Manager’s Guide toProductivity Gains With MultiphysicsSimulation

Manager’s Guide toProductivity Gains With MultiphysicsSimulation

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© 2009 COMSOL, Inc.

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For much of the history of engineering, theproduct development process has beenpainstaking trial and error — design, build proto-types, test, alter the design, build more proto-types. Computer simulation helped reduce thenumber of steps, shortening the time betweendesign concept and assembly line, but a signifi-cant problem remained: the software usedto create models could only tackle onelaw of na ture at a time. You couldperform a me chanical analysis oran electromagnetic analysis, forexample, but not both simulta-neously in an integratedmodel. To achieve true “vir-tual prototyping,” engi-neers needed to accurate-ly predict the behavior ofproducts in the real world,where multiple types of cou-pled physics interact. In the last decade, as

ever-faster computer hard-ware spurred software in -no vations, a new, cross-disciplinary ap -proach emerged: multiphysics simulation. Thisapproach replaces the artificial segregation of dif-ferent types of physics with a single unified simula-tion environment that replicates the complexbehavior of natural systems.Today, multiphysics simulation has gone main-

stream, with high-tech firms worldwide adopting itthroughout their engineering and R&D depart-ments. A pioneer and leader in multiphysics soft-ware is COMSOL, Inc. The first version of COMSOL’sflagship product, COMSOL Multi physics, was pub-lished in 1998 and the company has been innovatingever since.

COMSOL Multiphysics has a wide array of applica-tions across engineering disciplines, including struc-tural mechanics, fluid flow, electromagnetics, chem-ical engineering, heat transfer, and acoustics. “Ourcustomers are researchers and engineers workingfor leading technical enterprises, research labs, and

universities,” explained Dr. Jeff Hiller,Vice President of Sales at COMSOL.

“They make our cars and aircraftsafer and more energy efficient,they enhance the reception toour cell phones, they searchfor new energy sources, ex -plore the universe, developmedical equip ment enablingmore accurate diagnosis, andthey educate the next genera-tion of scientists.”One can get a good idea of the

commercial users of COMSOL bylooking at Forbes’ Fortune 500 list.Every company in the top 100 thatdoes any sort of engineering is a licensee

of COMSOL. The software is at work inalmost every industrial sector.

Where Are the Benefits?COMSOL Multiphysics is the number-one multi-

physics analysis package on the market, according toDr. Hiller. Not only does it have the highest namerecognition in the multiphysics field, but it also hasthe highest number of license seats worldwide. Byimplementing COMSOL Multiphysics, companiescan reduce costs, design better products, compresstime to market, and hone their competitive edge.

Reduce costs: By using COMSOL Multiphysics, thenumber of physical prototypes is drastically reduced.This means that both the materials cost of the proto-

Multiphysics Simulation: The Competitive AdvantageNew modeling tools are enabling companies of all sizes to cut costswhile boosting productivity.

Generator design using COMSOLMultiphysics.

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types and the labor costs associated with the iterationprocess are gone. In addition, an engineering teamcan try out many more virtual designs than theycould ever test physical prototypes. As a result, thefinal design could be cheaper to manufacture.

Design better products: Since virtual prototypesallow engineers to consider many more potentialdesigns (or redesigns), the design can be thorough-ly optimized with respect to all kinds of parameters.In addition, computer models provide a lot moreinformation than physical prototypes.

Compress time to market: Running virtual testsis much faster than building and testing physicalprototypes, yielding a satisfactory design in lesstime. While physical prototypes can take days,weeks, or even months to build and test, a typicalcomputer model can be set up and solved in a mat-ter of hours.

Maintain a competitive edge: By creating a comput-er model, users can easily evaluate whether a new con-cept is viable without expending a lot of resources.And since the process is so fast, inexpensive, and safe,it encourages creativity and innovation.

Why Choose COMSOL?Unlike some software, COMSOL was designed

from the outset to address multiphysics problems.“COMSOL is backed up by a team of engineerswhose sole focus is multiphysics analysis,” said Dr.Hiller. “Multiphysics analysis is not a side businessfor us.” Another plus: COMSOL is designed to havea very quick learning curve. The company offerstraining courses that cover all the fundamentals ofsetting up, solving, and interpreting a model inCOMSOL Multiphysics (see www.comsol.com/train-ing/). The latest version of the software, COMSOLMultiphysics 4 (October 2009 release), features an

all-new user interfacethat stream lines the modelingprocess, making it easier fordesigners with all levels of mod-eling expertise to build and runsimulations.

