INJECTION MOLDING METHODS DESIGN, OPTIMIZATION, OF PLASTIC TOY BUILDING BLOCK BY MOLD FLOW ANALYSIS

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1 INJECTION MOLDING METHODS DESIGN, OPTIMIZATION, Injection Molding Methods Design, Optimization, Simulation of Plastic Toy Building Block by Mold Flow SIMULATION Calculated by GISI ( OF PLASTIC TOY BUILDING BLOCK BY MOLD FLOW ANALYSIS Manmit Salunke 1, Rushikesh Kate 2, Vishwas Lomate 3, Gajanan Sopal 4 Volume 6, Issue 6, June (2015), pp Article ID: International Journal of Mechanical Engineering and Technology IAEME: ISSN (Print) ISSN (Online) IJMET I A E M E 1,2,3 Assistant Professor, Department of Mechanical Engineering, J.S.P.M. S B.I.T, Barshi, Solapur, Maharashtra, India 4 Associate Professor, Department of Mechanical Engineering, J.S.P.M. S B.I.T, Barshi, Solapur, Maharashtra, India ABSTRACT Mold flow simulation helps designers to see how their designs will be resulted after injection molding process without needing to do the Injection Molding process. The use of simulation programs saves time and reduces the costs of the Molding system design. Injection molding design simulation holds an important role in analyzing the outcome of the design. In this paper plastic toy building block part is analyzed and studied to solve the problems frequent rejections due to as shrinkage, weld lines, air traps, and sink marks. All the designs were simulated with Autodesk Mold flow Adviser. Autodesk Simulation Mold flow effectively eliminates the use of trial and error method by validating and optimizing the design of plastic before production. This not only improves the quality but also help us to guide about the selection of machines and the production planning. Keywords: Injection moulding, Mould design, Mold flow simulation, Optimization Plastic Injection mould, Mould Flow Plastic Advisor (MPA) 1. INTRODUCTION Injection Moulding is one of the common methods to do the mass-production of plastic product. Thermoplastics are science's gift to the toy industry. They can be melted at fairly low temperatures, molded in colors with fine detail, and stand up well to play wear because of their resilience.. Injection moulding is the most commonly used manufacturing process for the fabrication of plastic parts. A wide variety of products are manufactured using injection moulding, which vary greatly in their size, complexity, and application. Injection Molding is the way most of our plastic toys are created. The material is injected under pressure into a two-part mold. The material is allowed to cool, the mold is opened, and the solid product inside is ejected into a collection hopper. Common problems associated with injection molding are numerous editor@iaeme.com

2 2. COMPUTER AIDED SIMULATION Nowadays, Computer Aided Design is not limited to sketching and drafting, but also helps to create analysable models as needed for computer based process simulation. Moldflow software, used solution for Digital Prototyping, provides injection molding simulation tools for use on digital prototypes. Providing in-depth validation and optimization of plastic parts and associated injection molds, Moldflow software helps study the injection molding processes in use today. The Autodesk Simulation Moldflow results help to identify the main problem areas before the part is manufactured that are particularly difficult to predict with traditional methods. In conventional optimization process includes actual shop floor trials in which pattern, feeder size, shape and location cores, mould layout, gating etc are required to be changed in each iteration which is associated with machining cost, tooling cost, modification cost, melting cost, fettling and transportation cost as well as energy, materials, time are wasted in each trial until and unless the required results are obtained. Analysis is essential for designing and mould making through simulation step-up and result interpretation to show how changes to wall thickness, gate location, material and geometry affects manufacturability and also experiments with what-if scenarios before finalizing a design. Injection Moulding simulation software into the mould design process in order to analyze the product, foresee the possible defects, and optimize the design to achieve the maximum outcome of the products with minimum cycle time in each production cycle. 3. PROBLEM DEFINITION Here a plastic toy building block of 60 mm leangth, 34 mm width and 1 mm thick is analysed by taking different cases of Model and optimize runner. gating, sprue systems Determine potential part defects, such as weld lines, air traps, and sink marks, and then rework designs to avoid these problems. Create feed systems based on inputs for layout, size, and type of components, such as sprue, runners, and gates. 4. OBJECTIVES OF THE WORK 1. To analyze the behaviour of Thermoplastic material during the production cycle from the filling phase until the ejection phase. 2. To foresee the possible problem for a product design; and therefore able to op-timize the design in the mould design process. 3. To achieve the minimum production cycle time 4. To construct a rapid prototyping of the mould cavity design into a standard mould plate. 5.1 Model details A 3d model of part toy is created in solid Edge software Fig. 1.1 a) 2D dimension of part Fig. Fig. 1.1 b) Actual toy building block 34 editor@iaeme.com

