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| Welding Process |
One of our task in mechanical work is Welding. Good enggineer should known how to prepare his work. In this case is calculating welding rod. Before the enggineer calculating welding rod, enggineer must be understand about :
a. Techical Drawing,
b. Welding code.
Ok, lets us started to expalin how to calculating welding rod/wire requirement from the simple welding.
First step, we must find the volume of welding, ussualy we used triangular pyramid to simplify the calculation. example : we have data from welder about Area, Long & Thichness as bellow :
In this case for example the widh of las is 8 mm, then we can compute:
Surface Area (A) = ½ x 8 x 8 mm = 32 mm2
Las Volume 1 meter long for welding (V) = A x L = 32 mm x 1000 mm = 32,000 mm 3 = 32 cm3
So,
If the Specific Gravity = 7.85 gr/cm3 Mild Steel, then
Heavy Metal Las to 1 meter = 32 x 7.85 = 251.2 g = 0.251 Kg / mtr.
How to count applies to the form - the form of connection such as: U type, Double V butt joint type or without a groove.
Counts above applies to connections without reinforcement. If there is a reinforcement, then the amount of welding wire, plus about 3%.
CALCULATING NEEDS WELDING WIRE
To calculate the required welding wire used the formula:
G (The number of Las Wire) = GL x P / DE
GL = Heavy Metals Las per Unit Length (Meters)
P = Total length Connections Las
DE = Deposition Efficiency
Deposition Efficiency What is it ??????
Deposition Efficiency is the ratio between the amount of metals produced by Number Las welding wire used and expressed in percent.
Las DE = Heavy Metal (Weld Metal) / Weight Las wire used (Electrode Used)
Typically, data Deposition Efficiency is issued by the respective manufacturer of welding wire, but the average mean value (Average Value) Deposition Efficiency for each welding process is as follows:
Deposition Process Welding% Eff
- SAW 99%
- GMAW (98% Ar, 2% O2) 98%
- GMAW (75% Ar, 25% CO 2) 96%
- GMAW (99.99% CO 2) 93%
- Metal Core Wire 93%
- FCAW (Gas-Shielded) 86%
- FCAW (Self Shielded) 78%
- SMAW (length 300 mm) 59%
- SMAW (length 350 mm) 62%
- SMAW (length 450 mm) 66%
Note:
For SMAW Process, the rest is wasted electrode 5 cm / Trunk.
If we return to the above case,
Heavy Metals Las per meter is: 0.251 Kg / Meter
Its long-las = 1000 m
The amount of weld metal = 0.251 x 1000 = 251 Kg.
The amount of welding wire to be ordered in accordance with the welding process used is as follows:
Las Wire Welding Processes that Ordered (Kg)
- SAW 253 Kg
- GMAW (98% Ar, 2% O2) 256 Kg
- GMAW (75% Ar, 25% CO 2) 261 Kg
- GMAW (99.99% CO 2) 270 Kg
- Metal Core Wire 270 Kg
- FCAW (Gas-Shielded) 292 Kg
- FCAW (Self Shielded) 322 Kg
- SMAW (length 300 mm) 425 Kg
- SMAW (length 350 mm) 404 Kg
- SMAW (length 450 mm) 380 Kg
Note:
For SMAW Process, the rest is wasted electrode 5 cm / Trunk.
Taken from : Ir. Darmayadi
