Pinion cutterDesign, Selection and Troubleshooting

A pinion cutter is a gear-shaped tool. Mounted on a gear shaper, it reciprocates up and down in the helix (lead) direction and is given a rotation that meshes correctly with the gear blank, cutting out the tooth form (generating). Its great strength is that it can cut internal gears, stepped gears, and special gears with joined or missing teeth. It cuts on the downstroke and not on the upstroke, so it is less efficient than a hob, which cuts continuously.

Illustration: Pinion cutter — Illustration (not an exact drawing)

✎How to Design and Select

Stroke length = face width + upper and lower overstrokes. The wider the face, the longer the overstroke (5.0 mm for a 50 mm face in the Mitsubishi Materials diagram). For a stepped gear, a 3–5 mm clearance zone before the shoulder is needed so the cutter does not hit it (JTEKT; not needed with skiving). On the return stroke the table is relieved slightly so the tooth flanks are not scratched (back-off 0.2–0.8 mm). This is a schematic; dimension ratios are not to scale.

Open a heading to see its contents. When printed, everything is shown open.

Suitable workpieces and how it cuts

The cutter reciprocates along the helix direction to form a virtual gear, and the gear blank is forced through a relative motion that meshes correctly with it, so the parts of the blank that are in the way of the virtual gear's teeth are cut away. This principle allows gear cutting of (1) internal gears, (2) stepped gears, and (3) special gears with joined or missing teeth.^[1]One source / reference
It repeats a reciprocating motion: cutting on the way down and returning (not cutting) on the way up. Because it cannot cut on the return stroke, it is less efficient than a hob that cuts continuously.^[2][3]
To avoid scratching the tooth flanks on the return stroke, there is a table relief mechanism that moves the cutter and gear blank slightly apart (on large machines, a mechanism that relieves the cutter). The catalog's cutting condition tables call this amount "back-off", 0.2–0.8 mm.^[1]One source / reference
Gear shaper mechanism: a motor turns a crank, an arm swings, and the cutter spindle moves up and down. A guide inside the parent gear at the top of the spindle turns the cutter as it strokes: a straight guide with no twist for spur gears, a helical guide for helical gears. The gear blank rotates at a constant speed ratio through indexing branched off the cutter drive train.^[1]One source / reference
Helical gears normally need a helical guide, but there are also gear shapers that use NC control without a guide (Nidec's ST series).^[2]One source / reference
Gear geometry and tool selection (catalog table): pinion cutters (gear shapers) can be used for external spur, stepped, helical and stepped helical gears and for internal gears. Accuracy and efficiency are rated roughly ○. Use a shaving cutter or similar when finishing is needed.^[1]One source / reference

Choosing the tool shape (disk, bell, shank type)

Disk type: gear cutting of stepped gears and internal gears^[1]One source / reference
Bell type: gear cutting of stepped gears (when the stepped section has a large diameter) and internal gears^[1]One source / reference
Shank type: when the number of cutter teeth cannot be made large because of interference during cutting, etc. (mainly for internal gears). Small-diameter shank types are for small-diameter internal gears.^[1]One source / reference
Shapes include disk, hub (bell), shank and internal-tooth hub types, made of powder-metallurgy HSS (carbide in special cases) (Liebherr)^[4][1]
Part names: rake face, rake angle (δ), top relief angle (θ), side relief angle (ε), outside diameter (φdk), pitch circle diameter (φdo), whole depth (h), bore diameter (φd), mounting face, mounting face diameter (φd1), mounting face thickness (l), width (L), blade width (L1), hub diameter (φd2); shank type: pull screw, shank, neck diameter, neck length, overall length^[1]One source / reference

Module, pressure angle, helix angle (parameters matched to the workpiece)

The cutter's normal module and normal pressure angle must be the same as those of the gear being cut^[1]One source / reference
The cutter's helix angle on the pitch cylinder must be the same as that of the gear being cut^[1]One source / reference

