Welding and Fabrication

“Fabrication,” particularly when linked to industry, implies the building of structures, machines, products or other equipment by stamping, cutting shaping, joining and even assembling components from raw materials – most often metals.

It is commonly considered standard to assume that a fabrication operation includes welding also, but I have chosen to separate this out as some welding operations are now very specialist techniques and they merit their own section in this article.

Fabrication Shops

Often a small business that specialises in this type of work is known as a fabrication shop, but it should be noted that in most instances the individual parts and metalworking activities will overlap with machine shop work and sheet metal engineering or sheet metal work.

What sounds a simple activity such as cutting metal can mean many different things from shearing, sawing, to cutting torches and water jet cutters and finally to laser cutting tables and plasma cutting. Depending upon the speed and accuracy of what you want, and cost and quality requirements; you will always need to check on the capabilities and capacities of the fabrication facility that you intend to use.

In general terms the Fabrication and welding shop is likely to cover many of the following activities:

  • Cutting
  • Burning
  • Bending
  • Wheeling
  • Shearing
  • Folding
  • Forming
  • Punching
  • Milling
  • Tapping
  • Turning
  • Welding
  • Soldering

Welding

Welding is often a major part of metal fabrication and many formed parts and assemblies will be tack welded together prior to being checked for accuracy and fit.

Welding is a fabrication method which is predominantly about joining metals or thermoplastics by causing coalescence which is commonly achieved by melting the parts, adding a filler material to form the weld pool which, when cooled, becomes a very sturdy joint (the weld). This is different to brazing and soldering which does not induce melting of the initial components but melts a material between the components to form a bond between them.

There are lots of different forms of energy which can be used for welding other than the gas flame most of us recognise being also; laser, electric arc, electron beam, friction or ultrasound. Welding is a skilled operation and requires also several safety precautions to avoid burns, shocks, eye damage, fumes etc.

Starting in Blacksmiths shops with forge welding, shielded metal arc welding is probably the commonest form of welding used today as well as the semi and fully automated processes such as gas metal arc welding (MIG) and flux-cored arc welding and as the technology advances ever onwards so too does the welding systems such as laser beam welding and electron beam welding.

Some fabrication shops will offer specialist techniques such as MIG and TIG Welding, which are briefly outlined below:

MIG Welding

MIG welding (Metal Inert Gas) or metal arc welding was originally developed for welding aluminium and other non-ferrous metals. It is usually an automatic or semi-automatic process whereby an electrode joins two pieces of metal as a direct current is continuously passed through a welding gun. This is done at the same time as an inert gas is also passed through the gun which stops any air borne contaminants entering the weld area.

MIG welding allows the welding process to be much faster than other methods which makes it ideal for welding softer metals such as aluminium.

It produces continuous welds faster than traditional methods, and produces cleaner welds

As it is very versatile, MIG welding can be used with a wide variety of metals and alloys.

TIG Welding

Tungsten inert gas welding or TIG welding, for short, is an arc welding process that uses a tungsten electrode to produce the weld.

Similar to MIG welding in that the weld area is also protected from atmospheric contamination via an inert gas (usually Helium or Argon or a combination), and a filler metal is often used, although certain welds, called autogenous welds, do not require this. The constant-current produces energy which in turn, is conducted across the arc through a combination of ionized gas and metal vapours which is known as plasma.

TIG Welding is often used to weld non-ferrous metals such as magnesium, copper alloys and aluminium and thin sections of stainless steel and as the technique gives the experienced welder greater control over the weld it has some advantages over MIG welding in that it can produce even higher quality and stronger welds.

The filler rod is usually made from the same material as the base metal and is used for reinforcing joints and welding heavy metals.

Several joint types are used in TIG welding inclusive of butt joints (which do not always require the filler rod assistance), lap joints, corner joints and t-joints.

It is however, more complex than MIG welding and harder to learn and is much slower that most of the other techniques.

Top fabrication shops

Finally it is worthwhile checking to see if the fabrication shop offers other services which could be helpful to you – in today’s fast paced environment it is worth seeing if your chosen supplier offers a “One-Stop” shop which could benefit you – many will now offer other services such as:

Design and prototyping
Powder coating
Assembly
Testing and final inspection
Packing and Distribution

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