If you are using a TIG welder to weld aluminum, this can be a tricky process. This is because aluminum requires more heat than mild steel does. This may be anywhere in the range of 21 to 24 Volts.
If you are welding aluminum that is as thick as 14 ga. to 18 ga., you can use a TIG welder for the same. If the aluminum you are welding is thinner, you can opt for a TIG welder. One of the welding techniques you can use is pulse welding.
With pulse welding, you will alternate between low and high currents to weld through several materials. Read ahead to find out more about pulse welding.
- 1 What is Pulse Welding?
- 2 When Should You Use Pulsed TIG?
- 3 Why Should You Use Pulse MIG for Aluminum?
- 4 Advantages of Pulse Welding
- 5 Disadvantages of Pulse Welding
- 6 How Does Pulse Frequency Affect the Weld?
- 7 Recommended Settings on TIG for Steel and Aluminum
- 8 Recommended Settings on MIG for Steel and Aluminum
- 9 Endnotes
What is Pulse Welding?
A pulsed MIG welding system will be able to bridge this gap so that you can get the best return for your investment.
Pulse welding is a process where low and high current is alternated when welding. A pulse welding system will come with a foot pedal using which you can add or lower the heat. However, the output in a pulse welder comes in the form of a pulse instead of a set stable amperage.
While welding aluminum, you cannot follow the same process that you do for steel. When welding aluminum, there may be issues with excess heat input that lead to warping and even burn-through on thin materials like aluminum. It may also lead to excess spatter as you work. Those problems are solved with pulse welding
The regular MIG welding process may also result in difficulties in meeting productivity goals and finding expert welders who can work well with both steel and aluminum. A pulse MIG welding system can solve these issues and work efficiently with aluminum.
When Should You Use Pulsed TIG?
Pulsed TIG systems are a great option for you if you often weld aluminum. If you weld aluminum and steel that is less than ½ inch, you should go ahead and purchase a pulsed TIG system.
If your material is between 3 to 6 mm and you want a true spray arc, you should opt for a pulsed MIG. This is because it works well during a transition or mixed arcing phase. If you are planning on using a pulse welder on more than 10mm of steel, the process will be much slower.
In a pulsed TIG system, you will only get one droplet per pulse cycle. However, the pulse systems available today work at a much higher deposition rate, speeding things up for the operator.
A pulsed TIG welder is also a great option if you want a narrow but deep penetration as you weld. Further, the weld on aluminum will also have less porosity. It also achieves a much better color and is much cheaper to buy when compared to a Standard Spray MIG.
There are a lot of pulse welding machines in the market. If you are interested in pulse welding I would recommend acquiring a lower-mid-level machine in the price range. Such machines are LOTOS TIG200ACDC and this PRIMEWELD machine.
Why Should You Use Pulse MIG for Aluminum?
While mild steel has a density of 7.85 g/cm3, aluminum has a density of 2.70 g/cm3. Aluminum is also a metal that conducts heat five times better than mild steel does. It also tends to melt at a lower temperature than mild steel and is more ductile.
All of these suggest that aluminum demands a different welding approach compared to mild steel. Here’s why you should opt for pulsed MIG for aluminum.
A weld puddle is a molten metal that you see when you weld a metal. With aluminum, a weld puddle takes much longer to make than it does with mild steel. This is because aluminum is a good conductor of heat and quickly transfers heat away from the welding area.
At the same time, the thinner sections of aluminum tend to burn through due to the low melting point of aluminum. Hence, the heat input for aluminum needs to be controlled so that there are no problems during welding. Pulsed MIG can allow this process.
Modified Spray Transfer Process
A spray transfer process is used when the metal in question has to be cut in clean arcs without splatter. A high voltage is applied, and the electrode will not touch the metal as you weld. A true spray transfer is used in MIG welding systems.
These, however, can only be used in horizontal and flat positions, and you will not be able to weld out of position for better control. With pulsed MIG systems, you will be able to control the welding process better for both thin and thick metals.
This is due to the modified spray transfer process. Here, the welder experiences both a high peak current and a low background current. It switches between the two about 30 to 400 times every second. Here is how the switch is beneficial.
