Did you know that welds are not truly permanent? You can learn how to remove welds in a few minutes and a few practices. The processes used to remove the welds are relatively simple, and the tools are readily available.
You may want to remove a weld for one of three reasons. The most common one is to undo a bad weld or loose joint. The second reason may have something to do with salvaging a valuable part from a previously welded assembly. The last one is to destroy a welded joint between two or more different parts.
The weld removal process discussed here can help you destroy all types of welds from various welding processes such as TIG, MIG, and resistance welding. Keep in mind that you would have to adhere to all standard safety precautions when doing these procedures. Additionally, depending on which process you use, you should be ready to spend hours on the workstation getting rid of that weld.
A Brief Overview of Welding
To understand how to remove welds, we first have to dive into the basics of welding to understand why other weld removal processes can be tedious.
Welding is a fusion process of permanently joining similar or dissimilar materials through heat, pressure, or a combination of both. The joints between these materials are permanent because you would have to destroy part of the materials in one form or another to get rid of the joints.
When you think of welds, most people assume metals, but you can weld thermoplastics and even wood. The resultant weld is very strong, appearing stronger than the tensile strength of the original materials.
The weld is stronger because the materials used to make the welding rods have stronger and superior properties than the base metals. These properties include their tensile strength, yield strength, and mechanical strength.
As the welded part becomes stronger than the base materials, the adjacent parts next to the weld become weaker on some occasions. The phenomenon experienced here is called annealing. It is a heat treatment process in which heat application to material causes it to lose its hardness but increases its ductility.
Annealing can happen when you are welding, causing weaker joints. These joints are not because of a faulty weld but due to the reduced hardness of the adjacent part. Always bear these phenomena in mind to help you have a good welding technique to prevent poor welds that get removed.
Another thing to pay attention to is the different types of welding. Various types of welding are used for different applications to give a variety of sophisticated welds. The used types are arc (most common welding machines are MIG, TIG, GTAW, and SAW), friction, resistance (spot and seam welding), electron beam, and laser welding. Arc is the most popular.
The weld removal processes discussed here come in handy for any weld. However, they mainly pertain to arc welding and resistance welding to remover spot, butt, fillet, and slot welds.
How to remove welds: Step-by-step guide
You can remove welds through mechanical means, that is, using manual force and tools. Another way could be through thermal means, which involves the use of heat. Before embarking on either one of them, you must decide how smooth you want the removed weld to look. Some processes would provide a smoother surface finish than others.
Mechanical weld removal processes
The advantage of using mechanical weld removal processes is that you would not have to purchase any pricey equipment, let alone any in some cases. The downside to these mechanical means is the fact that they are not efficient at the job.
Mechanical processes involve using a lot of force and sharp tools that can affect the materials’ properties and joints. Some of the effects might be distortion, bending, and the destruction of the constituent metals.
To obtain a finer and smoother finish on the materials, stick to thermal processes since they provide extra versatility. However, if equipment availability and cost are far from your reach, then going with the mechanical process would do the job. Just be gentle, slow, and careful.
By use of a hammer and chisel
This process appears to be the simplest since all these tools are usually readily available in most homes. They are also cheap in case you have to buy one. The method is simple but can only be applicable when you have a small tack or short welds. You can use it for longer welds but the force and period needed to finish the process are too intensive.
This process would most definitely leave you metals with cuts, chisel marks, torn edges, and deformation marks from the hammer. Therefore, you should use the following steps only if you don’t mind damaging one or both of the adjoining metal parts:
- Mark the parts you want to remove the weld from using a marker or pencil.
- Place the piece in a vice or clamps to prevent them from moving when you apply force to them.
- Take the necessary safety precautions, such as using gloves, protective goggles, and a lab coat.
- If you want to sacrifice one piece for the other, use the hammer and chisel for popping off the weld in the direction of the sacrificial piece. It would prevent or at least minimize the damage done to the part you want to save.
- Proceed with the hammering while carefully using the chisel in between to separate the weld.
- After you have removed the weld, use sandpaper or a grinder to smoothen the surface.
A similar process to this involves the use of a hacksaw. A hacksaw is very applicable in tubular longitudinal rods since all it has to do is “cut straight through the weld.” The after-treatment would also involve the use of sandpaper and a grinder.
By use of angle grinders
Grinders are great tools for creating smooth surface finishes and cutting metal. Even though the metal removal process from the grinder is powerful, it does not compare to methods like plasma cutting. However, the advantage of using a grinder is that the base metal properties would remain due to insufficient heat that can’t deform the metals. The process is also cheaper.
Like hammering and sawing, you should use these steps only if you don’t mind destroying one or both base metals. Here is how to cut welds with a grinder:
- Start with marking the places you want to remove the weld. Follow this with a vice or clamp that holds the part in place.
- With the grinder turned on, lightly press on the weld starting from the furthest point from the surface. Gradually proceed to remove layer after layer of the weld, making sure not to damage the base metals carelessly.
