Smart Cleaning for Stamped Parts

Contributing Editor Parts for Stamped Smart Cleaning C M e k b c c p Parts for Stamped Smart Cleaning u i l r n e l n e i e o s c v t d t a a d h o t i n o n r a u h m o o i e c n e f a n l e -m g T p a m T n s m p a s . o s d a a n y e l d i r s s n n c t e t w s s e o t s k y s a m e m y i y l r o s r s f p r t n u f e n u l o r m y e l s e r w e s m t w s h d m t . i o t h A a t t A p o h e y dards. Thesekinds ofparts,suchas stringent, solvent-freecleaning stan- with heavycontaminantloads and applications areforodd-shaped parts F cleaning chemistriesthatcutwaste. manufacturing, andmorerecyclable low-footprint systemsforsmall-scale washers forcontinuouscleaning, including multi-stageconveyor technologies, surveyedbelow, addressed byvariouscleaningsystem resource use.Theseissuesare use, flexibility,andefficiencyin attention toprocessingspeed,easeof of cleaningsystemdoesrequireextra business likemetalforming,achoice secondary operations. painting, plating,welding,orother equipment topreparethemfor the-art cleaningchemicalsand parts don’talwaysrequirestate-of- with stampingprocesses,stamped simple partshapesthataretypical icals. Fortunately,giventherelatively parts-cleaning equipmentandchem- rigorous andaschoicesexpandin as cleaningstandardsbecomemore The decisionbecomeseventrickier depends onamultitudeoffactors. cleaning aparticularmetalpart LOW The mostrigorousmetal-cleaning However, inavolume-driven Choosing thebestapproachfor -T HROUGH R ESULTS some ofthemapproaching50 major-size plantinstallations, with lot ofpressuretocleanoff.” flux, andsoon,whichdon’ttakea ing oils,releaseagentsfrommolds, off. Asarule,you’recleaningstamp- with thesolidsyou’retryingtoclean tors,” hesays.“Alotofithastodo flow-through washerasotherfac- and forming,”saysKiebler. for thatstyleofwasherstamping system, “There’satremendousneed Given thecontinuousnatureof and comeoutdryattheotherend. lubricants andothercontaminants, ered withstampinganddrawing analogy—parts comeinoneendcov- of theprocessmightbeacar-wash ing stages.Anextremesimplification ious pre-soaking,cleaning,andrins- convey partsthroughatunnelofvar- washers tocleanmostapplications.” based, pass-through,orflow-through of things,we’restillusingaqueous- stamping, forming,fabricatingend Industries (Wichita,KS).“Butinthe gies, accordingtoEdKieblerofLS require complexcleaningtechnolo- aluminum cylinderheads,often fabrications. For example,Kiebler able forcleaningthelargestparts and in length.Buttheconceptis adapt- Pass-through systemscan be “Part shapeisn’tascriticalina Flow-through washers,ingeneral, ′ (16 m) 31 www.sme.org/forming&fabricating – 6/2002 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. “When you batch immersion process with tum- cell. These support a one-piece flow talk about thin-wall stampings, or bling, compressed air, or other forms environment, says Hesse, and can be light stampings, you eliminate typical of agitation. “placed as close together as possible 34 Line Rinse

Wash Tank Rinse Tank

Conc. Tank C.I.P. Tank R.O. Permeate Oil Discharge UF Reject 3 Way Valve R.O. Reject

