# Mig welding heat input calculation formulae.

## Formulae to calculate heat input is.

(60 x Amps x Volts) / (1,000 x Travel Speed in mm/min) = KJ/mm

It is standard formulae.
The unit of heat input calculated depends upon the travel speed unit you have taken. For example, if you take travel speed in inches/min then the unit will be KJ/inch similarly if you take Travel speed in CM/min then the unit will be KJ/CM.

## How to calculate travel speed?

= Divide Weld length by the time required to complete weld in minutes.

## Heat input calculation example?

Consider Your weld is 635mm long and it takes the welder 2 minutes to weld it. While he is welding, you notice the machine is displaying an amperage of 325 and Voltage 29V What is your heat input?

Solution.
Before calculating heat input you need to determine your travel speed.
Travel Speed = Weld Length/Time required to complete it in minutes.
= 635/2 = 317.5 mm/min
Now Applying heat input formulae =  (60 * 325 * 29 )/ (1000*317.5)=1.7811 KJ/mm is our calculated heat input.

If you are using Fronius TPS/I Power source you need not do this calculation. As machine itself give you heat input for every seam welded. You just need to check your logbook in power source or by connecting your Laptop to power source.
You can check heat input for any day,  any time and any weld seam. Check below Logbook taken from TPS/I system, Red marked area shows heat input for given weld entry.
 Mig welding machine automatic heat input display