K12 Series 4-Jaw Welding Chuck
Heavy-Duty 4-Jaw Self-Centering Chuck with Large Through-Hole
The K12 Series 4-Jaw Welding Chuck is a heavy-duty self-centering chuck designed for secure and stable clamping of large round workpieces in welding, cutting and fabrication applications.
The chuck uses a synchronized scroll mechanism to move the four jaws simultaneously, allowing the workpiece to be centered automatically during clamping.
With high rigidity, strong clamping force, large through-hole capacity and four-point workpiece support, the K12 Series is suitable for applications requiring stable workholding and large clamping diameters.
Jaw Configuration: 4-Jaw
Available Models: K12 400 – K12 1500
Maximum Clamping Range: Up to Ø1500 mm
Maximum Clamping Force: Up to 120 kN
Maximum Input Torque: Up to 1000 Nm
K12 4-Jaw Self-Centering Design Manual Welding Chuck Features
4-Jaw Self-Centering Design
The four jaws move simultaneously through the scroll mechanism, allowing the workpiece to be centered automatically during clamping.
Compared with a standard 3-jaw configuration, the 4-jaw design provides additional contact points around the workpiece, which can improve support and holding stability for suitable round components.
Heavy-Duty Construction
The K12 Series is designed for demanding workholding applications requiring high rigidity and strong clamping capability.
High Clamping Force
Depending on the model, maximum clamping force ranges from 60 kN to 120 kN.
The largest K12 1500 model is specified with a maximum clamping force of 120 kN.
Large Through-Hole
The large center opening provides clearance for pipes, cylinders, shafts and other large round workpieces.
Wide Size Range
The K12 Series is available in seven standard sizes from K12 400 to K12 1500, covering clamping ranges up to Ø1500 mm.
K12 Welding Chuck Performance Specifications
| Model | Maximum Input Torque | Maximum Clamping Force | Reverse Jaw Clamping Range | Positive Jaw Clamping Range |
| K12 400 / 500 | 500 Nm | 60 kN | Ø100–400 / Ø100–500 mm | Ø50–400 / Ø100–500 mm |
| K12 630 | 800 Nm | 72 kN | Ø200–630 mm | Ø100–600 mm |
| K12 800 | 900 Nm | 80 kN | Ø100–800 mm | Ø200–800 mm |
| K12 1000 | 1000 Nm | 90 kN | Ø300–1000 mm | Ø200–1000 mm |
| K12 1200 | 1000 Nm | 100 kN | Ø400–1200 mm | Ø300–1000 mm |
| K12 1500 | 1000 Nm | 120 kN | Ø500–1500 mm | Ø400–1500 mm |
Connection Size Parameters
| Model | D | D1 | D2 (H7) | D3 | H | H1 | H2 | L | Z-d |
| K12 400 | Ø400 | Ø368 | Ø340 | Ø170 | 100 | 40 | 6 | 125 | 3-M16 |
| K12 500 | Ø500 | Ø465 | Ø440 | Ø240 | 115 | 45 | 6 | 185 | 6-M16 |
| K12 630 | Ø630 | Ø590 | Ø560 | Ø320 | 125 | 50 | 12 | 250 | 6-M16 |
| K12 800 | Ø800 | Ø760 | Ø730 | Ø480 | 130 | 50 | 12 | 320 | 6-M16 |
| K12 1000 | Ø1000 | Ø950 | Ø902 | Ø642 | 150 | 60 | 15 | 350 | 6-M20 |
| K12 1200 | Ø1200 | Ø1140 | Ø1080 | Ø850 | 150 | 60 | 15 | 350 | 9-M20 |
| K12 1500 | Ø1500 | Ø1440 | Ø1380 | Ø1100 | 150 | 80 | 15 | 425 | 9-M20 |
Dimensions in mm.
These connection dimensions are based on the supplied technical data and are intended for product selection and equipment matching.
Positive Jaw & Reverse Jaw Clamping
Positive Jaw Clamping
The positive jaw position provides the normal clamping range for each K12 model.
Examples:
- K12 1000
Positive Jaw Range: Ø200–1000 mm - K12 1500
Positive Jaw Range: Ø400–1500 mm
Reverse Jaw Clamping
The reverse jaw position allows the chuck to cover different or larger workpiece diameters.
