In the precision grinding process for taps—particularly cutting taps—the selection of the grinding wheel dressing tool directly determines thread accuracy, groove quality, and production efficiency. Currently, the industry predominantly uses two types of diamond rollers: multi-tooth form-grinding diamond rollers ( 4 Tooth or 5 Gear dressing involves both rough and finish grinding, as well as the use of a single-arc diamond dresser for trajectory correction. These two approaches differ fundamentally in terms of their structure, dressing motion mechanisms, and application scenarios. This article provides a detailed analysis of each.

1. Multi-tooth Forming Diamond Roller

 1.  Structural Features

The working surface of such rollers is equipped with 4 one or 5 Each precision-formed tooth corresponds to a complete thread profile of the tap. The key design feature lies in the tooth grouping function:

-  Rough grinding teeth: Located on one side of the roller, with a slightly higher tooth height or a slight excess in profile, they are used to rapidly remove the surface layer of the grinding wheel and achieve preliminary shaping.

-  Fine-grinding teeth: Located on the opposite side of the roller, with a final contour dimension, they are used to finish the grinding wheel tooth profile, ensuring accuracy and surface finish.

-  Tooth count distribution: Commonly is 2 Coarse 2 Exquisite ( 4 tooth) or 3 Coarse 2 Exquisite ( 5 teeth), and they are also symmetrically distributed.

The grinding wheel does not complete dressing in a single radial pass; rather, it relies on the grinding machine. X The lateral movement of the spindle causes different teeth to engage in dressing sequentially.

2. Principle of trimming work ( X Step-by-step adjustment of axis motion)

The dressing process is carried out on a CNC thread grinder or a tool grinder, with the following typical steps:

1.  Positioning: The roller is mounted on the dressing spindle, and the grinding wheel rotates at high speed.

2.  Rough grinding stage: X The traverse (cross-feed) axis drives the roller to move axially along the grinding wheel, initially bringing the rough-ground teeth into contact with the wheel. The profile of the rough-ground teeth is slightly larger than the final tooth form, allowing for a substantial material removal rate to quickly establish the basic tooth geometry of the grinding wheel.

3.  Fine grinding stage: X The spindle continues to move, bringing the finish-grinding cutter into the dressing zone. The profile of the finish-grinding cutter is the precise final tooth form, enabling fine dressing of the grinding wheel with a small cutting depth and ensuring the ultimate accuracy of the tooth tip fillet, root fillet, and flank angle.

4.  Surface dressing: Perform fine grinding of the grinding wheel with no feed or only a very small feed, rotating the wheel several times to improve the surface quality.

Key point: Throughout the entire process, the radial feed of the roller is very small, and the primary mechanism is through X The lateral movement of the shaft enables sequential engagement between the rough-cut and finish-cut teeth. This design significantly reduces the load on each individual roller tooth, thereby extending roller life while achieving higher gear profile accuracy.

3.  Core Advantages

-  Coarse and fine finishing for high gear profile accuracy: coarse teeth for rapid shaping, fine teeth to ensure the final dimensions, with a tooth tip-to-root circularity error of ≤± 0.003mm。

-  Long roller life: coarse and fine teeth are分工, ensuring even wear; individual rollers can be resharpened. 2 Ten thousand～ 5 Ten thousand times.

-  High trimming efficiency: X The spindle moves at high speed, and a single complete dressing (rough + Fine) Only need 20 ~ 40 Seconds.

-  Suitable for high-volume standard taps: when the thread form is fixed, efficiency and consistency are excellent.

4.  Application Scenarios

-  Grinding wheel dressing for standard straight-flute taps and spiral-point taps.

-  High-speed steel tap thread grinding for mass production.

-  A production line that requires precise and consistent top-diameter rounding and root fillet radii.

1.1 Single-Arc Diamond Roller (for Trajectory Dressing)

1.  Structural Features

The working surface of a single-arc roller consists of only one precision arcuate convex surface (arc radius R0.05 ~ R5mm ), it lacks a multi-tooth structure. It cannot be formed by simple plunge cutting; instead, multi-axis coordinated trajectory motion is required to complete the dressing process.

2.1  Principle of Trajectory Correction

Installed in a facility that has X 、 Z 、 B (or C On the CNC dressing unit with multi-axis linkage, the roller moves relative to the grinding wheel along a predetermined spatial trajectory. During this motion, the roller’s single circular arc “sweeps” out the required complex curved surface—primarily the flutes of a tap.

- X Spindle: radial feed, controlling groove depth.

- Z Spindle: Axial movement, moving along the width of the grinding wheel.

- B Axis (rotation axis): Controls the roller’s orientation to accommodate the helix angle.

-  Through CNC interpolation, the center of the roller arc is made to follow a curve that is conjugate to the helical thread of the tap, thereby generating a helical groove profile on the grinding wheel.

