An effective approach to measuring real-time mold deflection during injection molding

2011 ◽  
Vol 31 (8-9) ◽  
Author(s):  
Chung-Ching Huang ◽  
Thanh-Cong Truong ◽  
Shen-Hong Chen
Keyword(s):  
Injection Molding ◽  
Real Time ◽  
Plate Thickness ◽  
Displacement Sensor ◽  
Injection Molding Process ◽  
Molding Process ◽  
Packing Pressure ◽  
Mold Deformation ◽  
Deflection Analysis ◽  
Injection Molded

Abstract This study develops an effective approach to measure real-time mold plate flexion, namely a displacement of a cavity plate. A mold-filling program was used to simulate the injection molding process. The predicted cavity pressure was then applied as an input for the subsequent mold deflection analysis. In this work, an amorphous polymethyl methacrylate (PMMA) was injection-molded into a 6-inch light guide plate (LGP) cavity, with cavity plate thicknesses of 35 mm, 55 mm, and 100 mm. To validate the predicted mold deflection, an inductive displacement sensor was placed underneath the cavity plate, and experiments were conducted using process variables identical to those of the simulation. Comparison between the simulated results and the experimental data shows that when the cavity plate thickness is reduced, the mold deformation increases significantly, and results in an increase in part thickness. In addition, an increase in packing pressure caused a rise in mold deformation. This study demonstrates that the proposed approach is able to measure the mold deflection.

scholarly journals Experimental And Numerical Studies of Shrinkage and Sink Marks On Injection Molded Polymer Gears

2021 ◽  
Author(s):  
Bikram Solanki ◽  
Hapreet Singh ◽  
Tanuja Sheorey
Keyword(s):  
Injection Molding ◽  
Injection Molding Process ◽  
Molding Process ◽  
Melt Temperature ◽  
Numerical Studies ◽  
Packing Pressure ◽  
Injection Molded ◽  
Sink Marks ◽  
Plastic Gears ◽  
Packing Time

Abstract Injection molding is an efficient and most economical process employed for the mass production of plastic gears and helps to reduce the processing time and cost required to produce the desired geometry. However, significant process and product qualification of plastic gears face the shrinkage and sink marks issues during cooling and after ejection. In present work, the best gate locations and flow resistance analysis along with a polypropylene (PP) were carried out using Autodesk Moldflow Insight 2019.05. The numerical and experimental study was conducted to evaluate the effect of packing pressure, packing time, and melt temperature on diametric shrinkage, mass, and sink marks of PP gear. The results show that by increasing packing pressure and packing time, the diametric shrinkage decreased but mass increased. However, as the melt temperature increased the diametric shrinkage also increased but the mass decreased. The minimum diametric shrinkage of 0.562% was found in numerical analysis and 1.619% found in an experimental analysis at the same injection molding process parameters. Mostly, the sink marks were observed in the gear surface between hub and dedendum circle.

Effect of gas counter pressure on shrinkage and residual stress for injection molding process

2017 ◽  
Vol 37 (5) ◽  
pp. 505-520 ◽  
Author(s):  
Wen-Ren Jong ◽  
Shyh-Shin Hwang ◽  
Ming-Chieh Tsai ◽  
Chien-Chou Wu ◽  
Chi-Hung Kao ◽  
...  
Keyword(s):  
Residual Stress ◽  
Injection Molding ◽  
Flow Direction ◽  
Injection Molding Process ◽  
Molding Process ◽  
Daily Lives ◽  
Counter Pressure ◽  
Packing Pressure ◽  
Sink Marks ◽  
Feedback Data

Abstract Plastic products are common in contemporary daily lives. In the plastics industry, the injection molding process is advantageous for features such as mass production and stable quality. The problem, however, is that the melt will be affected by the residual stress and shrinkage generated in the process of filling and cooling; hence, defects such as warping, deformation, and sink marks will occur. In order to reduce product deformation and shrinkage during the process of molding, the screw of the injection molding machine will start the packing stage when filling is completed, which continuously pushes the melt into the cavity, thus making up for product shrinkage and improving their appearance, quality, and strength. If the packing pressure is too high, however, the internal residual stress will increase accordingly. This study set out to apply gas counter pressure (GCP) in the injection molding process. By importing gas through the ends of the cavity, the melt was exposed to a melt front pressure, which, together with the packing pressure from the screw, is supposed to reduce product shrinkage. The aim was to investigate the impacts of GCP on the process parameters via the changes in machine feedback data, such as pressure and the remaining injection resin. This study also used a relatively thin plate-shaped product and measurements, such as the photoelastic effect and luminance meter, to probe into the impacts of GCP on product residual stress, while a relatively thick paper-clip-shaped product was used to see the impacts of GCP on shrinkage in thick parts. According to the experimental results, the addition of GCP resulted in increased filling volume, improvement of product weight and stability, and effective reduction of section shrinkage, which was most obvious at the point closest to the gas entrance. The shrinkage of the sections parallel and vertical to the flow direction was proved to be reduced by 32% and 16%, respectively. Moreover, observations made via the polarizing stress viewer and luminance meter showed that the internal residual stress of a product could be effectively reduced by a proper amount of GCP.

