Pulse or No Pulse? When and Why You Should Pulse Weld

Pulse Welding: An Overview  

Pulse welding is a welding technique where the amperage alternates between high and low levels. This method helps minimize overall heat input while ensuring proper penetration, making it ideal for various applications.  

Adjustable Parameters in Pulse Welding  

Pulse welding parameters can be fine-tuned to suit specific welds:  

- Pulse Frequency (Pulse Hertz): The number of pulses per second.  

- Peak Amperage: The higher amperage during the pulse cycle.  

- Base Amperage: The lower amperage during the cycle.  

- Duration: The time spent at each amperage level.  

Understanding Pulse Frequency  

Pulse frequency, or pulse hertz, refers to the number of pulses occurring in one second. For example, EACO AC/DC welding machines offer a pulse frequency range from 0.5 Hz to 200 Hz.  

- 1 Hz: One pulse per second, slow enough to follow visually.  

- 30+ Hz: Fast enough that individual pulses blur together.  

- 5–30 Hz: A mid-range frequency that can strain the eyes, similar to a strobe light effect.  

The choice of pulse frequency depends on the welding application:  

- Thin Materials: A fast pulse is preferable, producing a high-profile bead.  

- Thick Materials: A slower pulse works better, resulting in a low-profile bead.  

By adjusting the pulse settings, welders can achieve optimal results tailored to the material and desired weld characteristics.

TIG Pulse Welding: Techniques and Adjustments  

Pulse welding with TIG (Tungsten Inert Gas) follows the same basic principles as standard TIG welding but includes additional settings on the welding machine to control the pulsing. This method provides greater control over heat input and weld quality.  

Two Methods for Feeding Filler Rod  

When TIG pulse welding, you can feed the filler rod in two primary ways:  

1. Dabbing Technique  

   - With this method, you dab the filler rod into the weld puddle.  

   - Timing with Pulses:  

     - At lower pulse frequencies (e.g., 1 pulse per second), you can easily time your dabs to coincide with the peak amperage and pause during the base amperage.  

     - At higher pulse frequencies (e.g., 50 pulses per second), the pulses become too fast to visually time, so your dabbing rhythm remains consistent regardless of the pulses.  

2. Lay-in Technique  

   - This involves positioning the tip of the filler rod at the leading edge of the weld puddle and dragging it along as you weld.  

   - The rod continuously melts into the puddle, producing a smooth, penetrative weld.  

   - Appearance: While effective, this technique doesn't create the “stacked dimes” look typical of pulse welding but still results in a structurally sound weld.  

Using a Foot Pedal with TIG Pulse  

You can incorporate a foot pedal for additional heat control during TIG pulse welding:  

- Full Throttle:  

1. Pressing the pedal fully keeps the peak amperage at the preset level. For example, if your machine is set to 200 amps peak and 50 amps base, the peak will remain at 200 amps throughout the weld.  

- Pulsing Within the Pulse:  

1. If the weld becomes too hot, you can ease off the pedal to lower the peak amperage while keeping the base amperage constant. For instance:  

     - Set peak amps: 200  

     - Reduced peak amps (via pedal): 150  

     - Base amps: 50 (unchanged)  

2. This adjustment cools the weld overall by reducing the peak heat during the cycle.  

- Re-Adjusting Heat:  

3. You can return to full depression of the pedal to restore the peak amps to the original setting when more heat is needed.  

TIG pulse welding offers flexibility and control over heat input, allowing you to adapt to the material and application. By mastering both feeding methods and leveraging the foot pedal for fine-tuning, you can achieve precise, high-quality welds tailored to specific requirements.

MIG Pulse Welding: Single and Double Pulse Techniques

MIG pulse welding is an advanced technique that uses pulsing to improve the quality of the weld while minimizing spatter and excess heat. There are two primary types of MIG pulse welding: Single Pulse and Double Pulse.

Single Pulse MIG Welding  

Single Pulse MIG is a form of spray transfer welding, where the current alternates between a peak and a background current.  

- How it works:  

  - During the peak current phase, the wire feeds into the weld pool and metal droplets are "sprayed" into the weld, ensuring deep penetration and a clean, spatter-free result.  

