magma_training_pdfhpdc_tutorial_modified

1、MAGMAhpdcSimulation of High Pressure Die CastingTutorial2MAGMAHPDC TUTORIALThis document supports MAGMASOFT Version 4.2. No part of this document may be repro- duced in any form or by any means without prior written consent of MAGMA GmbH.The use of the software described herein is restricted by a li

2、cense agreement between MAGMA GmbH and the licensee.MAGMA and MAGMASOFT, MAGMAiron, MAGMAdisa, MAGMAlpdc, MAGMAhpdc and similar names are registered trademarks of MAGMA GmbH. The trademarks of all other products in this document are claimed as the trademarks of their respective owners.The informatio

3、n in this document is subject to change without notice.The information in this publication is believed to be accurate in all aspects; however, MAGMA does not assume responsibility for any consequential damages resulting from its use. The infor- mation contained herein is subject to change. Such chan

4、ges may be incorporated through revi- sions and / or new editions. Copyright 2003MAGMA GIESSEREITECHNOLOGIE GMBH KACKERTSTRAE 11D-52072 AACHEN GERMANYTEL.: +49 / 241 / 88 90 1- 0FAX: +49 / 241 / 88 90 1- 60 INTERNET: WWW.MAGMASOFT.COMEMAIL: MAILMAGMASOFT.DETABLE OF CONTENTS3Table of Contents1Preface

5、Why a Tutorial?7How to Use this Tutorial7How to Instal the Case Study Project82Process Overview92.12.2General Goals of Simulation9Simulation Goals Specifically Related to HPDC...6Introduction10Initial Solidification Simulation for Gating Design11Initial Filling

6、Simulation for Gating Design11Complete Filling Simulation11Detailed Solidification and Feeding Simulation12Stress Simulation122.3Casting Quality at Low Cost.2Quality Issues12Cost Issues133Case Study Drill DeckIntroduction15Flow Chart17First Version.23.3.3Idea18Geometry

7、 Modeling18Enmeshment Defining Mesh Parameters Visualizing and Checking the Mesh for Evenness Checking the Mesh for Critical Areas22Simulation243.3.44MAGMAHPDC TUTORIAL Defining Materials Defining Heat Transfer Coefficients HPDC Calculator and Cycl

8、es2 Controlling Die Opening2 Defining Solidification Simulation and Starting Simulation293.3.5Result Evaluation and Summary30Second Version3.33.4.4Idea33Geometry Modeling33Enmeshment35Simulation3 Defining Materials3 Defining Heat Transfer Coefficients

9、3 HPDC Calculator38Short Overview and Start38Geometry Data39Machine Data40Shot Sleeve Data41Process Data43Shot Characteristics4 Defining Casting Cycles4 Controlling Die Opening4 Cooling Control4 Defining Filling Simulation50 Defining Solidification Simu

10、lation and Starting Simulation52Result Evaluation and Summary5Third Version5.2Idea59Geometry Modeling60TABLE OF CONTENTS.4Enmeshment63Simulation6 Defining Materials6 Defining Heat Transfer Coefficients6 HPDC Calculator6 Defining Casting Cycl

11、es6 Controlling Die Opening6 Cooling Control6 Activating Tracer Particles70 Defining and Starting Filling and Solidification Simulation70Result Evaluation and Summary7Fourth Version7..4Idea79Geometry Modeling80Enmeshment83Simulation8

12、Process Chart8 Defining Materials and Heat Transfer Coefficients8 HPDC Calculator and Vents8 Casting Cycles, Die Opening and Cooling8 Pressurized Solidification8 Filling and Solidification Simulation8 Spraying of the Die91Result Evaluation9Sum

13、mary1004567MAGMAhpdc in Use101Further Reading103Table of Figures105Index1096MAGMAHPDC TUTORIALCH. 1: PREFACE71Preface1.1Why a Tutorial?This tutorial aims at providing a practical introduction into the simulation of HPDC processes. It uses a specific MAGMAhpdc project to explain typical simulation pr

14、oblems and their practical so- lutions.The MAGMAhpdc Tutorial mainly focusses on simulation aspects and processes specifically re- lated to HPDC castings and on result evaluation in the postprocessor, whereas the MAGMA- SOFT Tutorial, which you also have at your disposal, focusses on the basic point

15、s of simulation:sensibly structured geometry input, evaluation of mesh quality, use of the database, definition ofsimulation parameters.In order to understand all steps of the case study, you only need the MAGMAhpdc module of MAGMASOFT. No functions of other modules are used.Important requirements f

16、or using this tutorial are the participation in a training and the knowledge of how to use the programs functions. You should be ready to access the MAGMASOFT and MAGMAhpdc manuals and the latest MAGMASOFT Release Notes, as a complete description of all functions is beyond the scope of this tutorial

17、.1.2How to Use this TutorialThe tutorials central case study explains the procedure of casting a drill deck using the HPDC pro- cess. First of all, Ch. 2, page 9 pp supplies you with the basics of the HPDC process and with the most important rules for good simulation practice.What follows is the exp