The peak current allows good fusion and faster travel speeds for better productivity.
The peak current reduces the cold lap where a crack appears because the molten metal does not completely fuse with the cold surface.
The background current reduces heat input to overcome warping and burn-through.
The weld puddle stays cooler and enables all-position welding.
Hence, a pulse MIG system uses a modified spray transfer process that overcomes many of the issues that spray transfer MIG creates with aluminum.
Filler Wire Diameter
When you use a pulsed MIG system, you will have a larger filler wire diameter that is about 0.047 inches instead of 0.030 inches. Their wires are stiffer and feed much better.
Feeding performance may also include feed rate, which refers to the number of times in which the material passes through the system in a given unit of time. Better performance also improves the deposition rate.
The deposition rate is measured in pounds per hour (PPH) and refers to the amount of the filler that is deposited into the weld. This makes pulsed MIG welding an economical option.
A weld bead refers to the deposit of filler metal that comes from a single welding operation. A pulsed MIG system will let you create the right-sized beads by eliminating excess input of heat. Larger bead sizes can help tie in two sides of a joint easily.
On the other hand, smaller bead sizes provide good fusion right at the root of a joint. Pulsed MIG hence also improves bead appearance and can even be substituted for AC TIG in different welding operations.
In pulse welding, there are the peak current level and the low current level. Pulse duty balances the time between the two. At 50% pulse duty, equal time is spent between both peak and low levels.
Advantages of Pulse Welding
Pulse welding has several advantages that make it an ideal option for operators working with aluminum. Read ahead to find out.
Spatter Free Welding
When working with MIG welding, you may face issues with the spatter. This is especially true if the wire is dirty and the gun is not angled right. Spatter causes molten welded drops to fall outside the welding puddle and can prove a nuisance.
Compared to this, pulsed MIG reduces the spatter and fume that come with welding. This is because much of the melting wire is applied to the joint in pulsed welding. The time required to clean up is reduced by a lot by using pulse welding.
Welding Thick and Thin Materials
A pulsed MIG system shifts between peak and low current. Hence, a single wire can be used to work on multiple materials of various thicknesses. For instance, consider a 1.2mm wire. This wire can weld thin sheets of about 0.6 mm when it is set at about 26 amperes.
The same wire can go ahead and weld much thicker material. This occurs during the 500 amperes setting. Hence, pulsed MIG allows for versatile operation with different metals.
Eliminating Wire Change
This extends from its previous advantage of working well on both thick and thin materials. When you opt for a regular MIG system, various wire diameters of say 0.35 inches, 0.45 inches, and 0.52 inches would be necessary for different sizes and thicknesses.
With a pulsed MIG system, a single wire diameter can work well across thicknesses. With this, the cost of inventory is reduced by a lot. Each wire may come with its spare parts. The costs associated with all of this are reduced by a lot. This also saves up on changing time.
Hence, a pulsed MIG welding system is preferred over the regular one, especially for aluminum.
Weld penetration refers to the distance below the surface of the metal that the fusion line extends. Higher current increases weld penetration. By balancing the heat and penetration by switching between peak and low currents, a pulsed MIG system penetrates the metal well.
In good welding, the penetration should be deep and maximum rather than shallow. For every ampere used, pulsed MIG welding offers deeper penetration for stronger welds. Shallow penetration often leads to weaker welds.
Conventional MIG systems offer a wider but shallower penetration than pulsed MIG systems do.
Disadvantages of Pulse Welding
There are a few disadvantages of pulse welding when compared to standard MIG welding. Read ahead to find out.
Issues in Guidance
In regular dip transfer arc handling, there is contact between the electrode and the weld pool. This allows for better guidance of the weld pool. It also prevents undercutting.
With pulsed MIG welding, there is no direct contact between the electrode and the weld pool. Hence, the level of guidance is reduced.
How Does Pulse Frequency Affect the Weld?
When you understand welding, a key component is pulse frequency. Read ahead as we discuss pulse frequency and welds in detail.
What is Pulse Frequency?
