SIST EN ISO 12004-1:2021 PDF

Overview

EN ISO 12004-1:2020 (ISO 12004-1:2020) defines a practical, press-shop procedure for developing forming‑limit diagrams (FLDs) and forming‑limit curves (FLCs) for metallic sheets and strips with thicknesses from 0.3 mm to 4 mm. The standard specifies how to apply grid patterns, form test pieces in production‑like tooling, measure engineering strains at the onset of fracture, and plot forming‑limit curves to distinguish safe from necked (failed) regions. This edition supersedes the 2008 version and is intended for in‑shop, component‑ and process‑dependent FLCs (as distinct from laboratory characterisation covered in ISO 12004-2).

Key topics and technical requirements

• Scope and intent: Measurement and application of FLDs/FLCs in the press shop for sheet/strip materials (0.3–4 mm).
• Gauge length: Recommended gauge lengths 1.5 mm to 5.0 mm; actual lengths must be known to ±2%.
• Strain type: Uses engineering strain for forming‑limit determination in the press‑shop context.
• Uniform strain before necking: Test setups must ensure the critical area exhibits uniform strain prior to necking (clamping and tooling selection are important).
• Test methods and tooling: Any device satisfying Clause 6 may be used - stamping presses, universal testing machines, cupping presses, hydraulic bulge machines, etc.
• Specimen preparation and lubrication: Test pieces shall be clamped around the periphery or cut into strips to obtain varied strain states; surfaces between punch and specimen must be suitably lubricated (standard lubricants or polyethylene + lubricant allowed).
• Measurement procedure: Apply an accurate grid pattern, form until first fracture, measure three adjacent gauge lengths in the major strain direction (repeat until three values agree within ±10%, use average l0), measure the transverse gauge length, then compute engineering strains (e_major and e_minor) from measured and original gauge lengths.
• Documentation: Plot the FLC on the FLD and report test conditions; Annex A provides guidance on modifying FLCs and Annex B shows example grid patterns.

Applications and users

• Applications: In‑shop formability assessment, die try‑out, stamping process validation, failure analysis, production quality control, and baseline data for forming simulations.
• Who uses it: Press‑shop and stamping engineers, process and tooling designers, metallurgists, QA engineers, CAE/simulation specialists, and labs performing in‑shop material verification.

Related standards

• ISO 12004-2 - laboratory determination of FLCs under well‑defined conditions (material characterisation with true strain and multiple linear strain paths).
• EN ISO 12004-1:2008 - superseded by this 2020 edition.

Keywords: forming‑limit diagram, FLD, forming‑limit curve, FLC, sheet metal formability, press shop, EN ISO 12004-1:2020.