3 Fig.1.1c) Old design (2mm thikness at middle cavity) Fig. 1.1 d) new design (1mmuniform thikness) Fig.1) 3D cad model of toy part 5.2 Process settings Fig. 2 Mechanical Properties of ABS material Melt temperature: (C) Injection locations: 4 Mold temperature: 50.0 (C) Max. machine injection pressure: (MPa) 5.3Mold Data Mold material Tool Steel P-20 Mold dimensions X: (mm) Y: (mm) Z: 50.02(mm) Mold plate dimensions A plate: (mm) B plate: (mm) 5.4Material Data Family abbreviation-ldpe Familyname-polyethylenes (PE) Family abbreviation-abs Familyname - Acrylonitrile copolymers (abs, Trade name -(10% Rubber) Mold Temperature Range C C Melt Temperature 220 C 230 C Ejection Temperature 80 C 88 C Maximum Shear Stress 0.11 MPa 0.28 MPa Maximum Shear Rate /s /s Modulus Of Elasticity 124 MPa 3500 MPa Poison Ratio Shear Modulus MPa 1287 MPa Melt Density g/cm g/cm 3 Specific Heat 4230 J/Kg-C 2400 J/Kg-C Heating/Cooling Rate c/s c/s 35 editor@iaeme.com

4 5.5 Coolant information Cooling circuit 1 Cooling circuit 2 Inlet coordinate : , , , , Temperature 25.0 C 25.0 C Hose, Diameter mm Hose, Diameter mm Channel, Circular, Diameter (10.00 mm Flow rate (lit/min) (lit/min) 5.6 Quality prediction for LDPE and ABS materials Fig.3 a) single Part LDPE Fig.3 b) single Part ABS Fill analysis for single part toy shows part have good quality when ABS material preffered. 5.7 Optimum molding conditions for ABS material FIG.4 Optimum processing conditions Parameter Optimum Value (ABS ) Default Value (ABS ) Mold surface temperature 58 C 50.0 (C) Melt temperature 230 C (C) Injection time 5.2 s editor@iaeme.com

5 5.8Feed system cases details Sprue dimensions Runner dimensions Gate dimensions CASE I CASE II CASEIII CASE IV Cold, Circular Tapered, Cold, Circular Tapered, Cold, Circular Cold, Start Diameter (2.00 mm), Start Diameter (2.00 mm), Tapered, Start Tapered, End Diameter (4.00 mm) End Diameter (4.00 mm) Cold, Circular, Diameter (3.00 mm) Cold, Circular Tapered, Start Diameter (3.00 mm), End Diameter (1.00 mm) Cold, Rectangular, Width (3.00 mm), Thickness (2.00 mm) Cold, Rectangular, Width (2.00 mm), Thickness (2.00 mm) Diameter (5.00 mm), End Diameter (4.00 mm) Cold, Circular, Diameter (3.00 mm) Cold, Circular Tapered, Start Diameter (3.00 mm), End Diameter (1.00 mm) Circular Start Diameter (10.00 mm), End Diameter (8.00 mm) Cold, Circular, Diameter (15.00 mm) Cold, Circular Tapered, Start Diameter (3.00 mm), End Diameter (1.00 mm) 6. SIMULATION RESULT 6. A Gate Location Analysis Optimum gate locations may need to be examining by running the filling analysis on different best gate locations. Figure shows the result of gate location. Blue area represents the best gate locations for the part. Fig. 6A) best gate location 6. B Fill Time Analysis result The Fill time result shows the position of the flow front at regular intervals as the cavity fills. At the start of injection, the result is dark blue, and the last places to fill are red. If the part is a short shot, the section which did not fill has no colour. Fill time is the time taken to fill up the part inside the cavity; it is also to show how the plastic material flows to fill the cavity. Fig.6B) Fill Time Analysis result 37 editor@iaeme.com

6 6. C Confidance of fill analysis result 6. D Quality prediction analysis result Fig. 6C) Confidance of Fill Time Analysis result 6. E Injection Pressure. Fig.6D) Quality prediction analysis result 6. F RESSURE DROP Fig. 6E )Injection Pressure result Fig. 6F) pressure drop result 38 editor@iaeme.com

7 6.G TEMPERATURE AT FLOW FRONT 6.H. Time To reach ejection Temperature Fig. 6G) temperature at flow front result 6.I. AIR TRAP Analysis result Fig.6H) Time to reach ejection Temperature result 6.J) weld lines analysis result Fig. 6.I) air trap analysis result fig. 6J) weld lines analysis result 39

