Metals Metalworking is a general application that includes industrial processes such as dry metal grinding, buffing / polishing and other related processes which add value to metal components. Various types of abrasive materials are applied to the metals at high speeds with belts or discs to accomplish desired surface preparation, finishes or component size reduction. Metalworking processes are performed with both hand-held tools and with machines. Grinding is commonly used in applications such as welding preparation and dressing, sand casting post-processing and to remove rust or paint from surfaces. Buffing and polishing are usually multi-stage processes used to smooth rough surfaces and/or apply a desired finish to the working metal such as on tools, knives or appliances.
Key benefits from grinding dust and fume filtration include:
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Let's Get Specific
Contaminants generated from metal grinding may consist of surface coatings present on the component, the base material being worked and the abrasives or materials from the tool. The particulate size distribution is very broad due to the variety of materials included in the process and is generally between 1-20 µm. The particulate may be abrasive and pose a combustion or explosion hazard. Contaminants from machining processes fall into three broad categories:
Mists and fumes from metal working machines - when coolant lubricant is used to extend the tool life and prevent work pieces from deforming due to heat stress during the machining process. The amount of coolant smoke and mist generated by these types of machines depends on the size of the stock (diameter), type of machining performed (boring, thread rolling), the rotational speed of the operation, and the depth of the cut. In general, the larger the stock, the faster the rotation and the deeper the cut which results in heavier smoke and coolant mist emissions.
Dusts and fine particulates from dry processing machines and cutting applications - which range in both size and properties depending upon the dust type. The emissions from these dry processes are metal oxides which are similar in particle size to those generated in welding processes. The thickness of the material being cut, the cutting time per piece, and the hours of operation affect pollutant generation and loading. Smoke generated from the thermal cutting operation includes products of volatilization, dry metal oxides of the material being cut, coatings and atmospheric contaminant.
Buffing and polishing operations produce three types of contaminants: fine grit from abrasive wheels, fibers from the buffing wheels and waxy powders from rouge. Process dusts range from small spheres to elongated fibers. The particulate may also be combustible or explosive when collected.
Metal Fume Hazards
Exposure to fumes over time and in sufficient concentrations has been linked to respiratory, neurological and fertility problems including Metal Fume Fever and Parkinsonian Syndrome (manganism). Metalworking processes that contain chromium such as stainless steel or chromate coating are particularly hazardous and have been linked to various forms of cancer. In addition to health risks, uncontrolled weld fumes result in reduced worker productivity, product quality problems, factory maintenance issues and environmental concerns.
Recommended Approaches for Metal Fume & Dust Control
The recommended approach for controlling metalworking fume and dust depends on the method and process being used. A successful solution includes the proper hood or capture device, safe and efficient duct design, appropriate dust collection system and a properly sized fan. Below are some of the most common techniques employed on metalworking applications to control the process contaminants:
Source Capture. Whenever possible, capturing and controlling dust and fume at the source is the recommended approach. Source capture involves utilizing various types of hoods to extract the fume at or near the generation source to protect the worker and prevent the fume from migrating elsewhere in the facility. Source capture is the most effective means of capture and requires the least amount of energy and initial investment to accomplish. Source capture can be accomplished utilizing fume extraction arms or local fixed hoods.
Local Containment. Different than source capture in that it does not capture directly at the source, containment isolates the metalworking process from the rest of facility and protects the contained area. Containment can be used where hoods proximate to the machining are not practical but the process can be isolated from other parts of the factory.
Are you experiencing any of these issues in your operation?
• Insufficient air flow
• High differential pressure
• Dusty environment
We can help. We offer technical services that include inspection and evaluation programs which provide valuable insights toward understanding dust collection problems and solutions, from a piece of collection equipment to a single baghouse to your entire emissions control system. After nearly 50 years in the filtration business, we have dealt with billions of particles from hundreds of sources, in dozens of industries. We have the expertise to best optimize your air stream and plant operations.