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FAQ’S

We are often asked questions from our clients.  Below you will find frequently asked questions.  If your question is not here contact us and we will be pleased to help.

What is Mig welding?
 
  

 

1  What is Mig welding?

Mig welding is a process that uses a continuous coil of wire that is fed into the weld pool. The welding current is passed onto the wire and causes an arc to establish between the wire and the work piece, thus causing the wire to melt and a molten puddle to form. The molten puddle is protected from the atmosphere by an inert shielding gas.



2  What is Tig welding?

Tig welding is a process that uses a non-consumable tungsten electrode, which acts as jump point for the welding arc. This welding arc melts the parent material. Filler wire is applied separately in the form of long straight rods. The molten puddle and tungsten electrode are protected from the atmosphere by an inert shielding gas (mainly argon). The Tig process is very similar to an electric form of gas welding.




3  What are the advantages of Tig welding?

1.             Narrow concentrated arc.
2.             Able to weld ferrous and non-ferrous metals.
3.             Does not use flux or leave a slag.
4.             Uses a shielding gas to protect the weldpool and tungsten.
5.             A tig weld should have no spatter.
6.             The tig welding process produces no fumes, but can produce ozone.

 



4  What is Arc welding?

Arc welding – fusion welding is a melting and casting process in miniature, the various components of the welding process (base metal, weld metal, slag etc) forming the crucible and contents of a tiny electric furnace.





5  What are the advantages of arc welding over riveting or casting? 

1.
 

Welding is usually a cheaper process than riveting for any particular joint, and the joint can often be made much more quickly.
 2. Welding gives a stronger joint and permits the use of less material, thus reducing the weight and cost of the structure.

 3.
 

Weld seams are normally pressure tight, and do not need caulking as do riveted joints. Joints are smooth, which is important in many applications. For example, painting is much easier on welded joints and turbulence in pipes is reduced.
 4. Designs not practicable for riveting may be constructed by welding.
 5. Plate preparation for welding is generally cheaper than for riveting.
 6. Labour necessary can often be cut to less than one-third of that necessary for riveting.
 7. Welding is not as noisy as riveting, and permits building and alterations to proceed with the least disturbance to occupants.
 8. Welding is more versatile than casting; changes can be made quickly without having to produce a new pattern.
 9. Rolled section is often cheaper than cast section, and fabrication by welding of rolled section may be cheaper than casting the same article.
 10. No storage of patterns is necessary for welding, as with castings.
 11. Articles of consistent and known quality can be produced by welding, whereas castings may have external or hidden internal flaws causing their rejection, or failure in service.

 



6  What does CC and CV stand for?

CC = Constant current. Arc welders and Tig welders use constant current power sources.
CV = Constant voltage. Mig welders use constant voltage power sources.
 



7  What does OCV mean?

OCV stands for Open Circuit Voltage. This relates to the voltage at the weld terminals before welding commences.
 



8  Why do some electrodes have on the packet label AC: 50v and others have AC: 70v?

This relates to the minimum open circuit voltage required to run the electrode when using AC current.

 



9  What happens if I try to run an electrode which requires AC: 70v on a machine with a lower open circuit voltage?

You will find the electrode very hard to start, and if you were able to establish an arc it will extinguish very easily.
 



10  How do I choose the correct shade of welding lens? 

Welding Operation
Electrode / Wire Size
Approximate Amps
Shade Number
Shielded Metal Arc (stick)
2.0mm to 2.5mm
3.2mm to 4.0mm
4.0mm to 5.0mm
5.0mm to 6.0mm
Up to 100amps
100 to 200amps
200 to 300amps
300amps and over
9
10
11
12
Gas Tungsten Arc (TIG)

 
Non Ferrous
 
 
Ferrous
NA
Up to 30amps
30 to 80amps
80 to 110amps
110 to 150amps
150 to 200amps
200 to 260amps
260 and over
Up to 30amps
30 to 80amps
80 to 110amps
110 to 150amps
150 to 200amps
8
9
10
11
12
13
14
9
10
11
12
13
Gas Metal Arc (MIG)

 
Non Ferrous
 
Ferrous
0.6mm
0.8mm to 0.9mm
1.2mm to 1.6mm
0.8mm to 0.9mm
1.2mm to 1.6mm
 
9
10
11
11
12
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