In the following case studies, four diversecompanies explain how their adoption of COMSOLMultiphysics as a core technology has driven theirbusiness forward. From simulating the interactionof microwaves on materials and providing betterconsultation services to the oil industry, to assistingin the innovation of inkless printers and new bio-medical equipment, COMSOL has been put to thetest time and again with great success.

On the cover:A COMSOLMultiphysicsacousticssimulation of asubwoofermounted in a bassreflex enclosureand placed at the

corner of a room is shown. One of the mostimportant design parameters for a loudspeakerdriver is its sensitivity as a function of thefrequency. To isolate the driver’s performancefrom that of the environment in which it usuallyoperates, the driver is often set in an infinitebaffle. This model instead considers the influenceof the finite-sized room.

www.comsol.com

Shape memory alloy in a biomedical stent.

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Millipore Designs Solutions for Customers

Perhaps best known as a pioneer ofmembrane-based separation tech-nologies, Millipore (Billerica, MA) is amultinational life science corporationwith 5,900 employees worldwide andannual sales of $1.53 billion.Millipore’s Bioscience Division devel-

ops products aimed at improving drugdiscovery and advancing life scienceresearch in the areas of cell biology, stem

cell biology, protein research, and cellsignaling. Chris Scott, Manager ofDesign Engineering in the Bioscience Di -vision at Millipore, said, “My groupdesigns products for the life scienceresearch, drug discovery and develop-ment, and lab filtration business units.We work closely with the mechanical and

system engineers to design the variousdevices and systems with a focus on theend user.” These devices and systems are multi-

physics in nature. They involve fluidflow, optics, electromagnetics, acous -tics, heat transfer, chemical engineer-ing, and mechanics of materials, whichis why Scott’s group uses COMSOLMultiphysics in their product develop-

ment cycle. “We find incredible valuein the ability to use COMSOL forexploring these couplings. Early simu-lations can supplement informationgathered from state-of-the-art andstate-of-technology searches, which ispart of every new product developmentprocess.”

Putting COMSOL to UseThe design engineering group at

Millipore has been using COMSOL since2007. “We purchased the base packageand the Structural Mechanics Module ini-tially because we were not happy with our[then] current FEA package, and wantedto expand our simulation capabilities,”Scott said. Additionally, a key factor inchoosing COMSOL was that Millipore’sdesigners and engineers perform all sim-ulations and analysis themselves.According to Scott, COMSOL offers awide range of solutions in one package,which is highly beneficial for a smallgroup working on a variety of diverseprojects. “With COMSOL, we learned asingle, easy-to-use interface and can nowperform CFD, elecromagnetics, andmechanical FEA studies. I find that I cancome back to COMSOL after a month orso focusing on other tasks, and performa study without having to re-learn thesoftware. This can’t be said for a lot ofother software programs that we use.” During design and technology devel-

opment in the Bioscience Division,COMSOL is used to supplement knowl-edge gained through testing and experi-mentation. To establish a baseline formodeling, the physical testing of proto-types is used. “Building of capital equip-ment is a gating item in most productdevelopment schedules. We typically runsimulations while the equipment is beingdesigned, and can make changes beforea lot of time and money is invested in thecapital equipment,” Scott said. For example, when the group was

designing a single-use breakaway snaptab (a cantilever snap-fit hook for hold-ing two pieces together), they built abeta prototype and were looking to scaleit up for production. The purpose of thestudy was to look at different materialsand geometries to provide consistentbreaking of the snap tabs at a givendeflection value. This behavior was nec-essary to prevent disruption of biologicalelements within the device. “At thatpoint, we were ready to invest hundredsof thousands of dollars in capital equip-

Figure 1. 3D Model Results — observation of large deformations in the surrounding frame geometry. Resultsshow 95% of the deflection was due to the frame and not the tab.

“We have examples where we have saved three to six months by making a critical directional decision early in the project. Using results from COMSOL helps support the logic behind these key decisions.”

