Diamond Dressing GearDesign, Selection and Troubleshooting
A diamond dressing gear is a tool with diamond abrasive grains electroplated onto a gear-shaped steel body, used to form and dress the internal-gear-shaped wheel for gear honing. It has the same shape as the gear being ground, and that shape is transferred directly to the gear through the wheel, so profile accuracy in the μm range is required. At the end of its life the grains are stripped off and the gear is re-plated, so it can be used repeatedly.
✎How to Design and Select
Open a heading to see its contents. When printed, everything is shown open.
How it works and how to use it
5
- A gear-shaped tool with diamond abrasive grains electroplated on the tooth flanks, used to form and dress the wheel that grinds gears. It has the same shape as the gear being ground[1]One source / reference
- A grinding method in which the shape of the dressing gear is transferred to the wheel and the wheel then finishes the tooth flanks of the gear. Cycle times are short, so it suits mass-produced gears[1]One source / reference
- Gear honing generally grinds the gear with an internal-gear-shaped wheel. The dressing gear forms the tooth flanks of the wheel, and the dressing ring forms the wheel's minor diameter. The dressing gear is mounted in the same position as the gear to be ground and dresses the wheel in a short time[1]One source / reference
- The accuracy of the dressing gear is transferred directly to the gear through the wheel, so profile accuracy in the μm range is required[1]One source / reference
- Structure: diamond abrasive grains are bonded (electroplated) by plating onto the surface of a gear-shaped steel body, and the tooth flanks are then trued (profile ground) with a diamond wheel to finish[1]One source / reference
Handling bias profiles
2
- In automotive drivetrain gears, bias profiles, in which the profile changes continuously along the helix (lead) direction, are often used to improve tooth contact in mesh. A bias profile is obtained by the eccentricity of the pitch block used for the generating motion during profile grinding[1]One source / reference
- This grinding method uses a large-diameter wheel, but it is hard to make a large-diameter wheel accurately, so a dressing gear of good accuracy cannot be obtained. Mitsubishi Materials developed a 3-axis CNC gear grinder that uses a small-diameter wheel and achieved high-accuracy bias profile truing[1]One source / reference
Electroplating and choosing abrasive grains
4
- Because the grains are electroplated in contact with the body, variation in grain size makes the cutting edge height uneven, and some grains float up without being fixed to the body. Mitsubishi Materials uses a precision electroplating method that presses precisely graded grains tightly against the body[1]One source / reference
- Grain lineup: #80, #100, #120, #170. Grain size ratio 2 / 1.7 / 1.5 / 1, grain surface area ratio 4 / 3 / 2 / 1, average grain diameter 181 / 151 / 126 / 91 μm. Coarser grains hold more strongly[1]One source / reference
- #80 grains are 2 times the diameter and 4 times the surface area of #170, giving higher grain strength and holding force and a life 1.5–2 times that of #120 and #170. Profile accuracy is equivalent to conventional products thanks to precision electroplating and the semi-truing method[1]One source / reference
- Machining examples: for a gear with m3.0, PA17.5°, 28° LH, 20 teeth, face width 40, #80 machined 11,500 parts and #170 machined 6,000. For a gear with m2.25, PA17.5°, 30° RH, 50 teeth, face width 30, #80 machined 21,000 and #120 machined 14,500[1]One source / reference
↻Regrinding and Tool Life Management
- Life varies with the required accuracy of the gear being ground and with machining conditions, but in general one dressing gear can dress 400–500 times and machine 10,000–20,000 gears[1]One source / reference
- At the end of its life, the electroplated grains are removed from the surface and new grains are electroplated so the tool can be reused (re-plating)[1]One source / reference
◎Tool Inspection
- The evenness of grain cutting edge height is checked from the profile data after plating (profile data scatter differs between precision-plated and conventional products). The tooth flank is also checked with SEM photographs[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 |
|---|---|
| Workpiece data (m or DP and pressure angle are required; number of teeth, helix angle RH/LH, tip diameter, root diameter, tooth thickness, tooth thickness before heat treatment (pre-cut), profile shift coefficient, face width, profile control length, mating gear data) and input data for the gear measuring machine | The dressing gear is made the same shape as the gear being ground, so the workpiece data becomes the design values as they are[1] |
| Accuracy (new/old JIS grade of the gear), grain (#80/#100/#120), number of teeth, face width | Accuracy is transferred to the gear through the wheel. Grain size affects life[1] |
| Arbor (whether to be made, shrink-fit type / cap type, shared use for gear and ring) and dressing ring (order number, grain) | The dressing gear is mounted in the same position as the gear being ground, so the mounting method and the small-diameter ring are decided together[1] |
| Wheel design (wheel diameter φ300/φ350/φ400, crossed-axes angle 12°/10°/8°, constant or varying crossed-axes angle, low-helix side / high-helix side) and profile shift design and setup values (number of wheel teeth, crossed-axes angle, flank center distance and bore center distance, new and end of life) | Because the gear honing wheel and the dressing gear are designed as a pair[1] |
| Dressing gear (workpiece) profile and helix (lead) (true / see separate sheet / shown in drawing) and dressing gear shape (changes to bore shape, overall width, face width, hub width, hub diameter) | Because modifications such as the bias profile are built into the dressing gear[1] |
Printed from Kezuriba (kezuriba.net/en/gears/tools/dressing-gear/)
⚙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).