface.

In another example, a method includes a step of providing a rotary cutting tool having a cylindrical body that extends along a longitudinal axis towards an axial end, wherein the rotary cutting tool further includes a cutting face at the axial end. This method may also include a step of providing a plurality of grinding wheels (or other cutting tools) that each have a unique or different radius. This method may also include a step of plunging each of the plurality of grinding wheels into the cutting face, axially along the longitudinal axis, so as to form a plurality of gash grinds that each have a unique (or different) radius that is tangent to the axial rake face and the clearance face. By plunging the grinding wheels into the cutting face, each grinding wheel enters the cutting face so as to form or develop a gash grind having a radius that is tangent to the axial rake face and the clearance face, wherein the radii of the gash grinds are different from each other (i.e., unique). The grinding wheels may be plunged into the cutting face one at a time, or two or more of the grinding wheels may be plunged into the cutting face simultaneously. This method may also include a step of removing or withdrawing each of the plurality of grinding wheels from the cutting face, one at a time or simultaneously.

The use of directional terms such as above, below, upper, lower, upward, downward, left, right, and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the upward or upper direction being toward the top of the corresponding figure and the downward or lower direction being toward the bottom of the corresponding figure.