Shrinkage and Warpage in the Permanent Shape of Sape-Memory Polyurethane Parts

2022 ◽  
Vol 58 (4) ◽  
pp. 102-113
Author(s):  
Sukran Katmer ◽  
Cetin Karatas

The shape memory effect, as the most important ability of shape memory polymers, is a working property and provides the design ability to shape memory polymer features. Shrinkage and warpage are important parameters to control the dimensional accuracy of permanent and temporary shapes of an injection moulded shape memory polyurethane (SMPU) part. In this study, the effects of injection moulding parameters on the shrinkage and warpage of the permanent shape of moulded SMPU parts were experimentally investigated. The parameters of injection pressure, melt temperature, mould temperature, packing pressure, packing time, and cooling time, were chosen as the injection moulding control factors. Taguchi�s L27 orthogonal array design table was used with six injection moulding parameters and their three levels. The results showed that the part has different shrinkage ratios in three main directions, namely, the flow direction, perpendicular to the flow direction, and the direction through the thickness. The results of the analysis of variance showed that the cooling time is the most influential parameter on both the shrinkage (except in thickness) and warpage. The shrinkage in the flow direction as well as in perpendicular to the flow direction decreased with increasing the cooling time. Warpage also decreased with increasing the cooling time. Injection pressure and melt temperature were found to be effective on shrinkage in thickness. Effects of mould temperature, packing pressure, and packing time were found to be limited. A statistically significant relationship has been noticed among shrinkage, warpage, and residual stresses during the study.

2011 ◽  
Vol 189-193 ◽  
pp. 2477-2481 ◽  
Author(s):  
Dong Lei Liu ◽  
Chang Yu Shen ◽  
Chun Tai Liu ◽  
Yong Xin ◽  
Ling Sun

In order to further investigate the influence of mold temperature in rapid heat cycle molding on shrinkage of plastic past, a self-developed vehicle-used blue-tooth front shell high-gloss mold and an auxiliary device for controlling the mold temperature were employed in experiments. And the effect of the other parameters on shrinkage of part with fixed or changed mold temperature conditions was also studied. Results reveal that the shrinkage of RHCM part is reduced obviously compared with a conventional one, decreasing as quasi-linear with mold temperature increased gradually. At same mold temperature conditions, packing pressure, followed by packing time, is the most significant parameter on shrinkage of part, while cooling time has almost no impact on it. Melt temperature and injection pressure effecting on shrinkage of part exists a critical value, near the thermal deformation temperature of plastic. When mold temperature is set below this temperature, injection pressure has more significant than melt temperature, but it is the opposite. With being elevated gradually of mold temperature, shrinkage of part shows a slight decrease trend under same melt temperature and injecting pressure. While it fluctuates as a “V” shape with a narrow range under same packing pressure, packing time and cooling time presumed conditions, and reaches the minimum near the thermal deformation temperature of plastic.


2018 ◽  
Vol 7 (3.7) ◽  
pp. 14 ◽  
Author(s):  
Mohd Amran Md Ali ◽  
Noorfa Idayu ◽  
Raja Izamshah ◽  
Mohd Shahir Kasim ◽  
Mohd Shukor Salleh ◽  
...  

This study presents an optimization of injection moulding parameters on mechanical properties of plastic part using Taguchi method and Grey Relational Analysis (GRA) approach. The orthogonal array with L9 was used as the experimental design. Grey relational analysis for ultimate tensile strength, modulus and percentage of elongation from the Taguchi method can convert optimization of the multiple performance characteristics into optimization of a single performance characteristic called the grey relational grade (GRG). It is found that mould temperature of 62oC, melt temperature of 280oC, injection time of 0.70s and cooling time 15.4s are found as the optimum process setting. Furthermore, ANOVA result shows that the cooling time is the most influenced factor that affects the mechanical properties of plastic part followed by mould temperature and melt temperature.  