  - The background current phase is not hot enough to transfer metal but maintains the arc.  

  - This process offers the benefits of spray transfer welding—such as speed, no spatter, and deep penetration—without the excess heat associated with traditional MIG welding.  

  - Single Pulse MIG welding has a high-pitched buzzing sound, similar to AC TIG welding.

Double Pulse MIG Welding  

Double Pulse MIG welding involves two simultaneous pulses, providing more control and a cooler weld.  

- How it works:  

  - The first pulse operates like single pulse welding with a peak and base current, transferring metal during the peak phase and maintaining the arc during the background phase.  

  - The second pulse does not transfer any metal but controls the on/off cycle of the first pulse. When the second pulse is "on," the first pulse alternates between peak and base amps, creating the weld. When the second pulse is "off," no welding occurs.  

  - The off portion of the second pulse can be adjusted to vary the cooling of the base material, providing the opportunity to control the weld temperature. Keeping this phase cooler is recommended for optimal results.  

  - Double Pulse MIG is a cooler welding process due to more downtime between high amperage moments, so higher peak amps are needed for full penetration.  

  - It produces an aesthetically pleasing weld with a "stacked dime" appearance, similar to the results achieved with TIG welding but with a MIG machine. The process is accompanied by an on-and-off high-pitched buzzing sound.

Synergic vs. Non-Synergic MIG Pulse Welding  

- Synergic MIG Pulse: In synergic mode, the machine automatically adjusts settings for optimal performance, making it easier for the welder to focus on the joint without needing to adjust the parameters manually.  

- Non-Synergic MIG Pulse: In non-synergic mode, the welder must manually set all the parameters, which can involve more trial and error, especially with Double Pulse.

Welding with MIG Pulse  

Despite its complexity, MIG pulse welding is similar to standard MIG welding in practice. Once the machine is set up, the welder simply presses the trigger on the torch and moves along the joint, while the machine automatically controls the pulse cycle. Whether using Single or Double Pulse, MIG pulse welding offers cleaner, deeper, and more controlled welds with less effort from the operator.

Why Should You Pulse Weld?

Pulse welding helps to focus the arc and maintain a smaller bead, making the weld easier to control while still achieving full penetration.

During the base amps phase of the pulse cycle, the puddle cools and solidifies, allowing the weld to settle flat. The longer the weld stays in the background amps, the more pronounced the "puddle freeze" effect, which creates the aesthetically pleasing stacked-dime appearance.

Additionally, pulse welding eliminates spatter completely, reducing the need for post-weld cleanup and ensuring a cleaner, more efficient welding process.

When Should You Pulse Weld?

1. Out-of-Position Welding  

Pulse welding helps control the weld puddle, preventing it from dripping or sagging when welding in difficult positions. The cooling effect of the pulse keeps the weld in place, making it easier to manage.

2. Sheet Metal  

Because pulse welding incorporates low amperage moments, it produces less heat, minimizing distortion in thin materials like sheet metal. This makes it ideal for projects where precision is key.

3. Different Metal Thicknesses  

Pulse welding is especially beneficial when joining metals of different thicknesses. It helps control the weld puddle, ensuring that the thinner material doesn't get overwhelmed by heat, preventing spills when welding lap joints made of varied sizes.

4. Stainless Steel, Aluminum, and Other High Thermal Conductivity Metals  

Not only is pulsing good for keeping the distortion out of sheet metal, but it's also often used with metals that are known heat sinks. The cooler welding provides all the needed penetration without having to blast the metal with too much heat.

5. Filling Holes  

When filling holes, pulse welding reduces the risk of excessive heat buildup, which can blow through the metal. The controlled heat ensures a more precise, less risky process when sealing gaps.

6. No Spatter  

While spatter isn't a major issue with TIG welding, MIG welding benefits greatly from pulse welding's ability to reduce spatter. This leads to cleaner welds and less post-weld cleanup.

While pulse welding is not the only solution for these applications, it certainly simplifies some of the more challenging welding tasks, making them easier and more efficient to perform.