For many fabricators, one of handheld laser welding’s primary appeals is ease of use. Sales and marketing materials often claim that all you need to do is pick up the torch, select a preset, and weld.
And sometimes it is (almost) that easy.
However, relying exclusively on pre-built parameter sets – especially without understanding why they work – is a good way to leave performance on the table. For maximum optimization, critical welds, and self-certification, it is sometimes necessary to tweak your machine’s settings to match the application at hand.
While different machines may present parameters differently, the fundamental principles of laser physics remain the same. Fortunately, a basic understanding of laser welding variables is often all you need to start calling yourself a laser welding specialist.
Start with What You Have
Before jumping straight to fine tuning, you should familiarize yourself with your machine’s factory preset parameters. Most laser welding machines include presets (often organized by program number) designed to address common materials and thicknesses. These are your baseline.
For example, setting a LightWELD welding machine to “F1” provides excellent weld quality when welding 5000 series aluminum. Most of the time, all you need to do is change the power to match the material thickness and choose the appropriate wire.
For advanced users, or applications with particular requirements, it may be necessary to create a custom parameter preset. But starting with a factory preset makes it easier to make small adjustments to achieve specific results.
Mode Selection: Continuous Wave vs. Pulsed
One of the most important decisions you’ll need to make is between a Continuous Wave (CW) or pulsed mode of operation.
By default, handheld laser welding machines fire the beam in a steady stream of continuous power. This is known as CW mode and it is a great way to achieve high speeds, high-quality results, and the necessary penetration in most applications. You should consider this your default mode.
Many machines also allow you to automatically modulate this output using rapid laser pulses with durations measured in milliseconds. This is known as pulsed mode.
When to use Pulsed Mode
Pulsed welding typically offers improved weld quality and significantly reduced heat input. As a general rule, if the power required to make a sufficiently deep weld is relatively low (around a few hundred watts), pulsed welding will likely produce superior results.
The trade-off is a reduction in welding speed, although pulsed laser welding travel speeds are still relatively fast.
Pulsed welding is often the ideal approach for:
- Thin, heat-sensitive sheet metals
- Extremely thin foils
- Delicate metal meshes
Fine-Tuning Pulse Behavior
If you decide to use pulsed welding, you gain access to two critical variables: pulse length and pulse frequency.
Pulse Length
Pulse length refers to how long the laser beam remains active during each pulse (e.g. 10 milliseconds).
- Longer pulse lengths allow for faster welding speeds (by more closely mimicking CW mode) but introduce more heat into the weld.
- Shorter pulse lengths minimize heat input but reduce your travel speed.
Pulse Frequency
Pulse frequency refers to how often the laser beam pulses are fired (e.g. 200 Hz).
- Higher frequencies lead to faster welding but can increase weld spatter.
- Lower frequencies can result in higher quality and more aesthetically pleasing welds but reduce welding speed.
Mastering Power & Power Compensation
Power is the most basic parameter of your laser welder. Laser power is typically measured in watts, but some machines use percentages to represent relative intensity. Typical handheld units range from a few hundred to two thousand kilowatts, with some specialized units offering more.
At a basic level, more power equals more penetration and faster welding speeds. But more power is not always better – excessive power reduces your control, increases the risk of piercing through the material, and is often unnecessary.
The right power is usually a function of material (stainless steel, aluminum, copper, titanium, etc.) and material thickness. You can find laser welding power charts online or included with your machine to reference as a starting point. As a general rule, start with a lower power and increase it to increase penetration and travel speed as needed.
Power Compensation
Power compensation is a parameter used sparingly and typically by advanced users. This setting dynamically adjusts output power along the beam’s wobble width.
Different compensation levels result in different subsurface weld profiles, allowing for fine-tuned penetration control across the width of the weld bead.
Power compensation can dramatically impact a weld’s profile. No compensation (left) can create a tooth-like shape while significant compensation (right) may reduce the weld’s cross-sectional area.
Optimizing Beam Wobble
The laser beams used for welding are highly focused and create a small spot on the target metal. That means that creating a sufficiently wide weld seam requires some side-to-side motion (otherwise the result will be an exceptionally narrow bead).
Fortunately, this motion is automatic and not manually guided. Most handheld laser welders use optics inside the torch to automatically move the beam left and right. Known as “wobble”, this is typically enabled by default but the exact parameters can be adjusted.
