Computer Numerical Control (CNC) machining is a process where computer-aided design (CAD) and computer-aided manufacturing (CAM) programs are used to control the steps and functions of machine tool centers, allowing repetitive production processes to be programmed and automated. CNC machining and milling centers, as well as CNC lathes, are precision cutting machinery commonly used in industrial manufacturing applications such as metalworking. These centers have several axes, in which tools and workpieces move. Workpiece and tool changers supplement the systems so that complex geometries can be produced on one machine tool.
Today’s high-speed processing requires the introduction of cooling lubricants. These are used to cool the cutting edges on the direct contact surface to the workpiece during the cutting procedure, to lubricate the contact surface and remove any arising chippings through “purging”. Through the rotation and energy input, the cooling lubricant forms an aerosol mist, which is extremely hazardous to health if inhaled.
Let's explore how one metalworking manufacturer solved the problem of CNC machining emulsion mist and improved air quality in its production facility.
Mauersberger und Fritzsche is an SME with a long tradition in gear manufacturing for drive technology and in the production of high-quality structural steel cupped shears. The company has CNC machining and milling centers from renowned manufacturers, such as Monforts, Doosan, Yang and Mori Seiki, in which workpieces are cooled, purged and lubricated with water-soluble cooling lubricants (emulsions). To improve air quality and safety, the corporate management team turned to Parker Industrial Gas Filtration Generation Division to design a solution to remove the hazardous emulsion mist.
The company’s machinery comprises approximately 10 machine tools. For this reason, the advantages and disadvantages of single-station extraction units were weighed against a central extraction system.
The advantages of a central extraction system prevailed in this project. On balance, the investment costs are lower despite higher costs for piping and assembly, while maintenance is concentrated on a central point. In addition, a summer/winter set-up as hall ventilation can be easily realized with this concept. This allows exhaust air operation in the summer and a recirculated air operation in the winter to save heating costs.
In general, it is not possible to give one blanket answer to the question about single-station extraction units or central extraction systems. This must be decided on the facts of the relevant plant. However, as a general rule, the overall or life cycle costs of a central system with a ventilation system performance from 6,000m³/h tend to be lower. In this case, Parker recommended a SmogHog ESP two-staged electrostatic filter which reliably filters out harmful substances and emulsion mist, such as aerosols, and offers the client an approximately 15% reserve for production expansions.
The client was initially skeptical about an electrostatic filter solution. However, thousands of installed SmogHog electrostatic filter systems have proven successful for decades. Even oil and emulsion mists can be filtered with outstanding results if you have 50 years of knowledge like Parker. Knowledge, which can also be seen, for example, in the piping used for raw (polluted) gas, as this should be made of longitudinally welded steel and be oil-tight on the flange connections. “Cheaper” folded spiral-seam pipes are reputed to save costs but, according to Parker's experience, they carry a risk of a production hall becoming a “stalactite cave”. By visiting a comparable reference system near the client’s company, Parker was able to convincingly prove this knowledge, dissipate the reservations and win the trust of the user. This and independent measurements by the Institut für Luftund Kältetechnik convinced the client to award the contract to Parker.
The client is very satisfied with the performance and maintenance intervals of the system, especially as they clean the filter elements on-site and reuse the filter inserts.
Watch this video to learn more about Smoghog:
This article was contributed by the Filtration Team.
Thanks to Dr. Truschka and the company for approving this article and the pictures. Authors: Carlo Saling, Norbert Jedrzejak and Jörn Jacobs