Quick-change fixture applications (PDF)
Send the part drawing and the machine — we design the fixture →
A slim body that still holds rigidity, so small-diameter work can be reached without the fixture becoming the limiting factor. The clamping sleeve and drawbar are a single assembly — both clamping and release are driven by the drawbar, which is what lets the mandrel be built slender enough for long overhang work.
| Repeatability | under 0.01 mm |
|---|---|
| Clamping | High radial clamping force with an axial pull-back mechanism, so the part is pulled tight against the locating face |
| Vibration | Vulcanised rubber-bonded clamping sleeve damps machining vibration |
| Chip evacuation | Flushing channels built in between the workpiece and the clamping sleeve |
| Typical machines | Gear grinding machines — the interface is built to the machine you name |
Where the part allows front-end clamping through a deep bore, clamping rigidity improves substantially and with it the stability of the grind.
| Clamping range | ø20 to ø120 mm covered by five mandrel sizes |
|---|---|
| Concentricity | under 0.01 mm |
| Changeover | 1 minute on the quick-change system, repeatability 0.003 mm |
| Actuation | Standard hydraulic cylinder, manual or automatic |
| Locating blocks | Three mounting faces for different setups |
| Sleeves | Standard precision clamping sleeves from stock; interchangeable with turning mandrel fixtures |
Five mandrel sizes covering ø20 to ø120 mm is the practical point here — it is what keeps the number of fixtures in the cabinet down when the part mix changes.
Hydraulic expansion works on Pascal’s law: pressure applied to a sealed, incompressible fluid is transmitted evenly, so the elastic expansion element deforms uniformly through the full 360°. The result is that positioning and clamping happen in the same movement, on the bore or on the shaft.
| Clamping pressure | up to 100 MPa, adjustable |
|---|---|
| Repeatability | ≤ 0.003 mm |
| Contact | Seamless 360° surface contact; uniform clamping force, minimal deformation |
| Hydraulic system | Fully sealed internal medium, independent of external supply |
| Smallest workpiece | diameters down to 5 mm while keeping rigidity and accuracy |
| Size flexibility | Reducing sleeves and spline clamping sleeves cover several workpiece sizes on one fixture |
Maximum expansion of a hydraulic mandrel is about 0.3% of the clamping diameter. The requirement is the sum of three things — the workpiece tolerance, the fit clearance, and the expansion needed to transmit torque safely. The catalogue works it through for a ø25 H8 shank:
| Contribution | Condition | Value |
|---|---|---|
| Workpiece design tolerance | ø25 H8 | 0.033 mm |
| Clearance between workpiece and mandrel | manual clamping | 0.010 mm |
| Expansion for safe torque transmission | grinding | 0.030 mm |
| Required mandrel expansion | 0.073 mm |
0.3% of 25 mm is 0.075 mm, so this part is inside the range — which is exactly the check that has to be made before a mandrel is designed.
| Manual, no auxiliary tool | Inspection mandrels, where positioning accuracy matters more than force |
|---|---|
| Manual with auxiliary tool | The common method for metal cutting — higher clamping force for machining stability |
| Automatic | Mechanical, pneumatic, hydraulic or electromagnetic actuation of the clamping piston; semi- and fully automated machines |
| External pressure assisted | An external pressure mechanism drives the piston so several fixtures clamp at once at different positions |
| Fully enclosed | Body and clamping sleeve permanently assembled as one unit |
|---|---|
| Open | Body and clamping sleeve separable, so maintenance is straightforward |
| Axial support force | Support introduced along the axis — usual for chuck fixtures with axial locking |
| Radial support force | Support introduced from the outer diameter — mandrel or chuck fixtures |
| Central clamping force | Applied through the centre, directly on the mandrel section — mandrel-type fixtures |
| Internal spline expanding fixture | Clamping head inside a large sleeve for stable force and positioning. Workpieces to ø400 mm outside diameter. Built for internal spline shaping through the bore, optimised for vertical machines. |
|---|---|
| Hobbing mandrel | Clamping torque comes from radial expansion; force from the machine cylinder and drawbar. The locating shoulder positions and clamps in one action, so no separate axial clamp is needed. Oil grooves or wear-resistant coating raise torque capacity on small diameters. |
| Multi-workpiece gear grinding fixture | Parts are loaded and adjusted at an external setting station, then the mandrel and parts go to the machine together. Taper interface to the spindle ground to 0.003 mm runout. |
| Mandrel for automated loading | One end permanently on the spindle, clamping force from the machine cylinder. An internal mechanism drives an eccentric pin near the clamping position so a robot can load accurately; a guide sleeve on the tailstock centre pushes the part home. |
| Spline and precision bore mandrel | Two independent clamping positions, toothed sleeve for internal splines including helical gears. Dual centres plus elastic sleeve, manual radial clamping. Runout 0.005 mm. |
| Hydraulic mandrel with pressure conversion | Mounted on a quick-change fixture, centred by the sleeve on the base flange, pressure supplied by the machine. Changing the transition sleeve changes the workpiece diameter. Runout to 0.003 mm. |
| Large manual clamping | Clamping diameter to 400 mm, radial clamping force to 200 kN, with chuck mounting and dismounting tooling. |
The reason these fixtures hold their numbers is process control rather than a single clever feature. Mongtec runs 5-axis machining centres from Japan and Germany with robotic load and unload, in-line inspection and tool management, in a fully enclosed temperature-controlled and dust-free workshop with centralised oil mist extraction. Large-travel centres take work up to roughly 1 metre in diameter.
Heat treatment is in-house — vacuum hardening, high-frequency induction hardening, vacuum brazing, vacuum tempering, carburising and cryogenic treatment — alongside black oxide, nickel plating, sandblasting and shot blasting for steel parts.
Quick-change collet chucks → · Hydraulic fixtures for machining centres → · Internal expansion → · Collets and expansion sleeves → · All catalogues →