Why three quotes for one drawing rarely match
A buyer sends one drawing to three suppliers and receives three prices that differ by a wide margin. The drawing is the same everywhere, so the difference has to sit somewhere else: in how each supplier reads the scope, in how much uncertainty each one has priced in, and in the route each has chosen to make the part.
A made to drawing component is not priced from its drawing alone. It is priced from a route: the material purchased, the operations sequenced, the fixtures needed, the inspections performed, and the documents handed over at the end. Two workshops can reach the same geometry by different routes, and that is where most of the spread lives.
Realjet builds custom metal components for machinery OEMs to customer drawings, coordinating cutting, forming, welding, machining, finishing and inspection as one package. The sections below describe how those elements normally appear in a price, and which of them your own documents control.
The cost elements inside a machinery part quote
Every quote for a fabricated or machined part resolves into the same families of cost. The names change between suppliers, but a quote that cannot be mapped to these lines is hard to compare with any other quote.
| Cost element | What drives it | What the buyer should state |
|---|---|---|
| Direct material | Grade, thickness, plate size, market price, nesting yield and scrap allowance | Material standard and grade, and whether substitutes are allowed |
| Cutting and forming | Cut length, number of bends, tool access, machine capacity | Thickness range, bend radii, and any feature close to a bend |
| Welding | Joint type and count, weld length, access, position, distortion control | Welding standard and class, weld size, whether full penetration is required |
| Machining | Fixtured set-ups, tolerance class, surface finish, hole count and position | Which dimensions are critical, the datum scheme, the tolerance class |
| Heat treatment | Whether stress relief is specified, and at which stage | Requirement, or written confirmation that it is not required |
| Inspection and NDT | Inspection level, NDT methods and coverage, documentation | Standard, acceptance level, and who attends third-party inspection |
| Surface treatment | Preparation grade, coating system, masked areas | Coating specification, dry film thickness, colour, areas to be protected |
| Assembly and trial fit | Whether parts are trial assembled, and to what level | Delivery condition: loose parts, sub-assembly, or a finished unit |
| Packaging and freight | Size, mass, fragility, mode of transport, destination rules | Packing level, marking, Incoterms and delivery address |
| One-time work | Programming, fixtures, first article, documentation, approval drawings | Whether each item is quoted once or repeated per unit |
The list is also a checklist of ambiguity. Where a requirement is missing, a supplier does not quote zero for it. It quotes an allowance, and that allowance is invisible in the totals you compare.
Where your own documents set the cost
Four parts of the enquiry move the price more than the geometry does, and all four are under the buyer's control.
Tolerance class
General tolerances, such as those in ISO 2768-1, cover dimensions with no individual tolerance on the drawing. Once a dimension carries its own limit, the workshop has to control it, measure it, and sometimes add a set-up or a fixture to hold it. The practical question is not what the tightest achievable tolerance is, but which dimensions genuinely need to be tight. A drawing where every dimension is individually toleranced usually costs more than the part requires, and it can make a supplier reluctant to bid.
Welding and inspection scope
The welding standard and the acceptance level are priced, not assumed. A supplier working to a documented quality system such as ISO 3834-2 has to hold qualified procedures, qualified operators and recorded inspection, and those obligations appear in the price. The same applies to non-destructive testing: a visual check, dye penetrant and ultrasonic examination are three different operations with three different costs. Naming the methods and the coverage up front is cheaper than discovering after delivery that the joint has to be examined.
Material certificates and traceability
Ordinary mill certificates, certificates with specified test results, and certificates with third-party witnessed testing are three different purchasing routes under EN 10204. If the part is carrying a pressure boundary or a lifting duty, the certificate route is part of the specification and has to be stated, not requested at the end.
Finish, packing and delivery terms
Surface preparation grade and coating system are usually priced per square metre, so the coated area matters. Masked areas, threads and machined faces that must stay bare add labour. On the delivery side, sea freight packing, in-transit protection and Incoterms change both the cost and the risk transfer point. A price quoted free on board and a price quoted delivered are not comparable numbers.
One-time cost, batch size and the unit price
Fabrication quotes contain costs that happen once and costs that repeat with every part. Programming, fixture building, first article inspection, approval documentation and tooling belong to the first group. Material, machine time, welding, finishing and inspection belong to the second.
That split explains most of the shape of a price curve. A single bracket can be dominated by set-up; a run of a hundred spreads the same set-up across far more units. When a quote is compared at two quantities, the difference is not usually a discount. It is the one-time work being divided by a larger number.
Two consequences follow for buyers. First, ask for the one-time items as separate lines so the comparison can be made at the right quantity. Second, treat an unexpectedly flat price as a question: either the set-up has not been estimated properly, or the quantity was understood differently from the way you intended.
When a low price is a transfer of risk
The cheapest quote is usually cheaper because something has been left out, and the omissions are predictable. Common ones are inspection scope, material certification, distortion correction, trial assembly, and packing adequate for the journey.
Risk returns in the form of rework, delay, or a component that arrives within its drawing but not fit for the machine. Two procurement habits reduce that exposure. Ask every bidder to list exclusions in writing, and ask for the inspection and documentation plan alongside the price, so the deliverables are visible before the order is placed.
How to compare quotes that were not built the same way
Comparing totals is unreliable unless the scope is identical. A workable comparison needs five things from every bidder: the drawing revision priced, the material standard and certificate route, the welding and NDT scope, the finish and packing specification, and the delivery terms. When those match, the remaining difference reflects capability and efficiency rather than interpretation.
For larger spend, a simple normalised model is enough to test whether a price is plausible. Break the part into material, operations and one-time work, apply rough yields and cycle estimates, and compare the result with the quote. This is the same principle that public procurement cost analysis applies to proposals under FAR 15.4, where separate cost elements and profit are evaluated rather than a single lump sum. The model does not need to be exact. It needs to show which line explains the gap.
What a supplier needs to price the part firmly
A firm price needs the drawing revision, the bill of materials or a clear parts list, and the specification that sits behind them: material standard and grade, welding standard and class, tolerance class, NDT scope, finish system, marking, packing, quantity and delivery terms. Our note on contract manufacturing drawing and BOM readiness sets out that package in detail, and the welding procedure and NDT scope article covers the welding side.
Where a drawing does not answer a question, a supplier will either ask or assume. Asking is cheaper. Assumptions that turn out to be wrong are the most common reason a firm price moves after an order.
Next step
Before releasing an enquiry, decide which dimensions are critical, which standard governs the welds and how much of them will be examined, which certificate route applies to the material, and how the parts have to arrive. Then send the same package to every bidder, with the exclusions list requested in writing.
With those inputs, the manufacturing review for a made to drawing component becomes comparable across suppliers, and a price can be judged on scope rather than on the size of the number. Realjet reviews enquiries of this kind against drawings, material, volume, standards, documentation and delivery requirements, including the forming, welding, machining, finishing and inspection route the part needs.