Arc, Spot Welding Techniques:

Welding has become an integral part of the lives of many people. Just like there are various different welding machines available, all the way from Diesel Welders to Pro-Arc's, there are also numerous welding techniques that can be used. In this article, we will cover some of the popular welding techniques like:

(1). Arc (2). Spot

Here, we will talk about why Arc welding is important. Arc welding is usually done by making use of a diesel welder. In arc welding, high electric voltage is used, instead of a gas torch. The arc, or the spark, created from the electrode rod, used by the welder, is transferred from one metal to the other metal. This in turn causes the metals to heat up and melt together which creates a bond or a weld amongst them. Arc welding is known to create cleaner, smoother, accurate and stronger welds.

The second technique to be discussed is the Spot technique. In this method, the two metal sheets are held together tightly by the electrodes. The surface area of contact between the electrodes and the materials is very small, and hence it is called 'spot' welding. When a large amount of current is passed through the electrodes, it heats up the spots to the point of melting, which results in a sturdy weld. This technique ensures that the rest of the metal isn't heated up unnecessarily and also takes lesser time.

Instructions of Spot Welding:

1). Slide the sheet metal gauge onto one edge of the sheet metal to determine the thickness of the metal. When the sheet metal fits snug in a sheet metal gauge slot, read the number above the slot. This will show the thickness of the metal.

2). Set the hold, weld, squeeze and off-time of the spot welder by locating the thickness of the sheet metal on the welding chart affixed to the spot welder.

3). Clean the tips of both the top and bottom electrode by sliding the file over each tip. To weld correctly, the tip of each electrode should have no black carbon deposits.

4). Put on your leather work gloves.

5). Turn on the spot welder and open the cold water supply valve to flow water through the electrodes.

6). Stack the two pieces of sheet metal on top of one another.

7). Set the stacked pieces of sheet metal on the bottom electrode of the spot welder.

8). Depress the pedal of the spot welder to lower the top jaw of the spot welder and weld the sheet metal.

9). Twist the welded sheet metal a quarter-turn before releasing the pedal to avoid pulling a welding electrode from its socket.

10). Attempt to pull the sheet metal apart. If the metal bends rather than pulls apart, the spot welder is set correctly. If the spot weld breaks, increase the weld time of the spot welder and repeat the listed steps until you achieve a proper spot weld.

Auto Darkening Welding Helmets:

While some people still stick to using standard welding helmets, auto darkening welding helmets are now gaining more popularity in the market. Helmets with auto dark lens could decrease the penetration of light whenever it is energized so that the lens appears dark in the center but light towards the outer areas. It also gives lighter, clearer views in angles that are not perpendicular to the surface of the filter. It’s really easier and more comfortable to work with helmets that have auto dark lens. They normally come with filters too that protect the eyes from ultraviolet or infrared rays.

Since this type of welding helmets darken and lighten up automatically, those who use it do not need to take it off as they work. There is no need to adjust the shade since it’s quite automatic. It generally costs more than the standard helmets though. The price of auto darkening welding helmets normally range from a hundred dollars to five hundred dollars, with more expensive ones offering more features or being made of more pricey, durable and flexible materials.

Inert Gas Welding and Spot Welding Difference:

Unlike inert gas welding, spot welders do not require a shielding gas to eliminate weld contamination or filler metal to build up the weld.

A spot weld is a resistant weld that sits within the two pieces of metal. The finished weld is flush or slightly recessed to the exterior of the base metals and has a silvery or coppery appearance. The color of the spot weld will vary by the alloy of the metal being welded and the type of electrodes used to create the spot weld.

An inert gas weld is built up in a gap between two pieces of metal. The finished weld is humped up above the base metal and is easily visible. The high amount of heat generated by inert gas welding can cause the base metal to warp and twist.

Welding Procedures:

There are five basic steps when welding that must be followed.

• Proper Preparation - You first need to ensure that the metal you are welding is clean and dry. Remove rust, dirt, grease, oil and other contaminants by wire brushing. If not removed, these contaminants can cause porosity, cracking and poor weld deposit quality. You must also remove badly cracked, deformed or work-hardened surfaces by grinding, machining or carbon-arc gouging.

• Proper Preheat - The combination of alloy content, carbon content, massive size and part rigidity creates a necessity to preheat in many welding or hard facing operations. Most applications require preheating, as a minimum to bring the part to a room temperature of 70ƒ-100ƒ F. Medium to high carbon and low alloy steels may require higher preheat to prevent under bead cracking, welding cracking or stress failure of the part. Preheating can be done with a torch, oven or electrical heating device. Special temperature-melting crayons can help you verify proper preheat. Too much heat and you can often ruin alloy materials!