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ment to produce this part and we need-ed to be certain of its function. Es sen -tially, what we found through physicaltesting was that the tabs were not break-ing consistently, but we did not knowwhy,” said Scott.The group imported the 3D model of

the snap tab into COMSOL and ran a sim-ulation, which revealed a result not detect-ed during physical testing — when a force

was applied to the tabs in the model, largedeflections of the underlying geometryprevented consistent breaking of the tabs(see figure1). Based on the results, theframe was redesigned to be stiffer, whichallowed the tab to break more consistently. “Using COMSOL allowed us to quickly

ex plore areas computationally and gaines sen tial knowledge early in the de vel -opment process. Knowl edge through test-

ing a lone is specific to thetest performed and thetools used. Knowledgethrough simulation helpsto fill the gaps. When weperform physical testing,we are confirming. Whenwe run a simulation, we areexploring,” commentedScott.

The Model AdvantageThe design engineering

group in Millipore’s Bio -sciences Division contin-ues to use COMSOL intheir product develop-

ment process. Scott mentioned how oneof the most important aspects where sim-ulation can have a big impact is in improv-ing products. He believes that the betterhis group understands why the devicesand products behave the way they do, themore robust they will be to Millipore’s cus-tomers. “We also can make better deci-sions the deeper our knowledge. A bal-ance of research, simulation, and physicaltesting is essential for developing noveland robust products,” he stated. Scott described running a simulation

in COMSOL as an insurance policyagainst the company’s investment. “Forevery engineering and mold change thatcan be prevented, we can save from $10Kto $50K in general. Saving onedesign/build/test iteration cycle can savemonths on a project. We have exampleswhere we have saved three to six monthsby making a critical directional decisionearly in the project. Using results fromCOMSOL helps support the logic behindthese key decisions.”

Listen to our interview with Chris ScottFigure 2. Product Section — Partial view showing a cross section throughone of the snap tabs.

TerraTek Chooses COMSOL for Oil Reservoir Analysis

TerraTek is a leader in geomechanicsmeasurement and analysis with over 30years of experience providing expertise tothe U.S. government as well as the oil indus-try. Acquired in 2006 by Schlumberger —the global oilfield services company —TerraTek is known today as the TerraTekGeomechanics Laboratory Center ofExcellence, located in Salt Lake City, UT. Geomechanics is the mechanical behav-

ior of rocks in terms of their deformation,load-bearing capacity, failure, and fluid-flowproperties. The lab’s geomechanics analysisprovides vital understanding of the behav-ior of hydrocarbon reservoir rocks as theyundergo the mechanical changes associat-ed with oil drilling and production activity. One of the reasons geomechanics analy-

sis is im portant to the oil industry is to helpprevent failures while drilling. RobertoSuarez-Rivera, Ph.D., a scientific advisorand head of TerraTek’s Simulation &

Production Division, stat-ed, “In the oil industry, youdrill to a particular depthuntil you reach the reser-voir. Multiple operationsare then performed to startproducing oil; however,during drilling, a hole iscreated of diameters thatcan change from 20" at thetop to maybe 7" at 24,000-30,000 feet. A mechanicalinstability can cause theloss of a well. This loss canbe on the level of severalmillions of dollars.” Terra -Tek’s aim is to help theirclients decide whether or not a well can bedrilled without the risk of failure and if therisk is high, they help them decide on thenecessary actions to prevent failure or min-imize risk.

Minimizing Risk with COMSOLTo do this, the lab obtains samples —

rock cores from the reservoir — that aresubjected to simulated in-situ conditionsof high pore pressure, high stress, high

Model 1: Failure analysis of a multilateral wellbore junction (mechanicalevaluation). Failure is shown in white.