Calculation on the Residual Stresses of Injection-Molded Conductive-Carbon-Fiber-Filled Polymer Composites

2012 ◽  
Vol 629 ◽  
pp. 55-59
Author(s):  
Ai Yun Jiang ◽  
Jing Chao Zou ◽  
Bao Feng Zhang ◽  
Hai Hong Wu
Keyword(s):  
Carbon Fiber ◽  
Residual Stresses ◽  
Polymer Composites ◽  
Injection Molding Process ◽  
Molding Process ◽  
Filled Polymer ◽  
The Core ◽  
Packing Pressure ◽  
Core Areas ◽  
Injection Molded

For conductive-carbon-fiber-filled polymer composites, the residual stresses developed during injection molding process may affect not only the molding’s conductive property, but its dimensional stability as well. In order to improve the conductivity of the molding fabricated with this kind of composites, we investigated, using layer removal method, the distribution of the residual stresses of injection-molded conductive-carbon-fiber-filled polypropylene in this paper. The residual stresses were obtained under the actions of different processing conditions. Our results indicate that processing pressures have more significant effects on the residual stresses at the skin areas than the core areas of the sample because of fiber orientation. The tensile stresses of the molding at the core areas drop under the action of packing pressure, but the compressive stresses at the skin areas increase. The results reveal that the action of packing pressure may decrease the anisotropy of the residual stresses in the molding.

Interfacial Characteristics of Insert-Injection Molding by Using Acoustic Emission

2017 ◽  
Vol 728 ◽  
pp. 258-263
Author(s):  
Badin Pinpathomrat ◽  
Suchalinee Mathurosemontri ◽  
Supaphorn Thumsorn ◽  
Hiroyuki Hamada
Keyword(s):  
Acoustic Emission ◽  
Injection Molding ◽  
Adhesive Strength ◽  
Fracture Behavior ◽  
Acoustic Emissions ◽  
Injection Molding Process ◽  
Test Machine ◽  
Molding Process ◽  
Bonding Area ◽  
Injection Molded

Aim of this study focused on insert injection molding process, which is molded the melted polymer around an inserted part placed in the molded cavity of injection molding process. The interfacial adhesive strength between the inserted and an injected polymer parts were investigated by Intron universal test machine in order to investigate the effect of material in inserted and injected part. During tensile testing the acoustic emissions (AE) measurement was applied to evaluate the fracture behavior of insert injection molding. It was found that interfacial adhesive strength of insert injection molded of all specimens increased according with increasing the bonding area of adhesive interface. The fracture mode of the insert injection molded specimens was depended on the length of bonding area of the inserted part. The fracture of mode of the insert-injection molded specimens was confirmed by acoustic emission.

The simulation of the warpage rule of the thin-walled part of polypropylene composite based on the coupling effect of mold deformation and injection molding process

2018 ◽  
Vol 25 (3) ◽  
pp. 593-601 ◽  
Author(s):  
Jixiang Zhang ◽  
Xiaoyi Yin ◽  
Fengzhi Liu ◽  
Pan Yang
Keyword(s):  
Injection Molding ◽  
Coupling Effect ◽  
Mold Temperature ◽  
Injection Molding Process ◽  
Plastic Part ◽  
Molding Process ◽  
Melt Temperature ◽  
Packing Pressure ◽  
Thin Walled ◽  
Packing Time

Abstract Aiming at the problem that a thin-walled plastic part easily produces warpage, an orthogonal experimental method was used for multiparameter coupling analysis, with mold structure parameters and injection molding process parameters considered synthetically. The plastic part deformation under different experiment schemes was comparatively studied, and the key factors affecting the plastic part warpage were analyzed. Then the injection molding process was optimized. The results showed that the important order of the influence factors for the plastic part warpage was packing pressure, packing time, cooling plan, mold temperature, and melt temperature. Among them, packing pressure was the most significant factor. The optimal injection molding process schemes reducing the plastic part warpage were melt temperature (260°C), mold temperature (60°C), packing pressure (150 MPa), packing time (2 s), and cooling plan 3. In this situation, the forming plate flatness was better.