Choosing the number of teeth and pitch circle diameter

For helical gears the number of cutter teeth is set by the lead of the helical guide (formula 1); for internal gears the number of teeth is limited by interference.^[1]One source / reference
Standard cutters have pitch circle diameter Do = m × Z, with the number of teeth chosen so that Do is roughly constant for each nominal size (disk type 50–175, bell type 50–125, shank type 25 and 38). Example: for disk type size 100, m1.00 × 100 teeth = Do 100, m2.00 × 50 teeth = Do 100, m5.00 × 20 teeth = Do 100^[1]One source / reference
Cutters can also be made with a number of teeth, width, bore diameter or shape other than those in the standard dimension table, and cutters with missing teeth or joined teeth can also be made.^[1]One source / reference
Guide to tooth numbers for internal gears (Fig. 9): any combination of Zg (number of teeth of the gear being cut) and Zc (number of cutter teeth) inside the hatched area causes no interference. For PA20° standard teeth with Zg = 50, there is no interference when 22 ≤ Zc ≤ 32. The selection area for small Zg is also shown in the figure.^[1]One source / reference
Use a small-diameter shank type for small-diameter internal gears (standard sizes: size 25 m0.75–2.50 is Z34–10, size 38 m0.75–4.00 is Z51–13)^[1]One source / reference

Choosing and sharing helical guides

When cutting a helical gear, calculate the lead of the helical guide. The lead is set by the cutter's pitch circle diameter (= number of teeth) and helix angle (see the formulas for the equation)^[1][5]
Even for the same helical gear, changing the number of cutter teeth requires changing the lead of the helical guide (example: to cut mn2.5, PA20°, β20° RH, 40T, the lead is 688.905 with a 30T cutter and 1148.175 with a 50T cutter)^[1]One source / reference
Sharing a helical guide produces an error between the helix angle βo' of the cut gear and the reference helix angle βo, so take care.^[1]One source / reference
Conditions for sharing: (1) the required leads are nearly the same (within the permissible helix error), (2) the number of cutter teeth Z is an integer, (3) the helix direction is the same. The helix error must be within the gear tolerance^[5]One source / reference

Interference in internal gears (involute, trimming, trochoid)

Being able to generate internal gears is a major feature of pinion cutters, but interference occurs more readily than with external gears, which restricts the range of internal gears that can be cut and the design of cutters for internal gears^[1][6]
Involute interference: occurs when the difference in tooth numbers between the internal gear and the cutter is large, and the tips of the internal gear teeth are cut away^[1]One source / reference
Trimming interference: occurs mostly when the tooth number difference is small. When the cutter is fed in at the start of cutting, or on the cutter's return stroke during cutting, the cutter tooth tips cut away the tips of the internal gear teeth^[1]One source / reference
Trochoid interference: occurs when the tooth number difference is made even smaller than the trimming limit. After the involute curve has been generated, the cutter tips cut away the internal gear tooth flanks. If no trimming interference occurs, no trochoid interference occurs either^[1]One source / reference
Profile-shifted internal gears are prone to many kinds of interference, including involute, trochoid, trimming and fillet interference, and need thorough study in design and gear cutting (determined by the combination of tooth numbers and shift coefficients of the pinion cutter, internal gear and pinion)^[6]One source / reference

Deciding the clearance and stroke for stepped gears

The stroke length during cutting is the face width plus the upper and lower overstroke lengths. Varying the overstroke length with face width is recommended (Fig. 10: a linear relationship, longer for wider faces; 5.0 mm for a 50 mm face)^[1]One source / reference
Gear shaper cutting needs a 3–5 mm clearance zone before the stepped section (not needed with skiving)^[7]One source / reference
Use a bell type when the stepped section has a large diameter^[1]One source / reference
If the cutter hits the shoulder, or chips jam between the cutter and the shoulder, it causes cutter breakage and abnormal wear^[8]One source / reference
When ordering, state whether it is a shoulder gear, and give the shoulder outside diameter and the clearance^[1]One source / reference