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temperature, and any additional stressesthat may take place during the drilling orcompletion processes. The data is thenevaluated and used for engineering analy-sis and modeling, and the results are pro-vided to the clients. “We deal with geoma-terials that are highly heterogeneous andhave tremendous complexity in theirbehavior. The challenge is to understandand map heterogeneity at all scales,define the building-block units of the het-erogeneous system, and provide in-depthcomprehensive ma terial-property charac-terization of each of these building blockunits,” said Dr. Suarez-Rivera.For example, understanding a rock’s

behavior requires a very large number ofmeasurements on a large number of sam-

ple locations, which is dif-ficult. A particular prob-lem the industry faces is alack of data; therefore,either simple numericalanalysis is performedbecause of the lack ofmaterial-property repre-sentation, or very largeand complicated prob-lems are solved using astrong characterization ofmaterial properties on asmall and limited region.The goal is to find a goodmiddle ground to providereasonably well-represent-

ed solutions without the excessivedemands of properties that may be non-existent or difficult to obtain. “For me, COMSOL Multiphysics is a

good compromise of these two ends ofthe same problem. It is sufficiently com-

plete that it allows us to understand thephysics of the problem, provides satisfac-tory input for a reasonable characteriza-tion of the material properties, and mostimportantly, allows the simulation of cou-pled physics; for example, the integration

of mechanical deformation and fluid flow,the integration of thermal and mechani-cal strains, poro-elasticity, etc.,” he stated. Dr. Suarez-Rivera went on to describe

how fluid flow, and the mechanical, ther-mal, and geochemical aspects, all takeplace simultaneously, which makes it verydifficult to anticipate a priori which aspectis the most important. “COMSOL allowsus to couple all of these mechanisms in avery nice and simple way, allowing us tounderstand their combined effect. This isthe true power of the simulation. Onceinteraction by the relevant coupledphysics has been included, the modelbecomes useful and interesting.”

Convenience and SimplicityTerraTek has been using COMSOL

Multiphysics as part of their engineeringconsulting service for nearly a decade.The lab has developed several modelsusing this platform and over the years, ithas become an important component ofthe tools they use to provide solutions toclients. Dr. Suarez-Rivera explained,“COMSOL provides simplicity, a verygood user interface, and very powerfulgraphics. It also has a sufficient computercapacity for solving complex problems,without being an overwhelming program.This is a level of convenience that makesme really like this product.”Using COMSOL allows Terra Tek to

better understand the behavior of geoma-terials and thereby obtain better predic-tions to anticipate problems for their cus-tomers. Dr. Suarez-Rivera said, “By usingCOMSOL, we are able to easily demon-strate things such as the risk of failure tothe client. It has this ability of allowing usto turn off and turn on different aspectsof the physics in order to very quickly

identify those things that may be initiallyperceived as unimportant that do in factmake an impact on the solution. We solveour clients’ problems better by having amodel and having flexible computationalcapabilities.”

Model 2: Failure analysis of a multilateral wellbore junction (coupled mechanical and flow evaluation). Failure isshown in black and red.

Model 3: Simulation of a hydraulic fracture experiment on large block rocksample. The numerical analysis allowed TerraTek to understand the rela-tionship between fracture pressure and fracture aperture.

“COMSOL allows us to couple mechanisms in a very nice and simple way, allowing us to understand their combined effect. This is the true power of the simulation.”

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e2v Uses COMSOL to Explore New Application Areas

Headquartered in the United Kingdomwith approximately 1,700 employeesworldwide, e2v technologies Ltd. designsand manufactures advanced vacuum elec-tronic tubes, electronic systems, solid-stateimaging devices, and sensors. Cus tomersare in the medical and science, aerospaceand de fense, and commercial and in -dustrial markets. e2v is publicly traded,boasting sales of over $300 million.e2v continuously considers new applica-

tions and processes that could enhancetheir products. This has enabled the com-pany to move from supplying just compo-nents and subsystems to providing systemsand applications support; however, due tothe increased overall complexity and themultiple interactions with other systemcomponents, this has in creased e2v’sexposure to technical risk. Hence, it isvital that the company understand theunderlying science of these systems thusensuring the final equipment delivers thepredicted benefits to the end user.In order to support these new growth

areas, e2v reviewed their full suite of mod-eling software products to make sure thatthe new requirements would be met. “Indoing so it became apparent that [oursoftware] was good at tackling our usualrequirement (tubes, sub-systems, andimaging devices), but when it came tocombining multiple ‘physics’ interactionsinto one software domain, our currenttools were not the most appropriate,” saidStephen Hurrell, manager of e2v’sNumerical Modeling & Analysis Group.The company therefore made the deci-sion to try COMSOL Multiphysics fortheir modeling needs.

