Short answer: Send a 2D drawing (PDF or STEP) with material grade, all tolerances, quantity, and application temperature/media — and state which tolerances are critical. A drawing with three dimensions and “make it like the sample” generates three rounds of questions; a complete RFQ package gets a firm quote in 1–2 days.
PTFE parts are machined from stock shapes, so nearly every custom part starts life as a drawing. The quality of that drawing determines both your price and your risk: ambiguous drawings force suppliers to quote conservatively, which shows up as a higher unit price.
The Minimum Drawing Package
- A dimensioned 2D view (PDF) with all functional dimensions and tolerances marked, including cross-section details for seals or spacers.
- A 3D file (STEP or IGES) whenever the part is not a simple revolve — suppliers check machinability against it.
- Material callout: virgin PTFE, modified, or a filled grade with filler type and percentage (e.g., 25% glass-filled PTFE).
- Quantity and expected annual volume — prototype vs production changes the fixturing and quoting logic entirely.
- Service environment: temperature range, pressure, media. This lets the supplier flag grade conflicts before, not after, first article.
Tolerances: The Part Most Buyers Get Wrong
PTFE machines differently from metals — it is soft, springy, and moves with temperature. Blanket tolerances of ±0.01 mm force scrap rates and prices up. Mark critical functional dimensions (e.g., a seal groove diameter) at the precision you actually need, and leave non-functional features at general tolerance (±0.1 mm is routine for PTFE). Chunhuan routinely holds ±0.05 mm on critical dimensions with SPC batch records.
Common Drawing Gaps and Their Cost
| Missing from drawing | Consequence |
|---|---|
| Chamfer/deburr note | Sharp edges on sealing faces; leakage risk discovered at fitting |
| Critical vs general tolerance split | Overquoted price, or first article rejected for a dimension that never mattered |
| Surface finish callout on sealing faces | Wrong tool path; finish rework after delivery |
| Lot marking requirement | No traceability when a field failure needs investigation |
Checklist Before You Hit Send
Material grade stated / critical tolerances marked / quantity and volumes included / service conditions noted / finish and edge requirements called out / revision number on the drawing. A one-minute check against this list typically saves a week of back-and-forth.
Frequently Asked Questions
What file format should I send for a PTFE parts quote?
A dimensioned 2D PDF plus a STEP or IGES 3D file. The PDF is the contractual reference; the 3D file lets the supplier assess machinability.
What tolerances can PTFE machined parts hold?
General features routinely hold ±0.1 mm; critical functional dimensions hold ±0.05 mm with SPC process control. Blanket ultra-tight tolerances raise cost sharply.
Why do suppliers ask for service temperature and media?
PTFE grade selection depends on the environment — filled grades interact with some media, and creep behavior changes with temperature. Early disclosure prevents wrong-grade first articles.
Should I include annual volume in a custom PTFE RFQ?
Yes. Volume determines fixturing and batching strategy, which materially changes unit price and lead time.
English
Russian
French
Spanish