PART-7
CHAPTER 3.......Continues.......
METAL JOINING AND CUTTING PROCESS
Notes:
GMAW:
26.
GMAW: Gas Metal Arc Welding
27. MIG:
Metal Inert Gas Welding
28. MAG:
Metal Active Gas Welding
29. GMAW
is a semi-automatic welding process
30. MIG
uses inert gas shielding, such as argon and helium
31. MAG
uses reactive gas shielding such as Oxygen and Carbon dioxide
32. GMAW
Electrode Identification System
33. Completely
understand the picture of GMAW. The key words to identify GMAW are Consumable
electrode and Solid electrode wire
34. Constant
Voltage Curve
35. Gas
metal arc electrodes typically have increased amounts of deoxidizers such as
manganese, silicon and aluminum to help avoid the formation of porosity.
36. GMAW
uses Constant Voltage Power Source.
37. To
setup for welding, the welder will adjust the voltage at the power source and
the wire feed speed at the wire feeder.
38. The
melt-off rate of the electrode is proportional to the arc current.
39. GMAW
is having “Self-Regulating Constant Potential” System.
40.
There are four basic system of arc transfer in GMAW. They are Spray, Globular,
Pulsed Arc and Short Circuiting.
41. The
relative features of heat in welding and choice of size of base material is
shown in figure below
42.
Spray transfer is best for heavier sections
43.
Short circuiting transfer is best for sheet metal welding and joints having
excessive gaps due to poor fitup.
44.
Spray transfer can be achieved only when there is at least 80% argon present.
45.
Incomplete fusion occurs in GMAW.
46. E70C-6M
is a typical metal cored wire designation;
E:
Electrode
70-70000
psi tensile strength
C stands
for composite Metal Cored Electrode
6 is the
category of wire
M means
mixed gas
47. The
inherent problem in Short circuiting transfer is incomplete fusion due to
insufficient heat of the base metal
48. GMAW
Gun Nomenclature – To be remembered (Draw and study)
49. In
the above figure,
Standoff
distance - Stick out distance = Arc Length
50. The
electrode extension is also referred as the contact tube to electrode end
distance.
--will continue on next blog---
These are the important points of this chapter. This blog will be updated time to time to add or delete points depends on their importance felt to the author.
This is not an official blog of AWS. The recommended reading materials as per BOK are to be read throughly before taking the exam. The exam pattern and other details to be confirmed from AWS before taking the exam.
Disclaimer: Photos are taken from different websites. If this violates any copyright rules this will be removed. Please inform me if any of the photos or contents violates copyright rules. (through 13hareesh13@gmail.com). This blog is meant for educational purpose only. If it is used for any other means without the written consent from the author, the author will not be responsible. Author does not guarantee the accuracy of data used in this blog.All the information, data, photo/image, calculations presented in this blog should be used at the sole risk of the user. The blogger is not liable or responsible in any way for any damage, losses or costs arising from use of the blog for any purpose whatsoever or whosoever it may be.
Comments
Post a Comment