Have you ever wondered if those small tack welds are really sturdy enough to hold parts together? They play an important role in welding projects by temporarily holding pieces in place.

Is a tack weld strong, or will it fail under stress ? It doesn’t need to be as strong as the permanent weld. Its job is to hold positions until the main welding is done. However, the welds are still strong enough to hold parts together for the duration of final welding. 

We’ll discuss in detail what tack welding is, how it works, and give some tips for yielding better welding results. Keep reading!

What is Tack Welding?

Tack welding is a basic welding technique used to hold metal pieces together before completing the final weld. It involves making small, temporary welds called “tack welds” that act like glue to keep work pieces aligned in the right position. It allows a welder to make sure everything is lined up properly before welding the full joint.

The tack welds themselves are quite small, usually spaced about an inch apart. They only need to be strong enough to hold the metals still. 

Most tack welding is done with MIG welding. The MIG weld process uses a wire feed and protective gas to create welds fast. Only a second or two is needed at each point to form a small molten puddle that bonds the metals securely, at least temporarily. If a mistake is made in positioning the pieces, it’s also easy to remove a tack weld and re-align everything.

The welding type has many practical uses. Some common examples include:

• Sheet metal fabrication: Holding steel or aluminum sheet parts in place for sheet metal welding large assemblies.
• Automotive and aerospace construction: Temporary holding of parts during assembly of things, like engines, machinery, and electrical equipment.
• Construction projects: Tacking metal beams, pipes, etc. for structures like buildings and bridges.
• Precision machining parts: Precision machining companies in the construction and manufacturing industries may use this technique when joining delicate pieces. It could be especially helpful in repairing sophisticated machinery parts or making complex diagrams. 
• Pipe and pressure vessel welding fabrication: Aligning pipe sections, valves, and fittings prior to permanent welding.

Whether the job requires precision or simply holding items, tack welding is a handy technique for joining metal components.

How Does Tack Weld Work?

Is a tack weld strong? Well, it acts like temporary “tacks” but strong enough to keep workpieces securely in place until a permanent bond can be made.

Its working mechanism is pretty simple. The technique involves making small spot welds at strategic points along a joint using the same filler material that will be used for the final weld. Welding machines are set to a lower heat and voltage to create beads that are usually less than an inch long.

Only a few tack welds are needed for smaller pieces, while bigger workpieces may require more spaced further apart. The number and placement depends on the size and shape of joined metals.

The key purpose of tack welding is positioning. It lets welders precisely locate and align workpieces edge to edge before welding the joint completely. This ensures any gaps stay consistent and prevents warping while heating during the final weld. Tacks let sheet metal fabricators perfectly shape joints that would otherwise be difficult to hold with clamps alone.

An advantage of this method is that individual welds can be broken with a chisel or grinder if pieces need adjusting. This allows modifications rather than starting over from scratch.

Tips for Better Tack Welding Results

Getting strong tack welds is important in any welding task. But sometimes they might not stick as well as they should or they could cause issues later. 

We’ll give some tips so you can get better tack welds. We’ll look at common mistakes welders make and how to fix them. 

a. Make Tacks Stronger

Is a tack weld strong? Yes, but you can make it stronger by making it a little bigger. The key is to increase the throat size, or how wide the weld is.

You can also make the welds longer for added strength. Of course, too long and they become regular welds! More welds spaced along the joint gives overall greater strength too. Even just adding a few more tacks in between existing ones helps hold everything steady.

The material being welded can expand and contract with heat, putting stress on the joint. Stronger tacks can withstand this better. Having many tacks distributes the stress across more points.

b. Keep Your Workpiece Straight

Sometimes, when you’re tack welding, the metal can warp or bend out of shape from the heat. There are some things you can do to help prevent this from happening.

First, clamp or tie down your metal pieces tightly before you start welding. That way they can’t move around on you from the heat. It’s also smart to weld from the middle and work your way to the outside edges. That way the heat gets shared out evenly.

You should also take breaks between welds to let the metal cool a bit. If you weld one spot and then quickly do another right next to it, all that heat can build up and cause problems. Go from one side to the other, or do a few tacks and then let it sit for a minute.

c. Choose the Right Welding Current

You need to set the welding current right to create a strong connection between the welded pieces. But you don’t want too much heat either as that can damage the metal or leave a mess.

Start by checking your welder’s guide. It will say what current works best for what you’re welding, like steel or aluminum. Those are just suggestions though. You might need to tweak it a bit until it feels perfect.

Test out your tack welds too. Give them a little pull to see if they hold tight but don’t pull apart. Also look closely at how it looks. A good tack weld will be neat and clean, not too blobby or burned.

If a tack doesn’t look right, adjust the current up or down a bit and try again. With some practice, you can have the perfect tacks every time. 

d. Ensure Sufficient Penetration

Is a tack weld strong? It’s not when it’s poorly done. One issue is when the tacks don’t join the pieces deeply enough. This is called “insufficient penetration,” which can break down the whole weld. So, how can you avoid this? Here are a few things to try.

• Make sure the electrode tip is right where the metal meets. Hold it still for a second so it can sink in. 
• Pay attention to how much electricity you’re using. Too little and it won’t penetrate, too much and it could go all the way through.
• Moving your hand too fast or slow also makes a difference. Going slowly lets it heat up more, but going too fast won’t let it sink in right. Find the right speed through practice.
• Watch how thick your tacks are. You want them to join the pieces, not sit on top. Try different settings until you get tacks with the right thickness. Strong tack welds make your final welds stronger too.

e. Prevent Cracks and Defects

Cracks and defects in the welded joints is one common problem of tack welding. They can really weaken the weld and cause issues down the line. Luckily, there are some simple things you can do to improve your tack welds and avoid these problems. 

Let’s look at a few pro tips for better results:

Clean the metal pieces really well before tacking them together. Even small bits of dirt, oil, or rust left on the surface can get trapped in the weld and cause cracks. Take your time to wire brush or sand both sides until they are shiny and clean. 

Next, pay close attention to your welding settings. Go slower and use a smaller setting if needed to prevent burning through and limiting cracks. It also helps to hold the electrode at a slight angle, usually around 15 degrees, for a stronger weld. 

Then, keep the gaps small and consistent when lining up the pieces. Big uneven seams are more likely to end up with defects. 

Conclusion

Is a tack weld strong? When done correctly with the right techniques, tack welds can absolutely hold pieces firmly in place until the permanent weld is finished. If you follow our tips, you can make these welds stronger enough to do the important job of positioning metals accurately for quality welding. 

Do you need repairs or custom parts made correctly? Contact Zintilon. Our experts can provide high-quality welding and machining for any production needs. Get welding and sheet metal fabrication services to meet your project requirements. Reach out for an estimate!