18、lanation of the case study. It contains a complete MAGMAhpdc project, whose four versions show a continuous optimization process. The four versions are explained in detail.You are also supplied with a DVD that contains the complete case study project with all versions and files.This DVD enables you

19、to work through the whole case study or parts of it at your own computer. For example, you can load the drill decks geometry and make changes without being forced to input or import the whole geometry.8MAGMAHPDC TUTORIALThis tutorial contains many screen pictures, e.g. of the case studys results. Th

20、ese pictures are always supplied with a short explanation of how each window is invoked. This will support you toget a better understanding of the case studys contents.1.3How to Instal the Case Study ProjectIn order to work through the case study project at your computer, you have to copy the projec

21、t toyour hard disk. For details please refer to the enclosed installation instructions or the readme.txt file, which you can find on the case studys data carrier.CH. 2: PROCESS OVERVIEW92Process Overview2.1General Goals of SimulationTen golden rules for good simulation1)The first and most important

22、rule is to make sure that the process being simulated is the same as that being carried out in the foundry. Check very carefully that the HPDC machine param- eters are the same as those used in simulation. Make sure that the values for the followingparameters are the same:Alloy compositionPouring te

23、mperature (keep in mind that the temperature in the shot chamber is needed for simulation!)Material of the die Temperature of the die Shot curveCooling channels (dimensions, positions, cooling power) Spraying conditionsPlunger diameter and plunger velocities2)Define in advance the problem that has t

24、o be solved by simulation. Remember that mold filling simulation is very important in all casting processes.In many cases you can use a short preliminary filling simulation to get an indication that the gating system has been set up correctly, that is:3)First, do not perform a complete filling simul

25、ation (that is, until the casting has been filled completely).First, do not simulate several cycles.Stop the simulation once the gating system is filled (please refer to Ch. 2.2.3, page 11 for details).4)Continue with a more accurate simulation (several cycles, complete mold filling simulation).10MA

26、GMAHPDC TUTORIAL5)Be aware of parameter fluctuation in the foundry. Any changes of the process conditions (like stopping the machine if the die cools down and leaves the quasi-stationary equilibrium) are of special importance here.Make several simulation runs with different parameter values to see t

27、he effects on quality pre- diction and defect prediction.If you compare simulation results with casting trials, be aware of parameter variation during production.Look at several castings during this process of comparing.Use simulation to educate yourself. Try to understand the complex casting proces

28、ses as thor- oughly as possible.6)7)8)9)10) Store the results you get in a systematic and comprehensive way so that they can be re-used.2.2Simulation Goals Specifically Related to HPDC2.2.1IntroductionThe HPDC process is the most widely used casting process for light metal alloys. Like any other cas

29、ting process, HPDC has its strengths and weaknesses. It is very important to realize that the strength of HPDC is productivity and high exactness of shape. On the other hand, the way the melt is treated in the mold filling stage is against the quality rules we know and apply in other cast- ing proce

30、sses, e.g. calm mold filling.This means that the strength of the process is not to provide superior mechanical properties. (If you aim at that, you have to use the complex vacuum process or other processes than HPDC). In traditional HPDC, air is mixed into the microstructure due to violent mold fill

31、ing, which leads to problems with heat treatment and welding, but this feature also gives the advantage that often cheaper alloys can be used than in competing processes.Another limitation with the traditional gating technology is that the ingates freeze off early. This often leads to shrinkage poro

32、sities in the mass centers (hot spots), since feeding is not possible. (To avoid this, local squeezing in the mass centres may be applied).These aspects are very important to keep in mind for simulation projects. Simulation can predict most problems, but it is not always possible to eliminate these

33、due to the limitations in the process.CH. 2: PROCESS OVERVIEW112.2.2Initial Solidification Simulation for Gating DesignBefore designing or optimizing the gating layout it is a good idea to carry out a first solidification simulation in order to predict the hot spots in the casting. This information

34、can be helpful for de- ciding where to attach the ingates to the casting (the hottest metal for feeding will be closest to theingates; but even so it will not be possible to feed completely due to the freezing off of the ingates).2.2.3Initial Filling Simulation for Gating DesignRun the filling simul

35、ation until the casting is approximately filled to ten percent. (This option has not been used in this tutorials case study.) Use the results to design the gating system. Importantcriteria to fulfil are the following:Speed at the ingates should be 20 to 60 m/s for aluminium alloys. It may be higher

36、for mag- nesium alloys (about 40 to 90 m/s).Lower speed if the melt directly hits a wall or a core, higher speed if this is not the case.Avoid circulation of the melt within the ingate system (the melt should only move forward all the time). This means that the cross-section area of the gating syste

37、m should be continuously decreased all the way from the shot chamber to the ingates.Sharp corners should be avoided to secure that the gating channels are fully filled with metal also in the early state of mold filling. No air gap between the melt and the walls of the gating channels can be accepted

