Guides / Process

The Complete RFQ Checklist for Machined Delrin and POM Parts

September 25, 2026

The gap between a fast, accurate quote and a slow, padded one is almost always the RFQ itself. Two shops quoting the same finished part from two different levels of detail will not give you comparable numbers, and the difference is rarely the shop. This is a working checklist, built around what actually changes a quote, with a filled-out example at the end.

Why the RFQ decides the quote before the shop does

A shop pricing an acetal part has to make a series of assumptions wherever the RFQ is silent: which grade, how tight the real tolerance is, whether a stress relief cycle is needed, what the edges should look like, how many pieces will actually repeat. Every assumption the shop has to make is a place where two quotes for the same part can diverge for reasons that have nothing to do with the shop’s actual pricing or capability.

A complete RFQ removes those assumptions. It does not guarantee a lower price. It guarantees that the price you get reflects the part you actually want, and that multiple quotes for the same RFQ are actually comparable to each other.

The checklist

1. Geometry files

Send a STEP or IGES file for the 3D model. Both formats carry exact geometry that a shop’s CAM software can program directly from. Native CAD files work if the shop uses the same software, but a neutral format is safer when you do not know what the shop runs.

If you only have a 2D drawing and no 3D model, say so. A shop can often build the model from a complete 2D drawing, but it changes the quoting process and is worth flagging up front rather than discovering mid-quote.

2. A dimensioned drawing, even when you sent a model

The 3D model carries the shape. It does not carry tolerances, surface finish requirements, or notes about which faces matter. Send a PDF drawing alongside the model with:

• Overall dimensions and the critical ones marked separately
• A general tolerance callout for everything not individually toleranced
• Surface finish requirements, stated only where they actually matter
• Thread callouts with the full standard designation, not just a nominal size
• Any GD&T that applies

3. Material grade, stated deliberately

“Delrin” or “acetal” alone tells a shop to use whatever is on the shelf. If a substitution would be a problem, say so:

Material: acetal copolymer, natural. Substitution with homopolymer requires approval.

If you are not sure which grade the part needs, say that instead, and ask the shop to recommend one based on the service conditions you describe in the next item. A shop that machines acetal regularly can usually make a good recommendation once it knows what the part does.

4. Service environment

This one item resolves more material and process questions than any other single piece of information on the RFQ. State:

• Operating temperature range
• Whether the part is wet, submerged, or exposed to washdown, and how often
• Any chemical exposure, including cleaning agents
• Whether the part is load bearing, and whether that load is constant or intermittent
• Any regulatory requirement, such as food contact or a specific industry certification

5. Quantity, including the repeat expectation

State the quantity for this order, and separately, whether the part is expected to repeat. Setup and programming are paid once per order regardless of quantity, so a part quoted as a one-off looks very different in price per piece than the same part quoted with a known annual volume, even if the piece quantity on this particular order is identical.

6. Tightest tolerance, and which dimensions it applies to

Acetal’s thermal expansion, roughly ten times that of steel, means a stated tolerance is meaningless without an inspection temperature. Add one line:

Inspect at 20 degrees C after the part has stabilised at room temperature for at least two hours.

Without it, a part that measures correctly in a warm shop and a part that measures correctly in an air conditioned inspection room can be reporting two different realities about the same feature.

7. Surface finish and edge condition

State a maximum roughness only on the faces where it matters, such as a sealing face or a visible surface, and explicitly release the rest to a standard as-machined finish. Separately, state the edge break requirement. Acetal holds a fine, flexible burr that does not snap off the way a metal burr does, and deburring it is real labor that belongs in the quote only when the drawing asks for it.

8. Preferred supplier region, if it matters

If the part needs to ship from, or be inspected by, a shop in a specific region, state that upfront. It narrows the pool of shops a match can draw from, and it is better to know that before quotes come back than after.

9. Files or certificates required with the order

Material certificates, food contact compliance documentation, first article inspection reports and any other paperwork all take real time to prepare and should be requested at RFQ stage, not after the order is placed. A shop pricing a part with paperwork attached prices the paperwork too.

10. Needed-by date

A realistic date, not an aspirational one. If the part needs a stress relief cycle for a tight tolerance, that alone can add several days to lead time before the shop even starts finishing operations. Knowing the real deadline lets the shop tell you honestly whether it fits, rather than promising a date it cannot hold.

A filled-out example

Here is what a complete RFQ note block looks like for a real part:

PART: Gear housing bushing
FILES: bushing_rev3.step, bushing_rev3.pdf
MATERIAL: Acetal copolymer, natural. POM-C. Substitution with
          homopolymer requires approval.
QUANTITY: 25 pieces now, expected to repeat quarterly at similar volume.
TOLERANCE: General ISO 2768-m. Bore diameter and outer diameter
           (marked on drawing) held to +/-0.025 mm.
INSPECTION: 20 degrees C, part stabilised 2 hours minimum.
FINISH: Ra 0.8 max on bore (face A). Others as machined.
EDGES: Break all sharp edges 0.2 to 0.4 mm.
ENVIRONMENT: Indoor, 15 to 45 degrees C, occasional light oil
             contact, no washdown.
REGION: No preference.
DOCS: Material certificate with first shipment.
NEEDED BY: 4 weeks from PO.

Nine lines. That block removes nearly every assumption a shop would otherwise have to make, and it is short enough to write in a few minutes once the part is finalised.

Common RFQ mistakes and what they cost

No grade specified. The shop guesses. If the guess is wrong, you find out after the parts arrive, not before.

A blanket tight tolerance. Every dimension gets treated and inspected as critical, which inflates the price without improving the part.

No inspection temperature on a tight tolerance. Two shops using different shop temperatures produce parts that both measure “in tolerance” by their own gauge and disagree with each other.

No stated quantity trajectory. A one-off quote and a repeat-order quote price the fixed costs completely differently. Not stating which one this is leaves the shop guessing at your intent.

Files that do not match. A model and a drawing that disagree with each other force the shop to choose which one to trust, or to stop and ask. Either way, it costs you time.

What a complete RFQ buys you

Faster responses, because the shop is not stopping to ask basic questions. More comparable quotes, because every shop quoting is working from the same assumptions. And fewer surprises on the finished part, because the things that actually decide whether it works were on the page from the start.

Ready to send one? Send your RFQ using the checklist above, and we will match you with up to three shops that machine acetal regularly. Reply within 24 business hours.

Frequently asked questions

Keep reading

• Deburring and Edge Finishing Acetal Without Leaving Fuzz
• Cutting Delrin Sheet to Blanks: Waterjet, Router or Saw