CNC machining risks include injuries from sharp tools, machine entanglement, flying debris, exposure to harmful coolants, noise-induced hearing loss, electrical hazards, and fire risks. Regular safety training and equipment maintenance are essential.
Injury from Sharp Tools
CNC machining is among the dangerous works, involving sharp tools. Indeed, such tools are believed to be the greatest safety hazard and often result in the severest types of workplace workplace injuries. Primarily designed to go through such hard materials as wood, metal, and composites, cutters can just as easily go through human skin, inflicting severe cuts and punctures. An analysis of workplace accidents has shown that approximately 40% of machine-related injuries in the manufacturing industry are lacerations and punctures brought about by improper handling of the cutters or inadequate safety measures in place.
Although these are undeniable facts, there are several ways of safeguarding workers’ health and preventing cutter-related injuries. First, it is essential to observe stringent safety measures. The use of automatic tool changers eliminates direct contact with the sharp edges of the cutter while the machine is in operation. Frequent training sessions should ensure that no worker reaches into the machine while it is in operation and all the safety guards are in place and functional. Employers should also provide their workers with cut-resistant gloves, manufactured from such innovative materials as Kevlar.
They should not be mistaken, however, for cut-proof gloves, as Kevlar cutters are still able to inflict deep cuts. Finally, proper lighting prevents cutter-related injuries: Employers should safeguard adequate lighting in the workplace and provide each CNC machine with a proper light source. Lighting should be at least 500 lux, as it is the minimum level for the precision work where both safety and fine detail matter.
Machine Entanglement
Machine entanglement is one of the most severe risks in CNC machining, especially when the operator’s clothing, hair, or body parts become entangled with the moving parts of the machinery, leading to catastrophic injuries, or even death. A report on manufacturing accidents revealed that entanglement tends to be one of the most prominent contributors to rates of serious injuries, accounting for around 30% of all such injuries that occur in machine operations. The first method of preventing these kinds of entanglements is the institution of a dress code – in other words, operators must not wear loose clothing, any form of jewelry, or have unsecured long hair around the machinery.
Instead, their clothing must fit relatively snugly, and they should use a hairnet or a cap to prevent their long hair from leaving the necessary coverage. These simple guidelines will significantly reduce the chances of entanglement to occur. The second option is to minimize the chances of operator injury by installing physical barriers around the moving parts, as well as a safety interlock. Namely, if any part of the operator’s body comes near one of the moving components, these safety interlocks should trigger an emergency stop to prevent entanglement from happening.
These devices must be properly installed and maintained to be always functional and operable. As far as training is concerned, operators should know about the dangers of entanglement and the appropriate emergency stop procedures – thus, every professional must undergo both training and practical demonstrations. Finally, these are not the only courses of actions that may be applied in any unit – indirect methods of safeguarding operators from entanglement tend to be just as valid and should not be ignored.
Flying Debris
It is common for flying debris to be produced in CNC machining. High-speed cutting and milling produce chips, metal pieces, and other debris that are ejected from a machine with force. Such material falling on an operator can harm the eyes, cause cuts, or affect the body in other ways. Research has found that the reason for the majority of eye injuries in industrial settings is the poor or absent use of personal protective equipment and that small flying particles account for a great proportion of these occurrences.
For this reason, shields must be installed around CNC machines. They coincide with the research findings of being the most protective equipment. The shield plays an essentially physical role in preventing the debris from coming into contact with the machine’s operator. Considering this, its material must be strong or even high-impact. Otherwise, the fast particles could cause the shield to break, rendering the point of installing it obsolete.
The employer must issue safety glasses or face shields to be used by the machine’s operator at all times. It must also enforce the rule. Finally, since the protective gear must meet safety standards and the shields will not always provide 360-degree protection in one industrial setting, the machine’s operator should be provided with wraparound safety glasses. They protect the eyes from flying particles not only in front but also from the side, which is where the particles may come from.
Ideally, a dust and debris extraction system should be installed. It works by sucking away not only the dust but also the debris produced by machining. It profoundly diminishes debris production and thus the amount of flying particles.
Exposure to Coolants and Lubricant
CNC machining often implies exposing operators to coolants and lubricants, which can be highly harmful to one’s health. These substances may include chemicals causing skin irritation, symptoms of dermatitis, or even a threat to pass away if breathed in. According to the EPA report, workers who were exposed to oil-based coolants for a long period of time suffered from a 20% increase in skin disease rates.
Thus, it is essential to protect workers from both dermal and respiratory issues related to contact with harmful substances. To prevent machinists from contracting diseases due to the chemicals used in the process, less toxic alternatives should be used. In most cases, water-based coolants are less toxic than oil-based ones and decrease the risk of respiratory and skin conditions in-turn. Thus, their use should be promoted in CNC machining areas.
Implementing proper ventilation systems helps attain low concentration of harmful chemicals in the air. These systems should be adopted to make sure there is enough fresh air present in the machining area to dilute and remove harmful airborne particles:
1. introduce fresh air at a rate that ensures the concentration of airborne contaminant is diluted to a safe level;
2. effectively remove and take the contaminated air away .