Deciding cutting speed, strokes per minute, circumferential feed and radial feed

Guide by workpiece material (Table 1): carburized material cutting speed 40–80 m/min, S45C and above 30–50 m/min, FCD70 20–40 m/min. Circumferential feed 0.2–3.0 mm/str, radial feed 0.002–0.01 mm/str, back-off 0.2–0.8 mm (same for all three materials)^[1]One source / reference
Cutting speed is determined by the cutting length and the number of strokes. When the cutting width exceeds 25 mm, reduce the cutting speed by about 10%.^[1]One source / reference
High circumferential feed: with a higher feed (4.0/2.0 mm/str) than the conventional condition (circumferential feed 0.5/0.3 mm/str), chips were cut thicker and broken up, the load on the cutting edge was spread out, and both flank wear and crater wear decreased (m2.25, 27T, helix angle 31.5°, face width 15, SCM415, cutter 57T MACB with coating, 800/1200 str/min, radial feed 0.02/0.01 mm/str, cutting time 90 s → 35 s)^[9]One source / reference
With the conventional method, the load concentrates on the corner, and the opposite side wears easily from thin, long chips^[9]One source / reference
When there is no subsequent operation and feed marks are a problem, reduce the finishing feed. When finishing by shaving, feed marks are not a problem (the decision is up to the user).^[9]One source / reference
Conditions in the machining examples are given as rough/finish (some have three stages). Example 1 (MMC, KHAZ): m2.5, PA20°, 40T spur, SCr420H, 700/1,100 str/min, circumferential feed 0.50/0.31 mm/str, radial feed 0.02/0.014 mm/str. Example 2 (MMC, KHAZ + Violet): m2, PA15°, 80T, 20° RH, S45C internal gear, 500 str/min, circumferential feed 1.70 mm/str, radial feed 0.01 mm/str. Example 3 (Nidec, Super Dry): m2, PA20°, 38T spur, SCr420H, cutter 66T, 700/1200/1200 str/min, circumferential feed 2.51/1.26/1.26 mm/str, radial feed 0.01/0.015/0.015 mm/str^[1][2]One source / reference
High-speed gear shapers use a high-speed cutting range of 1000 str/min and above, and powder-metallurgy HSS and coated cutters contribute to longer life in this range and on hard, difficult-to-cut materials.^[1]One source / reference

Choosing cutter material and coating

Material selection table: KMC3 (first-choice conventional melted HSS): standard cutting ○, high-speed cutting ●. KHA (first-choice powder-metallurgy HSS): heavy cutting ○, high-speed cutting ●, hard difficult-to-cut materials ○. KHAZ (high-alloy powder-metallurgy HSS): heavy cutting ◎, high-speed cutting ●, hard difficult-to-cut materials ◎. High-speed cutting is possible by adding a coating layer (the symbol legend is not given in the catalog)^[1]One source / reference
Mitsubishi Materials' KHAZ is for gear shapers capable of high (circumferential) feed cutting. It is a high-alloy powder-metallurgy HSS with improved wear resistance and chipping resistance.^[1]One source / reference
Coatings: TiN has a film hardness of HV1,800–2,000 and an oxidation onset temperature of 600–700°C; Violet has HV2,700–2,900 and 800–900°C. TiN extends life greatly over uncoated tools, especially in high-speed heavy cutting. Violet has a film hardness about 1.5 times that of TiN (tool life ratio of 2 or more)^[1]One source / reference
Nidec's MX-1 is a material that combines the toughness of powder-metallurgy HSS with the wear resistance of melted HSS. Application example: a cutter with outside diameter φ30 and 20T (MX-1 + Super Dry) cutting m1.3, PA30°, 30T carburized steel spur gears produced 1000 pieces up to 0.06 mm wear (850/920 str/min, circumferential feed 1.5/0.50 mm/str, radial feed 0.020/0.012 mm/str)^[10]One source / reference
Applying a dry-cutting coating (Nidec's Super Dry) to the cutting face allows cutting without cutting oil, at more than twice the conventional speed and efficiency (tool life is 2–5 times that of conventional TiN under wet conditions)^[2]One source / reference

Mounting and cutting precautions

Runout when mounting the cutter and the gear being cut affects the closing step (the step left where cutting ends), so keeping it within 5 µm is recommended^[1]One source / reference
Large runout when mounting the cutter makes the cut workpiece discontinuous over one revolution and causes a closing step. The depth of cut varies, so OBD (over-ball dimension) scatters.^[2][1]
Because one pinion cutter tooth cuts one tooth space of the gear, take special care against broken teeth and abnormal wear^[1]One source / reference

÷Formulas

Helical guide lead calculator

Normal module mnNumber of cutter teeth ZHelix angle βo (°)Lead L' of the shared guide (mm, may be left blank)Face width B (mm)

The lead is L = πDo / tan βo = πmnZ / sin βo, from the cutter's pitch circle diameter Do (= mnZ / cos βo). Cutting with a guide of a different lead shifts the helix angle to βo', which produces a helix error of B × (tan βo' − tan βo) over face width B. Whether the guide can be shared is decided by comparing this error with the gear's helix tolerance.