2012 ◽  
Vol 488-489 ◽  
pp. 269-273 ◽  
Author(s):  
G.S. Dangayach ◽  
Deepak Kumar

In the present era, competition gets tougher; there is more pressure on manufacturing sectors to improve quality and customer satisfaction while decreasing cost and increasing productivity. These can be achieved by using modern quality management systems and process improvement techniques to reduce the process variability and driven waste within manufacturing process using effective application of statistical tools. Taguchi technique is well known technique to solve industrial problems. This technique is fast and can pinpoint the chief causes and variations. Plastic injection molding is suitable for mass production articles since complex geometries can be obtained in a single production step. The difficulty in setting optimal process conditions may cause defects in parts, such as shrinkage and warpage. In this paper, optimal injection molding conditions for minimum shrinkage were determined by the Taguchi design of experiment (DOE) approach. Polypropylene (PP) was injected in circular shaped specimens under various processing parameters: melt temperature, injection pressure, packing pressure and packing time. S/N ratios were utilized for determining the optimal set of parameters. According to the results, 2400 C of melt temperature, 75 MPa of injection pressure, 50 MPa of packing pressure and 15 sec. of packing time gave minimum shrinkage of 0.951% for PP. Statically the most significant parameter was melt temperature for the PP. Injection pressure had the least effect on the shrinkage. The defect rate was reduced from 14% to 3%.


2020 ◽  
Vol 841 ◽  
pp. 225-231
Author(s):  
Huei Ruey Ong ◽  
Ifwat Mohd Shah ◽  
Wan Mohd Eqhwan Iskandar ◽  
Md. Maksudur Rahman Khan ◽  
Chi Shein Hong ◽  
...  

Plastic injection moulding is widely used for manufacturing due to variety of plastic product. In this study, plastic part defects such as air bubble and gas mark defect are commonly occurs in thermoplastic part, specifically acrylonitrile butadiene styrene (ABS). In order to optimize the process parameters of injection moulding, design of experiment (DOE) with Response Surface Methodology (RSM) model was used. Process parameters such as melt temperature, mould temperature and injection pressure were selected for the DOE development. The experiments were conducted with melt temperature range from 200 °C to 240 °C, mould temperature from 60 °C to 80 °C and injection pressure from 90 to 99%. The result indicates that, all the selected parameters were significantly influence the rejection rate of the automotive ABS part. The optimum melt temperature, mould temperature and injection pressure were 220 °C, 70 °C and 98% respectively, in obtaining minimum rejection rate.


2016 ◽  
Vol 700 ◽  
pp. 12-21 ◽  
Author(s):  
S.M. Nasir ◽  
K.A. Ismail ◽  
Z. Shayfull

This study focuses on the analysis of plastic injection moulding process simulation using Autodesk Moldflow Insight (AMI) software in order to minimize shrinkage by optimizing the process parameters. Two types of gates which is single and dual gates have been analysed. Nessei NEX 1000 injection moulding machine and P20 mould material details are incorporated in this study on top of Acrylonitrile Butadiene Styrene (ABS) as a moulded thermoplastic material. Coolant inlet temperature, melt temperature, packing pressure and cooling time are selected as a variable parameter. Design Expert software is obtained as a medium for analysis and optimisation to minimize the shrinkage. The polynomial models are obtained using Design of Experiment (DOE) integrated with RSM Center Composite Design (CCD) method in this study. The results show that packing pressure is a main factor that contributed to shrinkage followed by coolant inlet temperature, while melt temperature and cooling time has less significant for both single and dual gates. Meanwhile, single gate shows a better result of shrinkage compared to the dual gates.


2017 ◽  
Vol 36 (2) ◽  
pp. 51-74 ◽  
Author(s):  
Ying-Guo Zhou ◽  
Bei Su ◽  
Lih-Sheng Turng

Water-foamed injection molding (WFIM) uses conventional injection molding (CIM) with water as a physical foaming agent. Compared to CIM, WFIM is a much more complicated process. As such, it is critical to determine the processing conditions for fabricating quality parts using WFIM. We used the design of experiment (DOE) method based on the Taguchi method to determine the influence of the processing conditions on the morphological structure and ductility of PP/LDPE WFIM parts, which were investigated by tensile testing and scanning electron microscopy (SEM). Our research suggests that fabricating PP/LDPE super-ductile parts using WFIM is indeed feasible. Our research also indicates that there is a close relationship between the ductility and the foamed structures, both of which are deeply influenced by the processing conditions. The analysis of variance results shows further that the water content had the greatest influence on the ductility, followed by the melt temperature, packing time, packing pressure, and PP/LDPE ratio. However, the ductility was only slightly influenced by the mold temperature, injection pressure, and injection time in WFIM. As to the number of cells, the order of influence was melt temperature, water content, packing time, packing pressure, mold temperature, injection pressure, PP/LDPE ratio, and injection time, in that order. In addition, applying DOE is a quite effective method for deducing the optimal set of effective factors in WFIM to produce super-ductile parts with a maximum number of cells. To our knowledge, this is the first time that the relationship among the processing conditions, ductility, and foamed structure of PP/LDPE WFIM super-ductile parts has been investigated and reported.


