Before the first pulse

Material Preparation Guide

Surface cleaning, oxide control, fixture checks, and shielding preparation for common materials.

Contact
SurfaceClean metal

Remove oil, oxide, coating residue, and loose particles before trials.

Fit-upStable gap

Clamp parts so the joint gap does not change across the sample.

ShieldingGas coverage

Set gas type, flow, nozzle distance, and purge before judging weld quality.

Material preparation by family

MaterialPreparation actionWatch for
Stainless steelDegrease, remove fingerprints, and keep stainless tooling separate from carbon steel.Heat tint, porosity, oxide film, and chromium-depletion concerns.
AluminumRemove oxide close to welding time and avoid touching the cleaned surface.Porosity from moisture or oxide; unstable coupling from inconsistent surface prep.
CopperClean oxide and oil; keep contact pressure and surface flatness consistent.High reflectivity, high conductivity, and variation between plated and bare copper.
TitaniumApply clean handling, dry shielding gas, and trailing or backside shielding when needed.Discoloration, oxygen pickup, and brittle surface contamination.

Fixture checks before welding

CheckActionReason
Joint gapMeasure at several points before clamping and after clamping.Gap changes can look like parameter instability.
Part movementMark reference points and inspect movement after tack or first pulse.Movement changes focus, penetration, and bead width.
Thermal contactKeep backing bars, chill blocks, and copper fixtures consistent across trials.Heat sinking changes penetration and HAZ width.

Next engineering checks