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AbstractnoUniwandstreetsandprocessK1.lastprocessasneofwengineering”).turesomeUnihasplasticshundredshousehold-electric,URL:0924-0136/$doi:10.1016/j.jmatprotec.2005.04.006Journal of Materials Processing Technology 175 (2006) 1519An example of simulation tools use for large injection moulds design:The CONTENURTM2400 l solid waste containerJ. Aisaa, C. Javierrea, J.A. De la SernabaT.I.I.P., C.S.I.C. Associated Unit, Department of Mechanical Engineering, University of Zaragoza, SpainbCONTENUR ESPANA, S.L., Polgono Industrial Los Angeles, Getafe, Madrid, SpainLarge containers with volumes above 1100 l are usually produced using procedures such as rotomoulding process. These techniques havepart weight or dimensional limits. T.I.I.P., injection moulding plastic group of the Department of Mechanical Engineering of the Zaragozaversity, developed with CONTENURTMa new product under European norms for solid waste containers up to 2000 l volume; the resultas a new main body up to 60 kg weight in one part. The design process combined several CAE tools (aesthetical design, mechanical designrheological simulation) and, in last June, showed final result and passed different tests. Nowadays, more than 5000 samples are on thewithout basic modifications in the mould (more than 100 tonnes weight). The paper focuses on the methodology used to integrate toolprocess design with product definition (i.e. injection pressure and clamp force versus thickness and part shape). Some parameters aboutcontrol in this particular mould (injection rate, temperature, viscosity, gate location, .) are detailed.2005 Elsevier B.V. All rights reserved.eywords: CAE design; Container; Injection mouldingIntroductionCAE tools have constituted an authentic revolution in theyears within injection of thermoplastics. The sequentialuntil the final solution (including several setups suchdevelopment, test of prototypes, modification of figures,w test, .) has been replaced by a faster one consistinga procedure with the designer, transformer and final clientorking together on the same computer files (“concurrentTherefore, the timing for mould manufac-and completion has been reduced enormously; however,interesting advices about CAE use are described in 1.The Workshop of Injection of the Plastics Industry of theversity of Zaragoza (T.I.I.P.), C.S.I.C. Associated Unit,been working with CAE tools on injection of thermo-for more than 15 years, with enormous advantage forof projects made in different sectors (automotive,packaging, toys, etc.). T.I.I.P. activitiesCorresponding author.E-mail address: tiipunizar.es (J. Aisa)..includedtion,diftheufcollaboratedAssociationtryinjectiontechnologicalorishresearchcascadetechniques2.the see front matter 2005 Elsevier B.V. All rights reserved.several research projects (rheological characteriza-semiautomatic mould design, .) working together withferent European companies.Nevertheless, this group has always been conscious ofnecessity to arrange simulation with procedure of man-acture next to the machine, of such a form that has beenand directed by the constitution of the Researchof the Workshop of Injection of the Plastic Indus-(a.i.T.I.I.P.) foundation, which provides services to thecompanies without a profit spirit (Fig. 1). Thiscenter has been supported by various nationalganizations such as the Aragons Government and Span-Department of Industry through different programs andlines (new processes like gas-assisted techniques orinjection moulding, new designs, process-measuringusing pressure and temperature devices .).The CONTENUR ProjectWhen, in 1999, the first Spanish company involved inmanufacture of containers for the collection of urban16 ProcessingsolidTpiecestestingofwithplasticofalltheplesbigmouldmakandtoandminimummaterial),J. Aisa et al. / Journal of MaterialsFig. 1. a.i.T.I.I.P. injection moulding area, general view.remainders (CONTENUR SPAIN, S.L.) went to the.I.I.P.a.i.T.I.I.P. Group to work jointly on the design ofof great size in injection, then arrived the moment forthe real possibilities of these programs in this field.The main objective of the project was the fast manufacturecontainers of great capacity (2400 l and more) to competemarket products with welded metallic plate solutions orones made by rotational moulding with the inclusionexpensive reinforcement structures. Obviously, betweenthe pieces that constituted the set, the main challenge wasmanufacture of a single part bucket.The literature shows several part and mould design exam-and failure advices 2,3, but it is not possible to findplastic parts up to 40 kg weight and a mistake in thissize will have no easy solution (tool transport to moulders manufacturing plant will be too expensive, and trialerror method is not available).For the design of this element, the following aspects hadbe considered:basic dimensions agreed with the European Norm EN12574 4;unloading resistance (discharge sides) (Fig. 2);high impact resistance for functional conditions and loca-tion (parking areas, for example);easily cleaning surfaces;friendly aspect, aesthetical design;minimum cost (not only for processing and assembly butalso for on-street maintenance);restriction of the clamping force imposed by the installedpress machine (big special machines with limited clampingrange between 5000 and 10,000 tonnes);prepared for labelling, that is to say, with visible free andflat spaces;material restrictions: same materials used for other CON-TENUR designs.Special mention requires two limitations: minimum costmaximum clamping force under mentioned limits. For acost, thickness is fundamental (by the cost of rawinasmuch as the time of manufacture; therefore,Fig.model,thethejectedstronglyaforcenottechniques(a)(b)TResultsMain(mm)/weightTechnology 175 (2006) 15192. Boundary conditions for unloading operation, nonlinear materialfinite element model.cost of the machine derived approximately depends onsquare of the thickness 5.On the other hand, to reduce the closing force, the pro-area of the piece and the distribution of pressures arerelated with part thickness (narrow sections causedhigh injection pressure, which could as well suppose a highof