Application AreasThe company has been using COM-

SOL as part of their product and applica-tions development for about two years.“COMSOL allows any number of physicalprocesses (e.g., RF/microwave joule heat-ing, eddy current heating, mechanicalthermal expansion, stresses and strains,diffusion and fluid dynamics) to be com-bined with any number of interdepend-ent variables. This capability, combined

with the ability to add custom functions,expressions, and equations makes it avery versatile tool — the ideal multi-physics tool to use for these new applica-tions,” said Jan Przybyla, technical spe-cialist in e2v’s Electron De vices and Sub -sys tems Di vi sion. And since much of the

work requires the prediction of howmaterials will behave when they interactwith environmental factors (temperature,RF fields, etc.), being able to combine thephysics simultaneously with varying mate-rial properties has al lowed e2v to look atmany applications and processes in amore detailed way. For example, one of the first applica-

tions e2v explored with COMSOLinvolved the investigation of enhancedcomminution of minerals (the liberationof minerals from ores) using microwave

radiation. It was performed outside themain project funded by the Aus tral ianMinerals Research As so ciation (AMIRA)and carried out by e2v in conjunctionwith the Uni versity of Notting ham andStellen bosch University. The AMIRA pro-ject’s aim is to provide the mining indus-

try with a more efficient process ofremoving minerals from ores. Sinceapproximately 3-5% of the world’s ener-gy is used to crush ore as part of the min-eral extraction process, improving thetechnique could have an across-the-board impact on energy savings. In addi-tion, when the project is fully completed,it will result in a developed system utiliz-ing e2v’s advanced vacuum electronictubes. In the simplest terms, the comminution

process requires that the ore be crushed

Microwave-assisted liberation of minerals from ore. Applicator showing micro-environment (electric field, resis-tive heating, and temperature plots).

“COMSOL allows any number of physical processes to be combined with any number of interdependent variables. Thiscapability, combined with the ability to add custom functions,expressions, and equations makes it a very versatile tool.”

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in large ball mills — requiring significantquantities of energy — until the valuablemineral particles are of a size so they areliberated from the bulk rock. By applyingmicrowave radiation, the mineral parti-cles are selectively heated, which causeslocal thermal expansion that results inlocal stresses and strains. This processcan significantly reduce the energyrequired to crush the rock and separatethe minerals. And in some cases, theyield of the process also can be increasedusing this technique. Przybyla explainedhow this is a classic case of fully coupledmultiphysics: “RF-microwave interaction with the ore

causes joule heating of the target mineralresulting in a temperature rise and accom-panied mechanical expansion. As the min-eral is mechanically restrained by othernon-useful materials, stresses are inducedin the mineral that can cause localized

material failure (cracks). Detailed knowl-edge of the material properties allows thesimulation to vary parameters such asdielectric constant and dielectric loss withtemperature. Microwave applicators of sev-eral cubic meters in volume have beenmodeled [in COMSOL] with mineral parti-cles of 50 um2 with interface dimensions ofless than 10 um being resolved. The abilityfor the model to resolve localized stresses(<10 um) due to the RF and microwaveinteractions aids in understanding of theprocess and contributes to the final detaileddesign of the RF/microwave system.”

Proven CapabilitiesFor e2v, COMSOL provided certain

capabilities that some of e2v’s other soft-ware did not possess. “We are more able tosimulate the ‘real world.’ By doing this wewould expect the results to have betteraccuracy. Using these results to drive key

design decisions has resulted in better andmore cost-effective products,” said Hurrell.Additionally, as a high-technology man-

ufacturing company, e2v believes that

maintaining a state-of-the-art portfolio ofmodeling tools is essential to keeping thecompetitive edge in their product andservice offering. “Initial results are prom-ising in terms of breadth of applicability,which is being demonstrated by trials andinitial results. We plan to continue todevelop the use and application of COM-SOL in e2v and to expand its use acrossthe more established engineering groupswithin the company,” Hurrell added.

