How to maintenance water chiller for fiber laser cutting machine?

Why does fiber laser equipments need a chiller?

The main working principle of fiber laser equipment is to convert electrical energy into light energy. Because the conversion between different forms of energy is not 100% efficient, while some of the electrical energy is converted into light energy, another part is converted into heat energy. In addition, the operation of the equipment and the friction with the metal can also generate a large amount of heat energy in the laser cutting head. Therefore, a chiller is needed to cool down the laser equipment and maintain its stable operation.

The heat energy remaining in the laser equipment and cutting head can affect the processing effect or even damage the components inside. As we all know, laser equipment and cutting heads have a high cost, and the cost of repairing or replacing them after damage is also very expensive. Therefore, using water cooling to dissipate heat can reduce the equipment's loss rate and maintenance costs.

How does a chiller work?

A chiller, also known as a water chiller, is a type of cooling water equipment that can provide constant temperature, flow, and pressure. Chillers are divided into air-cooled chillers and water-cooled chillers, with water-cooled chillers being the most common type used in laser processing and the focus of this article. Common laser equipment chillers can provide two channels of temperature-stable cooling media. One channel uses low-temperature coolant to cool the laser, while the other channel uses room temperature coolant to cool the cutting head.

The main working principle of a chiller is to convert electrical energy into mechanical energy. It uses its built-in compressor to compress overheated vapor into high-temperature and high-pressure gas, which is then discharged to the condenser and converted into high-pressure liquid. The liquid then flows through the expansion device (throttle valve or capillary tube) to reduce the pressure, finally becoming a low-temperature and low-pressure subcooled liquid. This subcooled liquid then enters the evaporator and vaporizes by absorbing heat, becoming overheated vapor. It then returns to the compressor and enters the next cycle to achieve cooling function.

How to maintain the water chiller?

Firstly, regular checks are needed. Every week, you should check whether the water level in the chiller's water tank meets requirements. Once a month, you should check whether the quality of the water in the chiller has changed (color, smell, impurities, etc.).

Secondly, regular cleaning and replacement are necessary. Here are some recommended cleaning and replacement cycles:

Filter cleaning cycle: Depending on the water quality, check whether the filter is blocked once a week (laser inlet filter, chiller filter). The laser inlet filter is usually located in the Y-shaped water inlet of the laser, while the chiller filter can be located on the outlet pipe of the chiller, depending on the chiller model.

Cleaning frequency and steps for dust filter: The dust filter is located on both sides of the water chiller, and it can be easily removed. When there is a lot of dust, the cleaning frequency can be increased. Remove the dust filter and use an air gun to blow away the dust. For oily dirt, use a neutral detergent to clean it. Before reinstalling the dust filter, it should be rinsed and air-dried.

Filter replacement period: Check whether the water chiller filter is polluted. The water chiller filter needs to be replaced at least every six months (depending on the actual machine model, some do not have filters).

Cooling water replacement period: According to the water quality, replace the cooling water. The cooling water tank of the water chiller is not sealed and is exposed to a dusty environment for a long time. Dust, metal shavings, and bacteria enter the cooling water, causing the water to deteriorate, producing insoluble substances that adhere to the inner wall of the laser waterway, thereby blocking the waterway and causing a decrease in water flow and cooling efficiency. If this happens, all deteriorated cooling water should be drained in time and replaced with new cooling water.

When selecting cooling water for a water chiller, it is recommended to choose distilled water or deionized water. The reason for choosing these two types of water is that they are less likely to produce scale during the circulating heating process. It is strictly forbidden to use bottled purified water or tap water.

How to replace cooling water?

Steps to replace cooling water:

1. Disconnect the power supply of the equipment and the water cooler.

2. Drain the water from the water cooler and laser, clean the water tank and drain the water.

3. Clean the water cooler's water filter, filter element (some water coolers do not have a filter element, consult the water cooler manufacturer for specific details) and the filter at the laser's water inlet.

4. Install the filter and filter element.

5. Fill the water cooler with distilled water to the standard liquid level.

6. Turn on the water cooler and let the water circulate. Check the water level display of the water cooler. If the level drops, add more distilled water. Note: To prevent the growth of bacteria and algae, you can add 10% alcohol to the cooling water.

In addition to the regular maintenance steps mentioned earlier, there are a few other things to keep in mind when maintaining a water chiller:

1. When the ambient temperature is 0°C or below, it is recommended to add antifreeze to the cooling water of the laser. This will lower the freezing point of the water and prevent it from freezing. However, antifreeze should not be used for extended periods of time, as it can cause corrosion and damage to the laser and cutting head components.
   

2. After the winter season, it is important to clean the system with distilled or deionized water, especially the filters and screens in the water chiller and laser inlet, and resume using distilled or deionized water as the cooling fluid.
   

3. If the machine is going to be shut down for an extended period, such as during the Chinese New Year holiday or before transportation, it is necessary to drain the cooling water from the chiller and blow out any residual water in the system with compressed air to prevent freezing or water leakage that could damage the components.