Cutting speed (gear shaper)

Cutting speed (m/min) = (stroke length (mm) × strokes per minute (str/min) × π) ÷ 1000^[1]1 source · reference

Stroke length: Face width + upper and lower overstroke lengths (mm)
Strokes per minute: Number of reciprocations per minute (str/min)

Helical guide lead

L=πDo/tanβo=πmnZ/sinβo^[1][5]

L: Helical guide lead (mm)
Do: Cutter pitch circle diameter (mm)
βo: Helix angle on the pitch circle (°)
mn: Normal module
Z: Number of cutter teeth

Worked Example　Helical gear mn2.5, PA20°, βo20° RH, 40T: lead 688.905 with a 30T cutter and 1148.175 with a 50T cutter (MMC). For m2.0, 30°, 71T (PCD163.967) the lead is 892.2123, and for m2.5, 25°, 48T (PCD132.405) the lead is 892.0370 (Nidec)

Number of cutter teeth determined by the helical guide

Z=L sinβo/(π mn)^[1]1 source · reference

Z: Number of cutter teeth
L: Helical guide lead (mm)
βo: Helix angle on the pitch circle
mn: Normal module

Helix angle and error when sharing a helical guide

βo'=tan⁻¹(πDo/L')=sin⁻¹(πmnZ/L'), error ⊿δ=βo'−βo (MMC). Helix error Δ=B×(tanβ'−tanβ) (Nidec)^[1][5]

βo': Helix angle on the pitch cylinder of the cut gear
L': Lead of the shared helical guide
βo: Reference helix angle on the pitch cylinder
B: Face width under accuracy control (mm)

Worked Example　A cutter with lead 892.0370 (m2.5, 25°, 48T) cut with a guide of lead 892.2123 → helix angle 24.99475°, helix error 3 µm at 24 mm face width → evaluated as shareable

Effect of rake angle error on the profile pressure angle (helical pinion cutter)

⊿α≒sin-1[tanδ{tanγ-tan(γ+⊿γ)} cos 2 α]^[11]1 source · reference

⊿α: Profile pressure angle error
δ: Side relief angle on the pitch circle (normally 2°)
γ: Rake angle (normally 5°)
⊿γ: Rake angle error
α: Cutter pressure angle

Worked Example　Fig. 2: for a rake angle error of −2 to +2°, the pressure angle error is about +4 to −4 minutes (two lines, α = 14.5° and 20°)

⚠Troubleshooting

Open a symptom to see the possible causes and fixes. The causes are not necessarily to be suspected from the top down. They change with the combination of workpiece, machine and tool.

Closing step (a step forms where cutting ends after one workpiece revolution)^[1][2][8]p.36

Main causes

Poor cutter mounting (large runout at mounting)
Poor rotational accuracy of the cutter spindle and the table
Poor mounting of the gear being cut
Poor cutter accuracy (tooth space runout, poor cumulative pitch accuracy)

Fixes

Check cutter and arbor runout (mounting runout of 5 µm or less is recommended)
Inspect the machine
Check the runout of the gear being cut
Check the cutter's tooth space runout and pitch error

Profile error (pressure angle deviation, irregular profile)^{[1][8][2][11]}p.36

Main causes

Poor grinding of the cutter rake face (rake angle error becomes pressure angle error)
Poor cutter tooth profile
Wrong sharpening angle or imbalance between left and right cutting edges (sharpening angle setting, uneven wear)
Poor guide accuracy
Poor rotational accuracy of the cutter spindle and table (master worm mounting error, uneven wear, etc.)
Poor cutter mounting
Poor pre-machining of the gear being cut

Fixes

Check the runout, surface roughness and rake angle of the cutter rake face
Inspect the guide for wear
Inspect the backlash and accuracy of the master worm and wheel, and the accuracy of the change gears
Check cutter and arbor runout
Inspect the bore and face runout of the gear being cut

