{"id":2306,"date":"2026-07-04T11:28:25","date_gmt":"2026-07-04T03:28:25","guid":{"rendered":"https:\/\/metalstampingparts.ltd\/?page_id=2306"},"modified":"2026-07-04T11:28:25","modified_gmt":"2026-07-04T03:28:25","slug":"stamped-assembly-datum-stack-up-fixture-guide","status":"publish","type":"page","link":"https:\/\/metalstampingparts.ltd\/stamped-assembly-datum-stack-up-fixture-guide\/","title":{"rendered":"Stamped Assembly Datum Stack-Up and Fixture Guide"},"content":{"rendered":"

Short answer:<\/strong> Stamped assemblies should be quoted with final datum stack-up and fixture requirements, not only loose-part drawings. The RFQ should define which features locate the assembly, the joining sequence, fixture clamp points, hardware or weld order, coating sequence, final inspection method, and whether dimensions are checked free-state or restrained like the mating product.<\/p>\n

A stamped assembly can be built from parts that each pass inspection and still fail fit because the datums stack in the wrong direction. Welding, riveting, inserted hardware, coating, and handling can all move the final locating features. The RFQ should define the final assembly condition before price is compared.<\/p>\n

Use this page with the stamped metal assemblies guide<\/a>, datum and functional gage guide<\/a>, riveted and staked assemblies guide<\/a>, and spot welded assemblies guide<\/a>.<\/p>\n

Stamped assembly stack-up decisions<\/h2>\n\n\n\n\n\n\n\n\n
Decision<\/th>\nWhy it matters<\/th>\nRFQ evidence<\/th>\n<\/tr>\n<\/thead>\n
Final datums<\/td>\nLoose-part datums may not match the assembled product.<\/td>\nAssembly datum scheme, mating part, and controlled final features.<\/td>\n<\/tr>\n
Joining sequence<\/td>\nWelding, riveting, staking, and hardware insertion can move dimensions.<\/td>\nOperation order, clamp points, and final check stage.<\/td>\n<\/tr>\n
Fixture restraint<\/td>\nFlexible parts can pass or fail depending on how they are held.<\/td>\nFree-state, restrained, functional gage, or mating fixture condition.<\/td>\n<\/tr>\n
Coating sequence<\/td>\nFinish buildup can change seating, hole fit, and hardware access.<\/td>\nMasking, thread protection, coating thickness, and post-finish checks.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Start with the final assembly function<\/h2>\n

The final product usually cares about where holes, studs, tabs, clips, seal faces, or contact pads end up after assembly. If each loose part is measured alone, the report may miss accumulated variation. The RFQ should show which final features locate to the mating product and which dimensions are only process controls.<\/p>\n

If the assembly uses welded nuts, clinch studs, rivets, tabs, or spot welds, define whether those operations happen before or after coating. A fixture that works before finish may not represent the final product if coating fills holes, changes thickness, or blocks access. For inserted hardware, connect the plan to the insert and stud orientation guide<\/a>.<\/p>\n

Choose a measurement condition buyers and suppliers can repeat<\/h2>\n

Flexible stamped assemblies often need a restrained check. A part may look warped on a table but fit perfectly when bolted down, or it may look acceptable free-state and fail once installed. The drawing should state whether the assembly is checked free, clamped, bolted, or located in a functional gage.<\/p>\n

For launch, the checking method should be part of the quote. A supplier may need a weld fixture, rivet fixture, go\/no-go gage, CMM program, optical check, torque check, or master assembly. If tabs and slots are used to hold location before joining, review the tab and slot self-fixturing guide<\/a> before final fixture cost is accepted. If the buyer owns the fixture, define calibration, storage, revision control, and what happens when the drawing changes.<\/p>\n

RFQ details to include<\/h2>\n