Examples:
- K12 1200
Reverse Jaw Range: Ø400–1200 mm - K12 1500
Reverse Jaw Range: Ø500–1500 mm
Why Choose a 4-Jaw Welding Chuck?
- More Workpiece Contact Points
Four jaws provide an additional contact point compared with a 3-jaw chuck, helping support suitable round workpieces more evenly. - Improved Holding Stability
The four-jaw arrangement can provide stable workholding for larger pipes, cylinders and fabricated components. - Suitable for Heavy-Duty Applications
Combined with the high rigidity and clamping force of the K12 Series, the 4-jaw structure is suitable for demanding welding and fabrication workholding. - Large Diameter Capability
Standard models cover workpiece sizes up to Ø1500 mm.
Typical Applications
- Pipe Welding
Suitable for holding large-diameter pipes during welding and positioning. - Cylinder Fabrication
The 4-jaw configuration provides stable support for cylindrical components. - Welding Positioners
K12 chucks can be used as workholding devices on compatible welding positioners. - Heavy Fabrication
The high rigidity and strong clamping force make the series suitable for large fabricated components. - Welding & Cutting Equipment
K12 chucks can be integrated into welding and cutting systems requiring centered workpiece holding.
How to Select a K12 Welding Chuck
1. Workpiece Diameter
Determine the minimum and maximum diameter of the workpiece.
2. Workpiece Weight
Consider the workpiece weight and actual holding conditions.
3. Required Clamping Force
Select a model according to the required holding force.
4. Jaw Position
Determine whether positive or reverse jaw clamping is required.
5. Mounting Dimensions
Check D, D1, D2, D3 and mounting-hole dimensions against the positioner or equipment interface.
6. Workpiece Geometry
For long or heavy workpieces, consider the center of gravity and clamping position before final selection.
K12 Model Selection Guide
| Maximum Required Diameter | Model to Consider | Max. Clamping Force |
| Up to Ø400 mm | K12 400 | 60 kN* |
| Up to Ø500 mm | K12 500 | 60 kN* |
| Up to Ø630 mm | K12 630 | 72 kN |
| Up to Ø800 mm | K12 800 | 80 kN |
| Up to Ø1000 mm | K12 1000 | 90 kN |
| Up to Ø1200 mm | K12 1200 | 100 kN |
| Up to Ø1500 mm | K12 1500 | 120 kN |
* The source performance table presents K12 400 / 500 as one combined row.
Note: This table is for preliminary selection only. Final selection should also consider workpiece weight, workpiece geometry, clamping position, jaw range and mounting dimensions.
Custom Options
The standard K12 product is supplied as a 4-jaw self-centering chuck.
For special applications, non-standard chuck sizes, customized jaw lengths and other custom chuck configurations may be evaluated upon request.
K11 vs. K12 Welding Chucks
| Feature | K11 Series | K12 Series |
| Jaw Configuration | 3-Jaw | 4-Jaw |
| Self-Centering | Yes | Yes |
| Max. Diameter | Ø1500 mm | Ø1500 mm |
| Max. Clamping Force | 120 kN | 120 kN |
| Max. Input Torque | 1000 Nm | 1000 Nm |
| Main Focus | Standard round-workpiece clamping | Additional contact & support |
| Heavy-Duty Use | Yes | Yes |
Request a Quote
Looking for a K12 4-Jaw Welding Chuck?
Send us your workpiece and equipment information for model selection and quotation.
K12 Model: __________
Workpiece Type: __________
Minimum Diameter: __________ mm
Maximum Diameter: __________ mm
Workpiece Length: __________ mm
Workpiece Weight: __________ kg
Required Clamping Range: __________ mm
Positioner / Equipment Model: __________
Mounting Dimensions: __________
Quantity: __________
For replacement applications, please send us photos, drawings or mounting dimensions of your existing chuck and equipment.
Frequently Asked Questions
The K12 Series is a 4-jaw self-centering welding chuck designed for secure workpiece clamping in welding, cutting and fabrication applications.
Standard models include:
K12 400, K12 500, K12 630, K12 800, K12 1000, K12 1200 and K12 1500.
The largest listed model, K12 1500, has a maximum clamping force of 120 kN.
The K12 1500 provides a clamping range up to Ø1500 mm.
The main difference is the jaw configuration:
K11 = 3-jaw self-centering chuck
K12 = 4-jaw self-centering chuck
Both series cover heavy-duty workholding applications, but K12 provides four workpiece contact points.
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