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How a 5-axis prototype is made, from STEP file to inspected part
A prototype is not a production part made once. The shop has no fixture, no proven program and no second chance on the material. This is the route a 1 to 200 piece order takes, and where your drawing changes the price.
The route through the shop
Four steps on every 5-axis prototype. The first two are paid once per order, which is why quantity per revision matters so much.
CAM and simulation
The shop builds toolpaths from your STEP model and runs them against a model of the machine, holder and fixture. On a one-off this is often the largest line in the quote.
Workholding
No dedicated fixture on a prototype. The part is held in soft jaws, a dovetail or by extra stock that is cut off at the end.
Cutting
3+2 positional for faces and holes at fixed angles, simultaneous 5-axis for blends and freeform. Most prototypes mix the two.
Probing and inspection
A spindle probe locates the stock before cutting and can check features in the machine. Critical features are measured afterwards on a CMM or with gauges.
Which method fits which feature
Read across from the feature on your part. Most prototypes have more than one row, and a shop will mix methods on the same part.
| Feature | 3-axis, several setups | 3+2 positional | Simultaneous 5-axis | Mill-turn |
|---|---|---|---|---|
| Flat faces on two sides | Fits well | Works, no real gain | Not needed | Not needed |
| Holes and faces at fixed angles | Extra setups, position drifts | Best fit | Works, costs more CAM time | Fits if the part is round |
| Features on five sides | Three or more setups | Best fit, one or two clampings | Works | Rarely |
| Twisted blade or blended port | Stepped surface, hand finishing | Partly, with visible facets | Best fit | Some machines, small parts |
| Deep pocket beside a tall wall | Long tool, chatter risk | Tilted short tool | Tilted short tool, continuous | Rarely |
| Shaft with angled holes or flats | Two machines | Needs a turned blank first | Needs a turned blank first | Best fit, from bar |
Simultaneous 5-axis needs tool center point control on the machine and a post processor built for its kinematics. Background on the method: multiaxis machining.
Holding a part that has no fixture
Workholding decides how many faces the head can reach in one clamping. On a prototype it is improvised for each order, and a small change to your model can make it much easier.
- Vise with soft jawsJaws machined to the part shape for the second side. Cheap and quick, limited reach on the clamped faces.
- Dovetail stockA small dovetail cut on the bottom of the block lets the head reach all five upper faces. The dovetail is removed in a last operation.
- Sacrificial tab or bossExtra material the shop clamps and cuts off. Adding one to your model can turn a three-setup part into a one-clamping job.
- Zero-point plateRepeatable location between the machine, the probe and the CMM. Useful for pilot batches where the same part comes back.
- Machinable wax or soft material proof cutA first run in wax or plastic to prove the toolpath on an expensive part before the real material goes in.
Secondary steps on a prototype
Each one adds days, and most happen outside the machine shop. Put them in the RFQ so the matched shops quote the same scope.
Deburring and edge breaking
By hand or with a 5-axis chamfer toolpath. State the edge condition, for example 0.2 to 0.5 mm x 45 degrees, or the shop decides.
Bead blasting
Uniform matte surface that hides tool marks. Specify the media if the part is cosmetic.
Anodizing
Type II for color and corrosion, Type III hard coat for wear, per MIL-A-8625. Coating builds on fits, so mask or allow for it.
Passivation
For stainless steel, per ASTM A967 or A380. Removes free iron left by machining.
Heat treatment
Done by an outside heat treater. Prototype parts that must be hard are often finish machined or ground after treatment.
Laser marking
Part number, revision and serial number. Useful when several revisions are on the bench at once.
Process questions
See also materials for prototypes and applications.
Why does a single 5-axis prototype cost so much?
Because programming, simulation and setup are paid once per order, whether the shop makes one part or ten. On a one-off they can be more than half the price. Ordering a few spare pieces of the same revision usually costs far less per piece.
Do I need simultaneous 5-axis or is 3+2 enough?
If every surface on the part is flat and every hole is straight, 3+2 positional machining is enough and usually cheaper. Twisted, blended or freeform surfaces need simultaneous motion. Use the self-check on the home page or send the RFQ and we tell you which.
Can the shop proof the program before cutting my material?
Many shops run a first cut in machinable wax or a cheap plastic when the material is expensive or the toolpath is complex. Ask for it in the RFQ if it matters to you, because it adds a little time and cost.
Will a prototype shop inspect every feature?
Only if you ask. Mark the critical features on the drawing and state the report you need, such as a first article report with measured values. Everything else is checked to the general tolerance class on the drawing.
Not sure which method your part needs?
Send one RFQ. We read the geometry, decide whether it needs simultaneous or 3+2 and match up to 3 shops. You hear from us within 24 business hours.