Heat Input Formula Question

Date 06-24-2009 18:30 Edited 06-24-2009 18:38

Chris...if you divide the 24" by 1.5 minutes(1 minute and 30 sec) you get 16 ipm

24" in 1:15(1.25 min) = 19.2 ipm
24" in 1:45(1.75 min) = 13.7 ipm
24" in 2 minutes flat = 12 ipm

By eekpod

Date 06-24-2009 18:59

OK, so it is another little formula I have to do before I plug it into the main formula.
Or said another way, I take my inches welded and divide by the time, take that answer and divide it into the numerator sum and I'll come up with the Kj/ per inch.

24" welded took 1:33 is 24/ 1.55= 15.4 in per minute.. then take that and divide into 330A X 30V X.06= 594

so 594 / 15.4 in per minute =38.5 Kj/ in.

sound right?

By jwright650 (*****)

Date 06-24-2009 19:08

I didn't run back through your math, but that end result looks about right.

By eekpod

Date 06-24-2009 19:29

I'm not familier with these values so I can't look at and tell if it's good or not.

Where does the .06 come from? any idea?

Also, thank you for your help.

Chris

By CWI555

Date 06-24-2009 20:26 Edited 06-24-2009 20:34

Heat input (Kilojoules/in.)= Amps X Volts x 0.06 divided by Travel Speed (in/minute).
Some formula / by 1000, .06x1000 =60 or 60 minutes. To move the decimal. .006 or 1000's of 60. it's just a short cut.

By drewp29 (**)

Date 06-26-2009 20:16 Edited 06-26-2009 20:27

1Amp x 1Volt = 1Watt = 1Joules/1second

converting the seconds to minutes to account for constant units with the Travel Speed (inches/min)

1Joule/1second x 60seconds/1min = 60joules/1min --> now changing the Joules to Kilojoules --> 60Joules/1min x 1kJ/1000Joules = .06kJ/1min which becomes our multiplication factor to account for consistent units in the original equation.

Thus,

Amps x Volts (J/s) x .06 (to convert to kJ/min) / TS (in/min) = HI (kJ/inch) --> the minutes end up in numerator and denominator and cancel each other.

Ahh, conversion factors . . . great for shortcuts, but when you don't know why they are applied they can be pretty confusing.

Drew

By 803056

Date 06-24-2009 19:38 Edited 06-24-2009 19:48

Heat Input = V x A x 60 / TS

Voltage times Amperage times 60 / Travel Speed (ipm) = heat input in joules per inch. Divide by 1000 to get kJ/in. Where travel speed equals:

Length welded divided by the time taken to weld the joint, so: (Length welded/ (minutes times 60 plus seconds to weld the length welded)) = travel speed in inches per second. Now multiply by 60 to get travel speed in inches per minute. Therefore the equation can be written as:

(V x A x 60 / (L/(m x 60) + s) x 60) / 1000 = kJ/in.

Where V = voltage
A = amperage
60 is a constant

L = length of joint welded
m = minutes
s = seconds

kJ = kilojoules

Your example: 300A x 30V x 60 / ((24 in/(93 sec)x60) / 1000 = 34.875 kJ/in. (there may be differences due to rounding errors or I could be wrong with my number crunching)

Hope this helps.

Best regards - Al

By eekpod

Date 06-29-2009 10:48

Sorry I didn't folow up, its been real busy getting ready for my audit. Thank you for all your input everyone. The first time I did this, I incorrectly figured the travel speed, and my values were way out of wack. I'm all set now.