Internal Clamping Collets: Precision Holding from the Inside Out

Schlenker Spannwerkzeuge offers internal clamping collets-precision tools designed to grip a workpiece from the inside. Built for demanding CNC machining and grinding jobs, these collets offer enhanced concentricity, rigidity and access to the part.

How Internal Clamping Collets Work

Also known as expanding mandrels or arbors, internal clamping collets hold a part by its inner diameter. The set-up usually includes a slotted sleeve over a tapered core. When the mechanism is engaged-usually with a drawbar or screw-the core moves lengthwise, expanding the sleeve outward into the bore of the part. That expansion locks the part in place from the inside while leaving the outside clear for machining or finishing.

Advantages of Internal Clamping

Internal clamping advantages include:

• 360° access: Clamping from the inside keeps the exterior free, so operators can machine the entire exterior in one set-up.
• High rigidity: A longer internal grip surface keeps the part steady, cuts down on vibration and holds strong under torque.
• No external marks: Since the clamping happens inside the part, the outer surfaces stay untouched-important for finished parts or follow-up operations.
• Tight runout: These set-ups hold tight TIR, making them a solid choice for precision work.
• Adjustable grip: Users can dial in how much holding force they need.
• Works with tubes or drilled stock: Suited for hollow or pre-drilled material.
• No wasted channel space: Run the part all the way through without hitting the clamp.
• Sealed options available: Fully sealed versions help keep coolant out of the bar feeder magazine.

Applications in Precision Manufacturing

Internal clamping collets show up in OD grinding, pickoff work on Swiss-type lathes and second-op set-ups on CNC turning centers. They are especially effective on thin-walled parts, precision sleeves and other round components where part stability and clean surfaces matter. Internal clamping is available on nearly all collet types, so the machine usually does not need modification.

Schlenker Spannwerkzeuge, based in Germany, focuses solely on collets, guide bushes, bar feed collets, rotating inserts and custom workholding. Everything is made in-house, start to finish. Edge Technologies has been the exclusive North American distributor for Schlenker for over 15 years.

For more information contact:

Edge Technologies

15703 Westport Commerce Drive

Maryland Heights, MO 63146

314-810-3959

orderdesk@edgetechnologies.com

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