⚙️ Large Thread Grinder

CGK-4000A / CGK-4000 / CGK-5000 / CGK-6800 / CGK-8500 Large CNC High-Precision External Thread Grinder

A heavy-duty CNC external thread grinder family for long ball screws and trapezoidal screws. Moving wheel-carriage architecture and full closed-loop control deliver Ra 0.32 μm surfaces over lengths up to 8200 mm.

Request a Quote Technical Specs ↓

Φ20–Φ500

Grindable Diameter

3800–8200 mm

Thread Length

Ra≤0.32 μm

Surface Roughness

±25°

Helix Angle

Grind Extra-Long Precision Screws Without Relocating

The CGK-4000A/4000/5000/6800/8500 series is built for finish-grinding the long arc ball screws, trapezoidal screws and special thread profiles used in heavy machine tools and large automation systems.

CGK-4000A / CGK-4000 / CGK-5000 / CGK-6800 / CGK-8500 large CNC high-precision external thread grinder in a long screw grinding shop

The CGK-4000A / CGK-4000 / CGK-5000 / CGK-6800 / CGK-8500 is a family of large CNC high-precision external thread grinders for the rolling-function-components industry. It finish-grinds arc ball screws, high-precision trapezoidal screws and other external thread profiles on workpieces up to Φ500 mm. The moving wheel-carriage design covers grindable thread lengths from 3800 mm on the CGK-4000A to 8200 mm on the CGK-8500, with optional side-bed extension supporting even longer workpieces. An industrial CNC control system with full closed-loop feedback runs single-pass and fully automatic grinding cycles, multi-start threads from 1 to 99 starts, dynamic tool setting, pitch compensation, pitch-taper compensation and automatic wheel-dress compensation. The result is thread geometry held to 0.006–0.008 mm within a 2π arc and surface roughness down to Ra 0.32 μm.

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Key Features & Working Principle

Six capabilities that make the CGK-4000A/4000/5000/6800/8500 the right choice for long and heavy screws.

1️⃣

Five Bed Lengths

CGK-4000A, CGK-4000, CGK-5000, CGK-6800 and CGK-8500 cover thread lengths from 3800 mm to 8200 mm for small-batch and high-volume long-screw production.

2️⃣

Moving Wheel Carriage

The grinding wheel carriage travels along the side bed instead of moving the worktable, keeping long and heavy workpieces stationary for better stability.

3️⃣

Full Closed-Loop CNC Control

Precision linear scale feedback on linear axes and a rotary encoder on the work spindle provide closed-loop positioning and repeatability over the full bed length.

4️⃣

Single-Pass & Automatic Cycles

Select single-pass grinding for setup and proving, or fully automatic cycle grinding for unattended long-screw production.

5️⃣

Intelligent Compensation

Dynamic tool setting, pitch compensation, pitch-taper compensation and automatic wheel-dress compensation keep size stable across the entire screw length.

6️⃣

Flexible Dressing & Accessories

Choose diamond roller, motorized diamond-point or CNC profile dressers, plus automatic wheel balancing, automatic tool setting and helix-angle locking.

Why Choose the CGK-4000A / CGK-4000 / CGK-5000 / CGK-6800 / CGK-8500

A large external thread grinder eliminates the accuracy loss and handling cost of grinding long screws in multiple setups.

🎯

Micron-Level Thread Accuracy

Profile error within 2π arc is held to 0.006 mm on CGK-4000A/4000, 0.007 mm on CGK-5000 and 0.008 mm on CGK-6800/8500; cumulative error over 300 mm is 0.012–0.023 mm.

🏆

Mirror Surface Finish

Thread surface roughness reaches Ra≤0.32 μm, giving long ball screws and trapezoidal screws the smooth flanks needed for long life and low noise.

⚙️

Wide Pitch Coverage

Metric pitches from 1.5 mm to 48 mm, imperial threads from 2 to 18 TPI and module threads from 1 to 18 cover most large ball and trapezoidal screw specifications.

📐

Large Helix Angle Range

Helix angles up to ±25° on all five models handle steep-lead ball screws and trapezoidal screws.

🛡️

Matched to Part Length

Five bed lengths let you match machine investment to your typical screw length instead of paying for capacity you do not need.

💰

Heavy-Duty Capacity

CGK-4000A supports disc-type workpieces up to Φ500 mm and Φ500 mm with steady rest, while the family spans machine weights from 20000 kg to 30000 kg.

CGK-4000A / CGK-4000 / CGK-5000 / CGK-6800 / CGK-8500 — Technical Data

Main technical performance indicators from the factory datasheet.

