Application of CAD/CAE/CAM Technology in Plastics Injection Mould Design and Manufacture. Ming He Dai,Zhi Dong Yun

Transcription

1 Advanced Materials Research Vols (2012) pp Online available since 2011/Nov/22 at (2012) Trans Tech Publications, Switzerland doi: / Application of CAD/CAE/CAM Technology in Plastics Injection Mould Design and Manufacture Ming He Dai,Zhi Dong Yun Mechanical & Electrical Engineering School, Guilin University of Electronic Technology, Guilin Guangxi ,China Keywords: Injection mould,solidworks,moldflow,mastercam Abstract. The process of injection mould design and manufacture was introduced by taking the cover as an example. Firstly, the 3D model of the part and the injection mould structure were designed based on SolidWorks software. Secondly, the injection molding progress was analyzed and simulated based on Moldflow software. Finally, the toolpaths of cavity and core were designed based on MasterCAM software, and its manufacture process and numerical control programming was simulated. The period of product development was shortened effectively and the quality of design and manufacture was improved by CAD/CAE/CAM integrated technology. Introduction The plastic injection molding technology has been more and more widely applied in the industrial production, its related mold and the processing technology gradually becomes hot in the mold profession. Computer aided design (CAD), computer aided Engineering (CAE) and computer aided Manufacture (CAM) to the injection mold which is important in the development of injection of mould technology can enhance the mold design and the manufacture level, shorten the research cycle[1]. This article takes injection molding cover as an example, which uses the current mainstream three dimensional parametrization design software SolidWorks, and injection molding process numerical analysis software Moldflow and numerical control processing software MasterCAM, thus realizing CAD/CAE/CAM integration for the injection molding product formation technology. CAD/CAE/CAM of Injection Molding Parts CAD / CAE /CAM System Process of Injection Molding Parts. CAD/CAE/CAM system flow of injection molding is shown in Figure 1. SolidWorks software is used as a platform for modeling and die design of plastic parts to realize the parametric modeling of plastic parts, parting, mold structure design and so on. Plastic parts CAE uses Moldflow software s MPI module, by which simulation analysis is carried on in the entire injection molding process, including the computation of the best gate location and the simulation of filling and cooling proc esses etc, and forecasts warp, structural stress and contraction and so on so that the designers can change the unreasonable design and obtain the best technological conditions of plastic molding according to the analysis results to ensure the best quality plastic parts. The reasonable toolpaths of cavity and core are designed based on MasterCAM software s milling module, and cutting tool s processing path is verified and numerical control processing program NC code is provided with the software s simulation processing function. CAD / CAE /CAM System s Data Conversion of Injection Molding Parts. SolidWorks software is outstanding three dimensional design software based on the Windows platform, and can quickly and easily create complex shapes entity by using parametrization and the characteristic modelling technology, with good data conversion capabilities and high conversion rate[2]. After the injection parts solid modeling has been completed in the SolidWorks software, product information will be converted to STL format file and output to Moldflow software. When the plastic trademark, All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, (ID: , Pennsylvania State University, University Park, USA-13/01/15,05:21:45)

2 2272 New Materials, Applications and Processes the appropriate injection molding temperature, the injection molding pressure and the injection molding machine are set in Moldflow, the injection molding analysis can be carried on, which provides the engineers with simulation results to instruct its inspection change the design and ensure the success rate of test mode. By realizing injection molding parts mould-parting, the cavity surface and core surfaces can be created in the SolidWorks software, and then import the MasterCAM software to realize the numerical control simulation processing by a dedicated data interface Mastercam Direct or the IGES format. Plastic parts CAD modeling Product mold design Product injection molding analysis N reasonable The determination of processig technology Y NC programming Mold manufacturing Fig.1. Flowchart of injection parts CAD/CAE/CAM. Plastics Injection Mould CAD SolidWorks software is taken as design platform for the injection mold. Firstly, the 3D solid plastic parts were designed by using SolidWorks software s powerful parametric modeling function, and then mold is designed by IMOLD plug-in. The entire design process is divided into three stages. The first stage is to process the part mode, and create the cavity / core by mould-parting tools; the second stage is to make structural design, to add mold and casting system, and to create slide top block and other structures ; the third stage is to create a trough cavity and drawing and so on[3]. Plastic products modeling process and solid model is shown in Figure 2. And the three-dimensio -nal mold assembly diagram is shown in Figure 3. Fig.2. Plastic products modeling process and solid model. Fig.3. The three-dimensional mold assembly diagram.

