While most turning, grinding, and milling machines are designed for safety, they are not failproof. CNC machine fires cause significant loss to life, limb, and property every year. These fires could result from excessive heat, tool failure, programming mistakes, a drop in oil level, and any other anomaly. When left unchecked, such fires can spread quickly and envelope other equipment or even the entire facility. In contrast, the timely detection of fires and suppressing them right at the start can protect the equipment, building, and lives.
When we think of fire protection, sprinklers, mass notification systems, and air sampling smoke detectors come to mind. An additional layer of fire protection at the machine level is a supplemental fire suppression system that is an automatic mechanism that can ensure the extinguishing, controlling, and prevention of the spread of fire. And why do you need it? Here’s why:
Oil-Based Coolants: A Necessary Evil
Ironically, oil-based coolants are the leading cause of fires during the operation of CNC machines. It so happens that CNC machines use oil-based coolants or metalworking fluid to increase tool life, reduce friction, cut down cycle time, and improve surface finish. However, these fluids are highly flammable with a low flashpoint of nearly 400° F, and in cases where the coolant is unable to dissipate heat evenly or gets struck with a random, stray spark, it results in a fire! The problem is compounded by the fact that even if the coolant is not necessarily in active use, the active oil-based charged oil vapors are present in the environment and waiting to start a flash fire in a spark! Such fires demand quick response as they can engulf an entire milling machine in a matter of a few minutes. And so, the installation of supplemental fire suppression becomes even more vital.
Sprinklers May Not Be Enough
The National Fire Protection Association (NFPA) mandates that machine shops install overhead sprinklers to contain fires. And while these are highly effective in suppressing fire, they have a generalized approach to it and fail to protect individual machines or even the entire building. In most cases, it is found that the CNC machines are completely ablaze even before the sprinkler systems get activated!
As such, once the matter is already out of hand, even the best sprinkler systems will fail to douse such fires. At the same time, whatever is left of the machines from the roaring fire would be lost in collateral water damage resulting from the discharge of the sprinklers. In short, it would be a lose-lose situation for you whether the fire is out or not. As a result, sprinkler systems must be complemented with effective supplemental fire suppression systems to make them more effective (and less harmful).
Chemical Fires Need Special Extinguishing Agents
Fine metal chips, such as those of metals like titanium, aluminum, etc., can combust if they get hot enough. It often happens when the coolant oils (having a flashpoint that is less than half of the metal involved) catch fire and increase the temperature to reach the flashpoint of the metal debris. The resulting fire poses a serious hazard and can impede machining action and put your entire workshop at risk.
Such fires are classified as Class D fires and are far more severe and damaging. They burn at exceptionally high temperatures and react violently to water and certain chemicals. If you rely on sprinkler systems to put down this fire, you will only be disappointed as they worsen the situation instead!
While such fires are statistically less common as metals are harder to ignite, you only need one to blow up and cause damage, death, and destruction.
Supplemental Fire Suppression for CNC Machines: How They Work
Modern-day milling machines come equipped with various on-machine fire suppression systems. Once triggered by detecting a fire, they release a stream of safe and effective fire extinguishing agents, such as foam, dry chemicals, CO2, or water. Some fire suppression systems also contain agents like 3MTM NovecTM 1230 and FM-200TM that are most effective against machine fires. Such chemicals are known to be “clean agents” as they do not leave behind any residue, can be cleaned up easily, are electrically non-conductive, non-toxic, non-corrosive, and eco-friendly, and will not damage your machines.
These fire suppression agents are quickly dispersed as gas within the CNC machine and virtually cover all areas within it. The quick response and the effectiveness of the extinguishing agent also protect the electronic components and circuitry present within the machine. Plus, the gaseous nature of the suppressant allows it to cover even the hard-to-reach spots.
With such a failsafe mechanism in place, you will no longer have to rely on the wits of the machine operator to save your equipment and are protected if running lights out!
Should You Install Supplemental Fire Suppression In Your CNC Machine?
Your answer to this question should be a resounding yes by now. It is found that more than 40% of businesses that are shut down due to a significant fire never really manage to reopen. And even if they do, about 25% of these fail within the first two years as they cannot recover from the aftermath of the fire. As such, prevention is the best possible cure in these settings.
About the Author: Peter Jacobs
Peter Jacobs is the Senior Director of Marketing at CNC Masters. He is actively involved in manufacturing processes and regularly contributes his insights for various blogs in CNC machining, 3D printing, rapid tooling, injection molding, metal casting, and manufacturing in general.