1. 3D model, not a picture
A STEP or X_T model with the material and blank condition attached. A 2D drawing is enough for an indicative band, but not for production: clamp positions, tool clearance and chip evacuation are three-dimensional problems. A PDF of a section view cannot tell the designer whether a clamp body will collide with the holder at a 45° approach.
If the model is confidential, send it with the critical features blanked and the envelope intact. A fixture can be designed from an envelope plus a datum scheme far more reliably than from a photograph.
2. Machine table drawing
This is the input most often missing, and it decides how the fixture is located: T-slot pitch and width, zero-point grid, pallet interface, maximum table load and spindle taper. A fixture that fits the part but not the table is a scrap casting.
Also state the machine model and the control, because the clamp sequence may need an M-code interface and the coolant-through arrangement depends on the through-spindle capability.
3. Operation list
Which faces are machined, in what order, on which machine, with which tool. Two operations on the same face with different tools may need two clamp positions, and that changes the station count and the price.
4. Tolerance stack
Not every dimension — the ones that matter. State the datum callouts and the fit class. If everything is ±0.1 mm, say so: it changes the design from a ground, pinned structure to a machined one, and that is a 40 % price difference on a multi-station fixture.
5. Annual volume and batch size
200 pieces a year and 50,000 pieces a year are different fixtures for the same part. At 200, a manual clamp on a modular body is rational. At 50,000, the operator's wrist is the bottleneck and the hydraulic unit pays for itself within a year.
6. Clamping preference and plant standard
If your plant standardises on a clamp brand, say so. Reusing your clamps cuts both the price and the spare-parts inventory. If you have no preference, say that too — being told “whatever you recommend” is more useful than being told nothing.
7. Inspection scope
Does the fixture need a full CMM geometry report, a first-article inspection on a trial part, or just a runout check? The difference between “report on the fixture” and “report on the part machined in the fixture” is a real cost, and it should be decided before the quote, not after.
What happens when one input is missing
The shop fills the gap with an assumption. If the assumption is about clamping force, the fixture may distort the part. If it is about the table interface, the base plate may need to be remade. Either way, the cost of the missing input is paid after the purchase order, not before it.
| Inputs supplied | Typical quote time | Typical revision rounds |
|---|---|---|
| Model + table + operations + tolerance + volume | 1 working day | 0–1 |
| Model + table, no tolerance stack | 2–3 days | 1–2 |
| 2D drawing only | 3–5 days | 2–3 |
| Sample part by post, no drawing | 1–2 weeks | 2–4 |
Questions
Is a 2D drawing enough for a fixture quote?
Do I need to send the CAM file?
What if I do not know the annual volume yet?
Published by Liuzhou Dongben Machinery Equipment Co., Ltd. · More notes