To source CNC turned parts in India, send a complete drawing package, shortlist shops that already turn parts of your size and material, and approve first-article samples before any volume order.
A CNC turned parts manufacturer is only as good as its inspection. The machines are easy to buy. Holding the same tolerance on the ten-thousandth piece is the hard part.
What goes into a good enquiry?
Most failed first orders trace back to an incomplete enquiry. Send a package that lets the shop quote the real job:
Our guide to what makes a turned component explains the basics. For brass parts, writing a specification for a turned brass component goes into more detail.
- A dimensioned drawing in PDF, plus a CAD file where available.
- The material as a standard designation, with the certificate type you need.
- General and critical tolerances, with the critical dimensions clearly marked.
- Surface finish, deburring, plating or heat treatment.
- Annual volume and the size of each release.
- Packing rules, such as separation of parts to avoid thread damage.
Fixed-head or sliding-head: which shop do you need?
Small, long, slender parts in large numbers usually suit sliding-head machines, because the bar is supported close to the cutting tool. Larger, heavier parts suit fixed-head turning centres. A shop with only one type may quote a poor fit to your part.
Ask which machines would run your job and how many of them. A shop with several of the same machine can cover a breakdown. A single machine is a delivery risk. Read about the CNC machines used in Jamnagar for the local picture.
How do you check a shop's quality system?
Look for measuring tools that match your tolerances: micrometres, bore gauges, thread gauges and, for tight work, an optical comparator or coordinate measuring machine. Calibration stickers should be current.
Ask for an in-process inspection plan. Good shops check the first piece after each setup, then check at set intervals, then record the result. Ask to see the records from a recent job.
Material traceability matters too. A mill certificate should link to the bar lot used for your parts. For the audit approach, see what a factory audit should contain.
Ask what happens when a part fails inspection. A mature shop quarantines the lot, finds the cause and records the fix. A weak one reworks the pieces quietly and ships them. Ask to see a nonconformance record from the last few months. If the shop says it has never had one, treat that as a warning, not a boast.
How do you move from samples to volume?
Approve a first-article report before the pilot lot. The report compares each drawing dimension with the measured value on the sample. Do not accept a sample that comes with only a photo.
Then run a pilot lot and inspect it before shipping. Tool wear, coolant and operator changes all show up over a longer run. Agree the inspection plan and the sampling level before production starts, and agree what happens to a lot that fails.
Next step
We shortlist turning shops, audit them, check the first articles and supervise the loading. If you have a drawing, book a free sourcing review and we will tell you which shops are worth sampling.