What Is Pulse Welding, And How Does It Work?

Welding, an essential part of various industries, has evolved over the years, introducing advanced techniques to enhance efficiency and precision. Pulse welding is one such innovation that has revolutionized the field, offering a controlled and versatile approach to joining metals. In this comprehensive guide, we will delve into the intricacies of pulse welding, exploring its mechanisms, applications, and advantages.

What Is Pulse Welding, And How Does It Work?

Pulse welding, a dynamic departure from conventional welding techniques, injects versatility and precision into the art of metal joining. Unlike traditional methods where the electric current maintains a constant flow, pulse welding introduces controlled pulsations, revolutionizing the welding landscape. Let's delve deeper into the intricacies of pulse welding and uncover the nuances that make it a preferred choice for welders seeking superior control and enhanced outcomes.

Pulse Frequency

At the heart of pulse welding lies the pulse frequency, a parameter that governs how frequently the welding current oscillates between high and low amperage within a single second. This frequency, a variable under the welder's command, determines the pace of these oscillations. Opting for lower frequencies, such as a pulse per second, becomes a strategic choice, fostering smoother and visually appealing welds. The careful modulation of pulse frequency empowers welders to tailor their approach based on the specific requirements of each welding task.

Peak Current/Background Current

Pulse welding orchestrates a dance between peak current and background current, a symphony that defines the energy dynamics during the welding process. The peak current surges, delivering a burst of energy that metamorphoses into a droplet of melted metal for each pulse. This droplet gracefully finds its way to the weld joint without making direct contact with the workpiece. 

Meanwhile, the background current steps in as the maestro of controlled cooling, ensuring that the weld pool doesn't succumb to excessive heat. This intricate balance between surges of power and calculated cooling forms the crux of pulse welding's efficacy.

Pulse Percentage

The pulse percentage is the arbiter of stability and quality. Often set at a balanced 50%, this percentage delineates the equilibrium between time spent at high current and low current during the pulse mode. This delicate balance contributes significantly to the overall stability of the welding process, resulting in weld seams of superior quality.

Pulsed TIG Welding

Pulsed TIG welding, a refined variant of pulse welding, introduces an innovative approach to the art of metal fusion. This technique utilizes a foot pedal to regulate the amperage output, offering welders an unparalleled level of control. The TIG torch, in a pulsating fashion, generates a waveform instead of a continuous current stream, enabling accurate adjustments during the welding process. 

Advantages of Pulsed TIG Welding:

Reduced Heat-Affected Zones: One of the standout benefits of Pulsed TIG welding is its ability to minimize heat-affected zones.

Minimized Spatter: Pulsed TIG welding excels in minimizing spatter during the welding process.

Enhanced Control Over Welding Parameters: Welders using Pulsed TIG welding benefit from heightened control over welding parameters.

Aesthetic Welds with Even Penetration: The pulsating waveform generated by Pulsed TIG welding contributes to the creation of aesthetically pleasing welds.

Disadvantages of Pulsed TIG Welding:

Equipment Cost: While Pulsed TIG welding offers a range of advantages, the associated equipment can be more expensive compared to traditional TIG welding setups.

Learning Curve: Mastering Pulsed TIG welding requires a certain level of skill and experience. The dynamic nature of the pulsating waveform and the ability to control parameters in real-time demand a learning curve for welders.

Limited Applicability: While highly effective in precision welding applications, Pulsed TIG welding may have limited applicability in certain scenarios.

Pulsed MIG Welding

In the expansive realm of MIG welding, pulsed MIG welding emerges as a stalwart technique, wielding unparalleled precision in welding thinner materials. This sophisticated process orchestrates a symphony of constantly changing low and high currents, meticulously produced by the welding machine. The result is a pulsing effect that, rather than maintaining a continuous heat input, strategically cools the weld pool intermittently.

Some welders like the SSimder SD-4050 Pro 10 in 1 welder&cutter. Which will provide good results for hobbyist Pulse MIG welding needs.

Pulse On Pulse Welding

Within the nuanced world of pulsed MIG welding, the technique known as Pulse on Pulse (POP) or twin pulse introduces an intriguing layer of complexity. Here, the feed motor engages in a dance of pulsations and breaks, intricately timed with the welding current's rhythmic surges. 

This unique interplay crafts a distinctive herringbone effect on the weld bead, adding not only visual appeal but also an element of versatility to the pulsing process. While Pulse on Pulse welding finds its prime application in aluminum welding, its adaptability offers a touch of artistry to the pulsing repertoire.

Advantages Of Pulsed MIG Welding

Reduced Spatter: One of the hallmark benefits of pulsed MIG welding is its ability to minimize spatter during the welding process.

High Deposition Rates: Pulsed MIG welding boasts impressive deposition rates, allowing for faster welding compared to traditional methods.

Strong Fusion: The controlled surges of energy in pulsed MIG welding contribute to robust fusion between the weld metal and the base material.

Aesthetic Weld Appearance: The pulsating effect not only serves a functional purpose but also imparts a visual appeal to the welds.

Disadvantages of Pulse Welding

High Heat Input: Pulsed MIG welding, with its surges of energy, can result in high heat input to the weld.

Limited Welding Positions: The nature of pulsed MIG welding imposes limitations on the range of welding positions that can be effectively employed.

Potential for Burn-Through: When working with thinner materials, there's a potential risk of burn-through due to the intense pulsations of heat.

What metals can you weld with Pulse MIG ?

Pulse MIG is ideal for metals and applications where controlling heat is difficult when using standard MIG process, and/or where high weld quality and appearance is desired.

