How to choose an ignition unit for the laser tube: ideal couple

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Sometimes our customers need to replace the laser tube with a more or less powerful one for production reasons. They do this but forget about another component of the machine’s system that also needs to be replaced in such cases. And that component is the ignition unit, which is inextricably linked to the tube!

Ignition unit

Sometimes, to get started, we need a spark. The laser tube is similar to us in this regard; it requires an electrical pulse from the ignition unit. Its main task is to stimulate the active gas inside the tube to emit radiation. 

How does it do that? Let’s recall how a laser tube works. 

A laser beam is emitted from the tube when the gas inside it is in an excited state. However, the atoms remain in this state for a short time before returning to normal. In order for them to stay in a state where they can generate the radiation needed to produce a laser, the ignition unit supplies the active zone with the required amount of energy. 

What is this required amount? Each tube has specific requirements regarding current and voltage, and if these are not fully met, the tube cannot operate at its full power. In other words, we ourselves may be limiting its capabilities. 

This is precisely why the ignition unit and the laser tube are inseparably connected. So when might the ignition unit need to be replaced? A new one is needed if:

1. You replace the tube.

2. The ignition unit itself has failed.

Let’s consider each scenario.

Choosing an unit depending on the laser tube

In order for the laser tube to reach its full potential, the maximum power of the ignition unit must match or exceed the tube’s power. Never less!

Be sure to compare the ignition voltage (kW) and current (mA) specifications of these two machine components when replacing one of them. You can also find compatible models of ignition units in the tube’s manual. For this reason, we recommend keeping all technical documentation, as it contains a lot of useful information and parameters for adjustment.

Keep in mind that if you purchase a particularly powerful unit, you will need to adjust it so that the output current does not exceed the value specified in the tube’s specifications. Otherwise, it could negatively affect the laser tube!

The ignition unit is out of order. How to understand that?

If your tube has started working poorly, intermittently, or has completely stopped generating a beam, don’t rush to immediately blame the ignition unit. First, check the display on your machine and see if there’s an indication of an ignition unit malfunction. If there is none, then proceed to check the following components:

• Optical path. The mirrors or lenses might have become too dirty or even damaged. In this case, the normal transmission of the beam to the cutting area is either interrupted or becomes less effective.
• Alignment. This is relevant if the laser has lost power. Another ‘symptom’ could be uneven cutting. We showed how to perform alignment in one of our videos!
• Laser tube. There’s a chance that it has simply reached the end of its lifespan and now needs to be replaced.

If all of these parts of the system are in good condition, then you can move on to checking the ignition unit, even if the machine didn’t notify you of a problem. It could have short-circuited or failed due to excessive voltage, an electronics malfunction, or contamination of the unit.

Let’s check

This process is done in four steps:

1. Open the cover on the laser machine to access the ignition unit.
2. Remove the large terminal from the high-voltage unit.
3. Take a non-conductive material (rubber glove or a glass object) and use it to press the ‘TEST’ button. It is located on the ignition unit’s casing. Do not press it with your finger, as you could get an electric shock.
4. Check if there is a pulse from the laser tube. If there is none, you will need to adjust the ignition unit.

Adjusting the ignition unit

So, what should you do if you need to adjust an existing or new ignition unit? You will need an ammeter or a multimeter. 

Below is the procedure for using an ammeter:

1. Turn off the machine.
2. Ensure access to the current adjustment screw.
3. Set the machine to maximum power.
4. Adjust the power control on the ammeter.
5. Press ‘pulse’ and monitor the ammeter readings. If you see that the current differs from the recommended value, use a screwdriver to adjust the screw: turn it to the right if the current is too low and to the left if the current is higher than necessary.

Before we provide the same procedure for working with a multimeter, let us first say: if you don’t have experience working with it, it’s better to ask us for help! These operations can be dangerous to your health.

1. Turn off the machine.
2. Connect the red high-voltage wire from the ignition unit to the anode part of the laser tube.
3. Connect the second black wire from the ignition unit to the ‘circuit’ between the multimeter and the unit.
4. Ensure access to the current adjustment screw, located on the side of the unit, and prepare a screwdriver.
5. Turn on the laser machine.
6. Set the machine to maximum power, between 80-99%.
7. Set the multimeter to the direct current measurement mode (mA).
8. Press the ‘pulse’ button on the machine’s panel and monitor the readings on the multimeter. If necessary, adjust the screw: to the right if the readings are lower than required, and to the left if the current is higher than recommended.

Keep it safe

As mentioned above, the ignition unit can fail if it gets dirty. This machine component also requires periodic maintenance. It is necessary to regularly remove dust from it using compressed air. Be sure to check that the ignition unit wires are insulated and not in an area where they can easily be bumped or damaged. Additionally, ensure the machine has proper cooling.

For this, we recommend using chillers. Our machines come with units from TEYU. They are manufacturers with over twenty years of experience, providing chillers in a wide range of sizes and purposes.

Also, periodically check the condition of the voltage stabilizers, and do not connect the machine to a power source without proper grounding! This could cause an electrical malfunction and, consequently, damage the ignition unit.

Conclusion

1. A laser beam is emitted from the tube when the gas inside it is in an excited state. In order for them to stay in that state, the ignition unit supplies the active zone with the required amount of energy. 
2. A new ignition unit is needed if: you replace the tube, or the ignition unit itself has failed.
3. In order for the laser tube to reach its full potential, the maximum power of the ignition unit must match or exceed the tube’s power. Never less! Be sure to compare the ignition voltage (kW) and current (mA) specifications of these two machine components when replacing one of them.