ZINK Imaging: A Model of Efficiency

Founded in 2005 and headquar-tered in Bedford, MA, ZINKImaging is a privately held companyworking to develop a revolutionaryprinting technology platform calledZINK™ Zero Ink™ printing. Thetechnology prints full-color digitalimages without the use of ink car-tridges or ribbons. The images areproduced using a single thermalprint head that passes over a coatedmedium — ZINK Paper™ —infused with layers of dye crystals.The crystals are melted using pre-cisely timed heat pulses and specifictemperatures from the print head.Colors are then released and com-bined to produce photographic-quality im ages. While ZINK Im -aging produces the paper, partnercompanies will produce the printing hard-ware. Current partners include Polaroid,Dell, Takara Tomy, Alps, Foxconn Tech -nology Group, and Lite-ON.The company is a cross-functional team

of chemists, physicists, engineers, imagescientists, and manufacturing and busi-

ness development professionals. BillVetterling, Ph.D., a Research Fellow andManager of the Image Science Lab -oratory at ZINK, mentioned the chal-lenges of complex product developmentin a startup without a corporate umbrella,and how the team had to move as quickly

as possible from product develop-ment to revenue generation inorder to support ongoing research.“In part, that meant going fromtraditional cut-and-try design ap -proaches to more efficient meth-ods in which computer modeling isused as much as possible to avoidnon-productive avenues.”

Design ChallengesAside from developing ZINK

Paper, ZINK Imaging also createstest models of the hardware toensure that the partner companieshave all of the information neces-sary to build the printers. Two sig-nificant challenges included choos-ing the best thermal print headdesign for the hardware and figur-

ing out how a thermal printer would printon the ZINK Paper. And since the ZINKsystem consists of a thermal print head,the paper moving beneath the print head,and a rotating platen, the relationshipsamong these parts is a multiphysics prob-lem. While the problem involves heat, it

Temperature profile following a heat pulse applied to the Zink paper.The color indicates temperature, with a scale from 273 K to 315 K.

Click to view animation

“Using these results to drivekey design decisions has resulted in better and morecost-effective products.”

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also combines the essentialeffects of mechanics and phys-ical chemistry.

The COMSOL Advantage“One of the virtues of mod-

eling is that you get to simulateexperiments, which you couldnot carry out in practice. Forexample, to try out a new ther-mal print head design mayinvolve a setup cost of tens ofthousands of dollars, anddesigning by trial and error istherefore not really feasible.However, with a good thermalmodel, you can predict resultswith high accuracy and only invest moneywhen you know what will work best,”observed Dr. Vetterling. For instance, when ZINK engineers

were studying the fluid flow throughtheir commercial coating head, theyknew that the thickness of these layershad to be kept accurate to a precisionbetter than one micron. During theiranalysis, it was discovered that thicknessvariations occurred from the middle tothe edges of the coating head. The natu-ral solution to this problem would be tore-engineer the head — either by makingan entirely new coating head or by creat-ing a device that could be placed insidethe existing head to alter the fluid flowand make things uniform again. Thesesolutions would have taken months.“Through the process of doing the simu-

lation using COMSOL, we discoveredthat simply changing the temperature ofthe fluid flowing into the head cured theproblem. This saved us a lot of time anda lot of money in terms of engineeringcosts. It also produced a solution that

resulted in it being online and workingin a matter of a few days.”Similarly, when ZINK constructed a

model for how a thermal printer wouldprint on the new media (ZINK Paper), amultidisciplinary situation again arose.Color development in the mediumdepends on how much heat passes from

the thermal print head intothe material, which in turndepends on how well the printhead contacts the surface ofthe medium. “When you domodeling of these things, youreally need to have a modelthat is considering not onlythe thermal effects of apply-ing heat to the media, but alsothe mech anical effects of themedia passing through theprint er,” explained Dr.Vetterling. “That’s really thereason why a multiphysicspackage like COMSOL isimportant.” Mod eling the

thermal printing process allowed theengineers to tune the media structureand to choose a print head that is opti-mized for a combination of energy effi-ciency and color gamut. The model alsoallowed them to investigate the depend-ence of the printing on the heating ofthe printer, and on ambient printingconditions.ZINK Imaging continues to use COM-

SOL on a daily basis. “Even though wenow have our initial products on themarket, there is no end to the questions:How to improve color, how to print withless power, how to manufacture at alower cost, how to modify the system toserve new market areas, etc. In otherwords, product improvement is just asripe an area for modeling as productdevelopment,” said Dr. Vetterling.

The Dell WASABI™ PZ310 photoprinter: one of the current ZINK-enabled products.

“Product improvement is justas ripe an area for modeling as product development.”

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