Wedge expansion clamping holds irregular, thin-walled and asymmetric parts that vise jaws cannot grip. We machine the fixture and the part on the same 5-axis platform, so setup stays short and tolerances stay at ±0.005 mm.
These are the failures we hear about most from engineers quoting odd geometry.
A tapered boss or a cast surface leaves three-point contact. The part rocks under load, the cutter grabs it, and you scrap a finished face on the last pass. Every scrapped part in a one-off run means a new setup and a new lead time.
Six hundred newtons of jaw pressure closes a 2 mm wall by more than the total tolerance band. The part measures fine in the vise and out of round on the CMM. Unclamping releases the stress, and the geometry springs back out of spec.
You flip the part for the second side, re-indicate, and pick up a new zero. Stacked setup error eats 0.02 mm before the tool touches metal. Two operators on two shifts can hit different numbers from the same drawing.
Designing and cutting a dedicated fixture for one part family adds days before the first chip. On a prototype build, the fixture can cost more than the part. If the design changes, the fixture is scrap.
Wedge expansion clamping, cut on the same machine that runs the part.
An OK fixture applies force through a wedge that expands a split collet or a segmented sleeve against the bore or the internal profile. Contact is radial and distributed, not two-point. That matters when the part has a curved back, an undercut or a bore that is not round.
Because the force is spread around the feature, you can hold a part with a 1.5 mm wall without crushing it. We set clamping pressure against the wall thickness and the material, not against a fixed vise setting.
Special-shaped parts usually need work on four or five faces. On a three-axis mill you re-fixture for each face, and every re-fixture adds error. Our 16 simultaneous 5-axis centers tilt the part or the spindle so the tool reaches an angled face in the same setup.
The fixture stays on the table and the part stays in the fixture. One datum, one zero, one inspection report. We hold ±0.005 mm on bores and mating surfaces, and Ra 0.8–1.6 μm on sealing faces.
Pick by geometry, not by habit.
| Part feature | Recommended workholding | Why |
|---|---|---|
| Round or near-round bore | Wedge expansion OK fixture | Radial load, no jaw marks |
| Flat plate, open top | Precision vise with soft jaws | Simple, fast, low cost |
| Tapered or curved back | Conforming soft jaws | Full surface contact under load |
| Thin wall under 2 mm | OK fixture with low pressure | Distortion stays inside tolerance |
| Deep pocket on five faces | 5-axis with tombstone fixture | One setup covers all faces |
| One-off prototype | Modular fixture plate | Reusable, no dedicated tooling |
The fixture is only useful if the machine, the material and the finish are all in one shop.
Simultaneous 5-axis cutting for angled faces, undercuts and contoured surfaces. 16 centers available, Ø400 mm rotary table for trunnion work.
12 four-axis mills and 27 three-axis machines for prismatic parts, slots and drilled patterns where five axes add no value.
16 mill-turn centers combine turning and milling so a shaft with cross-holes comes off one machine with one datum.
From one prototype to 10,000+ part runs, no minimum order quantity. Production can start within 24 hours of drawing release.
Anodizing, electroless nickel, bead blasting, polishing and laser marking with a minimum character height of 1.5 mm.
100% inspection before shipment. Raw material check, in-process monitoring and final inspection, with reports on request.
| Item | Range | Notes |
|---|---|---|
| Tolerance | ±0.005 mm (±0.0002 in) | On bores and mating faces |
| Surface finish | Ra 0.2–0.8 μm fine | Ra 1.6–3.2 μm as machined |
| Maximum part size | 4,000 mm | 4,000 × 400 × 150 mm travel |
| Aluminium | 6061-T6, 7075, 6082, 2024 | Also 5052, 5083, 6063, ADC12 |
| Stainless | 303, 304, 316L, 17-4PH | Plus 420, 430, 431, 440C |
| Titanium and special | TC4 (Ti-6Al-4V), Inconel | Magnesium AZ31B / AZ91D |
| Plastics | PEEK, POM, PC, PMMA, HDPE | ABS, PA, PP, carbon fibre |
Making parts since 2011. Fifteen years of fixtures for irregular geometry across aerospace, medical and industrial machinery work.
Held on bores and mating surfaces after wedge expansion clamping, verified on the CMM before the part leaves the shop.
Across production runs. Fixture repeatability is a large part of that number, because a part that seats the same way measures the same way.
Quotation and free DFM analysis within 12 hours. We flag unsupported geometry and thin-wall risk before you commit to tooling.
Three wholly-owned plants, 7,600 m² of floor and 150 technicians. Fixture and part can run on the same platform.
Uploads are secure and confidential. A non-disclosure agreement is available on request before you send drawings.
Thin ribs and tapered webs held without crushing. Report required for every face and hole.
Curved housings with bores that are not round. IATF 16949 and ISO 13485 controls apply.
As-cast surfaces that will not sit flat in a vise. Fixture seats on the machined bore instead.
Asymmetric links with bores on two axes. One 5-axis setup holds the bore-to-bore relationship.
If the part has a bore or an internal profile that a vise cannot contact evenly, an OK fixture is usually the better answer. Tapered bosses, curved backs, undercuts and near-round bores all qualify.
If the part is a flat plate with parallel sides, a standard vise with soft jaws is faster and cheaper. We will tell you when the fixture is overkill.
We set clamping pressure against the wall thickness and the alloy instead of using a default vise setting. Wedge expansion spreads the load around the feature rather than pinching it at two points.
For walls under 2 mm we also check the part on the CMM in the clamped state and after release. If the two readings differ, the pressure is too high.
Yes. Fixture and part run on the same machine platform, which means the fixture is cut to the same tolerance band as the part. That removes the mismatch you get when a fixture is made on a different machine.
For production runs the fixture is hardened and re-qualified so it holds its seat over thousands of cycles.
Aluminium 6061-T6, 7075, 6082 and 2024, stainless 303, 304, 316L and 17-4PH, titanium TC4 (Ti-6Al-4V), Inconel, magnesium AZ31B and AZ91D, plus plastics including PEEK, POM, PC, PMMA and HDPE.
Soft plastics and thin titanium need different pressure settings. Tell us the alloy on the drawing and we set the fixture accordingly.
There is no minimum order quantity. We run one prototype or a 10,000+ part production order on the same equipment.
A single prototype still gets a fixture review and a DFM note. The point is to catch geometry that cannot be held before you pay for tooling.
Quotation and free DFM analysis come back within 12 hours. Production can start within 24 hours of drawing release, and parts typically ship in 3–5 days.
If a fixture has to be designed from scratch, that design time is part of the quote, not a surprise added later.
Yes. Uploads are secure and confidential, and we will sign a non-disclosure agreement before you send drawings if your program requires it.
Inspection reports and material certificates are available on request and can be routed only to the people you name.
±0.005 mm (±0.0002 in) on bores and mating faces, with Ra 0.2–0.8 μm on fine finishes and Ra 1.6–3.2 μm as machined. Sealing faces usually land at Ra 0.8–1.6 μm.
Every part is inspected before shipment. Raw material check, in-process monitoring and final inspection are standard, not optional.
We review the geometry, flag what will not hold, and quote within 12 hours.
12-hour quoteFree DFM analysis100% inspectionNo minimum order
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Upload your 3D model or 2D drawing and get a quotation with a free DFM analysis. Maximum processing size 4,000 mm.
CNC Metals 13 grades
CNC Plastics 10 grades
Machines & processes 12 options
Surface & post-processing 10 options
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