Chamfering Tools (Fraising Cutters)Design, Selection and Troubleshooting
A chamfering (fraising) cutter is a gear-shaped tool that chamfers the end-face corners of a cut gear in a short time by meshing with it and pressing along the involute. The burr raised on the end-face side by the pressing is removed at the same time by the deburring cutter fitted with it. It is used on reduction gears and the like after gear cutting with a hob or pinion cutter.
✎How to Design and Select
Open a heading to see its contents. When printed, everything is shown open.
How It Works and Construction
5
- A gear-type tool that chamfers the end faces of a cut gear in a short time by pressing along the involute direction[1][2]
- A construction of two gears assembled together; the tooth flanks of each tool press the end faces of the tooth form. The raised material pushed to the end-face side is removed at the same time by deburring cutters set at different positions on both end faces[3]One source / reference
- After machining with a hob or pinion cutter, the corners at both gear ends are rolled (plastic working) to chamfer them, removing the burr from the previous operation and chamfering at the same time[2][4]
- Chamfering by forming (pressing) makes the chamfer on the tooth trace corner with a gear-shaped tool meshing with the workpiece. The material flows mainly toward the gear end face and is cut off with a single-point tool, deburring disk or file disk[4][5]One source / reference
- It is also built into hobbing machines with a chamfering function. Built into shaving machines, skiving machines and hobbing machines, it can run in parallel with or in sequence with the main machining[3][5]
Chamfered Areas (One Side, Both Sides)
2
- There are two types of chamfered area: one that chamfers only one side of the tooth flank, and one that chamfers the end faces of both the left and right flanks. Spur gears are chamfered on both sides; helical gears on one side (the acute-angle side) or both sides[1]One source / reference
- The left and right flanks can be adjusted individually. The chamfer size can be adjusted to suit gears with a modified helix angle (Gleason)[6]One source / reference
Choosing the Chamfer Shape
3
- There are three chamfer shapes: a taper type with different chamfer amounts at the tooth tip and tooth root, a parallel type with the same chamfer amount at the tip and root (tooth flank only), and a parallel type that also chamfers the tooth bottom (tooth flank + tooth bottom)[1]One source / reference
- Other manufacturers' documents also list three types: parallel, comma-shaped, and parallel with chamfering down to the root (Liebherr). Gleason lists comma-shaped, parallel, root chamfering, and acute-angle/obtuse-angle chamfers[7][4]
- The chamfer angle in press (rolling) chamfering is generally 20–30° (outside this range for some applications)[4]One source / reference
Gears with inclined end faces and chamfer size adjustment
3
- The gear end face is normally perpendicular to the axis, but inclined end faces can also be chamfered. Beyond 15°, confirm by calculation[1][7]
- Chamfer size is adjusted by changing the phase between the two blades. With a built-in eccentric pin, the phase can be adjusted with a bolt[1]One source / reference
- Tools are delivered preset and can be used on other workpieces if the gear data and face width are the same and there is no risk of collision with the workpiece shape. For workpieces with a different face width, use a set for each face width or a flexible chamfering disc with a holder (Liebherr)[7]One source / reference
Suitable workpieces and application range
4
- Mainly used for small cylindrical gears up to module 5 mm. Very fast; it can be used even for planetary pinions with cycle times of 10 s or less. In wet machining it has the lowest tool cost per part[5][4]One source / reference
- Also suited to shafted gears with almost no relief below the root diameter[5]One source / reference
- For gears larger than module 5 mm, cutting chamfering methods (chamfering hobs, fly cutters, end mills) are used[4]One source / reference
- Used for end-face chamfering of reduction gears for automobiles and motorcycles[2]One source / reference
Dealing with secondary burrs (bulges on the tooth flank side)
3
- Part of the pressed material also flows toward the tooth flank and forms a secondary burr (bulge). This is not a problem with shaving or threaded-wheel grinding, but if the next process is honing, a better condition is needed to protect tool life[4][5]One source / reference
- Two countermeasures: (1) use a chamfering tool with 180° as the chamfering section and the other 180° as a burnishing section, which presses the secondary burr into the tooth flank. (2) Split hobbing into two passes, with chamfering in between, so the second hobbing pass removes the secondary burr (usually adds 4–5 s)[4]One source / reference
- Secondary burrs on the end-face side are removed with a deburring disc or file disc[6][7]One source / reference
Other chamfering tools
3
- Cutting chamfering tool: designed specifically for each workpiece by simulation, it chamfers by generating motion on the workpiece end face in the same way as a hob. Like an ordinary gear cutter, it can be sharpened and recoated (Nidec)[2]One source / reference
- Chamfering hobs (one per tooth flank, workpiece-specific profile), contour chamfering with fly cutters (standard inserts cover m2.5–8; relief below the root is required), and end mill chamfering are also available (Gleason)[5][4]One source / reference
- Burnishing gear: a tool that removes burrs and nicks from heat-treated gears by being pressed against the gear and rotated, with a modified pressure angle and helix angle. Usually used as a set of three[1]One source / reference
Why chamfering is needed
1
- Sharp corners and remaining burrs become brittle in carburizing and quenching, and chip under load, damaging the transmission. Hardened burrs shorten tool life in later processes such as honing. Burrs are also unacceptable when the end face is used for locating or gripping. It also prevents injury when handling by hand[4][5]One source / reference
⚠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.
