Sheet hydroforming

In the worked example, a 1.20 mm starting sheet and 1.02 mm local formed wall give 15.0% local thinning and 0.02 mm nominal margin over a 1.00 mm local minimum. A mean thickness cannot establish the minimum. Measure critical regions and apply the agreed uncertainty and acceptance rule.

A fluid-cell diaphragm presses sheet against a rigid tool. In punch-assisted hydroforming, punch travel and pressure history together draw the sheet. Specify the arrangement before transferring parameters. Beckwood, Understanding Sheet Hydroforming, undated white paper

Distinguish the routes

The first two descriptions follow Beckwood's white paper. The tube distinction follows JSOL's tube-hydroforming simulation example, which identifies internal pressure and axial-feed timing as formability influences. Do not apply a tube-process pressure schedule or expansion result to an unrelated sheet process. Beckwood, JSOL, tube example, undated

Tooling and blank design

Quintus describes Flexform fluid-cell use with block, cavity and expansion dies and explains how a flexible diaphragm can accommodate different tools within one forming operation. This can reduce matched-tool requirements, but “one rigid tool half” does not mean no locating, restraint, wear protection or trimming provisions. Identify which tool surface controls the functional geometry and how the blank is positioned and extracted. Quintus, Flexform fluid-cell presses, undated

Blank shape is part of the route. Supply the finished model and the material specification, then agree the developed blank, rolling direction, locating features, trim boundary and any intermediate operations with the forming specialist. A final CAD surface does not establish the amount or direction of material available to feed a corner or flange. Keep any holes used for location separate from finished holes whose position must be accepted after forming and trimming.

Pressure does not replace material-flow control

Beckwood's Triform deep-draw description places the blank on a draw ring, then moves the male punch upward into the bladder while applying forming pressure at each step or punch height. After forming, the bladder decompresses and the punch retracts. This is a pressure–motion relationship, not a single pressure value. Existing punch and draw-ring tooling also requires review and potentially adapters for the proposed press. Beckwood, Triform deep-draw process, undated

Specify the material grade, temper/condition, thickness range, surface and lubrication requirements used in qualification. For a process change, identify which of those inputs changed before reusing a successful pressure program. Uniform applied fluid pressure should not be interpreted as proof of uniform strain, uniform remaining thickness or complete tool contact throughout a complex part.

Thinning, wrinkling and released shape

Churiaque and colleagues' original paper, published June 1, 2018, investigates fluid-cell hydroforming of UNS A92024-T3 aluminum. It identifies wrinkles, cracks and elastic recovery as relevant outcomes and compares real parts with simulations. The work examines material characterization, rolling direction and hardening descriptions as influences on the prediction. These results support material-specific validation, not a springback correction valid for all aluminum sheet. Original study, publication details and scope

Check shape after pressure release at the specified inspection stage. Tool-contact geometry under load and final released geometry are different states. If the proposed route includes hand correction, restriking, intermediate heat treatment or final machining, identify those steps explicitly and inspect the delivered condition. A claim of reduced secondary work is not acceptance evidence for the particular component.

Temperature is a qualified route variable

A Quintus-authored paper presented at ICAS, September 4–9, 2022, studies forming Ti-6Al-4V sheet at moderate temperature combined with high pressure. It describes the diaphragm separating the blank from the pressurizing fluid and a single rigid tool half. The existence of this developed thermal route is a reason to distinguish cold forming from temperature-assisted equipment and procedures; it is not permission to heat an arbitrary diaphragm press or use one temperature for every titanium alloy and condition. Quintus authors, ICAS 2022 paper

A bounded equipment and trial example

Quintus lists its Swedish application-center QFC 0.7 × 1.8–1400 with 700 × 1,830 mm usable tray area, 175 mm tray depth and 1,400 bar maximum operating pressure. These describe the named installation, not guaranteed part dimensions or required forming pressure. Tool height, diaphragm behavior, material and geometry still require an application review. Quintus, application-center equipment, undated

The center offers process development, logged trial results and separately scoped external evaluation of properties such as microstructure, mechanical behavior and fatigue. That distinction is useful when requesting a demonstration: an acceptable visual shape does not automatically establish the material or service-performance evidence required by the drawing. Agree the trial's purpose and examinations in advance. Same application-center description

Original thickness calculation

Assume an invented starting sheet thickness of 1.20 mm, a measured local post-form thickness of 1.02 mm, and an ordered minimum remaining thickness of 1.00 mm:

local thinning = (1.20 − 1.02) / 1.20 × 100 = 15.0%

nominal margin above minimum = 1.02 − 1.00 = 0.02 mm

Check starting-thickness variation, measure critical regions and apply the agreed decision rule. Use a qualified forming limit for development.

Manufacturing handoff and acceptance

Specify four groups of information:

1. Material: grade/condition, thickness envelope, rolling direction, surface and traceability.
2. Geometry: released shape, datums, local thickness limits, radii/flanges, trim and finished-hole requirements.
3. Route: fluid-cell or punch-assisted configuration, tooling and locating, pressure/motion program, thermal and secondary operations.
4. Acceptance: measurement stage/support, dimensional coverage, thickness mapping, crack/wrinkle/surface criteria and ordered material or functional tests.

Evaluate the complete delivered part rather than only the press capability. The cited supplier pages and Beckwood white paper have no separately verified issue date here; the dated research is identified above. Neither the source examples nor the original calculation supplies a universal pressure, draw depth, temperature or cycle recipe.