Nowadays, many manufacturing plants extensively use plasma laser cutting machines due to their high cutting efficiency and superior cut quality, earning the approval of numerous companies and clients.
However, during plasma cutting, harmful substances are produced, leading to air and noise pollution.
The dust generated from plasma cutting must be collected and filtered through purification equipment in accordance with environmental protection requirements.
In this article, I will guide you in understanding the hazards of plasma cutting dust and its purification solutions.
What Is the Dust Produced by Plasma Cutting Machines?
Plasma cutting machines, known for their high cutting efficiency and broad cutting range, do have a drawback – they generate significant amounts of dust during operation.
This dust, similar to welding fumes, is mainly composed of harmful gases and minute dust particles, including CO, C2, H2, Nx, and hydrocarbons.
Specific Hazards of Metal Dust
Here is a detailed description of the specific hazards posed by the metal dust produced during cutting:
- Ozone is a colorless, harmful gas with a distinct irritating smell. It strongly stimulates the respiratory tract and lungs. Short-term inhalation of low-concentration ozone (0.4mg/m3) can cause symptoms like coughing, dry throat, chest tightness, loss of appetite, and fatigue. Long-term inhalation can lead to bronchitis, emphysema, and pulmonary fibrosis.
- Carbon monoxide is a colorless, odorless, non-irritating gas that readily binds with hemoglobin in the human body. Thus, when a large amount of hemoglobin binds with carbon monoxide, it can potentially lead to tissue necrosis due to oxygen deprivation.
- The light radiation from plasma is intense, primarily composed of ultraviolet radiation, visible light radiation, and infrared radiation. Particularly, the ultraviolet intensity, like wavelengths 260-290μm, is 2.2 times that of argon arc welding. In addition to light radiation, there are other hazards such as toxic gases from dust, high-intensity and high-frequency noise, and the high-frequency oscillations that can cause harm to the human body.
- Nitrogen oxides are a toxic gas with an irritating odor, mainly composed of nitrogen dioxide. It’s a reddish-brown gas with a distinctive smell. Once inhaled, it enters the lung alveoli through the upper respiratory tract and gradually interacts with water, causing severe irritation and corrosion to lung tissue, leading to pulmonary edema.
Workers involved in cutting have noted that when using plasma cutting machines to cut 3-6mm carbon steel plates, a lot of yellow smoke is generated. This yellow smoke poses a significant threat to human health and can easily cause pneumoconiosis if inhaled over long periods.
Given these hazards associated with plasma cutting dust, it’s crucial to implement effective dust purification when performing plasma cutting work to reduce the incidence of occupational diseases.
How Harmful Is the Dust Produced by Plasma Cutting Machines?
Harms Operator’s Health
The dust produced by plasma cutting machines contains many inhalable substances (such as manganese oxide and oxides of potassium and sodium). Once these substances enter the human body, they can cause significant harm.
Workers who spend a long time working in conditions with dust from CNC plasma cutting machines have a significantly higher proportion of respiratory diseases like chronic bronchitis than others.
Moreover, these inhalable substances can accumulate in the body’s bones and blood, leading to a decrease in their function, and may even cause cancer.
Impacts Enterprise Benefits
Environmental protection has become an international and national trend. Pollution caused by dust could potentially result in fines for companies.
Additionally, not promptly managing dust pollution can affect the precision of production machines, thereby impacting production efficiency.
Given these two major reasons, the dust hazards of plasma cutting machines are significant and need timely purification treatment. So, how should the dust from plasma cutting machines be managed?
Plasma Cutting Equipment Dust Purification Solutions
Currently, there are two primary methods for managing dust from plasma cutting:
- Wet Dust Removal Method
This method involves setting up a water bed under the cutting platform, allowing the workpiece to be submerged in water. Cutting is performed underwater, so the oxides produced during cutting are collected by the water, thereby purifying the working environment. This method only requires a water-holding container as a one-time investment.
However, it can lead to secondary pollution (water pollution), and metal oxides are likely to agglomerate underwater, making cleanup challenging. For users in colder regions, the water in the cutting platform may freeze during winter, causing inconvenience.
