1. In Agriculture Systems 2
You will use Short Circuit Transfer GMAW to perform your assigned Weld Joints.

2. Modes of Metal Transfer
GMAW is a process that features several distinctive, individual methods and types of Weld metal transfer.

3. What is a Transfer Mode?
It is How the Weld wire (electrode) moves into and becomes the weld puddle.

4. Welding Variables
The mode of metal transfer is determined by a number of welding variables
Voltage
Amperage
Shielding Gas
By changing one or more variables, you can move from one metal transfer mode to another.

5. The Transfer modes are Short Circuit Transfer 16 to 22 volts
9/19/2018
The Transfer modes are
Short Circuit Transfer
16 to 22 volts
Globular Transfer
22 to 25 volts
Globular Transfer Generates Spatter!
Spray Transfer
25 to 32 volts
Needs an argon rich shielding gas
Mig Welding Parameters - Weld Voltage
Voltages for Short Circuit transfer are in the range of 16 to 21 volts.
Spray transfer weld voltages run between 25 and 32 volts.
Globular transfer generally occurs between 22 and 25 volts.
With welding parameters, when your given a range to work with always start out in the middle of that range. If you need to make a slight adjustment, do so, but keep it within the range.
Remember - If you commonly weld using voltages between 22 and 25 you are most likely in the Globular transfer mode and generating excessive spatter. Increase or decrease you voltage to attain the proper transfer mode (Short Circuit or Spray).

6. Short Circuit Transfer
This is the transfer mode you will use Ag Systems 2 GMAW welding.
Short circuit transfer refers to the welding wire actually “short circuiting” (touching) the base metal between times per second.

7. The Sound of the Arc A Rapid Smooth Crackle.
9/19/2018
The Sound of the Arc
A Rapid Smooth Crackle.
The crackle is caused by each short circuit.
The higher the frequency (more short circuits) the more consistent the arc.
This is an Arc On, Arc Off Cycle of operation
The Sound of the Arc
Once you’ve understood the differences between Spray and Short Circuit, you know when to use them and how to set their parameters, you can use your ears to fine tune the arc.
The sound of a Short Circuit transfer weld is a rapid crackle sound. The crackle is caused by each short circuit. The more short circuits per second the more consistent the arc. Your listening for the highest frequency, the most short circuits.
The sound of a Spray transfer weld is a consistent crackle sound.
When voltage is set too high, a quiet “Whooshing” sound can be heard.
If voltage is set too low a harsh, irregular crackle is heard.
The wire is driving into the puddle and spatter increases. Your in Globular transfer and you need to increase voltage to get out.

8. Short-Arc or Short-circuit Transfer
In short-circuit transfer the electrode touches the work and shorts out.
The metal transfers through the Arc as a result of the short.
This happens at a rate of 20 to more than 200 times per second.

9. A Versatile metal transfer mode
With short circuit transfer, wire feed speeds, voltages, and deposition rates are usually lower than with other types of metal transfer such as spray transfer.
This makes short circuit transfer very versatile allowing the welder to weld on thin or thick metals in any position.
Versatile & Useful Video Clip

10. Advantages Of Short Circuit Transfer
All-position Welding: including flat, horizontal, vertical-up or down, and overhead.
Handles poor fit-up extremely well.
Lower heat input which reduces weldment distortion.
Higher operator appeal and ease of use.

11. A relatively low deposition rate.
Disadvantages of short circuit transfer compared to other transfer modes:
A relatively low deposition rate.
Lack of fusion, it could cause cold lap on thicker metals.
Can produce more spatter.
Concerns of Short circuit Video Clip

12. Machine set up and Correct operation!
The disadvantages are minimized when correct welder set up and welding procedures and practices are followed.
** Short circuit transfer usually has a crackling (bacon frying) sound when a good condition exists.

13. Short Circuit Cycle described
Follow the steps, A-F, as the cycle happens.
It is pretty cool.

14. Short Circuit Cycle described
A - Electrode is short circuited to base metal. No arc, and current is flowing through electrode wire and base metal.

15. Short Circuit Cycle described
B - Resistance increases in electrode wire causing it to heat, melt and “neck down”.

16. Short Circuit Cycle described
C - Electrode wire separates from weld puddle, creating an arc. Small portion of electrode wire is deposited which forms a weld puddle.

17. Short Circuit Cycle described
D - Arc length and load voltage are at maximum. Heat of arc is flattening the puddle and increasing the diameter tip of electrode.

18. Short Circuit Cycle described
E - Wire feed speed overcomes heat of arc and wire approaches base metal again.

19. Short Circuit Cycle described
F - Arc is off and the short circuit cycle starts again.

20. View Short Circuit Transfer
See it in action
Click on the figure

21. Well Now! Lets see what You know about Welding in Agriculture Systems 2,
DO YOU:
know which Welding Process you are to use in Ag Systems 2…
know which Transfer mode you are to use in Ag Systems 2…
know which Joint designs and positions you are to use in Ag Systems 2…
Gas Metal Arc Welding
Short Circuit transfer
Lets find out!