• Adequate Penetration - Correct Welding Procedure - Identify the correct amperage, travel speed, size of weld, polarity, etc. Make sure the completed weld meets your expectations in regards to size and appearance. Welds should be smooth and uniform, free from undercut or porosity. If possible, watch a video showing the type of welding you will be doing so you know what things are suppose to look like.

• Proper Cool Down - Preheating is the most effective way of slowing the cooling rate of massive or restrained parts, which are inherently, crack sensitive. Insulating the part immediately after welding with dry sand, lime, or a glass fiber blanket also helps minimize residual cooling stresses, weld cracking and distortion. Never quench a weld with ice or water as this will lead to greater internal stresses and potentially weld cracking.

• Post Weld Heat Treatment - Some items may require tempering or heat-treating. What this means is that you warm the item up with your torch after welding and allow it to slowly cool.

Flux-Core Arc Welders:

Flux-Core Arc Welders use a wire that, in its core, contains materials that release the shielding gases necessary to be able to protect the molten metal from the environment. There is no need concerning any external shielding agent, and also the shielding gases released by the wire can even withstand powerful breezes.

The drawback to the Flux-Core Arc Welders is that they use a fairly forceful arc, creating a large amount of spatter. Additionally, there can end up being slag on the final welding job, as well as it's going to end up being removed for a neat, clean finish. Extra disadvantages can appear as a result of mechanical troubles, like irregularity in the wire feeding. The filler material will be also a lot more costly than that compared to a Gas-Metal Welders.

How to weld sheet metal using a stick welder:

The real trick to welding thin metal is to use a wire feed. Just kidding, this tip is to explain how to do it with a stick welder. A wire feed or tig welder is ideal for sheet metal, but we will assume that you don't have one. We need to establish what is considered thin metal. There is no absolute "according to Hoyle" answer, but I always considered anything less than 3/16″ to be thin. So from this point on we are talking about less than 3/16" material.

The first thing to figure out is what kind of welding rods and what size of welding rods to use. If you have nice new 1/8″ material, I would go with 3/32″ 7018 rods. If you have old rusty painted up 14 gauges, I might be inclined to use 1/8″ or 3/32″ 6011 rods. You might ask me, why don’t you just grind the rust off? Well if it’s just surface rust go ahead, but if it’s pitted out you will grind all the material away before you get it clean. Not only have that, but if you are just doing a quick repair job on something, just welded it. Chances are, if the material is that bad the weld will far out last the rest of the material anyway. Back to my point, 6011 is the rod I will pick anytime. It allows you to move a lot faster than 7018’s will.

As far as the actual welding goes, I like to use a whipping motion with the welding rod following the same direction as I am welding. Basically just a back and forth motion. The reason for this is to keep from building up too much heat all in one spot. If you were to drag the rod slowly you will have a pretty good chance of burning through. If you are welding vertically, don’t be afraid to run the 6011’s downhill. If the material is really thin, I will use the whipping motion downhill as well. I know it goes against some principles of burying slag but, when the material is thin it really doesn’t matter as much.

Most anything that is made from thin material is over welded. Say for instance you are patching an air compressor tank that has a hole rusted in it. You will weld the patch 100% because it needs to be air tight, not for strength. If you are making a section of air duct, you will weld it solid for air and not for strength, you get the point.

I guess the moral of the story is you can do just about anything with a stick welder in a pinch. It only takes a little bit of practice to make it happen. Just grab a piece of sheet metal to get the heat set correctly and go to town. A good heat setting for 1/8″ 6011 rods on thin material is about 80-90 amps. For 3/32″ 7018’s it’s about the same. Everyone is different but, those settings will get you in the ballpark.

MIG Welding Overview:

There are four primary methods of metal transfer in MIG welding: globular, short-circuiting, spray, and pulsed-spray. Each of these has distinct properties and corresponding advantages and limitations. Schrimpf Welding offers a variety of MIG Welding services depending on the individual details of the project. For the most comprehensive advice, we recommend contacting us with the specifics of your project, and we will be happy to supply you with a free estimate.

Some of the advantages to MIG welding are:

• Continuous weld, due to the continuous spool
• Almost no cleanup
• You are able to weld in all positions
• Can weld stainless steel, mild steel, and aluminum