Air Quality Issues in Automotive Manufacturing
The processes performed to assemble vehicles, plus the fume ventilation systems that keep employees safe, are detailed By TREVOR KENDALL, the technical director of VentMapping and engineering services at RoboVent (robovent.com), Sterling Heights, Mich. The opinions expressed in this article are those of the author. Reprinted with permission: The AWS Welding Journal Manufacturers in the automotive industry are often looking for ways to maximize efficiency and improve productivity. At the same time, they are tasked with building and maintaining a safer, skilled workforce. However, poor indoor air quality in a facility may negatively impact these goals and, simultaneously, increase health risks of existing staff. Metalworking processes used in automotive manufacturing may expose workers to a variety of airborne particulates. Common processes that create hazardous indoor air quality include welding, machining, cutting and grinding, rubber manufacturing, and plastic processing. Therefore, following established guidelines and using air filtration units are necessary. This article applies to automotive manufacturing, without sufficient mechanical ventilation, in enclosed spaces. Adhering to OSHA Regulations The automotive industry employs more than 425,000 workers in the United States alone, and a great number of those people work in manufacturing. The air in manufacturing facilities, if not properly filtered or cleaned, may be hazardous to worker health and productivity. That is why the Occupational Safety and Health Administration (OSHA) establishes exposure levels for various compounds of hygienic significance, such as beryllium, cadmium, hexavalent chromium, manganese, nickel, and zinc (see Table 1). In addition, the American Conference of Governmental Industrial Hygienists establishes threshold limit values. Overexposure to these elements may cause short-term and/or long-term health problems. Where Do Air Quality Concerns Come From? Many air quality problems in metalworking plants may be traced in part to weld smoke and fumes. Not only may weld fumes result in a visible haze throughout a facility, but the airborne particulates in weld fumes may settle on surfaces, including sensitive electronics and equipment, where the tiny particles may cause significant damage. More importantly, excessive weld fumes may pose serious threats to workers’ health. That’s why workplace policies and procedures that address regulatory indoor exposure limits need to be in place. For example, during manual welding, using fume extraction guns to remove smoke and fumes at the source can help — Fig. 1. Robotic Welding. Because robots operate with tremendous speed and efficiency, more and more processes are becoming automated in manufacturing environments (see lead photo). While there are potentially fewer workers in this vicinity who could breathe the weld fumes, the toxicity may be severe, and overexposure to robotic welding fumes may be dangerous. Proper containment and collection of these fumes are paramount. Laser Welding. Laser welding is a rapidly growing process in manufacturing because of its high level of precision and efficiency. While the initial investment for laser welding systems is higher than most other systems, the benefits are profound in terms of ability and speed. However, laser welding operations incur serious challenges when it comes to weld fumes. While laser welding machines operate in a closed cell, away from a human operator, lasers do produce small particulate that needs to be captured inside the cell. In addition to concerns regarding toxicity and safety, laser welding machines need a fume-free environment so the laser may perform at its optimal level. If fume builds up near the laser, the particles within the fume may refract the laser beam, making the process less efficient and precise. Resistance Welding. Resistance welding, including the common methods of spot and seam welding, relies on the heat generated at the faying surfaces of the metal components between two electrodes. This process generates smoke from surface contaminants, like oils, that burn off during welding. Machining. Machining often requires metalworking fluids or lubricants that may create fine oil mists in a manufacturing facility. Specific health impacts vary depending on the chemicals in the fluid and the size of the particles generated by the manufacturing process. When these mists are inhaled, they may irritate the skin, eyes, nose, throat, or lungs. Prolonged overexposure has been linked to asthma, chronic bronchitis, chronically impaired lung function, fibrosis of the lung, and cancer. Other factors of oil mist to consider are slip-and-fall hazards for personnel. Oil mist may require a collection system to create a safer work environment. Cutting and Grinding. Cutting and grinding metals and other materials used in automotive manufacturing may create large volumes of dust. Carbon fiber and composite dusts are associated with skin irritation, contact dermatitis, and chronic lung disease. When inhaled, some metal dusts, fiberglass, and epoxy resins may do damage to the respiratory system; some are even carcinogenic. This dust may require tools being connected to a vacuum or dust collection system. What’s the Bottom Line? Careful collection and filtration of weld fumes are important for both worker safety and regulatory compliance. With the shortage of skilled workers in manufacturing, a cleaner and healthier environment will attract new employees. Companies may also save money on recruiting, job training, and loss of production caused by high turnover and the effects of poor indoor air quality. In addition, when workers are ill, absenteeism increases; yet when employees come to work and they are not feeling well, the work quality suffers and they are not as productive. With continued overexposure, health complications will likely worsen and healthcare costs may increase. Without compliance to OSHA standards, businesses could face costly legal ramifications due to unsafe working conditions as well. How Do We Begin to Minimize Challenges? Because there are so many variables when it comes to indoor air quality, the first step is to get a clear picture of what your challenges are. By working with a qualified industrial safety professional or industrial hygienist, businesses may determine the concentration and composition of the particulate in a facility and then begin researching the best ways to overcome the challenges. An experienced and qualified industrial ventilation expert may also “map out” and accurately calculate airflow volumes required to optimize air filtration system efficiency and effectively predict resulting fume concentration levels in your facility. Before jumping into air filtration systems, there may be a few engineering controls that can be implemented to help manufacturers begin reducing fumes and minimizing overexposure in facilities. These points are listed below.- Confirm the use of the best welding parameters, processes, and consumables for the application.
- Weld fumes may be reduced by using power supplies that deliver pulsed current rather than a steady current.
- Adhere to the wire manufacturer’s recommendations regarding the voltage and amperage settings that minimize fume generation.
- Make sure welds are sized properly. Overwelding will increase fumes present in the facility.
- Take care to ensure welding surfaces are clean. Oftentimes dust, oil, paint, and other residues on surfaces not only weaken the weld, but also form other fumes that may be toxic.
- Adjust the position of the manual welder, welding machine, or location of the robotic welding cell to minimize overexposure to weld fumes.
- Hoods, cells, and arms work well for robotic and manual welding stations.
- Fume extraction guns remove the fumes directly at the weld. Modern fume extraction guns can be ergonomic and capture fumes at the source without compromising the quality of the weld. This is a useful option for welders working with large weldments that cannot be hooded. Fume guns also work well for welders who need to be mobile or work in tight spaces.
- Fume arms are a versatile solution for capturing dust and fumes. They are designed with movable arms that may be put into various movable positions to best capture fumes as weldments and welding positions change. Fume arms are not particularly cumbersome, but they do need to be moved into position by the welder.
- Crossflow and downdraft tables or backdraft hoods are a good option for welders working with smaller parts in a fixed location. This source capture system pulls contaminated air away from the welder’s breathing zone and returns clean air into the workspace.
- Unfortunately, fumes cannot always be captured at the source. In these cases, ambient air filtration systems are necessary for regulatory compliance. In some cases, plants will need to use both source capture and ambient extraction systems for the greatest effectiveness.