Smart Cleaning for Stamped Parts Cleaning systems need to Choosing the best approach for aluminum cylinder heads, often clean and comply with cleaning a particular metal part require complex cleaning technolo- depends on a multitude of factors. gies, according to Ed Kiebler of LS environmental rules. A The decision becomes even trickier Industries (Wichita, KS). “But in the as cleaning standards become more stamping, forming, fabricating end custom-mmade system may rigorous and as choices expand in of things, we’re still using aqueous- parts-cleaning equipment and chem- based, pass-through, or flow-through be the answer for the icals. Fortunately, given the relatively washers to clean most applications.” kind of parts your shop simple part shapes that are typical Flow-through washers, in general, with stamping processes, stamped convey parts through a tunnel of var- produces. parts don’t always require state-of- ious pre-soaking, cleaning, and rins- the-art cleaning chemicals and ing stages. An extreme simplification equipment to prepare them for of the process might be a car-wash painting, plating, welding, or other analogy—parts come in one end cov- secondary operations. ered with stamping and drawing However, in a volume-driven lubricants and other contaminants, business like metalforming, a choice and come out dry at the other end. of cleaning system does require extra Given the continuous nature of the attention to processing speed, ease of system, “There’s a tremendous need use, flexibility, and efficiency in for that style of washer for stamping resource use. These issues are and forming,” says Kiebler. addressed by various cleaning system “Part shape isn’t as critical in a technologies, surveyed below, flow-through washer as other fac- including multi-stage conveyor tors,” he says. “A lot of it has to do washers for continuous cleaning, with the solids you’re trying to clean low-footprint systems for small-scale off. As a rule, you’re cleaning stamp- manufacturing, and more recyclable ing oils, release agents from molds, cleaning chemistries that cut waste. flux, and so on, which don’t take a lot of pressure to clean off.” FLOW-THROUGH RESULTS Pass-through systems can be The most rigorous metal-cleaning major-size plant installations, with applications are for odd-shaped parts some of them approaching 50′ (16 m) Michael Tolinski with heavy contaminant loads and in length. But the concept is adapt- stringent, solvent-free cleaning stan- able for cleaning the largest parts and Contributing Editor dards. These kinds of parts, such as fabrications. For example, Kiebler www.sme.org/forming&fabricating – 6/2002 31 Solvents Face Uphill Fight Job shops that continue to rely on shapes, types of contamination, and ous system, so you can meet the ini- solvent-based cleaning methods may strict cleaning standards. “Certainly, tial standards for workplace safety soon find the trend towards aqueous a smaller company that’s tradition- while still using solvents.” cleaning too difficult to buck. These ally used solvents would make every Even though safe solvent clean- shops know that organic solvents are effort to find a way to continue ing may be possible, political forces highly effective for cleaning metal using them.” are strengthening against it, says LS parts and have continued to stick by Solvent users can face major hur- Industries’ Ed Kiebler. For example, them, even as regulatory pressures dles when installing new aqueous he notes that California has virtually have pushed other shops into cleaning equipment. “Typically banned solvent cleaning in manu- installing water-based systems. aqueous and semi-aqueous systems facturing operations, with tight con- “It was really just in the mid- involve more cleaning steps, and trols that may eventually spread to 1990s that there was this tremen- this takes up more space for equip- other states. dous shift from solvents to aqueous ment in the plant. Sometimes that Thus, solvent cleaning is in an and semi-aqueous cleaning systems,” means a complete redesign and ambiguous position. California says researcher Marilyn Bradshaw. reconfiguration of the whole produc- tends to have very stringent pollu- Bradshaw is with market research tion process.” tion laws, so similar nationwide firm Colin A. Houston & Assocs. Inc. Those who have stuck with sol- crackdowns on solvents may still be (Brewster, NY), which completed a vents are finding more environmen- a way off. And before a total ban study of cleaning surfactant use in tally safe solvents and solvent occurs, the death knell for solvents the metalworking industry over the blends, she adds. Moreover, to may be sounded by increasing costs period 1995-2005. meet regulatory standards, they’ve of solvent handling and disposal. But, she says this move to aque- improved their equipment to reduce But these factors must first win out ous cleaning isn’t technically or eco- VOCs (Volatile Oxide Compounds). against the sheer effectiveness of nomically feasible for every applica- A system upgrade