As we all know by now, new vehicles rolling off assembly lines today are no longer just made of mild steel. Rather, their construction consists of an amalgam of different substrates, including aluminum, high-strength steel, ultra high-strength steel, carbon fiber, plastic, magnesium, etc.
A lot has been discussed about how to repair these new substrates, but lost in the discussion has been how to keep technicians safe when working on these exotic materials. Technicians should always wear the proper protection when working on vehicles, but it might help to understand what new hazards these new materials might pose to their health to reinforce the need to follow safe guidelines.
In this article, we will address two of those materials: carbon fiber and aluminum.
The three primary areas of concern in performing repairs to carbon fiber-reinforced plastic (CFRP) structures have to do with 1) the possibility of obtaining slivers from the fractured fibers around the damaged area, 2) the dust created while cutting and grinding during the damage removal and repair preparation process, and 3) when handling, mixing, and distributing resins during the ply replacement (repair patch) fabrication and application.
Splinters from CFRP laminates are quite sharp and can penetrate deeply into the skin, however the material is inert and not considered dangerous. Deep splinters can be difficult to remove with tweezers, as they tend to be brittle and break easily. Heavy gloves can be worn to reduce the chance of getting splinters, but the best prevention is through awareness of this minor but potential risk when handling CFRP.
Dust from grinding CFRP is not considered to be of “respirable fiber” size (three microns or less in diameter, greater than five microns long, with an aspect ratio greater than 3:1). Carbon fibers are about six microns in diameter and don’t fall into this category, therefore they’re not likely to get caught in the fine alveoli of the lungs and cause long-term damage if inhaled.
While dust from CFRP can be dirty, it’s considered a “nuisance dust.” The personal protective equipment necessary for the operator typically consists of a shop coat or Tyvek suit, eye protection and a NIOSH-approved, N-95-rated particle respirator (dust mask). A portable vacuum or other dust collection system is also helpful in containing the dust to the local area where the repair is being performed.
When handling liquid resins or solvents, gloves made from chemical resistant material, splash resistant goggles, and an apron, shop coat or Tyvek sleeves are commonly worn for protection from skin and eye contact. Inhalation of any volatile organic compounds (VOCs) that may exist can be mitigated by performing the resin handling operations in a well-ventilated area or by wearing an appropriate organic filter respirator.
Another hazard with liquid resins includes the generation of toxic smoke or a risk of fire from a concentrated mass of an activated resin left for too long in a container or cup. This is considered an out-of-control exotherm, inherent to the chemical reaction of the mixed materials. The best way to reduce this hazard is to mix only the amount needed and distribute it into the cloth layers in a timely fashion.
In summary, performing repairs to CFRP structures presents minimal health and safety concerns as long as proper protective gear is employed and common sense is used when handling the resins or solvents that may be used in the process.
Tom Wright, director of sales and marketing at Martech, says, “Welding fumes from aluminum are much more dangerous than from steel.” That’s because welding aluminum releases gases like helium, argon and carbon dioxide that displace oxygen. “This can lead to suffocation, especially when welding in a confined space,” he explains.
“If you are welding under a wheel well, there is no way to keep those gases out of your respiratory system unless you have protection – positive air,” Wright says.
Martech provides a personal breathing unit called the Model P-20 that’s worn on a technician’s belt. It weighs 1 pound and is battery operated. The portability and less significant investment makes it an attractive option for smaller shops looking for a basic way to protect a technician from fumes, Wright says.
Have you ever heard of something called “metal fume fever”? This is a flu-like illness with symptoms of metallic taste, fever, chills, aches, chest tightness and cough. This is why proper training for technicians so they understand the potential hazards of working with aluminum is a must, says Eric Schmitz, vice president, EHS Products, and a product specialist for KPA. “Aluminum dust is a health hazard, and there are also flammability hazards we need to communicate to employees that are working around [the material],” he says. For more on this topic, see pg. 25 of the Aluminum Repair Guide in this issue.