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Understanding Potential Reactions in a 3D Printing Enclosure

June 07, 2016 at 12:30 PM

3d Printing

With additive manufacturers increasingly turning to reactive metals for 3D printing and welding applications, it's more important than ever to understand potential reactions of the materials and gases involved. When improperly handled, some combinations can have dire consequences.

Every so often, we read reports of companies that failed to protect their workforce and prevent such hazards, subsequently leading to anything from operator third-degree burns, to loss of buildings and lives from larger explosions. In cases regarding the 3D printing industry, mishandled titanium powder is often discovered to be the fuel.

To explain fully, fuel is one of three components of a fire, with oxygen and ignition being the others. Together, these make up what is referred to as the Fire Triangle. A fire cannot burn without oxygen. Likewise, a combination of fuel and oxygen will not catch fire without an ignition. You need all three components for a fire.

Interestingly, a block of titanium is air stable. However, when you break it down into high surface area particles, it becomes combustible and easily ignited by static electricity, open flame, electric arcs and more. This makes titanium powder very dangerous,especially when confined to a small space.

When a manufacturing application occurs in an enclosed space, such as 3D printing in a glove box, and involves a lot of fine powder, like titanium, two new components areadded to the fire equation: confinement and dispersion (of the powder). Now, the five factors of fuel, ignition, oxygen, dispersion, and confinement make up what is called an Explosion Pentagon -- and, as it sounds, carry greater risk.

To avoid an unwanted hazardous reaction, one element of the Explosion Pentagon must be removed. Though, it's wise to take a multi-faceted approach to precautionary measures, particularly with regard to oxygen levels and ignition sources.

Controlling ignition can be tricky when working with dusts and powders because there are many conceivable ignition sources in every manufacturing environment. Consider these tips:

  • Beware of hot surface temperatures and take caution with combustible lubricants or oils used on the same surface
  • Prevent static electricity with proper grounding
  • Eliminate potential contact with open flames or embers from candles, flares, furnaces, or smoking employees
  • Control mechanical sparks and friction
  • Maintain safe distance from industrial trucks that can create a spark when the engine is engaged or a truck backfires
  • Use tools properly to avoid shaking dust loose or creating sparks
  • Collect dust regularly to avoid smoldering nests
  • Monitor hot spots related to repeated impact or rotating equipment
  • Retain equipment and wiring that is incapable of releasing enough energy to cause ignition or explosion
  • Remove foreign materials using separator devices

To control oxygen levels in 3D printing and welding applications -- and eliminate risk of an unnecessary reaction -- a glove box with argon gas management system should be used. After removing oxygen (and moisture) from the argon inside the enclosure, a well-maintained gas management system will circulate, analyze, and purify the argon atmosphere, simultaneously displaying the real-time data that operators and quality assurance managers need to ensure a safe work environment and efficient output.

Considering all of the potentially negative outcomes when handling fine powders and dusts, it's understandable that there are many regulations and standards. If you want to learn more, the U.S. Department of Labor's Occupational Safety and Health Administration (OSHA) (https://www.osha.gov) has extensively published on the subject to help create safer work environments. Also, the National Fire Protection Association (NFPA) (http://www.nfpa.org) has several standards related to the hazard, including NFPA 484: Standard for Combustible Metals.

At Inert, we specialize in design and development of gas management systems to work with nearly any glove box or application. Talk to us about your unique requirements and find out what we can do for you.