22. Weld Joints, and Positions.
For Ag systems 2

23. *Welding Positions
Welding is often done on structures in the position in which they are found.
Techniques have been developed to allow welding in any position.
Some welding processes have all-position capabilities, while others may be used in only one or two positions.

24. There are four basic welding positions
All welding can be classified according to the position of the workpiece or the position of the welded joint on the plates or sections being welded.
The Face and the geometric center of the weld bead give reference to the position it is in.
GMAW can be used in all 4 position

25. Welds, Positions, and Joints for Agriculture Systems 2
Fillet Weld
Groove Weld

26. Welding In the Vertical Positions
Vertical welding, both up and down, can be difficult. This makes pre-weld set-up very important for making high quality welds.
To fight gravity, reduce voltage and amperage 10 to 15 % from flat position weld settings.
As the gun angle increases, penetration decreases.

27. VERTICAL WELDING POSITIONS
In this position, the axis of the weld is approximately vertical.

28. A Tip to help with Joint set up
Tack welds are often used to assist assembly or to maintain edge alignment during welding.

29. Your decision
Your choice to weld vertical up or down will depend on the application of the part, the thickness of the material you are welding, or your instructor or supervisor will direct you.

30. An informational Tip
Because vertical down welding helps avoid excessive melt-through, welders sometime place thin materials in the vertical position even if they could weld them in the flat position.

31. A mention of direction: up, uphill, down, or down hill, refers to weld progression.
Vertical down = less penetration.
Vertical up = more penetration.

32. The vertical down technique.
Can be used when welding thin metals because the arc penetrates less due to the faster travel speed.
In the vertical down welding, an upside down U pattern is used.
The welder must take care to pause at the side walls to obtain adequate tie-in to the base metal.

33. When welding vertical down
Begin at the top of a joint and weld down.
Keep the electrode wire on the leading edge of the weld puddle.
A very slight weave may help flatten the weld bead.
The travel angle of the gun is 5°–15° pointing up.

34. GMAW Vertical Down Tee Joint
To see a clip of 3F Tee joint Down ward progression

35. GMAW Vertical Down Groove joint
To see a clip of 3G But joint Down ward progression

36. When welding Vertical Up.
The vertical up weld in MIG is typically very convex.
See the yellow lines of movement.
If the weld is wide enough then you will get a good looking weld but otherwise it is a very convex weld in appearance.

37. The vertical up technique
Beginning at the bottom of the joint and welding up can provide better penetration on thicker materials (typically 1/4 in. or more).
The travel angle of the gun is 5°–15° pointing up.

38. Vertical up Fillet Tee Technique
ROOT PASS: Use a triangular motion See #1 progressing up. Make sure to push the puddle into the corner for Penetration.
Don’t just bridge (weave ) across the corner but melt in it.
Bridged over
Fused in the root

39. Vertical up Fillet Tee Technique
For a vertical up fillet weld a Christmas tree pattern is recommended with pauses at the side walls. The dots are places to pause .
The welder must take care of pausing at the side walls to obtain adequate tie-in to the base metal.

40. GMAW Vertical up Fillet Tee
Watch for:
“pushing the puddle into the corner”
and “pausing for more fill”.
To see a clip of 3F Tee joint Up ward progression

41. Technique
A side-to-side weave, pausing slightly on the sides until the feathered edges would melt through into the backing bar, creating a crater and filling it.

42. Welding Vertical up Groove
When welding vertical up you need to build a shelf of weld to work upward on.
A slight weaving motion can help control the size, shape and cooling effects of the weld puddle.

43. Steps for a 3 Pass, 3G Weld joint
1 First Pass = ROOT PASS.
2 Second Pass = FILL PASS.
3 Third Pass = CAP PASS.

44. Steps for a 3 Pass 3G Weld joint
1 First Pass = ROOT PASS.
First pass Started!
First pass Finished!

45. Cleaning the weld area between passes
It looks slag but it’s not, sometimes it’s called brown glass, it is silica deposits left from the wire electrode.
They are non metallic and must be removed from the weld joint after each weld bead.
Weld spatter must also be removed between passes to prevent inclusions and weld bead contamination.

46. Steps for a 3 Pass 3G Weld joint
2 Second Pass = FILL PASS.
Second Pass Start!
Second Pass Finished!

47. REMEMBER!!: Clean the weld area between passes
Garbage in the weld joint will result in Garbage in the Weld Bead!

48. Steps for a 3 Pass 3G Weld joint
3 Third Pass = CAP PASS.
Third pass
Finished
Weld bead

49. A Tip to help with Joint set up
Tack welds are often used to assist assembly or to maintain edge alignment during welding.

50. Practice & Practice & Practice
Each individual welder is different, holds the gun a little differently, uses a little different angle, uses different stickout, and uses different wire speed settings.
I am not sure any one GMAW welding technique could be called the best.
Learn and practice several.

51. The techniques that helps you produce quality welds REPEATEDLY is the one you should use!
“When you are not practicing, remember, someone somewhere is practicing, and when you apply for a job against they will be harder to beat!”

52. Get the assignment “Weld procedure My recipe for a good weld”.
Fill it out
Complete the weld
DO IT WELL!
Turn it in for evaluation.