Insights · Choosing a subcontractor

What should you look for in an aerospace machining supplier?

Last reviewed: 9 July 2026

The short answer

An aerospace or defence machining supplier should hold the right certifications (ISO 9001, ideally AS9100, JOSCAR for defence), prove full traceability, hold tight tolerances with CMM inspection, and have the capacity to deliver. Milltech meets these with ISO 9001, JOSCAR and full traceability.

Approving an aerospace or defence machining supplier is a high-stakes decision — the quality manager has a veto for good reason. Here is what to check, and the questions that separate a capable supplier from a risky one.

What certifications should an aerospace machining supplier hold?

Start with the compliance gate:

  • ISO 9001 — the baseline quality-management standard.
  • AS9100 — the aerospace quality standard, built on ISO 9001 with extra rigour.
  • JOSCAR — the shared pre-qualification register for aerospace and defence supply chains.
  • Cyber Essentials Plus — increasingly expected, to protect drawings and IP.

Milltech holds ISO 9001:2015 (approved by LRQA), is JOSCAR registered and holds Cyber Essentials Plus, and applies aerospace-grade documentation and traceability to defence work.

Why does traceability matter for aerospace parts?

Because the parts are flight-critical and audited. Full material and process traceability lets a buyer prove what each part is made of and exactly how it was made — and, if an issue ever arises, identify every affected part. Without it, a supplier cannot pass an aerospace audit or stay on the approved-vendor list. Milltech tracks every job live through Tricorn® ERP, from raw bar to dispatch.

What capability and capacity should you check?

Confirm the supplier can actually make your part, repeatably:

  • Multi-axis machining for complex geometry and undercuts.
  • Tight tolerances — and CMM inspection to verify them.
  • Material experience with the alloys your parts use.
  • Capacity and stability — enough machines, and a business that will still be there in five years.

How does Milltech meet aerospace supplier requirements?

Milltech machines flight-critical and defence components to tight tolerances on a deep multi-axis fleet, verifies them by CMM inspection, and supplies full traceability under an ISO 9001:2015 quality system — JOSCAR registered and Cyber Essentials Plus certified, with the capacity of 40+ CNC machines and the backing of the Indutrade Group. Send your drawings and requirements to discuss your programme.

FAQ

Frequently asked questions

What certifications should an aerospace machining supplier hold?

ISO 9001 as a baseline, AS9100 for aerospace quality management, and JOSCAR registration for defence supply chains. Cyber Essentials Plus is increasingly expected for data security. Milltech holds ISO 9001, JOSCAR and Cyber Essentials Plus.

Why does traceability matter for aerospace parts?

Because flight-critical parts must be auditable and safe. Full material and process traceability lets a buyer prove what each part is made of and how it was made, and identify affected parts if an issue arises.

What capability should an aerospace supplier have?

Multi-axis machining for complex geometry, the ability to hold tight tolerances, CMM inspection to verify them, and experience with aerospace materials — plus enough capacity to deliver on time.

What questions should I ask an aerospace machining supplier?

Ask about certifications, achievable tolerances and inspection, material and process traceability, capacity and lead times, financial stability, and whether they can machine and assemble in one place.

How does Milltech meet aerospace supplier requirements?

Milltech machines flight-critical and defence components to tight tolerances with CMM inspection and full traceability, under an ISO 9001:2015 system, and is JOSCAR registered and Cyber Essentials Plus certified.

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