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Materials for 5-axis prototypes: production grade, stand-in or wax first
On a production part the material is fixed. On a prototype it is a choice, and it decides what the test can prove, how fast the shop can start and how much of the quote is stock rather than machining.
Production material or stand-in
A stand-in answers some questions faster and cheaper. It also hides others. Pick it for what the test needs to prove.
| Production material | Common stand-in | What the stand-in proves | What it cannot tell you |
|---|---|---|---|
| Titanium Grade 5 | Aluminum 7075-T6 | Fit, assembly, toolpath and fixturing on the real geometry | Weight, stiffness, fatigue and the real cycle time |
| Stainless 316L | Stainless 303 | Fit and function at lower machining cost | Corrosion resistance, weldability, biocompatibility claims |
| Inconel 718 | Stainless 17-4PH or 304 | Geometry and assembly checks | High temperature behavior and the true quote for production |
| PEEK | POM-C (acetal) | Fit, snap and assembly at a fraction of the stock cost | Temperature, chemical resistance and creep |
| Aluminum 7075 | Aluminum 6061 | Geometry, finish and anodize color | Strength on thin ribs and highly loaded features |
| Any metal | Machinable wax | Proof of the 5-axis toolpath, collisions and reach | Everything about the material itself |
Grades prototype shops quote most
Designations are close equivalents for reading a quote. For a binding comparison, check the limits in the exact standard on your drawing.
| Grade | Designations | Stock for prototypes | What it means for a 5-axis prototype |
|---|---|---|---|
| Aluminum 6061-T6 | UNS A96061, EN AW-6061 | Plate and bar, wide size range | The default first prototype. Fast to cut, anodizes well. |
| Aluminum 7075-T6 / T651 | UNS A97075, EN AW-7075 | Plate and bar | Higher strength for thin, loaded features. Stock costs more than 6061. |
| Aluminum 2024-T3 / T351 | UNS A92024, EN AW-2024 | Plate and bar | Good fatigue strength, needs a coating against corrosion. |
| Stainless 303 | UNS S30300, EN 1.4305 | Bar | Free machining. Lower corrosion resistance than 304 or 316L. |
| Stainless 316L | UNS S31603, EN 1.4404 | Bar and plate | Slower to cut and harder on tools. Specify it exactly. |
| Stainless 17-4PH | UNS S17400, EN 1.4542 | Bar | Machined soft, then aged. State the condition, for example H900 or H1150. |
| Titanium Grade 5 | UNS R56400, Ti-6Al-4V | Bar and plate | Low cutting speed, fresh tools, rigid setup. Plan more time per part. |
| Titanium Grade 2 | UNS R50400, commercially pure | Bar and plate | Softer and gummier than Grade 5, easier on tools. |
| Inconel 718 | UNS N07718, EN 2.4668 | Bar, often to order | Few prototype shops take it. Long cycles and high tool cost. |
| Brass C36000 | UNS C36000, EN CW603N | Bar | Free cutting, short chips, good finish. |
| Copper C11000 | UNS C11000, EN CW004A | Bar and plate | Soft, burrs easily. Thermal and electrical parts. |
| PEEK, POM, PEI (Ultem) | Unfilled or filled grades | Rod and plate | Light cuts, careful clamping. Plastics move with heat and moisture. |
UNS numbers per the Unified Numbering System. Typical tolerances by material are on the home page.
Stock, cost and lead time on short runs
On 1 to 200 pieces the material line behaves differently from production. Five things to settle before you send the RFQ.
- Buy-to-fly on 5-axis partsOrganic shapes are often cut from a rectangular block, and most of it becomes chips. On titanium or nickel alloy the block can cost more than the machining. A near-net blank only pays off at pilot quantity.
- Order the whole revision at onceMaterial, setup and programming are bought once per order. Three pieces of one revision from one block of stock cost far less each than three separate orders.
- Ask for the certificate up frontIf the prototype goes into a test that has to be traceable, ask for a mill certificate such as EN 10204 3.1 in the RFQ. It cannot be added after the stock is cut.
- Say if a stand-in is allowedA shop may have 6061 on the shelf today and wait a week for 7075. Allowing a stand-in for the first revision can save that week.
- Stress relief on thin partsRemoving most of a block releases stress, and thin walls move. Shops rough, release, then finish. Tell them which features have to stay flat or straight.
Material and the method on the machine
Hard materials punish long tools. A 5-axis machine can tilt a short tool into a deep feature, which is often the reason a titanium or stainless prototype needs simultaneous or 3+2 machining when the same shape in aluminum could be cut on 3-axis with long reach tools.
Freeform surfaces show the material too: aluminum gives a clean finish from the toolpath, titanium and stainless show scallops unless the step-over is reduced, which adds machine time.
Write the material line like this
- GradeTi-6Al-4V Grade 5, annealed
- StandardASTM B348 bar
- CertificateEN 10204 3.1
- Stand-in7075-T6 allowed for revision A
Material questions
See also how a 5-axis prototype is made and applications.
Should my first prototype be in the production material?
If the test is about fit, assembly or the look of the part, a cheaper stand-in such as aluminum is usually enough. If the test is about strength, temperature, corrosion or weight, use the production material, because a stand-in will give you the wrong answer.
Which material is fastest to get as a 5-axis prototype?
Aluminum 6061. Shops keep it in stock, it cuts several times faster than stainless or titanium and it forgives a first program. 7075 and 303 stainless are close behind. Titanium, nickel alloys and filled PEEK can add days for stock alone.
Can I supply my own material?
Yes, many prototype shops accept free-issue stock or blanks, especially for expensive alloys or certified heats. Say so in the RFQ and give the stock size, so every matched shop quotes the same thing.
What tolerance can I expect in plastics?
Around plus or minus 0.05 mm is realistic for most machined plastic prototypes. Tighter values are possible on selected features in stable plastics such as acetal or PEEK. The home page lists typical tolerances by material.
Material decided, or still open?
Either is fine. Tell us the production material and whether a stand-in is allowed, and we match up to 3 shops that run it. You hear from us within 24 business hours.