Fire Suppression in CNC Machines

Introduction

A CNC (Computer Numerical Control) machine represents both a serious investment and an excellent source of revenue for companies involved in manufacturing and fabrication. Like all manufacturing machines the risk of fire is always present.

A damaging fire which takes a CNC machine out of service can have a serious impact on the company relying upon it. While proper care and maintenance can greatly reduce the fire risk, there can still be issues which are difficult to definitively prevent. With so much riding on having a fully functional CNC machine, it only makes sense to provide a fire suppression system to protect the asset, as well as the surrounding structure and personnel.

What is a CNC Machine?

A CNC machine is a manufacturing tool that uses pre-programmed computer software to control its movements and operations with high precision and efficiency. It automates the machining processes of cutting, drilling, milling, turning, and shaping materials such as metal, plastic, wood, or composites.

CNC machines are widely used for producing complex and accurate parts, allowing for repeatability, scalability, and reduced manual labor. They are essential for applications requiring tight tolerances and high-volume production. Industries where CNC machine use is common include:

• Aerospace
• Automotive
• Medical device
• Semiconductor and other electronics
• Furniture
• Jewelry and other retail products

CNC Machine Fire Risk

Fires involving CNC machines are somewhat uncommon; because of this, research into the rate of CNC machine fires and fire causes is scarce. But on the occasions when they do catch fire, the results are often extremely damaging and costly.

Because CNC machines are such complex devices, there is much that can go wrong. And many of these failures or errors can potentially cause a fire. Anecdotal industry research reveals that two of the most common culprits in CNC machine fires are: (1) metal chip and dust management; and (2) issues with coolant / lubrication. While these two factors may cause the most problems, there are a host of others which owners and operators should be aware of as potential fire risks.

Metal Chip / Dust Management
When metal is machined, it is accompanied by the production of metal shavings, chips, and dust. Metals such as magnesium, titanium, and aluminum are all readily flammable when they are finely divided and have large surface-area exposure.

When the process produces sparks, or a tool breaks creating a shower of sparks, the metal dust or shavings can ignite producing a hot fire that can be difficult to extinguish. Other materials such as wood or plastic also present a fire risk when they are in dust form, although they do not appear to experience a high rate of fires.

Lubricant / Coolant
In many instances, oil-based lubricants and coolants are used on CNC machines. These flammable, hydrocarbon liquids have a relatively low flash point—i.e., sparks or overheated tools and/or workpieces can be an ignition source. Also, since oil-based coolants do not dissipate heat as effectively as other coolants, there can be a fire risk from heat generation, particularly during high-speed machining runs.

Electrical
CNC machines are voracious consumers of high-voltage electricity. Whenever high-voltage power is handled, there is always a risk of fire. Most components on a CNC machine are electrically powered. While the servos and motors (such as the spindle drive) are the major consumers, there are numerous electrical functions taking place inside the machine as well. This can include AC to DC conversion, stepping up and down voltage, inverters, and power distribution. Any of these could experience a short circuit, have faulty or overloaded wiring, or not be properly maintained—all potentially causing a fire.

Tool Issues
Tools that are worn or dull generate excessive heat which can also lead to a fire. Tool breakage can also wreak havoc and create sparks. Improper tool use and excessive tool speed are other tool issues presenting a fire risk.

Operator Error
Incorrect programming or setup can lead to excessive tool loads, overheating, or unexpected movements. The operator is also responsible for coolant application, and insufficient cooling can readily cause a fire. Poor material handling and failure to manage dust/chip accumulation also creates a fire risk.

Lights-Out Operation
The term “lights out” means the machines can run unattended around the clock with the lights out in a plant. While cost effective, the possibility of problems going unnoticed is far higher; therefore, so is the risk of fire. The continuous nature of lights-out operations is also very wearing on the machines. Maintenance problems can develop which, if not remedied, could lead to a fire.

Effects of a Fire

A damaging fire that takes a CNC machine out of service is a serious matter on multiple levels. First, CNC machines are expensive—basic models cost tens of thousands of dollars. And when you consider industrial and production models, the range can be from low to high six figures. Highly specialized machines costing over a million dollars are not unusual.

If a CNC machine is salvageable following a fire, it is expensive to repair and can be out of service for extended periods while parts are sourced. Complete machine replacement may not be quick either, as many CNC machine manufacturers have healthy order backlogs. Either way, operators are looking at significant downtime and indirect costs in terms of lost revenue that may far outweigh the direct costs.

In the hands of a capable business, CNC machines are good earners. Depending on the machine and the industry, CNC machines can generate several hundred to several thousands of dollars in net revenue every hour. Any downtime can lead to substantial lost revenue. For a lights-out operation, revenue losses can easily be $20,000 a day upwards.