Poor pitch error and tooth space runout^[1][8]p.36

Main causes

Poor cutter pitch accuracy and tooth space runout accuracy
Poor mounting accuracy of the cutter and workpiece
Poor gear shaper accuracy (spindle and table rotational accuracy)
Poor grinding of the cutter rake face
Poor pre-machining of the gear being cut

Fixes

Check the runout, surface roughness and rake angle of the cutter rake face
Check cutter and arbor runout
Inspect the backlash and accuracy of the master worm and wheel, and the accuracy of the change gears
Inspect the bore and face runout of the gear being cut

Insufficient contact length (effective profile range too short)^[8]

Main causes

Insufficient cutter tooth depth
Excessive cutter tip radius
Poor cutter tip protuberance shape

Fixes

The source lists causes only (no remedies given)

Poor lead (helix)^[8]

Main causes

Poor gear shaper accuracy
Insufficient workpiece rigidity
Poor accuracy or insufficient rigidity of the workholding fixture

Fixes

The source lists causes only (no remedies given)

Poor chamfer (chamfer too large or too small, left and right chamfers differ, step in the chamfer)^[8][11]

Main causes

Wrong cutter chamfer height
Wrong workpiece outside diameter
Wrong gear cutting infeed dimension
Wrong cutter sharpening angle
Shifted grinding position when sharpening a cutter with chamfering
With a helical cutter, the chamfer side was fed in too far and the tooth depth fell short (step in the chamfer)

Fixes

The source lists causes only. When sharpening a cutter with chamfering, a shifted grinding position distorts the chamfer shape, so be careful (Nidec)

Poor tooth flank roughness, tearing^[1][8][2]p.36

Main causes

Poor grinding of the cutter rake face (rough sharpened surface)
Unsuitable cutting conditions or depth of cut
Built-up edge adhesion
Unsuitable or degraded cutting oil
Workpiece shape and insufficient mounting rigidity
Play in the drive system
Uncut tooth root, or over-infeed into the toothed step, of a helical pinion
Sticky (gummy) workpiece material
Relieving interference

Fixes

Check the runout, surface roughness and rake angle of the cutter rake face (a smoother sharpened surface reduces tearing)
Review the cutting conditions
Check the choice of cutting fluid and how it is applied
Review the fixture (rest setting for the gear being cut)
Inspect the machine
In one case, a treatment that reduces cutting face roughness (Nidec's SS treatment) reduced tearing

Short cutter life, abnormal wear^{[1][8][11][9]}p.36

Main causes

Too many strokes (unsuitable cutting conditions such as high cutting speed or high feed)
Insufficient machine rigidity and vibration
Unsuitable cutter design
Cutter base material too soft
Poor PVD treatment
Sharp corners at the tip radius
Insufficient clamping force on the cutter and workpiece
High workpiece hardness
Relieving interference
Cutter hits the shoulder, or chips jam between them
Cutting oil running out
Missing the right time to sharpen (large flank wear promotes welding)

Fixes

Review the cutting conditions
Inspect the machine
Ask the manufacturer to investigate
Sharpen when the wear width on the trailing side reaches 0.2–0.3 mm
In one case, high circumferential feed reduced flank wear and crater wear

Cutter breakage (sudden fracture)^[8][2][1]p.35

Main causes

Poor cutter base material (too hard, brittle)
Unsuitable cutting conditions (high cutting speed, high feed)
Crashing in during rapid traverse
Insufficient clamping force on the cutter and workpiece
High workpiece hardness
Relieving interference
Cutter hits the shoulder, or chips jam between them
Excessive depth of cut when re-sharpening
Grinding burn or cracks from sharpening (these trigger cutting edge breakage)

Fixes

The source lists causes only. Do not produce grinding burn or cracks when sharpening (Nidec)
Because one tooth cuts one tooth space, take special care against broken teeth (MMC)

Profile waviness on gears with few teeth^[2]

Main causes

Gears with few teeth have a low contact ratio and large load fluctuation, so the cutter and workpiece are shaken

Fixes

Reduce the cutting load to suppress profile waviness

Welding to the tooth flank^[11]