2014 ◽  
Vol 699 ◽  
pp. 20-25 ◽  
Author(s):  
Mohd Amran ◽  
Siti Salmah ◽  
Abdul Faiz ◽  
Raja Izamshah ◽  
Mohd Hadzley ◽  
...  

The application of Taguchi method to reduce warpage in an injection moulding process is studied. The objective of this paper is to analyze the effect of injection moulding parameters, i.e., injection time, packing time, melt temperature and mould temperature, on the warpage defect in dumbbell plastics part. Optical comparator horizontal type was used to measure the difference of warpage value on each part. L9 orthogonal array with 3 replications was done with 27 totals of specimens. The result collected was optimized using Taguchi method and percentage of contribution was calculated using analysis of variance (ANOVA). According to the analysis, it is found that the significant factors affected warpage are injection time (32.01%), packing time (29.73%), mould temperature (24.39%) and melt temperature (13.87%). The optimum parameters for minimizing the warpage were injection time (1s), packing time (5s), melt temperature (270 °C) and the mould temperature (21 °C). By using Taguchi method and ANOVA analysis, optimum parameters and the percentage of contribution of parameters can be obtained. Thus, it shows that design of experiment method is the good quality tools to get the best quality for production.


2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Nik Mizamzul Mehat ◽  
Shahrul Kamaruddin ◽  
Abdul Rahim Othman

Shrinkage behavior is a crucial problem in manufacturing plastic molded gear. This is because it negatively affects the dimensional stability and accuracy of the involute profile, as well as the concentricity, roundness, tooth spacing uniformity, and size of the gear. By integrating the Taguchi robust design, Grey relational analysis, and principal component analysis, we investigated the dimensional stability related to the shrinkage of tooth thickness, addendum circle, and dedendum circle of molded gear via the optimization of processing parameters and glass fiber reinforcement. The results revealed that the optimal combination of the processing parameters of the molded gear to achieve minimum shrinkage is melt temperature of 260°C, packing pressure of 60%, packing time of 5 s, and cooling time of 30 s. The melt temperature showed the highest comparability sequence among the four key process parameters examined, followed by packing pressure, cooling time, and packing time. Meanwhile, the presence of glass fibers induced higher deviations of tooth thickness, addendum circle, and dedendum circle than those of the unfilled polyamide 6 gears.


Author(s):  
Sanam Shikalgar ◽  
Mahesh Zope ◽  
Pratik Sonawane ◽  
Deepti Marathe

A part to be injection molded is evaluated by simulation for warpage analysis. The plastic part is a supporting plate to be used in the oil filter and it’s made out of nylon material. The effect of various parameters from design to processing of plastic parts is considered and validated by simulation results. The research involved in this was designing mould, computer-aided engineering, simulation analysis, and determination of plastic part processing conditions. In this work PA66 (Grade name – Zytel 70G13HS1LNC010) material is used and the material contains 13 % of fiber. Fiber orientation is nothing but the distribution of plastic melt inside the cavity and it also plays important role in deciding the warpage of part. The effect of process parameters on part warpage is investigated from various aspects in comparison with the conventional runner system. Hot runner mould system with innovative cooling channel designs is good results-driven. Results of simulations reveal that elevated mould temperature reduces the unwanted freezing time during the injection phase and thus improves mouldability and enhances part quality. Under similar mould temperature conditions, the effect of process parameters on warpage decreases according to the following order, packing time, packing pressure, melt temperature, injection pressure, and cooling time respectively.


2012 ◽  
Vol 271-272 ◽  
pp. 1190-1194
Author(s):  
Hsueh Lin Wu ◽  
Ya Hui Wang

In this study, volumetric shrinkage at ejection of the chair base in the injection process, application of the 3D CAD software pro/e to design the shape of the product, and then combines moldflow simulation analysis and Taguchi method with L25 Orthogonal Array to determine the optimal injection molding parameters combination. In the Taguchi L25 experimental design, the six controlling factors used are melt temperature, mold temperature, injection time, packing time, packing pressure and cooling time, the result of experiment revealed that the optimum combination of parameters was the A2 (melting temperature 265°C), B3 (mold temperature 40°C), C2 (injection time 1.7sec), D4 (packing pressure 95%), E5 (packing time20sec), F5 (cooling time 20sec). The results show that the combination of Taguchi method and Moldflow can not only improve the molding process parameters effectively, but also optimize the quality of the products.


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