Heat Input calculation 1

[migias]

Using the equation: heat input = V*A*60/travel speed

Which is the way to measure travel speed?
For example we measure the time and the length of the welding bed?
Can u tell me the practice used?

Thanx

 

[vpl]

low tech way: stop watch and tape measure

higher tech: radar, sonar, etc.

Patricia Lougheed

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[DVWE]

migias,

There are several common ways to measure travel speed.

1. For manual or semi-automatic welding, the above mentioned stopwatch and tape measure is probably the most common. For example, the weld is 14 inches long, and took 135 seconds to deposit. 135 seconds/60 seconds per minute = 2.25 minutes. Travel speed = 14in/2.25min = 6.22 in/min.

Alternatively for manual welding (GTAW, SMAW), the length of weld deposited compared to the length of electrode can be used. This is less common, but still used often. See Section IX for complete description.

2. For machine or automatice welding, the easiest way is to simply make sure your machine is calibrated properly, and record the number setting used for travel speed.

 

[Mr168]

Be warned on the machine/orbital welding. Travel speed can be deceptive here. When flat tracked, it's not a problem, but if you're welding pipe, the "travel speed" that is output by the machine's display is usually at the wheels/gears, and is not a 1:1 ratio at the weld joint. The taller your standoffs on the track, the more exaggerated the difference becomes.

 

[carbonear59]

on this issue , can anyone explain to me why the efficency of the actual process is never taken into account or at least approximated in the calculation ?

 

[JStephen]

I think the only reason for checking heat input is that you're limited to the qualified heat input in production welding, so presumably, efficiencies are similar in each case.