Production Machining

FEB 2013

Production Machining - Your access to the precision machining industrial buyer.

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TECH BRIEF Solvent-Based Cleaning In selecting the right cleaning medium, the "like dissolves like" principle of chemistry applies. In other words, for removing mineral oil-based (non-polar) contaminants such as machining oils, greases, waxes, corrosion inhibitors, or esters, a solvent is typically the preferred cleaning agent. As it washes away the oil, chips and particles present on Hydrocarbons and modifed alcohols are distinguished by their chemical compositions. Te modifed alcohol Dowclene 1601 from Safechem provides both hydrophilic and lipophilic portions in the structure and ofers exceptional solvency for a range of soils and contaminants. Tis feature enables the agent to efectively isolate contaminants and remove them from surfaces without re-depositing them, so the parts dry without residue. Tis modifed alcohol is also suitable for difcult applications such as cleaning lapped parts, sintered metals and high quality, high precision small parts. Solvent Cleaning Equipment :: To meet strict cleanliness requirements, solvent systems are frequently equipped with several media tanks and appropriate filtering technology. Image Source: Dürr Ecoclean the part surface, contaminants lose adhesion and can be removed mechanically—by ultrasonic cleaning, injection food washing, or other means. Solvents commonly used for machining processes include chlorinated hydrocarbons (CHC)—perchloroethylene, trichloroethylene and methylene chloride—as well as non-halogenated hydrocarbons (HC) and modifed alcohols. Non-fammable chlorinated hydrocarbons such as the perchloroethylene and trichloroethylene (sold by Safechem North America as Dowper SVG Double Stabilized and Neutri solvent, respectively) are chemically stable. Tey have minimal surface tension and ofer good recycling potential. Tese solvents allow for efective removal of non-polar oils and grease, even from components with complex shapes, without corrosion, oxidation, discoloration, and burning, dulling or other surface impairments. Historically, from an environmental and worker safety viewpoint, solvents for industrial parts cleaning have gained a bad reputation. For decades, the solvents were used in open, unsealed cleaning equipment and were often improperly handled and disposed of. Such open systems not only lead to high solvent consumption and wasted costs, but many solvents also generate emissions that are harmful to workers and the environment. Instead, for safer and more environmentally friendly processes, solvents can be used in fully closed, single-chamber cleaning systems with integrated distillation units for solvent reclamation. Solvent cleaning systems from Dürr Ecoclean ofer an integrated distillation unit, full-fow and bypass fltration, injection food washing (IFW), heat recovery, and several energy saving and emission reducing features as standard. Dürr machines can be adapted to specifc cleanliness, throughput, part geometry and preservation requirements via appropriate dimensioning, process engineering, fuid treatment and drying technology. Operating under full vacuum, these cleaning machines eliminate the need for additional explosion protection for combustible solvents (HCs and modifed alcohols). Additionally, they are equipped with redundant safety technology. A high vacuum performance in combination with strong pumps and large-diameter piping ensure maximum throughput cleaning efciency and fast drying even for very complex part geometries. Applications calling for oil-free surfaces in downstream steps such as hardening, CVD/PVD coating, brazing, welding or adhesive bonding often impose the need for ultra-fne cleaning. To this end, closed solvent cleaning systems can be equipped with several solvent tanks for a multi-stage cleaning process. An electropolished work chamber and optimized fow conditions ensure that productionmachining.com :: 39

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