Products Finishing magazine is the No. 1 industrial finishing publication in the world. We keep our readers informed about the latest news and trends in plating, painting, powder coating, anodizing, electrocoating, parts cleaning, and pretreatment.
Issue link: https://pf.epubxp.com/i/830013
PRODUCTS FINISHING — PFonline.com 29 The CTG Tech Center houses a cleanroom that is rated at class 10,000, using gravimetric Millipore filters (at left) to conduct microscopic particle size analysis (below). standard spray, total immersion, ultrasonics and high-pressure spray. Of these, the first and last are referred to as "line of sight" processes, in which anything on a part in sight is cleaned, even at the bottom of relatively shallow cuts and holes. The two remaining processes call for parts to be immersed in the cleaning solution, and even spun and agitated, in some cases. These work best for more complex parts with deep recesses in which chips and other debris can be hidden. This article covers how each process is performed, to what parts they are most suited, and the kind of work a machine shop is doing that would lead them to choose one process over another, and even to commission a custom system combining parts cleaning methods. Standard spray provides great flexibility among parts of different shapes, materials and sizes. Such systems are typically batch loaded for use in general industry, such as companies machining parts for appliances or garden equipment. Parts are positioned on a rotary table or within a specialized fixture, depending on their geometry, and they are sprayed with water mixed with different concentrations of surfac- tant, which disperses oil and debris from the surface of the part. Any remaining liquid is blown off using compressed air. More acidic cleaners are used with soft metals such as copper, brass and bronze, while steel products require that attention be paid to the pH level. A solution with a pH of less than 7 is considered acidic, while a solution with a pH higher than 7 is referred to as basic, or alkaline. A standard spray system can be modified—automated loading/unloading, the incorporation of additional cleaning systems for special applications—and is a simple, straightforward, cost-effective process for a variety of manufacturers. Total immersion is generally considered first when features or deep recesses on the part prevent direct line-of-sight inspec- tion. Cutting fluids, chips and other particulate matter can evade even high-pressure spraying, so some parts must be fully immersed in the cleaning solution. One approach involves loading parts into a basket, which is then introduced into the self- contained cleaning chamber. The parts are first sprayed while the basket rotates in a circle, and then the chamber is filled with an aqueous solution with whatever chemistry is required by the process. The basket is then agitated, plunged into, and then withdrawn from the bath, which serves to channel the solution deep into the recesses, thereby removing any remaining excess chips or fluids. This method basically picks up where a standard spray system leaves off, adding total immersion to the process, and then blowing the parts dry. Automation is also an option, as is the case with all four of the standard categories of aqueous cleaning. Ultrasonics can be layered on top of the standard spray and total immersion processes, adding the powerful element of cavi- tation to the cleaning system. There are four basic methods to performing water-based cleaning operations in metalworking: standard spray, total immersion, ultrasonics and high- pressure spray. PARTS CLEANING