Thailand CNC Processing Guide: How Sourcing Actually Works

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  What this Thailand CNC processing guide covers
• 2
  Five-axis and why it changes the part
• 3
  Tolerance, finish, and the cost of asking too much
• 4
  Material choice and its machining behavior
• 5
  Inspection, documentation, and what you receive
• 6
  Lead time, volume, and how a job is quoted
• 7
  Which process fits your part

A shop in Thailand can quote a part in an hour and still lose the job on a 0.02 mm bore that walks during finishing. This Thailand CNC processing guide explains the mechanics behind the numbers so you can read a quote sheet and know which tolerances are realistic, which materials need special handling, and when a five-axis setup is the only way to hit the drawing.

GreatLight runs three wholly-owned plants, 127 high-precision CNC machines, and 16 simultaneous 5-axis machining centers. Maximum processing size reaches 4,000 mm, and tight work is held to ±0.005 mm. Nothing here is a sales claim. It is the physical envelope that decides whether your geometry, material, and volume fit a given process.

Read this if you are an engineer or buyer comparing suppliers across the region, or if you already have a design and want to know what the shop will actually change before it cuts. The process sections below move from machine setup to inspection, because that is the order a real job flows.

On a three-axis mill, every new face means a new fixture and a new zero. That is where stack-up comes from. A five-axis center holds the part and tilts the tool, so a compound angle, a deep pocket, or a port with a curved exit can be cut in one setup. Fewer setups means fewer datum shifts, and datum shifts are the main cause of holes that do not line up after anodizing.

The limit is not the number of axes. It is stiffness at the tool tip. When you tilt a long tool into a deep cavity, the effective cutting diameter drops and chatter rises. In practice we cap unsupported tool length at roughly 4× diameter for finishing passes in aluminium, and lower for stainless or titanium. If a feature needs more reach, we adjust stepdown and feed rather than promise a number the setup cannot hold.

Rotary tables on our compact cells are Ø400 mm. Parts that fit there can be cut on all faces without re-clamping. Parts above 4,000 mm, or parts with a thin wall under 0.8 mm, usually need a different strategy: mill-turn, soft jaws, or a stress-relief step between roughing and finishing. A five-axis machine does not remove the need for a process plan; it changes which plan is possible.

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  Use five-axis whenCompound angles, deep 3D contours, or five faces in one datum.
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  Stick to three-axis whenFlat plates, prismatic blocks, and loose tolerances keep fixtures simple.
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  Watch the toolLong reach is the first thing that breaks tolerance.

A tolerance is a budget. You spend it on geometry, heat, and handling. General machining holds ±0.05 mm without argument. Below ±0.01 mm the shop starts controlling temperature, tool wear, and clamping force. At ±0.005 mm the part is measured in a controlled room and the process is locked. That is where GreatLight works for bores, spigots, and mating faces, but only on features that need it.

Surface finish behaves the same way. As-machined surfaces sit at Ra 1.6–3.2 μm. A good high-finish pass reaches Ra 0.8–1.6 μm, and fine finishing with the right insert and coolant gets Ra 0.2–0.8 μm. Asking for Ra 0.2 μm on a large face is possible but slow, and it rarely survives bead blasting or anodizing without a masking note on the drawing.

The trap is calling out one global tolerance in the title block. A shaft with a ±0.005 mm journal and a ±0.2 mm flange does not need the whole part held to the tight number. Put the tight callout on the feature that functions, and let the rest breathe. That single change often removes a grinding operation and cuts days from the route.

Aluminium 6061-T6 machines fast and holds a fine finish, which is why it carries most prototype and enclosure work. 7075 is stronger but more prone to distortion after heavy roughing; it usually needs a rough, a stress-relief pause, then a finish. 2024 behaves similarly and is common in aerospace brackets where strength matters more than corrosion resistance.

Stainless 303 is the free-machining grade and takes a clean thread. 304 and 316 work-harden if the tool rubs, so speeds stay high and feeds stay firm. 17-4PH (SUS630) machines well in the solution-treated state and is often heat treated after machining; the growth from that step must be planned into the stock. Titanium TC4 (Ti-6Al-4V) and Inconel cut slowly, generate heat, and wear tools, so they belong in jobs where the alloy is specified for a reason.

Plastics are not a shortcut. POM and PA move with temperature, PEEK needs sharp tooling and slow feeds, and carbon fibre destroys edges. For any of these, we plan the fixture and the coolant before the first cut. If your design allows a material swap, say so on the RFQ. A switch from 316 to 303 on a non-wetted part can cut machining time without touching function.

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  Aluminium6061, 6061-T6, 2024, 5052, 5083, 6063, 6082, 7075, ADC12.
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  Stainless303, 304, 316, 316L, 420, 430, 431, 440C, 17-4PH.
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  Titanium and specialTA1, TA2, TC4 (Ti-6Al-4V), Inconel, magnesium AZ31B / AZ91D.
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  PlasticsABS, PC, PMMA, POM, PA, PEEK, PP, HDPE, carbon fibre.

A part is not done when the spindle stops. It is done when it measures. We inspect 100% of parts before shipment, with a raw material check at goods-in, in-process monitoring during the run, and a final inspection against the drawing. Reports are issued on request. For a first article, that means dimensional results on the features you flagged, not a generic pass stamp.

The measurement method matters as much as the number. A bore checked with a plug gauge is not the same as one checked on a CMM with a scanned point cloud. If your assembly depends on position tolerance, ask for the method to be stated on the report. On tight work we use controlled temperature and record the result at the same conditions every time, so the data is comparable across lots.

Documentation supports the paperwork side too. GreatLight holds ISO 9001:2015, IATF 16949:2016, ISO 13485:2016, and ISO 27001:2022. For medical and automotive programs that means the quality system and the information controls are already in place. Uploads stay secure and confidential, and an NDA is available on request before you share drawings.

Quotation and a free DFM analysis go back within 12 hours. Production can start within 24 hours of a released order, and parts ship in 3–5 days for standard work. Those windows assume the drawing is complete and the material is available. If a feature cannot be cut as drawn, the DFM note tells you before the order, not after the first article fails.

Volume changes the method, not just the price. There is no minimum order quantity. One prototype and a 10,000+ part run both go through the same first-article check. At low volume we favor five-axis and mill-turn to avoid fixture cost. At higher volume we look at dedicated fixtures, pallet changers, and whether die casting or vacuum casting removes machining steps. That decision is made on the drawing, not on a sales target.

Late delivery carries real cost, so we track it. Historical late-delivery probability is below 2%, and the qualification rate is 99.99%. Those numbers come from the same inspection data described above. They are not a guarantee on your specific part; they are the baseline the shop is held to.