W hen Raytheon Mis-sile Systems at AirForce Plant (AFP)44 in Tucson, AZdecided to upgrade

its manual solvent-based cleaning andautomated vapor degreasing operations,environmental challenges with thecurrent solvents were laid out on thetable to take into consideration, alongwith the current and future projectedcleaning requirements. One challengewas high usage of IPA ( i s o p r o p y lalcohol). Use of a 10-year-old IPAvapor degreaser was resulting in nearlyone ton of VOC emissions per year. Asecond challenge was the high usage ofMEK (methyl ethyl ketone) duringmanual cleaning operations and varyingcleaning requirements, producingnearly one ton of both HAP and VOCemissions per year. Note: MEK wast a ken off the fe d e ral hazardous airpollutant (HAP) list in December 2005but still remains an issue in the State forArizona.

Goals and RequirementsConsidering these challenges, the

goals for the new degreaser were estab-lished that would give Raytheon themost effective cleaning and degreasingprocess during manufacturing, in-cluding implementing an automatedvacuum vapor degreasing system usinga non-HAP and preferably low-VOCcleaning agent, capable of removingboth polar and non-polar contaminants,

and continuing to meet “water breakfree surface” cleanliness requirementprior to painting or bonding. It wasimportant that production areas weregiven a competitive reason to switchfrom IPA vapor degreasing and manualMEK-based cleaning processes to acentral and automated process. Inaddition, Raytheon wanted to reduceworker exposure to solvents.

Vacuum vapor degreaser equipmentrequirements were determined via a SixSigma, team-based approach. A min-imum basket load size of 26.4" x 19.0"x 12.0" was needed to accommodate allprojected components entering thework area (see Figure 1). Since bothforeign and domestic equipmentsuppliers were invited to bid, a detailedperformance based equipment specifi-cation was written. DURR-Ecoclean( Wixom, MI) was selected. Dow’s(Midland, MI) modified alcohol-basedcleaning chemistry, DOWCLENE1601, was also selected. Finally, afactory buyoff of the fully operationalsystem was conducted at DURR-Ecoclean in Stuttgart, Germany usingRaytheon-provided missile com-ponents. Parts were cleaned to a waterbreak free surface in all cases.

Process Chemistry Getting back to the cleaning chem-

istry, Raytheon selected DOWCLENE1601 from Europe to use in thedegreaser. Through some very involvedlaboratory testing, DOWCLENE 1601was fully capable of removing bothpolar and non-polar contaminants, andwas more than able to meet a straight-forward water break free surface clean-liness requirement prior to painting orbonding. DOWCLENE 1601 was non-HAP and low VOC, and its price pergallon was comparable to similar chem-istries on the market and already in useat Raytheon. In turn, DOW agreed tosupply the chemistry for the first time inthe United States to Raytheon. Fi g u re 2shows the comparison of DOWCLENE1601 with IPA .

Programmable ProcessSequence

Trying out the programmable processsequence through test washing withDURR-Ecoclean, Raytheon’s trialsproved favorable to the cleaning pro-cess. Wash #1 consisted of removing allof or the bulk of contaminants, high-volume solution circulation (select-able), ultrasonics (selectable), partsload rotation or oscillation (selectable),and vapor degreasing (selectable),while wash #2 provided a much cleanerversion of wash #1, with the samecriteria, including optional vapor

Case StudyVacuum Vapor Degreasing at Raytheon Missile SystemsPaul W. Fecsik

Vacuum vapor degreasing process is better, cheaper,faster, greener and safer, reducing manual cleaningoperations and resulting in minimal worker exposureto solvents.

For More Information Circle No. 2534 | Process Cleaning Magazine May 2006

Figure 1Maximum process basketload size of 26.4" x 19.0" x12.0".

Image courtesy of Raytheon Missile Systems.

degrease and then vacuum drying at 1 mBar (seeFigure 3).

