CGK-82 / CGK-7630 / 7630D / 7640 / 7640D CNC Internal Thread Grinder & Nut Compound Machining Center
Grind Internal Threads and Compound Nut Geometry
The CGK-7630/7630D/7640/7640D series grinds internal thread raceways; the CGK-82 adds end-face and outer-diameter grinding for complete nut machining.
Internal thread raceways in ball screws, ball nuts and automotive steering gears must be ground to precise pitch, lead and surface finish so the rolling elements move smoothly and without backlash. The CGK-7630/7630D/7640/7640D series is a family of CNC internal thread grinders for these applications, with different chuck sizes, center heights and thread-pitch ranges. The CGK-82 nut compound machining center starts from the same internal-thread capability and adds the ability to grind the nut end face and outer diameter in one clamping, making it ideal for complete ball-nut, shaft-sleeve and similar compound workpieces. A purpose-built CNC control provides full closed-loop control, dynamic tool setting and automatic compensation for pitch, taper and wheel wear.
Request a Quote →Key Features & Working Principle
Six capabilities that let one machine family cover internal threads and compound nut geometry.
Internal Thread Raceway Grinding
Grinds ball-screw and ball-nut internal thread raceways, thread gauges, cutting tools, and trapezoidal or triangular internal threads with surface roughness down to Ra 0.32 μm.
Compound Nut Machining (CGK-82)
Besides internal thread grinding, the CGK-82 grinds the nut end face and outer diameter in one clamping, reducing datum shifts and handling time.
Full Closed-Loop CNC Control
A purpose-built CNC system with full closed-loop control and a human-machine dialogue interface manages grinding motion, wheel dressing and compensation.
Dynamic Tool Setting & Compensation
The control provides dynamic tool setting, pitch compensation, pitch-taper compensation, offset-nut automatic compensation and grinding-wheel wear compensation.
High-Speed Wheel Spindle
A high-speed wheel spindle — up to 36000 rpm on the 7630D — removes material efficiently while holding the profile accuracy needed for rolling contact.
Wide Pitch and Thread Range
Metric pitches from 0.5 mm to 60 mm and imperial threads from 3 to 48 TPI cover ball nuts, gauges, tools and general internal threads.
Why Choose the CGK-82 / CGK-7630 / 7640 Series
Against separate thread grinders and lathes, this family wins on internal-thread accuracy, compound geometry and automation.
One Machine Family, Many Applications
Five models span chuck diameters from Φ250 mm to Φ400 mm and pitches from 0.5 mm to 60 mm, so shops choose the size that matches their parts.
Micron-Level Pitch Accuracy
Adjacent pitch error within 0.003–0.005 mm and 100 mm cumulative error within 0.006 mm keep ball-nut and gauge threads within tolerance.
Complete Nut in One Clamping
The CGK-82 grinds internal thread, end face and outer diameter without repositioning, improving concentricity and reducing handling time.
Automated Compensation
Automatic pitch, taper, offset-nut and wheel-wear compensation keep size consistent across production shifts and wheel changes.
Fine Surface Finish
Surface roughness Ra≤0.32 μm gives rolling threads and gauges the smooth surface needed for long life and accurate measurement.
Operator-Friendly Control
A conversational human-machine interface with menu-driven input reduces programming time and training cost compared to general-purpose grinding controls.
CGK-82 / CGK-7630 / 7630D / 7640 / 7640D — Technical Data
Main technical performance indicators from the factory datasheet.
| Parameter | Unit | CGK-82 | CGK-7630 | CGK-7630D | CGK-7640 | CGK-7640D |
|---|---|---|---|---|---|---|
| Model | — | Nut compound center | Internal grinder | Internal grinder | Internal grinder | Internal grinder |
| Chuck diameter | mm | 250 | 250 | 250 | 400 | 400 |
| Max workpiece diameter | mm | 250 | 250 | 250 | 400 | 400 |
| Center height | mm | 300 | 260 | 180 | 230 | 230 |
| Arc thread diameter range | mm | Φ25–Φ100 | Φ16–Φ100 | Φ8–Φ100 | Φ20–Φ100 | Φ20–Φ200 |
| Metric thread pitch | mm | 1–24 | 0.5–24 | 0.5–24 | 1.5–60 | 1.5–60 |
| Imperial thread pitch | TPI | 3–20 | 3–48 | 3–48 | 3–12 | 3–12 |
| Max helix angle | — | ±10° | ±10° | 8°L / 11°R | ±10° | 8°L / 11°R |
| Max longitudinal table travel | mm | 400 | 460 | 450 | 750 | 750 |
| Wheel spindle speed | rpm | 24000 | 24000 | 36000 | 24000 | 24000 |
| Max grinding wheel diameter | mm | Φ100 | Φ100 | Φ100 | Φ150 | Φ150 |
| Min grinding wheel diameter | mm | Φ25 | Φ15 | Φ6 | Φ15 | Φ15 |
| Overall dimensions (L×W×H) | mm | 2600×2200×1800 | 2800×2000×1800 | 3000×2000×2000 | 2200×2500×1800 | 3000×2000×2000 |
| Machine weight | kg | 7000 | 5000 | 5000 | 5800 | 6000 |
| Adjacent pitch error (≤6 mm pitch) | mm | 0.003 | 0.003 | 0.003 | 0.005 | 0.003 |
| Pitch error over 25 mm (≤6 mm pitch) | mm | 0.005 | 0.005 | 0.005 | 0.005 | 0.005 |
| Pitch error over 100 mm (≤6 mm pitch) | mm | 0.006 | 0.006 | 0.006 | 0.006 | 0.006 |
| Surface roughness | μm | Ra≤0.32 | Ra≤0.32 | Ra≤0.32 | Ra≤0.32 | Ra≤0.32 |
Materials & Industries Served
Designed for manufacturers of ball screws, ball nuts, steering gears, thread gauges and precision internal-thread components.
Frequently Asked Questions
What is the difference between the CGK-82 and the CGK-7630/7640 internal thread grinders?
What internal thread applications do these machines cover?
What pitch range can the machines grind?
What thread accuracy does the series achieve?
How does the CNC control keep threads consistent?
What information is needed for a quotation?
Configure a CGK-82 / CGK-7630 / 7640 Series Grinder
Send us your workpiece diameter range, thread type and pitch, thread diameter, helix angle, surface finish requirement, daily production target, and whether you need the CGK-82 compound-machining capability. Include power supply, foundation and workshop layout details — our engineering team will recommend the CGK-82, CGK-7630, 7630D, 7640 or 7640D configuration and prepare a quotation.
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