closing).The methodology applied, developed by Castany et al.,only for injection moulding but also for other similar68, is as given below:Determination of the feasibility of the product: clampingforce evaluation and thickness part on an agreed basicgeometry to adjust dimensions with the European norm.Only general design lines, and not functional details,were included in this step. Some basic results are shownin Table 1. These analyses were made with basic param-eters for generic material family, high-density polyethy-lene (Table 2). For advanced steps, calculations weremade using several temperature conditions.Material selection, combining melt flow index (MFI) andmechanical behaviour, and injection point locations weresimulated, without even knowing the final geometry ofthe component. Best results were found for several injec-tion points arranged around the bottom area in the mainable 1for simple plastic model, first analysis using simulation toolsbody thickness(kg)Maximum injectionpressure (MPa)Required clampingforce (kN)6/52 96 166,0007/60 71 122,0008/68 55 94,0009/76 44 74,00010/84 35 59,000ProcessingTComputingMeltInjectionMouldFig.ments.(c)(d)J. Aisa et al. / Journal of Materialsable 2parameters for basic simulationstemperature (C) 240time at constant ram speedIn seconds 20In percent 50temperature (C) 403. Basic line, Pro-Engineer software, before final moulding arrange-body of the container. This criteria was also imposed bymould structure and part shape.Analysis of the body form and thickness of the partcomparing constructive alternatives: its sidewall shapes,metallic elements of reinforcement and, if necessary,inclusion of the tubes injected with gas-assisted tech-niques to increase inertia of the sections, etc., were con-sidered.Obviously, mould dimensions and the presence of under-cuts supposed a problem added for the design of pieceand mould. In this way, semicircular shape of the borderTBasicHeightWLength(e)thegeometrysettlingsoriessetwCompan(othertrial1.2.3.Fig. 4. Software C-Mold: plastic temperatureTechnology 175 (2006) 1519 17able 3dimensions for 2400 l main body (mm)1600idth 14801600of the upper container was a hard design problem; it wasrequired for functional use but supposed an undercut areainvolving slides in the mould.Part volume was adapted and different aesthetic formsappearedfeasible conjunction of the possible thick-ness by manufacture with the thickness and forms bymechanical resistance. In this step, finite analysis, solid3D design and filling simulation were made simultane-ously (Figs. 3 and 4). The final part dimensions are shownin Table 3.With these basic magnitudes calculated in these four steps,design team had an initial point for the final drawing ofand the inclusion of the elements of details likedown of output angles, radios, position of acces-of the set (cork, skid, etc.). Industrial flow analysis wasin definitive way, fixing optimum positions for manifoldorking together with the mould maker, Kyowa Industrialy with mould plants in the USA, Japan and Mexico.The main aspects of the process and their simulationsdetails cannot be presented in order to protect indus-know-how) are:Model of the figure with geometries type 2.5D.Location of the entry points to the cavity. The use of racetracks for a better control of the filling was considered,following rheological design rule for simultaneous end offilling at the end of the cavity (avoiding over-pack effect),especially considering the border shape with semicircularareas.Optimal conditions of process: the selection of temper-ature and its relation with thickness and cycle stronglyconditioned the permissible values for the design. Valuesbetween 210 and 250C were evaluated.at ejection and cooling lines layout.18 ProcessingFig.mould.4.tests(islatedbecausegradientscould5.J. Aisa et al. / Journal of Materials5. Real container model used for testing industrial conditions in 2400 lThe adjustment of the filling form by means of the cor-rect programming of speeds became essential. At constantspeed profile, the increase of pressure-supposed values ofinadmissible force of closing by the limitation imposedto the dimensions of the machine. In the final arrange-ment for container mould, several ram speed stages wererecommended.This procedure was experimentally validated with realusing already existing smaller dimension containerFig. 5).Typical ram speed profile calculated with CAE techniquesshown in Fig. 6, but this “function” cannot be trans-to the injection machine without practical arrangements,hydraulic systems are not able to follow all thoseexactly. Anyway, around 15% less clamping forcebe achieved after this optimisation procedure.After the filling possibilities were fixed, this was verifiedwith a new numerical model by the mould maker fromthe initial ideas sent by the design equipment and withthe final hot runner system data necessary for the mould.Fig. 6. Theoretical ram speed profile from computer results.6.detectingofcessing(2025ouslyTechnology 175 (2006) 1519Fig. 7. Real sample in CONTENUR assembly plant.The sequential technology was considered as a possibil-ity with the purpose of reducing filling pressure, but thepractical arrangement, the maintenance and possible shut-downs underestimated their use.Finally, the analyses of cooling of the mould, packing andwarpage induced by the process were developed. In thisway, different constructive materials were used accordingto their thermal conductivity, adjusting cooling layout pro-vided by Kyowa Industrial Company. Final mould weightwas higher than 150,000 kg (up to 150 metric tonnes).Actually, more than 6000 pieces were made withoutany problem in the injection, expulsion or the lifethe component in good condition (Figs. 7 and 8), and pro-rates are similar with other existing 1000 l containersparts per hour). Other components were simultane-designed and, in fact, it was more complicated to getFig. 8. Complete 2400 l waste container, including all components.J. Aisa et al. / Journal of Materials Processing Technology 175 (2006) 1519 19fine results, for example, in container lids, obviously smallerthan the body.For the authors, the final conclusion is that CAE tools werebasic in design pr