Employers should also ensure that every operator exposed to coolants and lubricants wears proper PPE, such as gloves and masks. Employers should provide training on how to safely handle such chemicals, informing workers employed on the site about the health hazards of each coolant and lubricant and the importance of wearing PPE.
Noise-Induced Hearing Loss
There are many risks associated with prolonged exposure to potentially damaging levels of sound in CNC machining where these kinds of operations involve high-decibel sound from cutting, milling, and grinding. The harm may be caused by the fact that the noise levels may easily be over 85 decibels, which is the critical threshold beyond which a person may not listen without the risk of permanent hearing damage.
Studies of people consistently exposed to noise at this or higher level show that permanent deterioration in hearing may be measured in a time span as little as six months. That is why it is very important for the organization to take many measures in order to spot the risks of hearing loss among the employees and eliminate them before anyone is harmed.
Undoubtedly, one of the most effective measures to alleviate the risk is the fitting of the sound dampening enclosures about the CNC machines. It has been estimated that these kinds of enclosures help reduce noise by up to 20 dB. It is also a good practice to implement the layout design in which noisy machines are as far from the workstation as possible. Finally, it is vital to supply the equipment operators with the personal protective equipment, namely: earmuffs and ear plugs.
The company has to check that the selection of hearing protection is driven by the values of the noise reduction rating needed for the supporting of protection that allows the wearing of PPE to keep the levels of sound to the safe minimum. Regular training of the personnel is vital in order to make sure that the operators know how to maintain the PPE and use it the most effective way. Making regular noise level audits are also vital in order to maintain an environment in which the exposure is never beyond the safe levels. The employer has to do these kinds of measurements at least once in every six months and change the levels of providing protection after the results of the measurements.
Electrical Hazards
Electrical hazards are among the most severe issues in CNC machining. There are many dangerous electrical systems that operate the CNC machines, and a risk of shock, burn, or electrocution is very high. Furthermore, about ten percent of all industrial fatalities are caused by electricity, according to the Occupational Safety and Health Administration . It is critical to prevent these accidents at all cost. One of the most effective ways to do so is to schedule inspections and testing of the electrical systems in all CNC machines. The inspection should be performed regularly, at three months intervals, by a qualified electrician.
The program should check machine’s insulation, connections, and functioning of safety cut-offs. This way, employers can be sure that machinery performs safely and that the risk of electrical incident is minimized. Lockout/tagout procedures (LOTO) should be in place during servicing. The procedure ensures that the machine is safely de-energized and that it cannot be started until the work is done and the machine is turned on again. LOTO makes sure that the machine does not start until the maintenance personnel is safely out of the way.
Training personnel goes without saying: CNC machine operators and those who service the machinery should know at least basics of electrical safety. They should know what exposed wires look like; they should know that when the machine acts funny, it may be an electrical issue; they should know that, if the circuit breaker is tripping, it is not the machine that is the problem. Finally, personnel that works with CNC machinery’s electrical parts should always wear the appropriate PPE: rubber insulating gloves and mats, and safety goggles at a minimum.
Fire Risk
The main reason for the increased fire risk associated with CNC machining is that both electrical equipment and machinery itself generate lots of heat in the course of work. Moreover, many types of CNC machining practiced in the industry involves the use of oil-based coolants. Already, a small spark may occur with the malfunctioning of electrical appliances or the extreme overheating of the equipment, and, thus, because oil-based coolants are highly flammable, the latter is not difficult to light. As Chitar and Ries explain, according to the existence statistics, fires occurring in industrial settings generally cause significantly more damage and injure more people than any other possible accidents.
The main reason is that, in halls with a large number of machines, there is always a danger that all members will quickly catch fire one after another, which is practically impossible to extinguish. Thus, it becomes apparent that the process of manufacturing the details are highly fire-prone, which emphasizes the importance of the development of the appropriate fire prevention measures. One of the most effective and, at the same time, easiest ways to prevent fires in the course of CNC machining is to install automatic machine fire fighting systems. They operate on the principle of the first signs of fire, such as an increased temperature inside the machine or the appearance of smoke, and then fire-fighting devices produce substances to kill the fire.
Moreover, a significant role in the containment of fires is played by fire-resistant barriers separating the machines and preventing the fire from moving to other units and machine tools. In addition, a mandatory condition for reducing the danger of fires related to the machining is the regular inspection of the electric devices and other parts of the machinery. I think that it is advisable to conduct such inspections at least once in two weeks, and, if any malfunctions are noticed, it is crucial to fix them as soon as possible. At the very least, in case the devices are already too bad damaged, it is preferable to replace them.
Finally, it is also of utmost importance to train all the staff in the issues related to fire safety. This involves, primarily, teaching employees to handle all of the used flammable liquids properly. It is also vital to train all machinists to recognize the signs of the overheating of the machinery and other devices and to make sure that all of the workers know how to act in the case of a fire. It might be a good idea along with exercises aimed at the evacuation of the hall in case of a fire using the emergency exits that the company should conduct such exercises at least once in six months.
