| 1. Sheet preparation | Coil decoiler, leveler, feeder, and sheet-cutting system | Feeds and levels sheet material, then cuts blanks to the required size. | Flat blanks for tub forming | Blank dimensions, flatness, surface condition, and material identification |
| 2. Tub forming | Hydraulic or mechanical press with dedicated forming dies | Forms the tub body from sheet; the method depends on the tub design and material. | Rough-formed tub body | Form depth, profile, wrinkles, cracks, and visible surface marks |
| 3. Trimming and hole-making | Trim press, punching tools, or CNC cutting equipment | Removes excess material and creates openings for functional features and assembly. | Tub with trimmed edges and specified openings | Hole position, edge quality, burrs, and dimensional accuracy |
| 4. Edge forming and flanging | Flanging press, hemming tools, or roll-forming equipment | Forms edges and mating surfaces needed for stiffness, sealing, or joining. | Tub panels with formed edges | Flange dimensions, edge consistency, and fit at mating joints |
| 5. Panel joining | Resistance spot-welding system, laser welding equipment, or mechanical joining tools | Joins panels or seams where required by the tub construction. | Joined tub structure | Joint position, weld or fastener consistency, distortion, and appearance |
| 6. Seam sealing | Metered sealant dispenser and controlled curing station, if specified | Applies sealant to designated joints when required by the product design. | Sealed tub seams | Bead continuity, placement, and curing condition |
| 7. Cleaning and surface preparation | Industrial washing, rinsing, and drying equipment | Removes process residues before inspection or downstream assembly. | Clean tub assembly | Residue, moisture, contamination, and surface condition |
| 8. Bracket and feature installation | Assembly fixtures, robotic or manual fastening tools, and gauges | Installs specified brackets, supports, or other tub-mounted features. | Tub with required attachments | Part presence, position, fastening condition, and fit |
| 9. Insulation application | Insulation cutting and placement fixtures or automated application equipment | Fits insulation around specified tub surfaces where the design calls for it. | Insulated tub assembly | Coverage, placement, retention, and clearance from interfaces |
| 10. Final inspection and leak testing | Dimensional gauges, inspection fixtures, and a suitable leak-test setup where applicable | Verifies assembly dimensions and checks specified joints or seams for leakage. | Inspected tub ready for the next assembly stage | Critical dimensions, joint condition, leakage result, and inspection records |