Expanding mandrel for bushings and thin-wall sleeves

Name: Expanding mandrel for bushings and thin-wall sleeves
Brand: Dongben Workholding
SKU: DB-MANDREL-EXP-01
Availability: InStock

Locate on the bore, clamp along the full land: the wall does not go oval.

Bore locationThin wallRunout ≤0.005 mmManual or hydraulic

An expanding (collet) mandrel that locates a thin-walled part on its internal bore and clamps evenly along the full length of the land. A three-jaw chuck applies three point loads and turns a 2 mm wall into an oval; the mandrel spreads the force over the whole circumference instead.

Used in turning, grinding and inspection of bushings, sleeves, rings and flanges, where concentricity between the bore and the outside diameter has to survive the clamping.

Technical data

Diameter range	20–150 mm, made to the part size
Runout at the land	≤0.005 mm
Clamping type	Split collet, manual screw or hydraulic actuator
Body	Alloy steel, hardened HRC 50–56, ground lands
Petals and land length	Selected to the wall stiffness of the part
Shank	MT4 / MT5, chuck flange or machine taper
Options	Interchangeable collets per diameter, coolant-through, axial stop
Verification	Runout report on centres, roundness check after clamping

How it is built

Clamping pressure follows the wall

The number of petals and the land length are chosen from the wall thickness: too few petals on a thin wall still produces lobing, too many on a thick wall will not grip.

Runout you can hold

The land is ground between centres and the runout is recorded on a report, so the accuracy you get is measured, not claimed.

Quick diameter change

On the interchangeable version, a new collet covers the next bore size without a new body, which matters if you have a family of similar sleeves.

Indicative price

Manual mandrel, 20–60 mmUSD 800 – 1,800

Manual mandrel, 60–150 mmUSD 1,800 – 3,000

Hydraulic mandrel with actuatorUSD 3,000 – 4,500

Product code: DB-MANDREL-EXP-01
Minimum order: 1 piece
Lead time: 4–6 weeks

FOB Liuzhou, indicative for standard configurations. A drawing moves the number inside the band.

Ask a question about this part

Questions

Why does a three-jaw chuck make a thin wall oval?

Three point loads at 120° produce a three-lobed deformation that springs back only partially when the jaws open. Measured roundness errors of 0.02–0.1 mm are normal on a 2 mm wall. Full-circumference clamping removes the cause, not the symptom.

How much interference do I need between mandrel and bore?

The collet is made to the bore's lower limit with 0.01–0.03 mm clearance, then expanded to grip. Sending the actual bore tolerance, not just the nominal size, is the single most important input.

Can it be used for grinding?

Yes, that is a common use. The mandrel body is hardened and the shank runs between centres, so the part can be ground on the outside diameter while held on the bore.

What about parts with a keyway or a spline in the bore?

A split collet bridges a keyway if the land is long enough; tell us the keyway width and we adjust the petal layout so the part does not tilt.