Pulse MIG welding Aluminium

Aluminium is a high thermal conductor (which means that heat is quickly transferred away from the weld pool), with a relatively low melting temperature. Pulse MIG process allows the operator much greater thermal control to apply enough heat for a successful weld, whilst avoiding distortion or burn-through.

Pulse MIG welding with Bronze wires (MIG brazing)

Bronze wires are typically applied at a temperate that is lower than the melting point of the parent material - where the materials are essentially "stuck" rather than welded together - and are commonly used on thin materials (eg car body panels) where low temperature welding is essential to avoid distortion. Also commonly used on galvanised or zinc-coated steels (up to 2mm thickness) because the weld metal does not rust and the lower application temperature prevents disturbance (evaporation) of the zinc coating. The ability to control and reduce heat makes pulse an ideal process for brazing wires.

Pulse MIG welding with Stainless-Steel

Because stainless-steel is a poor thermal conductor, heat is typically 'trapped' close to the weld zone. This can result in expansion/distortion and rust contamination due to concentrated carbon in the weld zone. The weld pool is comparitively sluggish with poor wetting/flow into parent metal. The pulse process allows stainless wires to be applied at lower temperatures to minimise distortion and imperfectons. Pulse MIG is especially beneficial for welding thin stainless material where it is often extremely difficult, if not impossible, to avoid warpage/distortion with conventional MIG process.

In all these applications, Pulse allows successful welding at lower temperatures with much better control of the weld pool.

What to look for in a Pulse MIG welder

Pulse MIG can open up a lot of new opportunities for your workshop or fabrication business, and improve your productivity. However, pulse is much more complex and costly than conventional MIG, which makes it important to chose a machine that will give you the best results and return on your investment in the long term. Here's a few points to keep in mind;

• Single-Pulse or Double-Pulse? Double-pulse takes the benefits of single pulse (weld quality, finish, etc) to a new level. Not all pulse MIGs will have double-pulse mode. Single pulse can be considered as an "entry level" option if you are learning or trialling pulse MIG, and will typically have fewer features and adjustments. However many operators nowadays prefer double pulse. Check the machine specs so you know what you're getting.
• Track Record: It's a fact that when it comes to developing a truly functional and reliable Pulse MIG, many welder manufacturers have tried and failed. As they say 'nothing beats experience', and this is certainly true when it comes to pulse. So our best advice is to chose a proven machine from a well established manufacturer.
• Simple vs Complex: Pulse welding is much less forgiving than conventional MIG and often it's the little things - for example a slightly loose connection, or an incorrect setting - that can make the difference between a happy result or a frustrating waste of time. It's easy to be wowed by a lot of features and options, but keep in mind that this also adds to the "list of things that can go wrong". The most reliable and user-friendly pulse machines are typically those with a comparitively simple design that is primarily focused around pulse MIG function.
• Controls: Sadly, it's not uncommon to find operators who have been lured by the benefits of pulse, but have found their machine difficult, confusing and time consuming to learn and operate. On the other hand, controls that are intuitive and easy to follow will maximise your welding time, and minimise down time.... and make it much easier to train new operators.
• Single Phase? As we have already covered earlier in this article, producing a single-phase Pulse MIG that works well is a very challenging task. Once again, look for a reputable and experienced manufacturer, and be wary of single-phase pulse machines that are 'loaded' with other functions not related to pulse MIG.
• Wire feed system: With pulse, it is critical that wire feeding is 100% consistant and reliable. Reputable drive systems are often made by specialist manufacturers who then provide this componentry to welding machine manufacturers, so it pays to dig into the detail of where the drive system comes from and its track record. Robust build is important, but other less obvious aspects are also critical, such as whether the system is purely mechanical or does it electonically synchronise with other machine controls.
• Push-Pull Ready? Once you get the hang of pulse welding, you'll likely want to do more of it. A push-pull torch (typically 8m long) is a great way to extend the reach and portability of your machine, especially when welding aluminium where using conventional torches longer than 3m can be troublesome. In the case of push-pull torches, both the torch 'pull' motor and the machine 'push' motor must be synchronised - which means that the torch and the machine need to be compatible with each other. With this in mind, you'll not only want a machine that is "push-pull ready", but you also want to make sure that; a) there's a push-pull torch available specifically to suit the machine you're looking at, and b) the torch is a tried & tested quality design from an experienced manufacturer to ensure you get reliability and value from your investment.

Conclusion

Pulse welding emerges as a powerful and versatile technique in the welding arsenal. Its ability to provide controlled heat input, reduce spatter, and enhance overall weld quality makes it a preferred choice in various industries. Whether in the form of pulsed TIG welding or pulsed MIG welding, this method empowers welders with precision and flexibility.

Frequently Asked Questions

What is pulse transfer welding?

Pulsated GMAW is an altered spray transfer procedure where the power source changes between high voltage or current and low current, occurring from 30 to 400 times every second.

What is trim in pulse welding?

Trim in pulse welding refers to adjusting the length of the arc and voltage by modifying the trim setting. Lowering trim reduces arc length and voltage while increasing trim has the opposite effect.

Why use pulse welding?

Pulse welding is preferred for its ability to achieve weld penetration with minimal heat, saving energy, reducing material distortion, and creating visually appealing and precise welds.

What does pulse do in welding?

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 so that short-circuit can't occur.

Is Pulse Welding strong?

Pulse MIG Welding Advantages

Higher deposition rates when welding out of position. Stronger welds due to better fusion compared to other transfer modes. Lower level of fumes compared to other modes of transfer.