8 6.L) cooling quality analysis result 6. M). Wrap Analysis Result Fig.6 L) cooling quality analysis result 7. RESULTS AND DISCUSSION Fig. 6M) Wrap analysis result CASE I CASE II CASEIII CASE IV Fill tab Actual filling time 0.72 (s) 0.70 (s) 0.73 (s) 2.22 (s) Actual Injection pressure (MPa) (MPa) (MPa) (MPa) Clamp force area (cm^2) (cm^2) (cm^2) (cm^2) Max. clamp force during filling (tonne) (tonne) (tonne) (tonne) Velocity/pressure switch-over at % volume (%) (%) (%) (%) Velocity/pressure switch-over at time 0.69 (s) 0.68 (s) 0.69 (s) 2.12 (s) Estimated cycle time (s) (s) (s) 35s Total part weight at the end of filling (g) (g) (g) (g) Shot volume (cm^3) (cm^3) (cm^3) (cm^3) Cavity volume (cm^3) (cm^3) (cm^3) (cm^3) Runner system volume (cm^3) (cm^3) (cm^3) (cm^3) Pack tab Maximum clamp force during cycle (tonne) (tonne) (tonne) (tonne) Max. wall shear stress (MPa) (MPa) (MPa) Total part weight (g) (g) (g) (g) Cycle time (s) (s) (s) 40 editor@iaeme.com

9 Cooling Quality Maximum and minimum temperature variance Maximum and minimum cooling time variance 5.1 C & -1.2 C 0.49 (s) & (s) 7.8 (C) (C) & C 1.47 (s) & (s) 5.1 (C) & -2.5 (C) 0.49 (s) & (s) Cool tab Maximum temperature, part 49.2 (C) 49.4 c 49.3 (C) 53.5 c Minimum temperature, part 32.6 (C) 32.5 c 32.6 (C) 34.7 c Average temperature, part 41.1 (C) 40.9 c 41.1 (C) 45.2 c 7.3 (C) & -9.5 C Mold exterior temperature 27.4 (C) 27.3 c 27.4 (C) 28.6 (C) The comparison of initial and modified designs on various parameters 1.65 (s) &-1.25 (s) 1) Considering initial design for plasic toy, 2mm thikness at moddle cavity, simulation result showing cooling time of part not uniform and have very high value.fill analysis shows poor quality for part. So model is redesigned for unform wall thiknes 1mm.Then simulation result shows better quality of part. 2) After fill analysis shows part have lower quality for LDPE material and high quality for ABS material.different four cases of runner sprue and gate system are analyzed by using ABS material for plasic toy. 3) In case IV have large filling time and more runner system volume so wastage of material is high. Case II have lower filling time but more shrinkage. 4) Case I have lower cycle time, high confidence of fill, high quality. So have good optimum design solution for defect free part. 8. CONCLUSION The filling time and the cooling time of a four cavity design does not increase to four times longer than having a single cavity. So the cycle time for four cavities design is the most optimum and efficient to be used in the production process. The analysis work shows the parameters such as sink marks, fill time, weld line, air traps etc. that will affects the quality of the finished product. Plastic Flow Simulation Simulate the flow of melted plastic to help optimize part and mold designs, reduce potential part defects, and improve the molding process and decrease the cycle time and to improve the Quality of the Product. REFERENCE 1. Auto desk Mold-Flow Insight material data warehouse. 2. wikimedia Foundation, Inc, InjectionMoulding. [online] Available at: < wikipedia. org/wiki/injection_moulding> [Accessed 28 August 2010] 3. Bryce, D. M., Plastic injection molding: Manufacturing process fundamental. Society of Manufacturing Engineers, (1996) 4. Sri. P V S M Varma and Sri. P N E Naveen, Optimizing Injection Moulding Tool Cost by Using Virtual Software Techniques International Journal of Mechanical Engineering & Technology (IJMET), Volume 4, Issue 6, 2013, pp , ISSN Print: , ISSN Online: editor@iaeme.com

10 5. Mr. A.B. Humbe and Dr. M.S. Kadam, Optimization of Process Parameters of Plastic Injection Molding For Polypropylene To Enhance Productivity and Reduce Time For Development International Journal of Mechanical Engineering & Technology (IJMET), Volume 5, Issue 5, 2014, pp , ISSN Print: , ISSN Online: Mr. A.B. Humbe and Dr. M.S. Kadam, Optimization of Critical Processing Parameters For Plastic Injection Molding of Polypropylene For Enhanced Productivity and Reduced Time For New Product Development International Journal of Mechanical Engineering & Technology (IJMET), Volume 5, Issue 1, 2014, pp , ISSN Print: , ISSN Online: Moldflow Plastic Insight, Moldflow Tutorial. [Software tutorial] Mold-flow Corporation 8. Tang, S.H., Kong, Y.M.,Sapuan, S.M., Samin, R., and Sulaiman, S., Design and thermal analysis of plastic injection mold, Journal of Materials Processing Technology, Vol. 171, pp ,