Guides / Process

Weldments and Machine Frames for Tool Builders

September 24, 2026

Frames, bases, covers and cabinets are unglamorous work, and they are one of the places where the local supply base is genuinely strong. Fabrication capacity in Vietnam grew up around shipbuilding, construction and general industry, so welding a large structure is not the hard part. Holding alignment on it afterwards is.

The sequence that decides the result

1. Cut and prepare, with stock left on every face that will locate something
2. Fit and tack, checking squareness before any full weld
3. Weld, with a sequence planned to balance heat input rather than working along one side
4. Stress relieve, thermally or by another agreed method
5. Finish machine mounting faces, bores and datums, ideally in one setup
6. Finish and paint, masking machined surfaces
7. Inspect against the datum scheme, then pack and crate

Skip step four and the structure keeps moving. Do step five before step three and the alignment is gone before it ships.

What to specify

Requirement	Why it matters
Weld standard and inspection level	Defines acceptance before an argument. Visual, dye penetrant or ultrasonic
Welder qualification	Especially where the weld carries load or forms a boundary
Stress relief, stated in the sequence	The difference between a stable frame and one that walks
Datum scheme for the machined faces	So squareness is measured the way the machine uses it
Flatness over the span, with the measurement method	A long face measured differently reads differently
Paint or coating with masking	Machined faces and threads must stay clean
Lifting points and crating	A two metre base needs a defined handling method

Flatness over a long span

Flatness on a 200 mm plate and flatness across a 2 metre frame are different problems. The part sags under its own weight, the measuring method changes the answer and the temperature in the shop matters more than most people expect.

Say how it will be measured and in what condition: supported at stated points, or bolted to a surface plate. Then require the method on the report. A number without a method is not comparable between two suppliers, which is the whole point of measuring it. The same argument applies to plates, covered in flatness, parallelism and datums.

Where the cost sits

Material is a bigger share here than on small precision parts, so section choice and nesting matter. After that:

• Weld metres and preparation, which scale with joint design rather than with part size
• Stress relief, which is an oven cycle plus transport if the shop does not own one
• The finish machining setup, where a shop that can hold the whole assembly at once beats one that has to reposition
• Crating and freight, which is real money on anything over a cubic metre

Machining a large frame far from the port adds cost that never appears on the quote, which is one of the few cases where geography belongs in the sourcing decision. That is covered in where machining capacity sits in Vietnam.

Why this work suits the local base

A tool builder sourcing frames is buying welding discipline, a big machine and crating, not cleanroom process control. That is the part of the market with the deepest bench here, and it is often the easiest first project for a buyer who wants to test a supplier relationship before trusting it with chamber hardware.

If you have a frame or base to quote, send the RFQ with the weld standard, the stress relief requirement and the datum scheme included and we will match shops that can machine the assembly after welding rather than only weld it.

Frequently asked questions

More on process

• Packing and Shipping Machined Parts to a Fab or Test Floor
• What Cleanroom Machining Actually Requires
• Machining Gas Delivery Components for Semiconductor Tools
• Test Handler Change Kits: What Buyers Should Specify

All guides and the sourcing glossary.