Main causes

The side relief angle of a pinion cutter's flank is small, normally about 2°, so welding to the tooth flank readily occurs together with flank wear
Flank wear grows because the right time to sharpen was missed

Fixes

Sharpen when the wear width on the trailing side reaches 0.2–0.3 mm

Feed marks remain^[9]

Main causes

Circumferential feed was raised

Fixes

When there is no subsequent operation and feed marks are a problem, reduce the finishing feed (not a problem when finishing by shaving)

↻Regrinding and Tool Life Management

Sharpening grinds only the rake face. The rake angle is normally 5°^[11][1]
When to sharpen: cutting edge wear is generally greatest on the trailing-side tooth flank, and it is economical to sharpen when the wear width there reaches 0.2–0.3 mm^[11]One source / reference
How to sharpen: for spur cutters, the cutter is tilted by the rake angle on an electromagnetic chuck and rotated, and the rake face (a conical surface) is ground with a grinding wheel. Helical cutters are ground one tooth at a time (MMC Fig. 11). Liebherr also states that spur cutters have a conical rake face and helical cutters a stepped rake face, ground with a cup wheel^[1][4]
Sharpening errors are generally not very large because the method is simple, but eccentricity of the ground conical surface causes cutter runout, and rake angle error causes pressure angle error^[1][11]
Helical pinion cutters are ground tooth by tooth, so accuracy is harder to keep stable than with spur cutters, and it often affects the profile. The sharpening angle is not necessarily perpendicular to the cutter's helix angle^[11]One source / reference
With a chamfering cutter, a shifted grinding position distorts the chamfer shape^[11]One source / reference
The roughness of the sharpened surface is within 3.2 µmRy in JIS, but making it as smooth as possible lengthens life and gives a cut surface with less tearing. A rough sharpened surface shortens tool life, and grinding burn or cracks trigger cutting edge breakage^[1][2]
Tool life evaluation example: the cutting length (m) until flank wear reaches 0.3 mm, converted to one cutter, is used as the tool life evaluation coefficient Lp^[1]One source / reference
When ordering, you can choose whether the rake face is coated^[1]One source / reference

◎Tool Inspection

Specify the cutter accuracy grade from AA, A and B (order specification sheet)^[1]One source / reference
Tool-side items to check when problems occur: tooth space runout, pitch error (cumulative pitch), rake face runout, roughness and rake angle, cutter and arbor runout^[1][8]
Items to check around the profile: cutter profile, rake angle and sharpening angle, tooth depth, tip radius, tip protuberance shape, and chamfer height for chamfering cutters^[8]One source / reference
Evaluate wear by the trailing-side tooth flank (flank wear width) and crater wear depth. The crater shape differs between the leading and trailing sides^[9][11]One source / reference
After mounting, measure the runout of the cutter and the gear being cut and keep it within 5 µm^[1]One source / reference

☑What to Specify When Ordering

These are the items to give the tool maker when requesting a quotation or manufacture. Most of them are determined from the gear data table (the table on the drawing).