3 Advanced Materials Research Vols Plastics Injection Mould CAE Pre-processing. The plastic parts model created in SolidWorks is imported into Moldflow in STL file format and meshed. Choose grid type Fusion (surface mesh), set the grid unit length of 3mm (the grid unit length usually taken a minimum wall thickness of 1.5 to 2 times), and then generate the model grid. In order to ensure the accuracy of analysis, the grid condition needs to be examined before analysis and the unit which has effects on calculation results needs to be modified. Aspect ratio oversized triangular elements are found and modified by the grid diagnostic tool, and the recommended maximum aspect ratio should not exceed 20 in the analysis of Fusion type grid, the grid unit matching ratio should be greater than 85%[4].Through the grid diagnosis and correction, statistical information of plastic grid in this case is as follows: triangles, 7345 nodes, 16.5 maximum aspect ratio, average aspect ratio, 87.3% matching rate and 0 cross-unit. The requirements of analysis are accurate and grid division is quite satisfactory. The material whose trademark is ABS AF303 produced by LG Chemical Corporation is selected. Molding process parameters include: 200 melting temperature, 60 mold temperature, 140MPa maximum injection pressure, and the injection control and the speed/pressure control are set to automatic. The structure of this die adopts a two-cavity mold layout scheme, analyses gate location with MPI / Gate location module.the design of gate position based on the analysis results can effectively avoid plastic parts defects caused by the improper location of the gate. According to the shape of plastic parts, materials and process parameters, the gate location area through MPI calculations are shown in figure 4 and the best position of gate is at node N2001. best water inlet the best gate area gating system worst Fig. 4 The best gate position analysis chart. Fig. 5. The grid diagram of gating system and cooling system. In Moldflow, the gating system and the cooling system are manually created. The gate cross-section shape of gating system is conical with the whole end diameters of 1.5mm and 3.5mm; and flow channel cross-section shape is circular with a diameter of 6mm; and mainstream cross-section shape is conical with beginning diameter of 5mm, taper angle of 1º. In cooling system, the cross-section of pipe is circular, the diameter of 12mm, coolant inlet temperature of 25, Reynolds number of The gating system and cooling system s related designs are completed and then the design object is meshed, as shown in Figure 5. The using of the connective grid diagnosis tool can ensure that each unit of the gating system and cooling system of plastic parts is connected. Injection Molding Simulation and Analysis. Filling analysis can simulate the whole process from the beginning of the plastic melt into the cavity to the cavity full of plastic melt. According to the simulation results, melt s flow behavior information in the whole cavity can be obtained to determine whether the mold structure, gating system, process parameters are reasonable or not. Fig. 6 shows the simulation result chart of filling time. As can be seen from Fig. 6, products filling time is 2.907s, the filling time of its both ends is respectively 2.889s and 2.891s in the direction of both sides on the gate. In conclusion, the entire plastic product is reasonably filled and its flow balance is better.

