As metal additive manufacturing (AM) continues to grow in use, it’s time to pay attention to the safe use of these systems.
Some may ask, “Why do I have to worry so much about safety? And what do I have to be concerned about?”
The answer is, “Everything,” said Paul Bates, Manager of the UL AMCC, and industry-recognized additive manufacturing veteran, in a recent webinar we held. “Working safely in any manufacturing industry is important and in metal manufacturing with additive it’s extremely important,” he continued.
Plus, you need to comply with certain regulations regarding additive materials. You can be penalized civilly and criminally if you do not follow standards, particularly OSHA, as well as some of the transportation agencies requirements on maintaining the safety of AM materials and equipment.
Of course, the OEMs that sell the equipment work hard to make sure customers are aware of safety issues and can operate them safely. But safety is evolving, and it’s important to know how to maintain a safe environment for additive manufacturing.
The risk of explosion is high with powdered metal. While inert gas is often used in an additive machine’s enclosed build chamber to control this risk, inert gas itself requires safe handling. Powdered metal, oxygen, and an ignition source, like electrostatic discharge (ESD) are pretty much all that’s needed to turn powdered metal into a flaming substance.
Therefore, do you have a safety protocol? Is there a safety system in place so if something happens to workers, others know what to do? Do you have a training program for the safe use of metal additive machines?
Here are a few basic tips for safety from the webinar. We will have more safety tips from future webinars.
Protect, eyes, skin, and lungs
Use personal protective equipment (PPE) before you start working with any piece of equipment. PPE is equipment you wear to create a barrier between you and something that could cause harm. Facemasks, gloves, and full Hazmat gear are examples.
In metal additive manufacturing, you are exposed to metal dust, and it can get into your body in several ways.
- Inhaling the dust is the most common way.
- Metal dust can also be absorbed through the skin, particularly your hands. If you use your hands to touch certain parts of your face, such as your eyes or nose, metal dust can enter in that way. The general rule is to not expose bare skin to metal powder. But there is also machine coolant to think about.
- Ingestion is another route. If you eat near the metal additive machine, you could be ingesting metal dust as well.
- Finally, metal dust can enter through injection. Either you have a cut or open wound where metal dust can enter, or you receive a cut working with the equipment.
Types of PPE equipment.
- Face masks and goggles are one type. When working with metal powder, a full-face shield is more protective than a paper facemask. Over time metal powder builds up on the paper mask. Remember, paper burns fast. A paper mask will be more of a liability than protection. Goggles protect your eyes, but do not cover breathing or ingesting metal dust.
Be aware that while goggles can protect from dust, they may not be adequate to also protect your eyes from damage caused by looking into a class 4 high-powered laser. If you are using the machine properly, you’re not actually exposed to a full class 4 laser. Proper use changes the categorization to a class 2, which is safer but caution is still advised.
- Respirators. These protection devices have a rating. UL recommends using the NOSH ratings, which are a U.S. standard. Europe has its own standards. Ratings of N100 and P100 come closest to keeping 100% of particles out. The difference between N and P is that N100 is not resistant to oil and the P100 is.
- Gloves. Use gloves that cover you up to your elbows, especially if you will be handling metal powder. They should be puncture resistant, too. Be sure to remove them properly to minimize the chance metal powder gets on your bare skin.
PPE alone will not eliminate hazards. This equipment is best used in conjunction with other safety measures. Plus, it is not a substitute for proper engineering, proper work practices, or good administrative controls.
Supporting equipment requires safety practices too
Ensure that supporting equipment, such as wet separators, are well maintained. Some of this equipment can be dangerous to have around if not.
Make sure powder is in the proper storage container and that the containers do not show signs of wear or damage. Materials need to be handled properly before they are moved to the AM equipment. Safety includes the testing and validation of materials before you even start using them.
Manage waste properly. The exact requirements for waste disposal vary by region. Work with your disposal agencies to put together the right plan. Test your materials and check on how they should be properly disposed.
Metal additive machines often use some type of inert gas, such as argon and nitrogen, to manage the flammability and explosion potential of metal powers. A caution about these gases–nitrogen and argon will displace oxygen in a room. They don’t smell and there’s no color, so you won’t know if there is a leak, until people in the room start passing out.
Make sure the valves on equipment are certified leak-proof. Use gas monitors. Use an oxygen monitor. Make sure there’s an audible alarm and a flashing light and make sure they’re positioned properly in the space so they can detect the gas at the optimum levels so that you can get out safely.
It’s a good idea to either have ESD damping flooring or wear ESD safe footwear. Other tips for reducing the possibility of ESD include:
Ground your equipment
Have employees wear grounding straps
Ground the facility
Minimize any potential source of ignition
The cleaner you keep your facility, the safer it’s going to be.
Finally, ensure that workers in your facility have been trained. They need to be aware of all the hazards and risks. They should know the materials in the lab and what they’re going to be exposed to, whether it’s solvents, metal powder, or gases.
Advice and help are available to ensure you have safe additive manufacturing facilities. UL is one of the third parties available to help you design the safety protocols you need to make parts safely as well as fast.