Whereas before, Raytheon engineers had to handclean parts one at a time with MEK, now they couldload 48 parts into a degreaser and set a six-minuteautomated cleaning cycle. Even though this operationis not large-scale by any means, the overall initialsavings have been calculated at over $70,000 per year,making for about a three-year payback for equipmentand installation.

ResultsRaytheon is very pleased with the vacuum vapor

degreasing process using DOWCLENE 1601. It is abetter, cheaper, faster, greener and safer process. Inaddition it eliminates all IPA vapor degreasing exceptfor one legacy missile program component having acritical pyroceramic-to-titanium bond. A c l o s e dworking system with no solvent emissions, thevacuum vapor degreaser reduced manualcleaning operations, thus reducing the use of

MEK and other HAP/VOC containing solvents, andresulted in minimal worker exposure to solvents. Adistillation unit significantly reduces hazardouswastes since the cleaning solution is continuouslyrecycled. “Our hats are off to the equipment supplierDURR-Ecolean and to Dow, as we are very pleasedwith the results of the new equipment and process,”

May 2006 Process Cleaning Magazine | 35For More Information Circle No. 23

Figure 2The comparison of DOWCLENE 1601 with IPA.

Figure 3Process flow sheet for vacuum vapor degreaser.Diagram courtesy of DURR-Ecoclean GmbH (Stuttgart, Germany)

vacuum vapor degreaser

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36 | Process Cleaning Magazine May 2006

says Senior Materials and Process Engineer Bruce T. Miller (see Figure 4). PCMPaul W. Fecsik is a project manager for Raytheon Missile Systems in Tucson, AZ.

For more information on this Raytheon Missile Systems’ cleaning process contacthim at (520) 794-4105 or via e-mail at pwfecsik@raytheon.com.

Figure 4Automated vacuum vapor degreaser at AFP 44 in Tucson, AZ.

Ultrafiltration SystemsSeparation Dynamics’(Fountain Inn, SC) Extran™Ultrafiltration System is aproven and dependablefiltration system designed toclean contaminated partswashwater for re-use and tofilter oily wastewater fordischarge. When applied toan industrial parts washer, thesystem can significantly improvethe washing process and extendthe life of your cleaning solution.This system continuouslyremoves oil and particulatefrom the process fluid andreturns the purified solutionto the process for re-use.The automated system drawscontaminated fluid from your tank and processesit through a series of filters and coalescers to remove free oil andsolids, followed by Separation Dynamics’ proprietary cellulose membrane,which separates the emulsified oils from the process fluid.

Following are the main components of the Extran Ultrafiltration System:• Feed pump—automatically draws fluid from the process, as needed. • Feed filter—for removing large particles from the solution. • Coalescing tank—stainless tank that incorporates coalescing media, baffles

and weirs to enhance the concentration and removal of contaminants. • Process pump—continuously re-circulates fluid through the filters. • Process filter—removes fine particulate from the concentrated solution • Extran membrane module—separates oil and contaminants from solution • Waste tank—collects concentrated waste for disposal. • Automated controls—automated valves, level switches and microprocessor • Ancillary components—valves, hoses and gauges. Stainless steel is

standard. • Flexible plumbing—feeds and returns filtered solution to the process For more information circle 201

CleanersEco Concepts’ (Miami, FL) AllPurpose Cleaner & Degreaser(APCD) is a highly effectivecleaner and degreaser. Its safeand powerful cleaning actionremoves grease, oil and heavysoiling from hard surfaces. TheAPCD can be used with a mop,spray and wipe, pressure washer,foam system, etc. It is safe touse on concrete, vinyl floorcoverings, terrazzo, quarry tiles,plastics, ceramics, rubber, glass,enamel, formica, stainless steel,painted, varnished and othersurfaces.For more information circle 108

©2006 Communication Technologies Inc. Reprinted from Process Cleaning Magazine.Contents can not be reprinted without permission from the publisher.