Thank you for visiting our Blog. Today I hope to teach you a little bit about welding, it’s history and eye safety practices while performing it. We will start with the definition of the word “ weld” from the dictionary.
Verb (used with object): To unite or fuse (as pieces of metal) by hammering, compressing, or the like,especially after rendering soft or pasty by heat, and sometimes with the addition of fusible material like or unlike the pieces to be united.
1590–1600; variant of well2 in obsolete sense “to boil, weld”( from dictionary.com)
So we see that welding is the joining together of two or more objects. There is plastic welding , glass welding but for what we will be exploring we will focus on the welding of metals. The earliest examples of welding date back 5000 years ago to the Bronze Age or around 3000BC. Some examples are swords made by the Sumerians in what is today Iraq. A double walled gold goblet and a gold bowl were also found that were made using a brazing technique. It was found that the Egyptians heated iron ore in a fire to soften it and then hammered pieces together. This was the first recorded use of pressure, or solid state welding.
Today there are many welding processes. But all of them can be divided into two major groups. Fusion Welding and Solid State Welding. Fusion welding is the most common welding process and is where heat is used to melt the base metals and join them. When they cool and go back to a solid state the two pieces are joined. Very often a filler metal is used to add strength and to help the metals to join more readily.
One type of fusion welding is Arc welding where an electric arc provides the heat and a filler metal is used to help the weld along. This filler metal is usually incorporated into the electrode that is used to perform the weld. If you have ever seen someone welding this is the ‘stick’ they use to touch to the metal that is being joined.
Another is Resistance welding. This is where two metals are clamped together and the weld is made by passing an electric current between the pieces. Electrical resistance creates a great amount of heat and the two pieces become joined.
Oxyfuel gas welding is where typically a mixture of oxygen and acetylene gas are pumped into a torch head and then burned to create a great heat that will melt the metals to be joined. Cutting metals is also often done using this technique.
There are other fusion welding techniques like electron beam welding and laser welding. Basically any time heat or energy is being applied to cause the metal to change from a solid to a liquid state is considered fusion welding.
Solid State Welding is where pressure or a combination of heat and pressure causes the metals to be joined. This is the earliest example of welding and includes forging, hammering and pressing. In modern days a few examples of this style of welding are Diffusion Welding, Friction Welding and Ultrasonic Welding.
Friction welding is perhaps the most common in metal. This is where one piece is stationary, and the other piece is moved against it to create heat. This technique allows for dissimilar metals to be joined (Aluminum and Steel for example) and is widely used in the aerospace industry.
Ultrasonic welding is achieved by clamping two pieces together and introducing ultrasonic waves parallel to the surfaces. This removes surface films and causes the two pieces to bond on the atomic level. This technique is widely used in the plastics industry. In fact that pool float you drift around on is made using ultrasonic welding.
We will cover torching and brazing in the next installment, as well as the eyewear to use while performing these operations. Check out our user friendly website www.phillips-safety.com for all your welding eye protection needs.