The welding heat input calculator works out the heat input of a laser weld and compares it with TIG, MIG or another arc process, using the EN ISO 1011-1 method. It also gives the laser power density at the spot and whether the weld is likely to run in conduction or keyhole mode.
Low heat input means less distortion and discoloration. Explore Arcus CNC laser welding machines or ask for a welding trial.
Formulas
Arc energy and heat input follow EN ISO 1011-1 and are given per unit length of weld:
| Symbol | Meaning | Unit |
|---|---|---|
| Q | Heat input | kJ/mm |
| k | Thermal efficiency of the arc process | — |
| U, I | Arc voltage and welding current | V, A |
| P | Laser power | W |
| v | Welding speed | mm/min |
| d | Laser spot diameter | mm |
Thermal efficiency factors (EN ISO 1011-1)
| Process | k |
|---|---|
| Submerged arc welding (SAW) | 1.0 |
| MIG / MAG, stick (SMAW), flux-cored | 0.8 |
| TIG and plasma | 0.6 |
The standard gives no k factor for laser welding. Most procedure records state the line energy P / v, which the calculator shows with η = 1. Enter a lower factor if you want to account for the share of laser power absorbed by the metal.
Conduction and keyhole welding
At lower power density the laser melts the surface and heat spreads by conduction, giving a wide, shallow weld. Above roughly 10⁶ W/cm² the metal vaporizes and forms a keyhole that carries the beam deep into the joint, giving a narrow, deep weld with low total heat input. Between about 10⁵ and 10⁶ W/cm² the process is in transition and sensitive to small changes.
Frequently asked questions
Why does laser welding cause less distortion?
Its heat input is often a fraction of an arc weld's for the same joint, because the energy is concentrated in a small spot and the welding speed is high. Less heat into the part means less shrinkage and warping.
What heat input should I aim for?
It depends on material and thickness. Welding procedure specifications often set a maximum for stainless steels and quenched and tempered steels to protect corrosion resistance and toughness. Use the value from your qualified procedure.