CNC Machining Insights

Engineering notes from our shop floor in Shenzhen. These guides cover the decisions that actually move part cost and lead time - process selection, tolerance allocation, surface finish, material choice, and how to vet a supplier - written for engineers and buyers who are specifying turned and machined parts from China.

• Swiss-Type vs Conventional CNC Lathe: How to Choose — guide bushings, the L/D rule, part size envelope and cost per part.
• DFM Checklist for CNC Turned Parts (12 Checks) — the checks to run before you send a drawing for quotation.
• CNC Machining Tolerances: What Is Achievable — standard vs precision bands, how tolerance drives cost, and datums that work.
• CNC Surface Finish Guide: Ra Values & Anodizing — what Ra means, as-machined finishes, anodizing types and how to specify.
• CNC Machining Materials Guide — aluminium, stainless, steel, titanium and plastics - grades and machinability.
• What Drives the Cost of CNC Machining in China — the cost structure behind a quote, and how to lower unit cost honestly.
• Vetting a China CNC Supplier: A 10-Point Checklist — due diligence on licences, certifications, equipment and IP before you commit.
• Lead Time and Shipping for CNC Parts from China — how lead time is built, and how parts actually reach the US and EU.
• 5-Axis vs 3-Axis CNC Machining: When to Use Which — what the extra axes buy you, and when three is enough.
• CNC Machining vs 3D Printing for Prototypes — material, tolerance and cost crossover between the two routes.
• Low-Volume and One-Off CNC Machining — how a single part is quoted, and how to make small runs economic.
• Machining Humanoid Robot Joint and Finger Parts — tolerances, materials and DFM for joint and finger components.

Why this section exists

Most of the cost in a turned or machined part is decided before the first chip is cut - in how the part is designed and which process it is routed to. A feature that adds hours on a fixed-headstock lathe can be routine on a Swiss-type machine, and a tolerance that looks harmless on a drawing can double the inspection burden.

These articles are written by our engineering team at CHX Metal (Shenzhen Changhexin Precision Hardware Co., Ltd.), a precision CNC machining manufacturer founded in 2013 in Shenzhen, China. We run 220 machines in-house - including 70 Tsugami Swiss-type sliding-headstock lathes, 50 CNC lathes and 100 CNC machining centres - with 8 in-house inspection instruments including a CMM, and a monthly capacity of up to 5,000,000 pcs.

The goal is simple: give you the same rules of thumb we use when we quote a part, so you can design for the process instead of discovering its limits after a quote.

How we work

We accept 2D PDF drawings, 3D STEP/IGES models or physical samples. Every order is quoted by an engineer who works to your drawing revision. Standard tolerance is +/-0.005 mm, with +/-0.005 mm on critical features, verified by CMM. DFM feedback is returned with the quotation.

CHX Metal holds ISO 9001:2015 (certificate NOA198428, valid to 2028-06-30) and ISO 14001:2015 (certificate NOA2100184, valid to 2027-01-04), issued by NOA, an IAF Multilateral Recognition Arrangement member. IATF 16949 and ISO 13485 are being implemented and are not claimed as held.

Frequently asked questions

Do you write these guides for your own products, or as general engineering references?

Both. The rules of thumb here are general machining principles, and where we describe capability we describe what our own shop does, so you can compare it against your requirements.

Can I send a drawing for a DFM review even if I am not ready to order?

Yes. Send the drawing or 3D model and you will get DFM feedback and a quotation - there is no obligation, and there is no strict MOQ. We run a single prototype through to volume production.

How quickly do you reply to a quotation request?

Quotation requests are returned within 12 working hours. Prototypes typically ship in 3-7 days and production batches in 7-15 days, plus 5-10 days if surface treatment is required.

Shenzhen Changhexin Precision Hardware Co., Ltd. (CHX Metal) · Shajing Street, Bao'an District, Shenzhen, Guangdong, China · ISO 9001:2015 (NOA198428) · ISO 14001:2015 (NOA2100184)