38、.Soft curves and large radii are a must while designing the gating system.Design the gating channels in a way that minimize the heat loss: semi cylindrical or trapezoidal shape.2.2.4Complete Filling SimulationSimulate the complete filling process. It is important to check that the temperature distri

39、bution in the casting after filling is good. It is very important to use these results when analyzing the feeding behavior later on, aiming at minimizing the shrinkage in the hot spots. You should take this oppor- tunity to check if a danger for cold shot exists.Design the vents so that the speed of

40、 air is less than 300 m/s. Place the vents in a way that min- imizes the mixing of air into the melt.12MAGMAHPDC TUTORIALPosition the overflows at those places where the melt flows into the mold cavity last.2.2.5Detailed Solidification and Feeding SimulationDepending on the goals of the simulation,

41、several aspects can be analyzed:Is the porosity level in the hot spots acceptable? If not, the layout has to be changed, and a new simulation project is to be carried out.Are the cooling channels working properly? If not, either the cycle time may be too long, the casting is having unnecessary feedi

42、ng problems or the temperature of the die in certain re- gions is too high, which makes the melt stick to the die.How high is the thermal load on the die? How large is the temperature variation in the die dur- ing a casting cycle? A too high temperature variation will reduce the life of the die.When

43、 does the ingate freeze off? Is it possible to prolong the solidification time in the ingate? If yes, how?2.2.6Stress SimulationIt could be of interest, too, to predict distortion and residual stresses in both the casting and thedie. You can use the MAGMAstress module for this purpose.2.3Casting Qua

44、lity at Low CostToday we experience an increasing demand for better quality castings at even lower costs. Forthis reason it is very important to focus on both quality issues and cost issues.2.3.1Quality IssuesIt is necessary to focus on all aspects that can result in a lowering of the quality and ev

45、en lead to faults in a specific casting. This is also necessary from a cost point of view, since quality is not expensive. What is indeed expensive is lack of quality, which leads to scrap, complaints and lostorders.CH. 2: PROCESS OVERVIEW13In HPDC the melt quality is often not so critical, since th

46、e violent mold filling process (where the melt is atomized quite often) sets the limit for the mechanical properties that can be achieved anyway.Make sure that the quasi-stationary production stage (equilibrium) can be reached within a few casting cycles. This makes sure that the production is much

47、more robust and less sensi- tive to disturbances.The methoding (rigging) of the casting should not reduce the quality of the melt. Follow the guidelines given in Ch. 2.2.3, page 11.As good as required is a better guideline than as good as possible. Take care to make re- alistic quality agreements wi

48、th your customers.2.3.2Cost IssuesAs mentioned above, lack of quality is really expensive, since it leads to scrap, rework, complaintsand loss of customers and new orders. In order to avoid this, keep the following in mind:Optimize the yield and dimensionize the gating properly.Use the HPDC machines

49、 closing force in an optimal way. Too big machines do not work with- in the most efficient range, too small machines significantly reduce the process window.Make sure that all castings in a die are cast as identical as possible to reduce scrap tendency.Optimize the cycle times.The simulation with MA

50、GMAhpdc can assist you in performing these steps and to reduce costs with quality remaining constant or even being improved. As shown in the following case study, you can conveniently check directly at the screen if your own ideas can be realized. You can quicklycorrect eventual errors, which enable

51、s you to lower the production costs significantly.14MAGMAHPDC TUTORIALCH. 3.1: CASE STUDY INTRODUCTION153Case Study Drill Deck3.1IntroductionIn this case study, the casting of a drill deck will be simulated. It is being casted with an aluminium alloy, using High Pressure Die Casting. Please find the

52、 MAGMAhpdc project on the enclosed data carrier. It is called drilldeck.In the following you will be supplied with a short overview of the projects versions. The project consists of four versions that are successively built on each other.In the first version, only the casting and the die are created

53、. The goal is to find those places that solidify last and those places where the ingate can be constructed later on. Thus only the castings solidification is calculated and evaluated.In the second version, the complete casting system including plunger, plunger cooling and biscuit is constructed, bas

54、ed on the first versions results. The goal here is to receive exact data regarding heat regulation and cooling. A full filling and solidification simulation is carried out. The HPDC calculator, which is vital for the MAGMAhpdc module, is consequently used here for the first time.Mold filling (melt f

55、ront), cooling and productivity are not satisfactory in the second version. There is a need to optimize these. Thus, a two-cavity die, flow aids and cooling channels are used in the third version. What is more, tracer particles are used for controlling the melt flow. As complete data is available no

56、w for heat regulation, all five casting cycles are simulated. From now on, the scope of result evaluation in the postprocessor is not limited to the casting, but is being extended to the die.The fourth version serves for further optimizing the process. The quality of mold filling and heat regulation is not yet satisfactory and must be improved. A flawless cast structure shall be guaranteed, too. For this purpose overflows are attached to the casting. Cooling and flow aids are being modified. The feeding is simulated and evaluated. Three HPDC-sp