Furthermore, this method is not suitable for purifying dust from metals like aluminum and magnesium, which produce explosive dust during cutting.
- Dry Dust Removal Method
Dry dust removal involves adding a dust capture device to the CNC cutting platform. The captured dust is directly transported to a dust filter and purification device. After treatment, the purified air is then discharged.
Dust produced during plasma cutting is mainly formed below the workpiece’s cut, making exhaust-type negative pressure cutting platforms the most common dust capture device. Because of its simple structure, reliable operation, and effective dust removal, the dry dust removal method is widely used.
The dust collector for a plasma cutting machine is designed and manufactured based on the machine’s specifications, with a focus on economic efficiency, easy maintenance, economical operation, and minimal subsequent costs while ensuring effective dust removal.
Depending on the width of the cutting work platform, it can be divided into a single-side down-draft air door style workbench and a double-side down-draft air door style workbench.
Plasma Cutting Machine Dust Collector Workflow
The goal is to collect the dust produced during plasma cutting. The collection method can be side suction, bottom suction, or top suction, with the dust directly drawn into the pipeline by the fan. A dust removal device is added to the pipeline’s end, and the collected dust is directly purified by the dust removal equipment before being discharged inside or outside the workshop. Within the designed air volume, the purified dust can meet environmental emission requirements.
The Blow-Suction Type Plasma Cutting Machine Dust Removal System
The blow-suction type plasma cutting machine dust removal system involves placing a square suction duct on one side of the cutting platform, which has a suction port that can move with the cutting machine.
Related reading: CNC Plasma Cutting Dust Removal: Explained
On the other side of the cutting platform is a blower port with a small axial flow fan. The suction port and the blower port are both fixed on the cutting machine and kept consistent with the cutting head.
The lower part of the cutting platform is equipped with an exhaust duct with vertical plates, which ensures that suction occurs at the position where dust is generated within a limited width during cutting. When the plasma cutting machine dust removal system operates, the sealing strip can closely adhere to the top of the square suction duct under the effect of the pipeline negative pressure to play a sealing role.
The suction port has two rollers where the sealing strip is lifted, allowing the smoke to enter through the suction duct of the suction port, and then be sucked into the dust removal equipment for filtration and purification.
What Are the Hazards of Plasma Cutting?
Plasma cutting can pose several hazards:
- Exposure to the arc light during the cutting process can result in eye damage;
- A substantial amount of harmful gases are generated during the cutting process. Once inhaled, these can have a detrimental effect on health;
- Sparks flying during the cutting process can cause skin burns;
- The process often generates high-frequency noise, which can cause harm to the ears over time;
- Another significant point is that the high frequencies and electromagnetic radiation generated by the high-frequency oscillator during plasma cutting can cause bodily harm. Long-term exposure could potentially lead to severe damage for workers in the field.
The harm caused by plasma cutting can be divided into two categories:
- Short-term direct harm: The arc light of the plasma can seriously stimulate the eyes, causing eye damage, mainly due to the infrared and ultraviolet radiation emitted by the metal.
- Long-term indirect harm: The radiation generated by the plasma arc can affect cell division in the long run, leading to various sub-health conditions. The inhalation of smoke or gases generated during the process, and the metal oxides and metal fumes that enter the lungs, can stimulate the respiratory tract and potentially cause pathological changes over time.
Safety Considerations for Plasma Cutting Machines
The harmful factors in plasma arc cutting mainly include harmful gases, metal dust, noise, arc light (infrared) radiation, and high-frequency electromagnetic fields. The main risk is electric shock.
Hence, it’s critical to prioritize safety and protection during plasma arc cutting.
1. Electric Shock Prevention
The no-load voltage of the power supply for plasma arc cutting is relatively high, especially during manual operation, posing a risk of electric shock. Therefore, the power supply must be properly grounded during use, and the cutting torch and areas touched by hands must be reliably insulated.