The chamfer shape is deformed / the chamfer at the tooth tip side is small / large burrs appear at the outer periphery[3]
Main causes
- Heavy damage at the tool's contact areas with the workpiece (overused)
- Operating conditions that affect tool life have become harsher (smaller shapes, dry machining, etc.)
Fixes
- Strengthen the tool material (current SUJ2 (bearing steel) → SKH51 (HSS, higher hardness))
- SKH51 + harder surface
Secondary burrs (bulges) remain on the tooth flank, shortening honing tool life[4][5]
Main causes
- Material flows toward the tooth flank during press chamfering
Fixes
- Press the secondary burr into the tooth flank with a chamfering tool that has a burnishing section
- Split hobbing into two passes, chamfering in between and removing the secondary burr in the second pass
↻Regrinding and Tool Life Management
- It was once thought to last almost indefinitely, but with the spread of hobbing machines with chamfering functions, smaller shapes, and dry machining, conditions have become harsher and it is now a tool whose life must be managed (damage example: m2.3, pressure angle 17.5°, helix angle 30°, 39 cutter teeth, 150,000 parts machined)[3]One source / reference
- A disc that has reached its wear limit can be turned over and reset in a short time for reuse (Liebherr rolling deburring disc). Coating extends life further[7]One source / reference
- Latest tool designs have greatly extended life, especially in dry machining (Gleason). Some tools can be used dry or wet[5][6]One source / reference
◎Tool Inspection
- Judge overuse by looking at damage at the tool's contact areas with the workpiece and at the chamfer shape on the workpiece (tooth-tip chamfer size, burrs at the outer periphery)[3]One source / reference
- Accuracy is specified by, for example, old JIS grade 4 for gears (order specification)[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 (always required), number of teeth, helix angle (RH/LH) | Because this is a gear-shaped tool that is meshed with the workpiece and presses the burr flat, the workpiece gear data is required[1] |
| Tip diameter, root diameter (root diameter / tooth depth / tool addendum), tooth thickness (after gear cutting: circular tooth thickness / span measurement ZM / dimension over pins; for double-sided chamfering, the tooth thickness at chamfering), profile shift coefficient, face width, profile control length (length of contact / TIF diameter / rotation angle) | Workpiece data items in the order specification[1] |
| Workpiece material and hardness | Item in the order specification. In some cases, dry machining and smaller diameters increase tool damage[1][3] |
| Chamfer shape (parallel / tapered / parallel (root chamfering)) and chamfer location (helical gear, one side (acute-angle face) / helical gear, both sides / spur gear, both sides / as per workpiece drawing) | Items specified by choosing from drawings in the order specification (they correspond to the 3 chamfer shape types and 2 chamfer location types of Mitsubishi Materials)[1] |
| Gear form (open gear / shoulder gear (shoulder outer diameter, clearance), parallel end faces / tapered end faces) | An inclined end face over 15° must be confirmed by calculation. Tool reuse requires that there be no collision with the workpiece shape[1][7] |
| Mating gear data (number of teeth, outside diameter, center distance) | Item in the order specification[1] |
| Number of cutter teeth (specified directly, or left to the maker by giving a nominal size of 175/200/225/250/300 type, or specified by upper and lower limits of center distance and outside diameter) | Item in the order specification. Specify the number of teeth, or leave it to the maker by giving the nominal size, center distance, and outside diameter (upper/lower limit)[1] |
| Cutter material (SKH51, etc.) and accuracy (old JIS grade 4, etc.) | Material changes tool life (example: improving life by moving from SUJ2 to SKH51 with a hardened surface)[1][3] |
| Meshing gear (required / not required) and weight reduction (left to maker / specified) | Item in the order specification[1] |
| Bore and keyway shape (bore diameter φ, key width, R, C) and mounting type (TYPE-1 to 3, other) | Item in the order specification (choose the mounting type from TYPE-1 to 3 in the drawing, or specify another)[1] |
Printed from Kezuriba (kezuriba.net/en/gears/tools/chamfering/)
⚙Other Gear Cutting Tools
📚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).