3.1  Core Advantages

-  Exceptional flexibility: The same grinding wheel can be dressed to achieve varying helix angles, groove depths, and groove geometries by simply changing the CNC program.

-  Ideal for small-batch, multi-variety production: no need to change rollers when switching products—simply update the program. The best choice for non-standard and custom taps.

-  High arc accuracy: The manufacturing accuracy of a single-arc roller can reach ± 0.002mm , The fillet at the bottom of the groove exhibits excellent consistency.

-  Adjustable helix angle / Tapered taps: Achieve complex curved surfaces through trajectory control—something forming rollers cannot accomplish.

4.1  Application Scenarios

-  Truing of tap-flute grinding wheels: truing of straight-flute, helical-flute, and even variable-helix-angle flute wheels.

-  Truing of tap-back grinding wheels: back rake angle and relief for complex curved surfaces.

-  Production line for small-batch, multi-variety, non-standard taps.

1.3 Comparative Summary of the Two Types of Rollers

The following compares the two types of rollers across seven dimensions:

( 1 ) Main Uses

-  Multi-tooth forming roller: dressing the grinding wheel for tap threads.

-  Single-arc roller: used for dressing tap flutes and back-grinding wheels.

( 2 ) Roller structure

-  Multi-tooth forming rollers: feature multiple forming teeth, divided into rough-grinding teeth and finish-grinding teeth.

-  Single-arc roller: a single arcuate surface.

( 3 ) Correction exercise

-  Multi-tooth forming roller: X The shaft undergoes lateral motion, with the coarse teeth engaging first, followed by the fine teeth.

-  Single-arc roller: multi-axis coordinated trajectory ( X+Z+B ), arc sweep.

( 4 ) Adjustment time

-  Multi-tooth forming roller: faster, 20 ~ 40 seconds / Time.

-  Single-arc roller: slower, 1 ~ 3 minute / The number of times depends on the length of the trajectory.

( 5 ) Accuracy characteristics

-  Multi-tooth forming rollers: complete tooth profile with high precision and excellent consistency.

-  Single-arc roller: high local accuracy of the arc, with the overall surface profile controlled by the trajectory.

( 6 ) Flexibility / Changeover cost

-  Multi-tooth forming rollers: low flexibility; tooling change requires replacing or dressing the rollers.

-  Single-arc roller: highly flexible; tooling change requires only updating the CNC program.

( 7 ) Applicable batch and lifespan

-  Multi-tooth forming roller: for high-volume production of single-variety standard taps; service life 2 Ten thousand～ 5 Ten thousand adjustments.

-  Single-arc roller: small to medium batch production, diverse product range, non-standard taps; service life 1 Ten thousand～ 3 Ten thousand adjustments.

1.4 Selection Recommendations

Select a multi-tooth forming roller ( 4/5 Tooth, coarse + Scene of refinement:

-  Mass production of standard-specification cutting taps (such as M3 ~ M20 ).

-  The thread profile remains unchanged over the long term, ensuring maximum efficiency and consistency.

-  The grinding machine is equipped with X Precise lateral axis movement and step-by-step dressing functionality.

-  The dimensions and geometry of the addendum circle and root fillets must be strictly controlled.

Scenario for selecting a single-arc trajectory for roller dressing:

-  Manufacturing helical-groove taps with frequently varying helix angles and flute geometries.

-  Small-batch, multi-variety (non-standard, custom taps).

-  The groove grinding wheel or back-chamfering wheel requires dressing, as the workpiece surface is a complex curved surface.

-  The grinding machine is equipped with CNC multi-axis simultaneous trajectory correction capability ( X+Z+B (Three axes or more).

Recommended combination:

In a specialized tap production line, two types of rollers are used in combination:

-  Thread grinding: employs a multi-tooth form roller ( 4/5 Tooth, coarse + precision), through X Axial motion for rapid, high-precision dressing of thread grinding wheels.

-  Groove grinding: Utilizes a single-arc roller for trajectory correction, enabling flexible machining of various groove profiles, including straight grooves and helical grooves.

-  Back-face grinding: A small single-radius roller or a dedicated form roller may be used.

1.5 Conclusion

Accurately understanding the distinction between multi-tooth form-grinding diamond rollers and single-arc trajectory dressing rollers is crucial for optimizing tap-grinding processes and enhancing production-line efficiency and flexibility.

We specialize in custom electroplating and Chemical Vapor Deposition Diamond roller, comprising:

- 4 tooth /5 High-tooth gear-forming roller.

-  Single-arc trajectory dressing roller.

We welcome the submission of tap drawings and grinding machine parameters, and we will provide you with the optimal roller solution and recommendations for dressing parameters.

E-mail:

saisudiamond@gmail.com

Tel: 
+8617339586706

Address: 

No.921, 300 Meters West Of The Intersection Of Xiangjiang West Road And Chuangye Road, Yuanhui District, Luohe City, Henan Province, China