Study on Improving the Life of Stereolithography Injection Mold

2012 ◽  
Vol 468-471 ◽  
pp. 1013-1016 ◽  
Author(s):  
Hua Qing Lai
Keyword(s):  
Injection Molding ◽  
Injection Molding Process ◽  
Injection Mold ◽  
Molding Process ◽  
Molded Parts ◽  
Injection Molded ◽  
Plastic Parts ◽  
Assembly Operations ◽  
Conventional Injection Molding ◽  
Shape And Size

Molding is one of the most versatile and important processes for manufacturing complex plastic parts. It is a method of fabricating plastic parts by utilizing a mold or cavity that has a shape and size similar to the part being produced. Molten polymer is injected into the cavity, resulting in the desired part upon solidification. The injection-molded parts typically have excellent dimensional tolerance and require almost no finishing and assembly operations. But new variations and emerging innovations of conventional injection molding have been continuously developed to offer special features and benefits that cannot be accomplished by the conventional injection molding process. This study aims to improving the life of stereolithography injection mold.

Dynamic Response Optimization for Cemented Carbide Injection Molding

2014 ◽  
Vol 68 (4) ◽  
Author(s):  
Sri Yulis M. Amin ◽  
Norhamidi Muhamad ◽  
Khairur Rijal Jamaludin
Keyword(s):  
Injection Molding ◽  
Palm Stearin ◽  
Processing Parameters ◽  
Cemented Carbide ◽  
Metal Injection Molding ◽  
Injection Molding Process ◽  
Molding Process ◽  
Response Optimization ◽  
Injection Molded ◽  
Injection Temperature

The need to optimize the injection molding parameters for producing cemented carbide parts via Metal Injection Molding process is crucial to ensure the system’s robustness towards manufacturer and customer’s satisfactions. Defect free product with best density can be produced while reducing time and cost in manufacturing. In this work, the feedstock consisting of WC-Co powders, mixed with palm stearin and polyethylene binder system was injection molded to produce green parts. Several processing variables, namely powder loading, injection temperature, holding pressure and flowrate, were optimized towards the density of the green body, as the response factor. By considering humidity level at morning and evening conditions as the noise factor, the results show the optimum combination of injection molding parameters that produces best green density. The green part exhibited best density by following this optimum processing parameters, A2B3C1D1, that are flowrate at 20 ccm/s, powder loading at 63% vol., injection temperature at 140°C, and holding pressure at 1700 bar.

Computer Aided Engineering Design of Powder Injection Molding Process for a Dental Scaler Tip Mold Design

2007 ◽  
Vol 534-536 ◽  
pp. 341-344 ◽  
Author(s):  
Chul Jin Hwang ◽  
Y.B. Ko ◽  
Hyung Pil Park ◽  
S.T. Chung ◽  
Byung Ohk Rhee
Keyword(s):  
Injection Molding ◽  
Low Cost ◽  
Powder Injection Molding ◽  
Powder Injection ◽  
Injection Molding Process ◽  
Molding Process ◽  
Cross Model ◽  
Computer Aided Analysis ◽  
Computer Aided ◽  
Deflection Analysis

Powder Injection Molding (PIM) has recently been recognized as an advanced manufacturing technology for low-cost mass production of metal or ceramic parts of complicated geometry. With this regards, design technology of dental scaler tip PIM mold, which has complex shape and a slim core pin of 0.6 mm diameter, with the help of computer-aided analysis for powder injection molding process was developed. Computer-aided analysis for dental scaler tip mold was implemented by finite element method with non-Newtonian fluid, modified Cross model viscosity, PvT data of powder/binder mixture. The core deflection analysis of dental scaler tip PIM mold during PIM filling process was also investigated. Compter-aided analysis results, such as filling pattern, weldline formation, and air vent position prediction were investigated and eventually showed good agreements with experimental results.

Influence of Injection Molding Process Parameters on Sink Marks of Injection Parts Based on Moldflow

2013 ◽  
Vol 347-350 ◽  
pp. 1163-1167
Author(s):  
Ling Bai ◽  
Hai Ying Zhang ◽  
Wen Liu
Keyword(s):  
Injection Molding ◽  
Process Parameters ◽  
Mold Temperature ◽  
Processing Parameters ◽  
Injection Molding Process ◽  
Molding Process ◽  
Melt Temperature ◽  
Packing Pressure ◽  
Sink Marks ◽  
Research Show

Moldflow software was used to obtain the best gate location and count. Influence of injection molding processing parameters on sink marks of injection-piece was studied based on orthogonal test. The effects of different process parameters were analyzed and better process parameters were obtained. Results of research show that decreasing melt temperature, mold temperature, the increasing injection time and packing pressure can effectively reduce the sink marks index.

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