Frequently Asked Question
Plastic deformation
Forging, rolling, and extrusion impose plastic strain under predominantly compressive stress. Material flow, friction, die fill, temperature, strain rate, lubrication, draft, radii, and grain flow determine load and defect risk. A process window must cover billet or sheet condition, tool temperature, reduction, speed, and trimming or finishing.
ε is true thickness strain, h0 and hf are initial and final thickness, and K,n describe a simplified hardening law.
Worked example
Reducing thickness from 10 mm to 6 mm gives ε = ln(10/6) = 0.511. The actual load still depends on friction, die geometry, temperature, and strain-rate sensitivity; use the result as a comparison, not a machine-capacity guarantee.
Engineering check
For Forging, Rolling, and Extrusion Fundamentals, record the material condition, tool or fixture identity, process settings, measurement method, sampling plan, and reaction rule. Confirm that the measurement system is capable of resolving the requirement and that the process is stable before using capability or first-article data to justify release. Reconfirm the limits after a material, tool, or route change.
Engineering note
For Forging, Rolling, and Extrusion Fundamentals, state the intended use, input range, dominant mechanism, units, boundary conditions, acceptance criterion, and evidence owner. Use an independent balance, limiting case, repeat measurement, or sensitivity check to challenge the result. Document the configuration and uncertainty so another engineer can reproduce the reasoning and determine whether the result remains valid after a design, material, boundary, or process change.