However, the above scenario assumes that the damage is limited to the machine. It is entirely possible that the machine fire could spread to other machines, stock, and the surrounding structure. Fire spread to the surrounding structure is a real risk. According to a 2023 report from the NFPA (National Fire Protection Association), “Equipment or heat source failure was a leading cause of structure fires in industrial and manufacturing properties.”

A CNC machine fire is the type of fire that can severely damage a business. Consequently, it is important to recognize the fire risk and take measures to prevent or mitigate it. Fortunately, there are several steps owners sand operators can take to prevent a fire in their CNC machine, and others that can address a fire should it occur despite these prevention efforts.

Protecting CNC Machines

The best way to safeguard a CNC machine is to have a comprehensive approach which addresses prevention, preparation, processes, and protection from fire.

Prevention
A key prevention measure is to perform maintenance according to the manufacturer’s recommendations, including regularly inspecting the machine and its work area. Operators should also consider using fire-resistant coolants and lubricants, if possible. And chip management needs to be a focal point.

Preparation
An investment like a CNC machine should only be entrusted to qualified and competent operators. A well-trained operator is less likely to make critical errors during setup, operation, or maintenance. Operators should receive ongoing training that covers topics such as:
• Proper machine setup and operation
• Safe handling of flammable materials (e.g., magnesium or titanium)
• Correct coolant application and monitoring
• Warning signs of overheating, tool wear, and coolant issues

Processes
There are several processes which operators can take to reduce fire risk. Programming errors can be detected by using simulation software and/or automating programming verification. Operators can set a safety culture by performing good housekeeping, using high-quality tools, and having a policy of addressing all alarms and alerts. Operators should also develop and use special precautions when machining flammable materials.

Protection
Because operators cannot control every variable, they should always prepare for the worst and provide a fire suppression system on the machine. The system should be able to detect and extinguish a fire before it can spread or cause significant damage. Properly selected and installed fire suppression devices can quickly extinguish a fire, and often allow the machine to return to service in a timely manner.

Fire Protection for CNC Machines

When considering fire protection for CNC machines, some operators make the mistake of thinking that because they have a fire suppression system in their facility, it will protect the CNC machine. A sprinkler system installed in a machine shop will only react to a fire once it has grown in size, outside the machine enclosure, and generates enough heat to activate a nearby sprinkler head. The machine will be a total loss, and all the other equipment in the area will receive a thorough soaking with water. This is not the best outcome to reduce operational downtime.

It is far better to protect a CNC machine at the device level, inside of the enclosure. The suppression system should have the ability to quickly detect a fire and discharge sufficient agent to extinguish multiple classes of fire. The system needs robust construction capable of operating in an enclosed, dirty, and hot environment.

The ideal system will be simplistic, unobtrusive, and capable of both automatic and manual activation. It should be simple to install, easy to maintain, environmentally sustainable and approved for use in occupied spaces. It also needs to be safe to use on the machine itself and not damage any components.

The Stat-X^® Solution

The good news for operators is that there is a fire suppression system available that meets all of the requirements listed above for the ideal protection of CNC machines. That product is Stat-X.

Stat-X uses a proprietary potassium-based condensed aerosol agent which disperses quickly to flood the enclosure, interrupt the fire’s chemical chain reaction, cause flame collapse, and effect extinguishment.

Stat-X units are self-contained, install easily with no piping or wiring, and feature sturdy construction that is well-suited for the enclosed, hot, and dirty environment inside of a CNC machine. The units can be activated either manually, or, automatically when exposed to a preset temperature or via a signal from a fire detection device. Stat-X is effective on Class A, B, and C fires.

Aside from Stat-X’s effectiveness, one of its best features is the level of testing and certifications. Stat-X is approved for use in normally occupied areas. It has zero global-warming potential, zero ozone-depletion potential, and zero atmospheric life. The compact units are virtually maintenance-free, and have a fifteen-year service life. Stat-X systems can also be easily retrofitted int6o existing machines without the need for costly infrastructure work.

Conclusion

CNC machines are often the heart and soul of a manufacturing facility. They are big earners and make difficult tasks look easy. It only makes sense to protect these vital assets.

Facility sprinkler systems are intended for structural protection, and to assist in occupant evacuation, not asset protection like CNC machines. Further, relying on employees with portable extinguishers, in a high stress environment, can be a risky proposition.

Stat-X offers CNC machine owners and operators a cost-effective option providing positive protection to quickly suppress a fire and keep the machine in service earning revenue.