Pulse frequency is measured for a second. It refers to how often in a second welding ampere changes from low to high. For instance, you can set the pulse frequency at 0.5. In this case, it will pulse once every two seconds. You can also set the pulse frequency at 100. In this case, each second will see 100 pulses.
Using Pulse Frequency
You can opt for a lower pulse frequency setting at one every second or lesser. In this case, the filler rod becomes easier to feed and remains in sync with the pulse. This is a good option if you are aiming for a uniform weld.
As the thickness of the metal increases, you will also have to aim for a higher pulse frequency to accompany it. For a 12mm metal, a pulse frequency of about 100 may be appropriate. For thinner metals, a lower frequency is ideal.
This suggests that a pulse frequency of 50 pulses every second may be appropriate for 3mm steel.
With a pulsed MIG system, you will benefit from the pulse frequency and will see welds that are deeply penetrated. A fixed amperage will only make your weld puddle grow as you move and weld.
With a high and low setting and appropriate pulse frequency, you will be able to enjoy the benefits of better penetration with less heat output as you weld. With less heat output, you will see that distortion from heat is much lesser and that burn-through for the heat-affected zone is also lesser.
Recommended Settings on TIG for Steel and Aluminum
If you are using a TIG system for welding, a few settings will help you work well with aluminum. If you are an amateur welder, these starting settings can help you weld well.
If you are welding, say, 5mm of aluminum using TIG, you can begin by keeping ac on. In the beginning, you can keep your pulse off. You can use a power of about 200 amperes. You can also use a frequency of about 100 Hertz.
As you begin to get the hang of it, you can go by this rule. For every 0.001 material thickness, you can use 1 ampere. If the material is thicker than ¼ inches, you won’t need as much amperage anymore. For a stacked dimes look as you weld, you can go ahead and use the foot pedal to vary amperage.
If you are a beginner to TIG welding, you can begin with steel that is anywhere between 2mm and 3mm. This makes it much easier to control the weld pool. You can set the welder to 50 amperes. You can then go ahead and use a tungsten and filler rod, both at 1.66 mm.
You can hold the torch at an angle of 20 degrees from the vertical. For the 1.66 mm tungsten, you can keep a gap of 2mm between the work and the tungsten. Perform a dry run once across the material before you begin welding.
Recommended Settings on MIG for Steel and Aluminum
Here are the settings you can use on your pulse MIG for aluminum and steel.
If you are using a 1.2mm diameter wire, here are the settings you can use on a MIG pulse welder for aluminum. You can begin by using aluminum between 1.5mm to 5mm.
With this, you can opt for a start current of 20%. This brings the right ampere for the beginning of the weld. Towards the end of the weld seam, you can move slowly from about 100 amps to 50 amps instead of directly moving from 100 to 0.
When you pulse weld aluminum, you can set the wire about 1mm away from the weld pool. This will avoid any spatter that comes from setting it too close. You will also have to adjust the arc length control.
If you opt for more wire, you will get a shorter arc length. If you want a longer arc length, you can increase the voltage for a shorter wire that burns quickly. You can also opt for a frequency of about 2 Hertz.
Getting the settings right on a pulsed MIG system for mild steel can be a little difficult. You can do this by practicing with common wires used for pulsed steel welding. These are mostly 0.8mm, 0.9mm, and 1.2mm. You can use these with low currents for no splatter.
If you want to look for a welding system that works well with both aluminum and mild steel, a pulse MIG system may be ideal. These alternate between peak currents and low ones so that there is no excess heat produced at the welding pool.
This prevents a material like aluminum from burn-through that results from its low melting point. It also concentrates heat just enough to result in some deep and well-penetrated welds. This is even though aluminum conducts heat much faster than steel does.
Because of its pulsing current, a pulsed MIG welder works rather well, even on thinner sheets of mild steel. It reduces spatter and improves productivity. It also saves up on welding time due to its high deposition rate which is especially seen with newer generations of pulsed MIG welders.
We have listed several reasons why these pulsed welders are beneficial for aluminum. We have also listed just when and how you can go about using pulse welding.