A lower voltage can be used to ignite the non-transferred arc before connecting the higher voltage transferred arc circuit. If the switch is placed on the handle, an insulating rubber sleeve should be applied to cover the exposed switch, to avoid direct hand contact with the switch. Whenever possible, automated operation is encouraged.
2. Arc Light Radiation Prevention
The intensity of arc light radiation is high, mainly consisting of infrared radiation and visible light radiation. The light radiation from plasma arcs is stronger than other arcs, especially ultraviolet light, which can severely damage the skin. During manual cutting, operators must wear proper masks, gloves, and also protect their necks.
Apart from having dark glasses on the mask, it is better to include lenses that absorb ultraviolet light. During automatic operation, a protective screen can be set up between the operator and the operating area. Plasma arc cutting can be performed underwater, utilizing water to absorb the light radiation.
3. Dust and Smoke Prevention
The plasma arc cutting process accompanies large amounts of vaporized metal steam, ozone, nitrogen compounds, etc. Combined with the large airflow during cutting, dust on the working site can be massively stirred up, causing serious impacts on the operator’s respiratory tract and lungs.
Therefore, the workspace must be equipped with good ventilation equipment and dust prevention measures. When cutting, an exhaust device can be installed below the grid worktable, or underwater cutting can be used to reduce dust.
4. Noise Prevention
High-intensity, high-frequency noise is generated during plasma arc cutting, especially when using high-power plasma arc cutting, the noise is even louder. This could significantly affect the operator’s auditory and nervous system. The noise level mainly depends on the cutting current; the larger the current, the stronger the noise.
When noise energy is concentrated within the 2000-8000Hz range, operators are required to wear earplugs. If possible, try to use automatic cutting, with the operator working in a soundproof room.
Underwater cutting can also be utilized, using water to absorb noise. Placing the workpiece underwater for cutting can significantly reduce noise. Test results show that when cutting is performed underwater, the noise is reduced by 22-24dB compared to dry cutting.
Moreover, using a water curtain cutting torch (with a water flow rate of 70-80L/min) can reduce noise by about 20dB. When the cutting current is below 100A, the noise is relatively low, and the impact on the surrounding environment is not significant.
5. High-Frequency Electromagnetic Field Protection
Plasma arc cutting requires a high-frequency oscillator to ignite the arc. However, high-frequency can cause certain harm to the human body.
Preventive measures mainly include:
- Selecting an arc ignition frequency between 20-60Hz, shielding the high-frequency oscillator with a shield, ensuring a good ground connection for the workpiece;
- Cutting off the power to the high-frequency oscillator immediately after the main electric arc is ignited;
- Minimizing the time when using high-frequency sparks to check the center of the electrode pair.
Plasma Arc Cutting Protection Tips
- Avoid directly looking at the cutting arc during the plasma arc cutting process, wear professional protective glasses to prevent arc light from burning the eyes.
- Large amounts of toxic gases are produced during the plasma arc cutting process, a multi-layer filtered dust mask should be worn.
- Towels, gloves, foot protectors, and other protective equipment should be worn during the plasma arc cutting process to prevent spattering sparks from burning the skin.
Safety Precautions
The following safety precautions should be observed when using a plasma cutting machine:
Grounding is required: The plasma cutting machine must be grounded to ensure safety.
Prevention of electric shock: Measures should be taken to prevent electric shocks from all components and gas pipes of the cutter to protect users.
Oxygen safety: Care must be taken when using oxygen to prevent leakage and accidents.
Avoiding gas poisoning: Improper use of gas indoors can lead to poisoning. Choose a well-ventilated space and change the air regularly when using gases.
Maintain safe distance: Keep a safe distance during operation to prevent accidents during cutting.
Wear protective equipment: When operating a plasma cutter, wear safety equipment such as a protective mask, insulating gloves, fire and explosion-resistant work clothes, and shoes to ensure personal safety.
Avoid cutting dust: Plasma cutting machines generate a lot of dust, so protective glasses and masks should be used to protect the eyes and respiratory system.
Follow standard procedures: Adhere to the standard operating procedures of the plasma cutter, strictly follow the instruction manual to avoid operational errors and accidents.