You control wobble with two settings:
- Wobble length: Determines how far the beam travels left and right (e.g. 5 mm). This effectively sets the width of your final seam.
- Wobble frequency: Determines the speed of the side-to-side motion (e.g. 50 Hz). Adjust your wobble frequency based on material thickness. Typically, you should use a faster frequency for thinner materials and a slower frequency for thicker materials to ensure proper fusion without burn-through.
Wire Material & Feed Speed
While lasers can weld autogenously (without filler material), standard MIG wire is often used to fill gaps and increase weld strength.
Selecting Your Wire
Wire material is determined by the weldment material, usually following standard MIG welding rules. Wire thickness is primarily a function of your desired bead size and the thickness of the material.
A note on single vs. dual wire feeding: Handheld laser welders utilize single wire feed setups by default but may also be equipped with dual wire feeders. Dual wire feeding is useful for filling even wider gaps, increasing final weld strength, and creating larger beads. Whether you use a single or dual wire feeder will impact your wire thickness but not your wire material.
Determining Wire Feed Speed
Your wire feed speed is a highly dependent parameter defined by your ideal travel speed, which is in turn defined by nearly every other parameter (like power, wobble, CW vs. pulse mode, etc.).
At the same time, your chosen feed speed has a strong impact on the physical process. This is because laser welding with wire is controlled primarily via the wire deposition – rather than the welder actively controlling the speed, the wire pushes against the workpiece, guiding their hand at a steady rate along the weld path.
Travel Speed
When laser welding, your travel speed is determined by a variety of other parameters and requirements. Here’s how they impact it, broadly speaking:
- Power: Higher powers lead to higher travel speeds and vice versa.
- CW vs. Pulsed: CW welding is always faster than pulsed welding. If using a pulsed mode, longer pulse widths and lower pulse frequencies lead to faster travel speeds. Shorter pulse widths and higher pulse frequencies result in slower travel speeds.
- Wobble: Wider, slower wobbles will naturally slow down your welding speed. Narrower wobble widths with higher wobble frequencies will increase your travel speed.
- Desired penetration: While offset by increasing power, your travel speed will be slower when you require deep penetration and faster when you are targeting shallower penetration.
- Material: Conductive materials like aluminum, copper, and nickel alloys require higher powers and ultimately limit your travel speed. Conversely, titanium and stainless, mild, and carbon steels allow for higher travel speeds.
- Wire width: Thick wire widths (especially when using a dual wire feeder) will subtly slow down your weld travel speed, and vice versa.
Gas Flow & Gas Type
Laser welding is almost always performed with shielding gas to protect the weld pool and prevent oxidation and porosity. First, you will need to choose a gas based on your material. Second, you will need to choose a flow rate based on your gas and welding speed.
Choosing a Shielding Gas
The appropriate shielding gas for a laser welding application is almost always determined by the material being welded. The following list is a good starting point.
- Stainless steel: Nitrogen is the most common choice for stainless steels because it is inexpensive and helps slightly increase weld penetration. Argon can sometimes improve quality in specific applications.
- Mild & carbon steels: Again, nitrogen is the most common choice. Argon can be considered if you are experiencing embrittlement.
- Galvanized steels: Nitrogen is normally sufficient for laser welding galvanized steel. Argon and Argon/Nitrogen mixes can provide improved results in specific cases.
- Aluminum: Argon is the correct choice for the majority of aluminum laser welding applications. If you experience porosity issues, consider ultra-high purity (UHP) argon.
- Copper: Always use argon when laser welding copper by hand.
- Titanium: When welding titanium, argon and handheld laser welding combine to offer benefits like reduced oxidation and embrittlement.
- Nickel Alloys: Always use argon when welding nickel alloys with a handheld laser welder.
Determining Gas Flow
The ideal gas flow is largely dependent on the chosen gas.
- Nitrogen: 15-25 L/min (roughly 32-53 CFH)
- Argon: 10-20 L/min (roughly 21-42 CFH)
As a rule of thumb, start toward the lower end of those ranges and increase your flow rate gradually if you are experiencing oxidation. Higher rates may be preferable for thicker materials or higher travel speeds.
Getting Started with LightWELD
Considering adding handheld laser welding to your toolkit? Our laser welding experts are here to help. Whether you just want to learn more about LightWELD or want to try it for yourself, getting started is easy.
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