Feed Pump R.O. UF Membrane 5µ FilterCartridge (0.005µ) 1µ Cartridge

A schematic of a typical cleaning wastewater recycling system. Wastewater travels through filtration, ultra-filtra- tion (“UF”), and reverse-osmosis (“R.O.”) units, which remove contaminants not drawn off in the concentration tank. In Ransohoff’s “neutral-based chemistry” system, streams fed back to wash, and rinse units contain reusable cleaning agents that retain their effective cleaning power through the loop. to reduce the operator’s walking dis- based cleaning, the soaps and surfac- So cleaning system suppliers are tance between operations.” tants in use are typically classified as developing systems in which little or For more continuous parts wash- alkaline (the most often used) or none of the cleaning agent is ing, he points to alternatives that use acidic. And these choices have stripped during filtration, leading to “hopper style” loading. For example, expanded, as metal cleaning contin- near-zero chemical waste. By com- Stoelting’s “Mini Parts Washer” and ues to move away from what used to pletely recycling cleaning chemicals, VersaForce models are typically posi- be the main chemicals for removing manufacturers have reduced clean- tioned right after the stamping press. non-water-soluble contaminants: ing costs by extreme amounts, The parts come off and drop into a organic solvents (see the sidebar in claims Ken Schapker of Ransohoff hopper or immersion bath and con- this article). Inc. (Cincinnati). “We had a cus- tinue through spray-wash, rinse, rust- But aqueous cleaning requires a tomer that had $300,000 in chemical inhibitor, and drying stages. Hesse lot of water and creates a lot of waste. costs, which has been basically says the washers can support a pro- Thus, the question of how best to reduced to something like $5000 per duction rate of one part per second or treat the wastewater and reclaim its month.” He says such reductions are greater and have compact footprints useful chemicals has become a cen- possible with the “neutral-based” sur- ranging from 3 × 5′ (1 × 1.5 m) to 3 × tral issue. Often, cleaning agents can factant/polymer cleaning chemistry 12′ (1 × 4 m) or 7 × 7′ (2 × 2 m). be partially reclaimed from the wash- the company calls Evercycle UCI. er’s wastewater as it’s recycled, “The reason it’s a recyclable CHEMISTRY NEUTRALIZES WASTE although some of the cleaning power chemistry is because it splits oil—it Integral to the selection of a parts- usually is diluted, or “stripped,” by doesn’t pull it into an emulsion— cleaning system is the choice of the filtration units that remove dirt whereas alkaline materials tend to cleaning chemicals. For aqueous- and oils. emulsify the oil,” explains Schapker. www.sme.org/forming&fabricating – 6/2002 35 This allows the chemistry to stay in removes drawing oil and particulate the confidence or motivation to the recycling loop. Also, the chemi- from the drawing process but also switch to a fully recyclable system. cals work at lower temperatures than excess latex sealant from the filter There are also practical concerns alkaline cleaners, and they’re safe on sealing process. that hinder change, adds Carman. all parts, including aluminum. “The reason Fram wanted to “To make a change, they may have However, he does admit that alka- make the change was that the alka- to go to their customer and get lines are good for cleaning strong, line cleaner they were using was not approval to change. In a painting tenacious oils, and that neutral-based recyclable,” says Carman. Part of operation, they would have to do chemistry isn’t for every situation. the alkaline chemicals would be extensive pre-testing to make sure For one neutral chemistry “success stripped away by the ultra-filtration the quality’s the same.” Still, cutting story,” Schapker points to an installa- membranes, but the neutral chemi- waste can be a strong motivator. ❒ tion at an oil-filter manufacturer. The cals pass completely through them. Honeywell Fram plant in Greenville, This recyclability is said to have OH, has been using the neutral chem- allowed 80% savings in chemical istry system for over a year. The plant costs, along with energy savings, cleans millions of deep-drawn filter labor savings, and major reductions housings before powder-coating them in rejected parts because of process in the final assembly. consistency. For more information about parts In making its conversion to neutral The neutral-based cleaner is used cleaning, circle the following numbers chemistry, the plant didn’t need to at 3% concentration (by volume) in on the reader service card. For faster replace the operation’s belt-conveyor the washer’s wash and rinse cycles. results, visit the following manufactur- washer, says Schapker. “It’s just a con- No pure-water rinse is needed ers’ web sites via www.sme.org. Scroll down to and click on the Forming & veyor-belt washer—anybody could because none of the cleaning resi- Fabricating logo. Under “Issues On- have built it. It was one they already due interferes with the powder Line,” select June 2002, then “Smart had in the process when we got called coating process, says Carman. The Cleaning for Stamped Parts.” in.” Rather, Ransohoff installed closed-loop recycling has allowed wastewater-handling and reverse- the plant to operate since May of Company Circle osmosis filtration systems for recy- last year with no discharge of ICA Cinetic...... 360 cling the new cleaning chemicals. cleaner or rinse water. Jenfab ...... 361 Field engineer Lyle Carman says Carman says the change to neu- that only the filter housing’s outer tral chemistry was “totally transpar- LS Industries...... 362 metal surface is cleaned; it’s internal ent” and that it mainly just takes a Ransohoff ...... 363 components are shielded from the willingness to change to apply it to washer. “Filters are placed on the other cleaning situations. However, Stoelting ...... 364 conveyor in such a way that water people who already have a cleaning can’t get inside.” The system not only process that “works” may not have