A welded robot module can have clean beads and still fail at the mounting pads, actuator axis or mating hole pattern. It can also meet an overall dimension while a local weld is undersized, obstructed or positioned against the drawing. Inspection therefore has to connect three levels of evidence: the weld itself, the completed geometry and the assembly’s functional interface.
For buyers of robotic welded OEM assemblies, a request for “full inspection” is too vague. The RFQ should identify what is checked during first article, what is monitored during production, which gauges are acceptable and what records must travel with the lot. The released drawing and inspection plan—not a generic shop practice—set the acceptance criteria.
DRAmetal’s scope is build-to-print mechanical manufacturing and agreed inspection. The robot OEM or integrator owns loads, motion, controls, weld-process qualification, functional safety and final machine validation.
For commercial sourcing, use the robotic welded OEM assembly manufacturing page for multi-part modules and the robotic welded OEM bracket page for individual localized brackets. The upstream bracket DFM guide covers joint and fixture choices; the distortion and flatness guide covers restraint state and datum-based dimensional evidence.
Start with the final assembly interface
Before selecting gauges, map the features that decide whether the welded module can be installed and perform its mechanical function. Typical examples include a base plane, machined pads, pilot bores, actuator axes, cross-member spacing, cable clearance, hardware orientation and a mounting pattern shared across several parts.
These features form the inspection hierarchy. Local component dimensions support the hierarchy; they should not replace it. If three brackets are individually within tolerance but their welded relationship prevents the motor from seating, separate part reports do not prove assembly conformity.
Create a characteristic list tied to the drawing. For each item, record:
- Characteristic or balloon number and drawing revision.
- Nominal value, tolerance and datum reference.
- Inspection state: in-process, as-welded, post-machined or finished.
- Free-state, restrained or installation-simulating condition.
- Measurement method and responsible inspection source.
- Sampling or frequency defined by the buyer’s quality plan.
- Required result format, photographs or setup record.
This list becomes the backbone of the welded assembly FAI and later production evidence.
Use FAI to verify the released manufacturing route
First-article inspection is most useful when it proves more than a final set of numbers. It should confirm that the released materials, component revisions, fixture configuration, weld sequence, machining route, finish and measurement setup can produce an acceptable assembly.
Review the FAI at defined stages when later work will hide or alter a feature. Joint fit-up may need checking before welding. A machined pad may need stock confirmation after welding but before cutting. A threaded insert may become inaccessible after a cover is installed. The buyer and supplier should agree these hold points before production begins.
Do not let a production fixture silently become the inspection standard. The fixture may be appropriate for an in-process check, but the final assembly could relax or move after unclamping. When the drawing calls for a free-state result, measure it in that state. When restrained inspection represents installation, define the support points, fastener or clamp sequence and permitted restraint.
The downloadable robotics frame FAI and datum checklist provides a practical structure for characteristic IDs, equipment, results and deviation records.
Match weld gauges to the specified characteristic
Weld gauges are simple and valuable when they are used for the characteristic they can actually assess. A fillet gauge can compare leg length or throat-related geometry depending on its design and application. A bridge-cam-style gauge can support checks such as reinforcement, undercut or offset. Feeler gauges can document an accessible fit-up gap. None of these tools proves hidden penetration, metallurgical condition or complete-system strength.
The drawing should define weld symbols, size, length, location, contour and any special acceptance criteria. The inspection plan should then name the method and access condition. If a gauge cannot seat because a gusset blocks it, the team needs an approved alternative—not an estimated result.
| Inspection question | Possible evidence | Important limitation |
|---|---|---|
| Is the accessible fillet profile consistent with the symbol? | Appropriate fillet gauge and visual record | Does not prove hidden fusion or strength |
| Is undercut or reinforcement within the released criterion? | Suitable weld gauge at defined locations | Surface access and gauge orientation matter |
| Was joint fit-up within the approved range? | Feeler or gap gauge before welding | Must be checked before the joint closes |
| Did welding shift the mounting relationship? | Fixture check, height gauge, CMM or qualified method | A weld gauge cannot prove assembly geometry |
| Is a defect internal or subsurface? | Drawing-defined NDT from a qualified source | Visual and dimensional tools are insufficient |
If welding procedure specifications, operator qualifications, NDT or third-party inspection are required, name them in the RFQ so the correct route can be reviewed and quoted. Do not infer certification from the presence of inspection records.
Separate weld quality from dimensional conformity
Weld evidence and dimensional evidence belong in the same release package, but they answer different questions. Weld evidence addresses the released joint requirements. Dimensional evidence addresses where the components ended up after fit-up, heating, contraction, machining and finishing.
Measure important relationships from functional datums rather than convenient rough edges. On a motor module, that might mean the pilot axis relative to the base pads. On a robot frame, it may be the relationship between mounting planes. On a guarded sensor module, it can be the sensing face relative to the installed bracket pattern.
The measurement method must suit the tolerance, geometry and part size. A CMM report can be useful, but only when the alignment, probe access, uncertainty and inspection state are appropriate. A purpose-built checking fixture may be faster for repeat production, but its masters, wear checks and correlation to the drawing need control.
Ask the FAI package to show both the measured result and the setup that produced it. A photograph or simple setup record showing supports, datum simulators and restraint often prevents disagreement between supplier and receiving inspection.
The robotic welded OEM subassembly RFQ checklist explains how BOM, assembly drawings, datums and machining requirements should be released before this evidence is requested.
Define production evidence before the first lot
An excellent FAI does not automatically define routine production control. The buyer should identify which characteristics are checked every unit, by lot, after a tooling change or at another released frequency. The choice depends on risk, process stability, detection method and contractual requirements; there is no universal sampling rule for every robot weldment.
A practical evidence package may include:
- Purchase order, released drawing and approved revision list.
- Material or supplier records only where specified and available.
- Traveler showing the agreed manufacturing and inspection stages.
- Fixture or nest configuration used for the assembly variant.
- In-process fit-up and weld checks required by the plan.
- Final dimensional report for specified CTQs.
- Weld visual, gauge or drawing-defined NDT results.
- Hardware, finish and complete-module verification.
- Nonconformance and approved deviation records, if applicable.
- Packout identity tying the assembly and loose items to the correct revision.
When a process, fixture, component source or design changes, define whether the existing FAI remains valid. Requalification triggers should be written into the quality plan rather than decided only after a dimensional problem appears.
Review evidence for usefulness, not page count
A large report can still miss the installed relationship. Before approving an FAI, check that characteristic IDs match the current drawing, results include units, missing checks are explained, deviations have approved dispositions and the measurement state is reproducible.
For repeat lots, look for trends around the features most sensitive to heat and tooling wear. A locator that gradually shifts may remain within tolerance today but indicate a maintenance need. The buyer owns any capability or trend requirements and should state them explicitly if they are contractual.
DRAmetal’s quality-control page describes the project-defined boundary for inspection methods and records. It does not imply a sector certification or finished-robot approval.
Use representative scenarios carefully
Related customer project: Modular Robot Assembly: One Shared Datum Plate.
For a quote-ready package, provide the assembly model, component drawings, BOM, weld symbols, functional datum map, CTQ list, machining stages, finish, required qualifications, inspection state, report format, variants and quantities. The robotics industry hub can help place the module within the broader mechanical program.
DRAmetal can review a released build-to-print package for fabrication and agreed inspection. The OEM or integrator retains responsibility for structural adequacy, robot motion, process qualification, controls, guarding, safety and final machine acceptance. When the evidence and supply boundary are clear, submit the robotic welded assembly RFQ.
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