Welding: A Beginner’s Guide to Earth Clamps
The fusing of the same or different materials using heat and pressure to form new and intricate objects has existed for millennia. From the exquisite gold jewellery of ancient civilizations to rudimentary metal weaponry at the beginning of the industrial age, metal-working and welding have literally built the foundations of modern society. With technological advancements like the widespread use of electricity, welding today has a multitude of diverse uses, from large-scale industrial projects like construction and shipbuilding to basic home repairs.
Welding began to take its present shape in the late 19th century, with scientific experiments in the principles of electricity and the discovery of coated electrodes. Stick welding was born and with it the technologies that fuelled both World Wars. Further post-war discoveries gave rise to other welding types, with the use of different gases as shielding components. MIG or Gas Metal Arc Welding (GMAW), TIG or Gas Tungsten Arc Welding (GTAW) and Flux-Cored Arc Welding (FCAW) have proven effective in welding thinner surfaces like aluminium car panels or bicycle frames, where greater speed and precision are required. Today, Laser and Friction welding have been utilized in robotic manufacturing in the aerospace and military industries, in electronics and medical equipment, and more.
Stick Welding
Stick Welding, also known as Shielded Metal Arc Welding (SMAW) was the first type of welding to see widespread use and is the usually first type of welding most newcomers learn. It gets its name from the stick, or electrode, that melts when being fed electric current. The electrode is the filler material that forms the joint between the two pieces of metal being welded.
The relative simplicity of stick welding means there are few essential tools required. You’ll need an electric power supply able to provide a constant voltage. This comes in the form of a stick welding machine. Next, you’ll need stick welding rods or electrodes that form the welded joints, an electrode holder that houses the electrode, and an earth clamp that forms the ‘arc’ or closed circuit of current that serves as the heat source.
To start welding, connect the electrode holder and earth clamp lead to the welding machine. Place the working end of the earth clamp close to the metal you’re welding, either a metal workbench or the material itself. Insert an electrode into the electrode holder, and strike the area you want to be welded. The electrode will start burning and dissolving, fusing the two metals. The outer coating of the electrode forms a ‘shield’ that protects from oxidisation, giving you a finished weld.
To provide constant current and reduce heat build-up and resistance, your welding tools need to be in good condition. This is important not only for safety reasons like side-stepping the dangers of leaking current but also for the quality of the weld. Welding is one of the most dangerous forms of metal fabrication, and the likelihood of electric shock, burns and serious nerve damage are high. Personal protective gear will only insulate so far as you have a stable, insulated arc to work with. Here, a well-maintained, quality earth clamp can mean the difference between a quick and clean effective weld, or an overheated mess with the chance of electrocution.
Earth Clamps
So, what makes a good earth clamp? A good clamp will have enough conductivity to complete the electrical arc or circuit, while also grounding the current to prevent unwanted sparks or shocks. Earth clamps come in different build types, are made of a combination of metals, and have varying amperage levels.
Build Styles
Spring-loaded earth clamps are the most common grounding clamps in standard-duty welding. The spring opens the clamping jaws made of a conductor like braided brass or copper, and clamp onto the welding table or the metals welded. Connected to the jaws is a cable terminal or lug, fitting to the welding cable. Spring-loaded alligator jaw earth clamps are relatively easy to use. They provide strong clamping force for a stable arc and are easily disconnected once you’re done.
Magnetic clamps are used when welding difficult surfaces, like car panels, where a traditional spring-loaded clamp will either damage your job or simply won’t fit. Magnetic clamps attach easily to the welded surface of metal welding tables, or your welding surface. The welding ground fits through a lug on the top.
G earth clamps are for large industrial projects where metals of higher thickness are used. The jaws open significantly wider than spring-loaded earth clamps and are adjusted via a screw-down mechanism. They are best suited for permanent grounding.
Materials
Earth clamps are made of metals with high electric and heat conductivity. The most commonly used metals are copper, with decent conductivity, and found in slightly more expensive clamps, and brass with lower conductivity, though adequate for welding. For the highest conductivity look for silver clamps, though prepare to pay a premium.
Amperage
Clamps with 140 Amps are fitting for small welding jobs. Most general-purpose clamps hover between 300-400 amps, with industrial clamps being rated at 500 Amps or more.
When to Get a New Earth Clamp
Rusted, damaged clamps pose safety risks and will adversely affect your welding. Day-to-day use will result in heat build-up, which over time will render the clamp useless. You’ll be constantly adjusting the current gauges on the welding machine to the needed output for the job. Regularly checking the condition of earth clamps and any damage to jaws, lugs or springs prior to any welding will save you both time and unwanted hassle. If your earth clamp doesn’t work as it should, you risk becoming a conductor in the electric arc and risk being electrocuted.
Where to Buy Earth Clamps
Earth clamps are basic welding supplies found in all stores selling welding gear. Here, you’ll also find other basic items like welding machines, various electrodes, PPE welding gear, and other equipment if you decide to move on to MIG and TIG welding. If you’re new to welding or need a backup set, you can find complete kits for different welding types along with quality earth clamps. Earth clamps are relatively cheap and often sold in pairs or bundles with discounts. Look for quality clamps made of durable build and materials, suitable for your next welding application.