4 2274 New Materials, Applications and Processes time volume pessure clampingforce flowrate state filling time Fig. 6. Plastic products filling time analysis. Fig.7. Filling analysis process From the progress of filling state, the correlation time, filling degree, pressure and clamping force, the melt flow rate and V / P conversion can clearly be seen in Fig. 7. At the beginning of injection, the inlet pressure is 17.85MPa ( at 0.14s ) ; when filled to 98.99%, volume control is converted to pressure control ( at 2.86s ) ; when pressure is 46.14MPa, clamping force is 41.56t, the maximum flow rate of melt is cm 3 /s. After the conversion point, gate location pressure is reduced to holding pressure 36.91MPa (80% V / P conversion pressure), but clamping force is still increasing, and melt flow rate is greatly reduced ; meanwhile, melt continues to fill the entire cavity under the pressure control. Holding pressure for a period of time, and when the gate was solidified, the pressure acting on the plastic product is removed until the product can be topped out, which is known as cooling. The cooling analysis goal is to optimize the cooling pipe set, determine a reasonable cooling time and improve the quality of the product formed by simulating heat transfer condition in the mold. Fig.8. The temperature distribution chart of plastic parts after being cooled Fig.9. Loop wall temperature distribution chart Fig.8 shows the temperature distribution of plastic parts after cooling cycle. The temperature distribution is uniform in the plastic surface, which can be seen in Figure 8. Fig 9 shows the temperature difference between the cooling pipe wall temperature and the die wall temperature is less than 5. In addition, the temperature difference of cooling medium in loop between inlet and outlet temperature is 0.2, which is also smaller than the standard value of 2 ~ 3. Analysis indicates that the cooling channel layout is reasonable and the cooling effect is good. Warp analysis aims to predict the product s warp degree in the process of forming and to analyze the reason. Fig.10 shows the overall warp diagram of plastic parts and the maximum deformation is mm. The maximum warp locations of plastic parts in the two free ends are mainly caused by contraction while cooling and molecular orientation factors have a smaller effect. The CAE analysis shows that the design of plastic parts meets the quality requirements.

5 Advanced Materials Research Vols deformation, all factors: deformation scale factor=1.000 Fig.10. The warp analysis result of plastic parts. Fig.11. The simulation processing effect chart of the cavity and core. Injection Mold CAM After injection analysis have been finished, the cavity parts and the core parts produced by SolidWorks parting are imported into MasterCAM software by a dedicated data interface Mastercam Direct or IGES format. The toolpaths of cavity and heart are set respectively in Mastercam, and then machined roughly and finishly in two steps with parallel milling mode. Rough machining uses 15mm milling cutter and finish machining uses 8mm ball-end-milling cutter. After simulation of cutting process has achieved satisfying results, NC program of the cavity and the core are generated by the post processing, and then transmitted to the CNC machine tool to process parts. Fig.11 is the simulation processing effect chart of the cavity and the core. Conclusions CAD / CAE / CAM technology is a trend of mold design and manufacturing. In the actual product and mould design, firstly, product parametrization model is established by applying SolidWorks software and mold cavity and core is generated by parting processing, and then the mold assembly structure is created ; secondly, the relevant information is imported into the Moldflow software for analysis, and injection mold will be optimized according to the results of analysis; lastly, parts processing information extracted from the SolidWorks is converted to the MasterCAM software for toolpaths design and the final generation parts NC program. Three kinds of software integration not only shortens the product development cycle, but also improves product design and manufacturing quality. References [1] F.Z. Li: Mold Advanced Manufacturing Technology (China Machine Press, China 2003). (In Chinese) [2] H.B. Jiang: SolidWorks2006 Chinese Version of the Basic Application and Case Analysis (China Machine Press, China ). (In Chinese) [3] SolidWorks Corporation: SolidWorks Mold Design (China Machine Press, China 2005). (In Chinese) [4 ] Q.Liu: Plastic Injection Moldflow Practical Guid (China Machine Press, China 2008). (In Chinese) [5 ] B.Li: Mastercam X Practical Guide [ M] (China Machine Press, China 2008). (In Chinese) [6 ] X.Q. Xu: Plastics Industry, (2005) No.12, p26 (In Chinese)

6 New Materials, Applications and Processes / Application of CAD/CAE/CAM Technology in Plastics Injection Mould Design and Manufacture /