A Comprehensive Guide To Pulse Mig Welding: What It Is, How It Works, And Why It’s Used
Pulse MIG welding is a process that offers fast, high-quality, and low-spatter welds with better thermal control compared to conventional MIG welding. While it is commonly used for welding aluminum, it is also an excellent process for welding with stainless steel and bronze wires. In fact, Pulse MIG can achieve results comparable to TIG welding, but with greater speed and productivity.
Technically speaking, Pulse MIG is a highly-controlled spray-transfer MIG process that operates differently from the traditional ‘short-circuit’ MIG process. In Pulse MIG, the filler metal is transferred from the wire to the weld pool without the wire contacting the weld pool. The current alternates, or pulses, between a high peak current and a low background current at a frequency of up to several hundred times per second. With each pulse, the peak current pinches off a droplet of wire and propels it to the weld joint, while the background current maintains the arc at a low enough power level to prevent short-circuiting.
Why It’s Used
Pulse MIG welding offers several benefits, making it a desirable choice for welding. These benefits include:
- Lower heat, which results in minimal distortion and reduced burn-through.
- Reduced spatter, which significantly reduces or even eliminates the need for cleanup.
- Visually appealing welds, which add value to the finished product.
- Higher deposition rates, which increase efficiency and allow for faster travel speeds.
- Tighter weld pool control, which makes it ideal for out-of-position welding.
- Reduced welding fumes, which create a safer and cleaner work environment.
What metals can you weld with Pulse MIG?
Pulse MIG welding is suitable for metals and applications where controlling heat is challenging when using the standard MIG process, and where high-quality welds and appearance are desired.
When Pulse MIG welding aluminum, the operator can achieve greater thermal control to apply enough heat for a successful weld while avoiding distortion or burn-through. Aluminum is a high thermal conductor, meaning that heat is quickly transferred away from the weld pool, and has a relatively low melting temperature.
Pulse MIG welding with bronze wires, also known as MIG brazing, involves applying the wires at a lower temperature than the melting point of the parent material. This process is commonly used on thin materials, such as car body panels, where low-temperature welding is necessary to avoid distortion. It is also used on galvanized or zinc-coated steels up to 2mm thickness because the weld metal does not rust, and the lower application temperature prevents disturbance or evaporation of the zinc coating. The ability to control and reduce heat makes Pulse MIG an ideal process for brazing wires.
When Pulse MIG welding with stainless steel, heat is typically trapped close to the weld zone due to its poor thermal conductivity. This can result in expansion, distortion, and rust contamination due to concentrated carbon in the weld zone. The weld pool is also sluggish with poor wetting and flow into the parent metal. However, the Pulse MIG process allows stainless steel wires to be applied at lower temperatures to minimize distortion and imperfections. This process is especially beneficial for welding thin stainless steel material, where it is often challenging, if not impossible, to avoid warpage or distortion with conventional MIG welding.
Pulse MIG welding enables successful welding at lower temperatures with significantly better control of the weld pool in all of these applications.
Pulse MIG welding mild steel
Mild steel does not pose the same thermal challenges as other metals like aluminum or stainless steel, and therefore, Pulse MIG welding does not necessarily offer the same advantages. As a result, conventional MIG welding is still the preferred process for welding mild steel in many applications, especially in the material thickness range that can be achieved with single-phase machines.
Pulse MIG welding can provide productivity benefits for welding heavy steel. However, this requires a high “peak” current that is only available from three-phase pulse machines.
What is Double-Pulse MIG?
Dual-pulse or pulse-on-pulse (PoP) welding involves adding an extra pulse wave, where the current alternates between the main current level and a secondary current level. This technique effectively amplifies the benefits of single-pulse welding, resulting in even better thermal control, weld quality, and appearance.
TIG welding is typically the preferred process when there is a requirement to weld materials to a higher standard in terms of quality and appearance than conventional MIG welding. TIG welding is commonly used for welding aluminum and stainless steel, as these materials are frequently utilized in projects where the final product’s finish is crucial, such as boats and marine applications, architectural fixtures, and food handling equipment.
One of the drawbacks of TIG welding is that it is a relatively slow and inefficient process, which can increase costs and processing time.
However, Pulse MIG welding offers a solution to this problem. Essentially, Pulse MIG welding provides:
In many applications, Pulse MIG welding provides weld quality and finish that is comparable to or very close to TIG welding.
Compared to TIG welding, Pulse MIG welding offers superior speed and efficiency.
Pulse MIG welding typically requires less skill and is easier to learn compared to TIG welding, which can reduce training time.
Although the TIG process will always have its significance, Pulse MIG welding is increasingly becoming the preferred choice for many applications, particularly in production work, as it offers several advantages over TIG welding.
If you have access to a 3-phase power supply, it is usually advisable to choose a 3-phase machine for higher output and capacity. However, if you do not have this option or prefer the portability of a single-phase machine, there are a few factors to consider.
Single-phase (230/240V) pulse MIG machines have fewer options available on the market for a good reason. They present a particularly challenging task for welder manufacturers. Pulse welding is more complex, with multiple current levels (start, base, peak, secondary, and end current), all of which must be factored into the limited input and output power range available from a single phase. This makes it difficult to develop a machine that works well, and it also affects the capacity or maximum thickness that a single-phase pulse MIG can weld.
What is the maximum thickness you can weld with a Pulse MIG?
The machine’s welding capacity depends on whether it is a 240V/single-phase or 3-phase machine. Three-phase machines, with 415V of power, can typically weld up to 10-20mm thick material or even more (depending on their rated size).
Single-phase Pulse machines, on the other hand, can typically weld up to a maximum of 5-6mm if they are in pulse mode. Here are a few things to keep in mind:
In pulse mode, higher output (amps) is required compared to non-pulse mode, which results in a lower “maximum weldable thickness” in pulse mode than in non-pulse mode.
The same principle applies to single-pulse and double-pulse welding: Single-pulse welding typically allows for the welding of slightly heavier materials compared to double-pulse welding.
In non-pulse modes (essentially converting the machine into a conventional MIG), single-phase MIGs can weld 8-12mm material, depending on their rated size.
The maximum thickness capacity can differ from one application to another, and one crucial factor is the “heat sink.” Larger workpieces tend to absorb more heat than smaller components, particularly aluminum, which is an excellent thermal conductor. This means that more or higher current is necessary, which, in turn, reduces the maximum weldable thickness.
Based on the information provided above, a MIG welding machine was recommended to you.
This MIG-160I inverter MIG welder is a multi-function welding machine. This MIG welder spatters less, have easier arc starting, a deep welding pool, and a high-duty cycle that you will appreciate. The MIG-160I offers:
1. Full bridge IGBT converter guarantees stable output power.
2. Digital control system and multi-functional control panel which can achieve MIG/MAG, Gasless flux cored wire welding and MMA.
3. Compact design, lightweight, but robust.
4. User-friendly and cost-effective.
5. Effective spatter control, improved penetration, and better welding effect.
6. Equipped with a trimmer potentiometer on the control panel, it is more convenient for the voltage compensation of welding to make the welding effect more perfect.
7. Ideal for use in outdoor and indoor conditions.
8. Operation safety protection against over-voltage, low-voltage, over-current and over-heated.