might mean solvents. “Given there were no tion. Organic solvents used in vapor enclosing cleaning equipment better restrictions or limitations,” says degreasing and other processes, or finding a better way of reclaim- Kiebler, “everybody would prefer to besides being effective, are often ing solvent. “It’s not as big an use solvents because they do a won- required for certain part sizes and investment as switching to an aque- derful job.” mentions two systems LS recently quoted that are large enough to clean entire car frames. Another kind of flow-through sys- tem has just been put into produc- tion to clean some of the largest stamped components: automotive fuel tank halves. The “Centri-Spray” washer system for Ford Motor Co. fuel tank production is supplied by ICA Cinetic Automation Corp. (Farmington Hills, MI). www.sme.org/forming&fabricating – 6/2002 In production, upper and lower tank halves formed in a large press are manually loaded onto chain con- veyors for pass-through cleaning. Parts are conveyed through the washer by an indexing chain, a mechanism similar to the chains on a roller coaster, says ICA vice president Mark Pehrson. The washer’s soapy solution contains a rust inhibitor and degreaser and is sprayed with the force necessary to remove stamping Given the continuous nature of most stamping processes, LS Industries’ oil and other contaminants that flow-through parts washer is a typical approach for parts cleaning in met- might have fallen onto the tank’s alforming operations. large surface area. The washer has six 32 This large chain-conveyor washer is being installed by ICA Cinetic to clean the stamped halves of vehicle fuel tanks (shown foreground and right). Critical in the operation is not only cleaning stamping oil and residue from the parts but also the final drying stage, since water can corrupt the welding process. stages of washing, rinsing, and dry- applications for stampings, which are CELLULAR AND LEAN CLEANING off cycles—all of which are done in spray systems,” explains Edward Cleaning systems designed for an 18-second cleaning cycle, says Tulinski, vice president of Jensen flexible manufacturing show how Pehrson. After the drying stage, part Fabricating Engineers Inc. (Jenfab, much specific operation characteris- halves are inverted and passed on to Berlin, CT). tics complicate the choice of a clean- a welding operation. “Typically, when you get into thin, ing system. For instance, Jenfab’s The most difficult challenge for light parts and try to convey them on custom systems for “lean” cleaning this application isn’t the washing, but a belt washer, you have great diffi- provide necessary production flexi- the drying, says ICA’s Ford account culty keeping them in the machine or bility, but only for the shop they’re manager Walt Cunial. “Drying is the keeping them lined up like little sol- designed for and its range of parts. most critical part, because if there’s diers.” Thus, the movement caused “Our newest technology is complete any water contamination or droplets, by the spray pressure makes consis- cellular manufacturing systems,” says they could cause problems during tent cleaning more difficult. Tulinski. “We’ve made four or five the welding process.” The necessary Actually, the limitations of con- for customers, but each one is appli- “bone-dry” condition and part clean- veyor spray washers have more to cation-driven; I can’t say that one is liness is verified with random checks do with part shape than weight, he better geared for small stampings using a sprayed, contaminant-sensi- explains. “If the part has a lot of flat than another.” tive chemical. surfaces and is lightweight, it tends Generally, stamping operations to move around in the spray section. are continuous processes that don’t www.sme.org/forming&fabricating – 6/2002 SMALL-PART OPTIONS It makes it difficult to clean because lend themselves to cellular concepts. Conveyor washing works for you’ll start getting nesting and “Many stamping operations generate many larger parts, but cleaning stacking. very high part volumes, in which smaller parts is another issue, says LS “So a lot of small stampings are case, a ‘lean cell, one-piece, or small- Industries’ Ed Kiebler. “The only done on rotary drum systems, and a lot flow’ concept would not be dilemma you have with a flow- lot are done in baskets with agitation appropriate,” says Roger Hesse of through style washer is that your processes.” Tiny progressive-die Stoelting Inc. (Kiel, WI). parts have to be heavy enough to stampings, for example, might be For specialized stamping or low- keep from being blown around.” sent continuously from the press to a production jobs, cleaning systems are In general, small parts can often rotary-drum washer. Or depending available that are small enough to fit be poor fits for any system that uses on volumes and part size, shape, and between manufacturing cells or high-force sprays of cleaning solu- weight, they might be suited for a portable enough to shift from cell to tion and belt conveyors.