Parameter	Unit	CGK-4000A	CGK-4000	CGK-5000	CGK-6800	CGK-8500
Max grindable diameter (disc type)	mm	Φ500	Φ400	Φ400	Φ500	Φ500
Max grindable diameter with steady rest	mm	Φ500	Φ300	Φ300	Φ300	Φ300
Min grindable diameter	mm	Φ20	Φ20	Φ20	Φ30	Φ30
Max distance between centers	mm	4000	4200	5300	6800	8500
Max grindable thread length	mm	3800	3900	5000	6400	8200
Center height	mm	350	250	250	320	320
Metric thread pitch	mm	1.5–48	1.5–48	1.5–48	1.5–48	1.5–48
Imperial thread pitch	TPI	2–18	2–18	2–18	2–18	2–18
Module thread range	module	1–18	1–18	1–18	1–18	1–18
Max grindable helix angle	—	±25°	±25°	±25°	±25°	±25°
Grindable thread starts	—	1–99	1–99	1–99	1–99	1–99
Workpiece speed	rpm	0–150	0–150	0–150	0–150	0–150
Table moving speed	m/min	0–6.0	0–6.0	0–6.0	0–6.0	0–6.0
Wheel carriage in/out speed	m/min	0–1.5	0–1.5	0–1.5	0–1.5	0–1.5
Dresser feed speed	m/min	0–1	0–1	0–1	0–1	0–1
X / Y / Z axis resolution	mm	0.001	0.001	0.001	0.001	0.001
C-axis resolution	—	0.001°	0.001°	0.001°	0.001°	0.001°
Wheel carriage cross travel	mm	220	220	220	220	220
Wheel spindle speed	rpm	1000–3000	1000–3000	1000–3000	1000–3000	1000–3000
Grinding wheel size (OD × ID)	mm	Φ510 × Φ305	Φ500 × Φ305	Φ500 × Φ305	Φ500 × Φ305	Φ500 × Φ305
Overall dimensions (L × W × H)	mm	8500 × 2200 × 2100	8500 × 2200 × 2100	9500 × 2200 × 2100	10500 × 2600 × 2600	12500 × 2600 × 2600
Machine weight	kg	20000	20000	22000	23500	30000
Helical accuracy within 2π arc	mm	≤0.006	≤0.006	≤0.007	≤0.008	≤0.008
Helical accuracy over 300 mm	mm	≤0.012	≤0.012	≤0.016	≤0.023	≤0.023
Thread surface roughness	μm	Ra≤0.32	Ra≤0.32	Ra≤0.32	Ra≤0.32	Ra≤0.32

Applications

Built for manufacturers of long precision threaded drive components across machine-tool, automation, energy and heavy-equipment industries.

🔩

Long Arc Ball Screws

Large ball-screw raceway grinding

⚙️

Planetary Roller Screws

Long planetary screw thread grinding

📐

Trapezoidal Screws

High-precision trapezoidal threads

🔧

Power Worms

Heavy power-transmission worm profiles

🏭

Custom Thread Profiles

Special tooth forms and pitches

🤖

Rolling-Function Components

Large linear-motion drive parts

Frequently Asked Questions

What parts can the CGK-4000A / CGK-4000 / CGK-5000 / CGK-6800 / CGK-8500 grind?

The machines grind high-precision arc ball screws, planetary screws, trapezoidal screws, worms and other external thread profiles on workpieces up to Φ500 mm.

What thread lengths do the five models cover?

CGK-4000A covers 3800 mm, CGK-4000 covers 3900 mm, CGK-5000 covers 5000 mm, CGK-6800 covers 6400 mm and CGK-8500 covers 8200 mm grindable thread length. Optional side-bed extensions can support even longer workpieces.

What pitch and helix range can be ground?

Metric pitches from 1.5 mm to 48 mm, imperial threads from 2 to 18 TPI, and module threads from 1 to 18. Helix angles reach ±25° on all five models.

How is grinding accuracy maintained on such long beds?

An industrial CNC control system with full closed-loop feedback from precision linear scales and a rotary encoder controls all axes. Pitch, pitch-taper and wheel-dress compensation corrects process variation automatically, while the moving wheel carriage keeps the long workpiece stationary.

What is the difference between CGK-4000A and CGK-4000?

CGK-4000A is the heavy-duty variant with a 350 mm center height and Φ500 mm disc-type capacity with or without steady rest. CGK-4000 has a 250 mm center height, Φ400 mm disc-type capacity and Φ300 mm with steady rest.

What information is needed for a quotation?

Send us your workpiece diameter and length, thread form and pitch, helix angle, number of starts, accuracy class and surface-finish requirements, material and hardness, and annual volume. Include power supply and workshop layout details — we will recommend the right model and prepare a quotation.

Configure a CGK-4000A / CGK-4000 / CGK-5000 / CGK-6800 / CGK-8500 Thread Grinder

Send us your workpiece diameter and length, thread form and pitch, helix angle, number of starts, accuracy class and surface-finish requirements, material and hardness, and annual volume. Our engineering team will recommend the right model and prepare a quotation.