- You can then alternate the angles at which you orient the grinder to save on time and provide a better cut. You need this skill to help you while learning how to grind off a weld.
- After letting the metal cool down, proceed with the after-treatments using sandpaper and the grinder to give the parts a smooth surface finish.
By use of drills, spot weld cutter kits, and belt sander
Wondering how to remove spot welds? This process seems best for you. It is great for removing spot welds and other short welds that haven’t penetrated deep enough to need thermal processes. Spot welds are usually used to weld plates together or plates onto other parts.
This process seems perfect if you are learning how to remove welding joints at home. It is more so great if you do not mind sacrificing one base metal for the other.
- With a marker or any sharp object, mark all the centers of the spot welds. You must identify all the spot welds to avoid deformations when you finally yank the pieces off. Some may be small and rusted, therefore hard to identify.
- The next step is to take a drill bit and make the centers of the spot welds more prominent.
- Proceed to use the purchased spot weld cutter kit. The kit consists of a mini hole cutter with a drill bit at the center used with a hand drill to cut metal around the spot welds. Unlike a hammer or grinder, this kit takes some practice for effective use.
- With the spot weld cutter attached to a drill, gentle press the spot welds while cutting the holes around them. You do not need to cut all the holes at once; you can use a chisel to separate the metals as you continue to make more holes.
- Please turn on the belt sander and use it to flatten the spot welds. You use the belt sander at this stage to reach those areas where you don’t want the cutter or drill to reach. The belt sander also gives you more precision and control when the spot weld is almost getting removed.
- Continue sanding the spot welds while still using the chisel to pry off the sacrificial plate. Once the plate is off, use the belt sander or regular sandpaper to create a smooth surface finish.
Thermal weld removal processes
Thermal processes are more tolerant of the state of the base metals. However, they are more hazardous since they involve intensive heat and skillful procedures that can be dangerous. Some of the hazards may include molten metal splatter and random bursts.
Cutting using plasma cutters
A plasma cutter is a welding removal machine that uses a jet of ionized hot gas to melt and propel molten metal from a cut. The ionized gas, usually argon, can be at high temperatures of up to 20,000 degrees Celsius. The steps are simple. The only problem might be the availability of a plasma cutter. Apart from that, plasma cutting is by far the best way to remove weld joints.
Start by taking the necessary safety precautions and clamp the part on a vice. With the plasma cutter turned on, approach the weld spot and slowly cut it. Make sure to match the metal removal rate with your approach speed to prevent melting parts of the base metals.
The process is ten times faster than torch cutting and metal, making it more preferable for heavy tasks. The downside is the slag, basically molten inclusions, contaminants, and shavings, that gets stuck on the cut edges. You would need to sand them out with an appropriate tool
Torch cutting with an oxy-acetylene torch
Oxy-acetylene can not only be used to weld but also cut metals. The process is very effective but requires enough space on the welding joint so that the base metals are not damaged. If a welded part is on top of another, the torch will cut through the second part. Such action would create space for the slag to pass through. You would also require after-treatment processes for this procedure.
The torch can heat the steel to 900 degrees Celsius, causing the metal to melt. It can even go up to 3500 degrees Celsius, depending on the material. The molten metal is blown out of the way by the pressure jet of the torch.
Start the procedure by clamping your part and wearing protective gear. Mark the places you would like to cut and light up the torch. Make sure to regulate the flame so that you do not have too much or little heat. Follow the markings to achieve your cut.
The advantage of torch cutting is that it does not cost much. Additionally, using the torch isn’t that hard if you use it for a while. If you are good at welding, torch cutting won’t be a challenge for you.
Q: Can you Unweld metal?
A weld needs to be a permanent fusion. You cannot unwind metal. You can, however, break or cut the weld using mechanical means or thermal means to separate the base materials.
Q: Does grinding down a weld weaken it?
There are two ways to use a grinder on a weld; to make the surface finish smoother or remove the weld. In creating a smooth finish, grinding does not weaken the weld since you always make sure to remove the surface layers of the weld. By removing materials from only the protruding weld surface, you avoid penetrating the whole weld with the grinder.
Using a grinder to remove a weld, on the other hand, would weaken the weld since that is the intended purpose.
Q: Can you drill through a weld?
Drilling through a weld would weaken the weld but is not a stand-alone procedure for cutting welds. It would just weaken the weld and cause a huge mess. To use a drill for weld removal, incorporate it with weld cutters and belt sanders.
Your choice on which method to use would come down to equipment availability, the time you have, and the amount of material you want to save. For a more precise, fast, and reliable method, go with plasma cutting.
For those looking to remove short welds on plates and sheets, you won’t need thermal processes since they would destroy the materials. Go with the spot weld cutter and belt sander. A grinder is a good option for cutting straight through a weld between two rods or prisms.