Item	Why it is needed / how to decide
Module (or DP), pressure angle	Required item. The cutter's normal module and normal pressure angle must be the same as those of the gear being cut^[1]
Number of teeth (external or internal) and helix angle (RH/LH)	For internal gears, interference limits the usable number of cutter teeth. For helical gears, the helix angle and hand are needed to design the cutter and guide^[1]
Tip diameter, root diameter (root diameter / tooth depth / tool addendum), tooth thickness (circular thickness / span measurement ZM / over-pin dimension)	Items in the workpiece data of the order specification sheet. Give the tooth thickness as circular thickness, span measurement or over-pin (between-pin) dimension, state whether the value is after shaving (SV) or grinding (GR) or after gear cutting, and also give the SV allowance (GR allowance: circular / span / OBD / BBD)^[1]
Profile control length (contact length, TIF diameter, rotation angle), mating gear data (number of teeth, outside diameter, center distance), and root radius	Insufficient cutter tooth depth, excessive tip radius and poor tip protuberance shape cause insufficient contact length^[1][8]
Chamfer amount (radial, circumferential, along the slope, chamfer diameter)	With a chamfering cutter, the chamfer amount changes with the chamfer height, sharpening angle and infeed dimension^[1][8]
Face width and gear form (open gear / shoulder gear (shoulder outside diameter, clearance) / taper gear)	The diameter of the stepped section determines the tool shape (disk or bell) and the stroke and overstroke. Hitting the shoulder or chip jamming causes breakage^[1][8]
Workpiece material and hardness	Needed to select material and cutting conditions (cutting speed differs for carburized material, S45C and above, and FCD70; choose the material for hard, difficult-to-cut materials)^[1]
Cutter shape (disk / bell / shank)	Determined by the stepped section and the size of the internal teeth of the workpiece. For the shank type, also specify overall length, tooth width, neck diameter, taper shape (MT2/MT3/MT4/F type), taper length and pull screw (thread diameter, effective length)^[1]
Number of cutter teeth (specified, or left to the manufacturer by nominal size 50/75/100/125/150/175)	Related to the helical guide lead and interference in internal gears^[1]
Helical guide (left to the manufacturer or specified)	If you use a guide you already have, its lead determines the number of cutter teeth. Sharing a guide causes an error in the helix angle^[1][5]
Accuracy (AA, A, B), coolant (dry / wet oil-based or water-soluble), material, surface treatment, rake face coating	Choose material and coating by cutting mode (standard, heavy cutting, high speed, hard difficult-to-cut material) (MMC material selection table). For dry cutting, a dry-cutting coating (Nidec's Super Dry) is applied to the cutting face so that cutting is done without cutting oil^[1][2]
Overall width, tooth width, bore diameter (31.742/44.45/31.75 etc.), keyway shape	Mounting dimensions. Choose the bore diameter from 31.742, 44.45 or 31.75, or specify another (bore diameter and tolerance). Key: none / JIS bore key / special bore key / end face key (width, depth, R)^[1]
Rake angle (5° or other), sharpening angle	Rake angle error becomes pressure angle error. The sharpening angle of a helical cutter is not necessarily perpendicular to the helix angle^[1][11]
Profile (standard finish, P, PG, S-TOP, PS, PGS, PP, PGP, PSP, PGSP; stop grinding / through grinding) and whether topping is required	Profile modifications (pressure angle correction, crowning, tip/root relief, topping, protuberance, etc.) can be built into the cutter^[1][4]
Special notes (special spacing, unequal tooth thickness)	Cutters with missing teeth, joined teeth, unequal tooth thickness, etc. can also be made, so state clearly how the cutter differs from the standard^[1]

Printed from Kezuriba (kezuriba.net/en/gears/tools/pinion-cutter/)

+Related Topics

Special-profile and non-involute pinion cutters

Pinion cutters that can cut a gear and a cam at the same time, such as for the ratchet gear of an automobile reclining seat, can also be made. Module is mostly m0.5–m1.0. Non-involute profiles are handled on consultation^[1]One source / reference
For non-involute profiles such as circular arc, cycloid and sprocket, there are examples handled with NC profile grinding machines that can grind from tip to root (Nidec)^[2][4]
Some manufacturers can supply standard profiles such as DIN 3972, DIN 5480, DIN 5482 and DIN 8197 from stock with short lead times (Liebherr, 10 working days from semi-finished blanks)^[4]One source / reference

Wafer cutters

A disposable cutter in which a thin coated disk is clamped in a dedicated holder. Wear does not change the profile, and no machine adjustment is needed after replacement. Suited to mass production^[4]One source / reference

How to read cutting efficiency and life

Cutting efficiency coefficient CFp = average chip removal per second (mm³/sec); tool life coefficient Lp = cutting length (m) until flank wear reaches 0.3 mm, converted to one cutter. Changing the material raises Lp, and raising the conditions raises CFp (Fig. 12, for SCr420H)^[1]One source / reference

⚙Other Gear Cutting Tools

Hob Skiving cutter Shaving cutter Broach Diamond Dressing Gear Chamfering Tools (Fraising Cutters)Gear Cutting Tools and Cutting Conditions: Overview Comparison of Gear Cutting Methods Machining Trouble Encyclopedia

📚Sources

Values without a mark agree in two or more sources from different publishers. Grade and coating names are the makers' product names, and no comparison between makers has been made. "p." is the body page of the Mitsubishi Materials catalog (C004J-H).