CNC Precision Gears Tooling and Fixture Guide for Automotive Tier Suppliers: the 2026-2027 cycle Guide No.1098

For the UK, CNC precision gears sit inside a longer supply chain, and a small dimensional error at the machine shop becomes a large assembly problem downstream. This guide for Automotive Tier Suppliers sets out what to specify, what to check and what to document before you place the order.

Where the Price Actually Comes From

Freight, duty and inland handling can add more than the unit price difference, so compare landed cost rather than ex-works price. Payment terms are part of the price: a discount paid for with a larger deposit is not a discount. Most quotation gaps come from a different material grade, a different finishing route or a different inspection level, not from shop margin. Ask what the price would be at double the quantity; the answer shows you how much of the quotation is fixed cost.

Finishing, Packaging and Delivery

Confirm who arranges the export documents and the certificate of origin, because that task is often assumed by both sides. Photograph the packed pallet before it leaves the shop; it settles most damage arguments before they start. Rust prevention is the detail that decides whether a shipment arrives usable, especially for ferrous parts on a humid route.

Choosing the Right Material

A good CNC precision gear starts with the case-hardened alloy steel or bronze, so agree the grade, the temper and the certificate before you discuss price. State the material standard, the temper condition and the traceability requirement by number, not by adjective. Cheap substitutes usually appear in the material grade and the finishing step, so inspect those areas first. Ask for the mill certificate rather than a description of the alloy, because the certificate is the only document that travels with the parts.

Choosing the Right Supplier

Visit or video-audit the floor; ten minutes of watching how a shop handles first articles tells you more than a page of certificates. Confirm who owns the drawings, the fixtures and the part programme, especially if you may move the part to another supplier later. Find out whether the shop runs a formal first-article process or simply measures the first good part and ships it. Look at how the shop stores material and tooling; housekeeping on the floor is a reliable predictor of process discipline.

How the Part Is Actually Made

Ask how the part will be held during machining, because fixture design usually decides whether a tolerance is repeatable. Confirm the datum scheme before production, because inconsistent datums produce parts that look right and still will not assemble. Ask the shop to state the process capability it will hold, and to report actual measurements rather than a pass or fail.

Compliance and Traceability

Confirm that the test house is accredited and that the report names your material or your part, not a generic specimen. Traceability claims need heat numbers or lot numbers that follow the parts through every operation. Ask for quality system documentation such as ISO 9001, IATF 16949 or AS9100, dated and covering the site that will run your parts.

Buyer Checklist

Release the drawing, approve the first article, book the inspection, lock the packing and prepare the paperwork. Five steps, and the programme runs smoothly.