Complete guide
What a Machined Weldment Costs
A machined weldment is priced in two halves that rarely sit in the same part of the shop. The welding half is labour and consumables. The machining half is machine hours and workholding. Shops are strong in one or the other, so the same drawing comes back looking like it was for different parts.
Here is what sits inside those numbers, and which of it you control.
The eight lines that move
Roughly in order of how much they swing a quote on a typical industrial frame.
Plate grade and thickness
High strength and abrasion resistant plate cost more per kilogram and are slower to cut, bevel and weld. Thickness drives weld volume, which drives almost everything downstream.
Weld length and joint preparation
Total weld length and whether the joints are fillets or prepared full penetration welds. A full penetration joint needs a bevel, more passes and usually an inspection method.
Weld quality level and inspection
ISO 5817 level B on every joint costs far more than level C where it matters and level D elsewhere. Ultrasonic and radiographic testing add a supplier, a report and a few days.
Stress relief
Oven time, handling and freight if the shop does not own an oven that fits the part. It is cheap compared with scrapping a machined frame that moved.
Machining envelope and setups
Whether the part fits one machine in one setup. Every re-fixture on a heavy weldment is hours of crane time and a new alignment, and it puts tolerance at risk.
Flatness, parallelism and bore position
Tight geometric tolerance across a long part means slower cuts, more measurement and sometimes a second pass after the part relaxes.
Coating and masking
Blast, prime, paint or galvanising, plus masking every machined face and thread. Galvanising after machining will move the part, so the sequence has to be decided at quote time.
Weight and freight
Weldments are heavy and bulky. On a large frame the transport line can rival the machining line, which is why supplier region is a real question and not a preference.
What you control, and what you do not
Negotiating the shop rate is the least effective lever on this list.
- You control the weld quality levelPer joint, not per drawing. The single biggest avoidable cost in this niche.
- You control the inspection scopeName the method and the extent per weld with a weld map. "NDT per drawing" gets priced as the worst case.
- You control the geometryTight tolerance only where the machine design needs it. Across a long part the error budget is fixed while the distance grows.
- You control how many setupsMachined features on fewer faces is a fundamentally cheaper part. Every re-fixture on a heavy frame is crane time and a fresh alignment.
- You do not control plate availabilityThe most common reason a quoted lead time slips, and it sits outside the shop entirely.
- You do not control subcontract queuesStress relief, galvanising and radiography are often bought in. Your part joins a queue in a business you have no relationship with.
- You do not control the rework loopA rejected weld is grind out, re-weld, re-inspect, with more heat into the part each time.
- You do not control freight physicsWeldments are heavy and do not stack. On a large frame transport can rival the machining line.
Go deeper
- Why Two Shops Quote the Same Weldment 40% ApartThe eight lines that decide what a machined weldment costs: plate grade, weld length, quality level, inspection, stress relief, setups, geometric tolerance and freight.
- A36, S355 or A514: What the Grade Does to Your Weldment PriceHow structural steel grade changes welding, preheat, distortion and machining on a weldment, and when the higher strength plate is worth paying for.
- Why One Setup Is Cheaper Than Three on a Two Tonne FrameHow machine envelope, crane capacity and the number of setups drive the machining cost and the tolerance risk on a large weldment, and how to design for fewer setups.
- Coating a Weldment Without Ruining the Faces You Just MachinedMasking, coating sequence and the distortion risk of hot dip galvanising on machined weldments, plus what to specify so machined faces arrive usable.
- Why a Machined Weldment Takes Ten Weeks and Not ThreeA realistic breakdown of machined weldment lead time: material, cutting, fit-up, welding, stress relief queues, machining, inspection and coating, and how to compress it.
Related: the complete machined weldment guide, tolerances, and the machining allowance calculator.
Questions about price
Why do two shops quote the same weldment so differently?
Because each one prices its own bottleneck. A shop with a large horizontal boring mill and a small welding bay prices the welding high. A shop with twenty welders and one old bed mill does the opposite. Both quotes can be honest and land far apart on the same drawing.
What single change reduces a weldment price the most?
Applying the weld quality level per joint instead of across the whole frame. A blanket ISO 5817 level B note slows the welding, adds grinding and creates rework on joints nobody was worried about. Level B where the joint is loaded and level C or D elsewhere is usually the largest saving available on the drawing.
Does a higher strength steel cost more overall?
Not always. Higher strength plate costs more per kilogram, but if it lets you use thinner sections the weight, weld volume, machining time and freight all fall. Where it loses is on parts governed by stiffness, because every structural steel has essentially the same elastic modulus and thinner plate simply deflects more.
Is stress relief worth paying for?
On a heavily welded frame carrying machined features that must hold position, yes. Oven time and two crane moves are cheap next to finish machining a frame that then relaxes and takes a bow into the bore alignment.
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