A Between Center Expanding Collet Chuck is a precision internal (ID) clamping workholding system designed to hold components between centers while gripping them from the inside diameter.
This combination delivers true concentric rotation, distortion-free holding, and excellent roundness, making it ideal for turning and grinding long, thin-wall, or high-precision components.
By eliminating external clamping forces, it preserves the finished OD and maintains centerline accuracy throughout the operation.
Applications
- Between-center turning & cylindrical grinding
- Bushes, sleeves, rings & hollow shafts
- Thin-wall and finished-OD components
- Automotive & precision engineering parts
- Toolroom and production grinding
- High-accuracy finishing operations
Key Features
- ✔ Uniform 360° internal expansion (ID clamping)
- ✔ Between-centers support for perfect alignment
- ✔ Distortion-free holding for thin walls
- ✔ High concentricity & repeatability (≤ 0.01 mm TIR)
- ✔ Positive torque transmission without slippage
- ✔ Hardened & precision-ground expanding segments
- ✔ Suitable for turning and grinding
- ✔ Custom designs as per component bore & length
Working Principle
The workpiece is supported between the headstock and tailstock centers.
An axial actuation (mechanical draw, spring-assisted, or hydraulic—application dependent) drives a tapered cone that expands the collet segments radially inside the bore.
Centers maintain alignment while the expanding collet provides secure, even grip.
Types & Configurations
- Mechanical Between Center Expanding Collet
- Spring-Loaded Expanding Mandrel (Between Centers)
- Hydraulic Between Center Expanding Collet
- Step / Multi-Bore Expanding Designs
- Thin-Wall Safe-Expansion Collets
- Custom Length & Torque Capacity Designs
Technical Specifications
- Clamping Type: Internal (ID expanding), between centers
- Material: EN31 / EN24 / Alloy Steel
- Hardness: 58–62 HRC (working parts)
- Accuracy: ≤ 0.01 mm TIR (≤ 0.005 mm on request)
- Expansion Range: Application-specific (controlled)
- Torque Capacity: Designed per operation
- Customization: As per drawing or sample
Advantages
- Superior roundness & cylindricity
- Protects finished OD surfaces
- Reduced vibration and chatter
- Consistent results across batches
- Ideal for high-precision grinding & finishing
