What is welding?
Welding is the fusion/bonding/melting of two metals to each other making use of modern technology using electricity running through a machine called a welder.
Starting off with the description of an ARC welder, or MMA as it is also called, very similar in principal to a MIG welding machine, which will be covered.
An ARC welder uses what is called an electrode, welding rod, clamped in a holder, which is a thin steel wire (common sizes varying in thicknesses from 2 – 5mm) coated with what is a called a flux core around the wire. (This flux is to combat against oxidation around the area while being welded, plus it adds to the welding rod material composition). The welding rod tip melts as the rod comes into contact with the metal area to be welded. There are 2 heavy cables coming from an arc welder. One going to the welding rod holder, the other is called the earth cable, connected to the work piece to be welded. The cable outlets on the welding machine will be marked + or - . Positive or negative. Welding rods will specify how to set up your welding machine and also give you the range of amperage to work within. You will normally find earth to be the positive but always check the welding rod box for information.
Melting temperatures of steel when welding are in excess of 16000 C
Welding techniques are a form of art
To be able to weld proficiently takes a lot of dedication and practice. There are many tricks in being able to guide the molten metal in your control to flow evenly and precisely to gain full strength of the metal to be joined together.
There are many factors to take into consideration.
· The thickness of the material to be welded
· Choice of welding rod size and type for the application
· Welding amperage settings for each application
· Different types of metal to be welded and choosing the appropriate
welding machine for the application
· The welding of dissimilar metals together and what welding rods to use
· The technique of welding two materials of dissimilar thicknesses
together and how to guide the heat away from the thinner material
· Weld weaving. Different techniques and effects
· How to gain maximum strength through optimum penetration when
welding two materials together
· How to strengthen a join by adding plates and where to place them
· How to avoid undercut when welding, plus, how to rectify undercut
after it has occurred
· How to avoid pin holes in your weld (constantly watching the weld
pool) and how to get rid of pin holes effectively so as not to
compromise the strength of the weld
· How to avoid gaps in a weld and how to fix them if they do occur
without causing any detrimental effect on the strength of the weld
· Welding slightly downhill (using gravity to your advantage) rather than
welding uphill, and the benefits
· The angle of a welding rod to the area to be welded is crucial, and the
different effects achieved by changing the angle of the welding rod
· Distance of welding rod from welding pool and how to gain fine control
of the weld pool temperature
· Weld weaving techniques
· Horizontal welding – push or pull?
· Vertical up welding techniques – Triangle/Christmas tree technique
· Vertical down welding techniques
· Upside down welding
· How to counteract distortion of materials through heat
· Preparation of material before welding commences
· Advantages and disadvantages over ARC/MMA versus MIG welding
The different types of welding machines
I specialise in mobile onsite welding. Travelling to my customers to solve the welding problems for them. Most of my work involves coded structural welding and water, gas an oil pipe welding plus numerous other welding activities such as aluminium welding of motor cycle accident repairs, bicycle welding repairs, cast iron welding repairs, stainless steel welding.
I have found over the past years most of the work I do on construction sites call for the use of ARC/MMA welding. MIG welding is not practical on construction sites because of the elements of winds blowing the argon gas away from the working area which causes bubbles in the weld because of oxygen getting into the area being welded, which in turn will compromise the strength of the weld.