Unit 6 Lab 1: Case Problem
Materials and Processes in Design
Chapter 15 Case Problem 1: Welding Thin Materials
I have to disagree with both, the experienced welder and the production supervisor. Arc welding is not the ideal process for thin metals. It takes many years for a welder to acquire the skills to arc weld thin metal and ever the most experienced welders mess up and ruin product. TIG welding would work with the thin metal but will take a lot longer and cost a lot more. It also takes the longest to master. Gas MIG (GMAW) is the process I recommend for the thin metal. I will explain the three processes in the following paragraphs.
Arc Welding is one of the oldest welding processes around. It can be the cheapest to start with as there is not a lot of equipment needed. It is also very versatile as there are a lot of ...view middle of the document...
This process works of AC (used on aluminum) or DC (used on ferrous metals (steels)).
TIG welding is also very versatile and produces the highest quality welds. It also takes a considerable amount of practice and is the least productive of the different types of welding. TIG uses a torch with a tungsten electrode. To protect the weld and tungsten, argon must be used as a shielding gas. In this process an arc is struck between the tungsten and the work piece and a short gap is maintained. As the weld progresses, filler wire is dipped in the weld pool. In this process a constant current (AC or DC depending on the metal used) must be maintained. This is a physically complicated process because you must, control the torch, feed the wire, move at the right speed and also use the correct current. This process is much easier for bench work. TIG can weld just about any metal with AC and DC power sources.
Gas MIG welding is also called GMAW (Gas, Metal Arc Welding). It uses a thin wire as an electrode and is filler fed by a wire feeder to the gun. This process requires a power source that has a constant voltage (CV) DC. This process produces very clean weld with no slag or spatter. You must use argon/CO2 or straight CO2 as a shielding gas. The filler wire used in this process is less expensive than the wire used in TIG. This process is great for thin metals of all types. MIG is the easiest process to learn but requires gas and a wire feeder so it is not as portable.
This is my conclusion: Arc welding is the most difficult on thin metals. Gas MIG welding is the easiest on thin metals and has the cleanest welds. TIG is the most expensive process, easiest to control and is great for aluminum. In the circumstance of this case problem, I recommend Gas MIG welding to produce the patio furniture frames. It will cost a bit more than the Arch welding but will cost less than TIG welding. It will require a wire feeder, gun, gas bottle and regulator. This process is easy to learn and is great for large quantity production.