Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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Page 72 of 707

Analytical techniques such as infrared microprofiling (developed by Sandia National Laboratories), X-ray photoelectron spectroscopy (Oak Ridge National Laboratory), and light reflective technology (Dow Chemical Inc.) have been used to analyze for residual contaminants in critical cleaning operations. If soils are doped with compounds that exhibit fluorescence exposure of cleaned parts to ultraviolet light will confirm the presence or absence of residual soils. Tests based on surface tension have been used to determine the cleanli- ness of surfaces. Care must be taken to ensure the use of test solutions specific to the substrate surface. SAFETY Unfortunately, one of the most overlooked aspects of industrial cleaning is safety. The use of chemicals for industrial cleaning exposes the user to potential injury if proper safeguards are not employed. The potential problems are well docu- mented in Material Safety Data Sheets, books, and articles that have been writ- ten over the years. The warnings are of little value unless they are read, understood, and acted upon by those handling, using, or working in areas in which the chemicals are used. A summary of the safety aspects of chemical cleaning are as follows. Acids The use of acidic cleaners containing appreciable amounts of sulfuric acid can expose the worker to potential splashing due to exothermic reactions that can result in localized boiling. Additions should be made in a slow, controlled man- ner to prevent splashing and localized boiling. Acids should be added to water. Water should not be added to con- centrated acids. Addition of acid cleaner concen- trates to replenish working solutions should always be made to cool solu- tions (<100oF). Without exception, acid-resistant goggles, face shield, boots, apron, and gloves should be worn by workers to minimize the potential for body contact with the acidic solutions. Acid cleaners containing fluoride compounds can result in severe tis- sue damage. Precautions should be taken to avoid any contact with flu- oride-containing solutions. If fluo- ride compounds are used, person- nel should be trained in the treatment of fluoride burns. The use of acid cleaning com- pounds can result in the evolution of flammable and explosive hydrogen gas. Care should be taken to avoid uncontrolled release of pressure when parts are cleaned in sealed Turnkey Parts-Cleaning and Processing Systems Cleaning Nital Etching Steel and Titanium Etching Titanium and Aluminum Anodizing Pickling Chromating/Alodine Passivating Electropolish Chemical Polish for Steel Process design, equipment design and experienced world-wide installation ® 716.763.4343 71

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