Plastic Injection Moulding Research Articles

Analysis of Equipment for Testing the Processability by Injection Molding of Plastics on the Basis of Axiomatic Design Principles

The obtaining of information concerning the processability by injection of plastics could facilitate a better design of injection manufacturing processes of parts made of such materials. With this aim in view, equipment for testing the processability by injection of plastics was designed. On the other hand, there are known the possibilities of using the axiomatic design principles to solve equipment or various design activities problems. Within this paper, an evaluation of the complying with the requests of the axiomatic design by the designed equipment was developed. The axiom of independence of the functional requirements necessary to be achieved by the equipment was applied. The analysis allowed the formulation of some remarks concerning the fulfillment of some principles of axiomatic design by the constructive solution proposed for the equipment for testing the processability by injection of plastics.

Minimum Warpage Prediction in Plastic Injection Process using Taguchi Method and Simulation

Plastic materials are used in automobile, electrical and electronic applications, agricultural utilization, household and furniture products, and medical equipments. Among various plastic manufacturing process, injection molding is one of the most commonly used and common methods applied for forming plastic products in the industry. The process requires a molten polymer being injected into a cavity of a mold, which is cooled and the product ejected from the mold. During the Plastic Injection Molding (PIM) process, various defects, such as volumetric shrinkage, warpage, weld line and sink mark can occur. This paper presents a method to minimizing warpage defect on PolyPropylene AZ564 via PIM simulation using Moldflow software. The approach was based on Taguchi method.Through the effectiveness of this proposed method, it is confirmed using simulation by Moldflow software. The effect of the process parameters on the warpage of a motorcycle number plate bracket, is studied using analysis of variance (ANOVA). From the ANOVA, the significant parameters affecting the process are holding time, holding pressure and injection pressure. The result of the Taguchi prediction shown that minimum warpage is 1.078 mm, which is 7.14% and 9.09% different from the simulation result and experiment, respectively.

Occupational ergonomics research and applied contextual design implementation for an industrial shop-floor workstation

The aim of this original research article is to identify the occurrence of work-related ergonomics risk factors, in order to implement context specific human centered design interventions in the injection molding shop-floor workstations of plastic furniture manufacturing factories within the framework of industrially developing countries. Questionnaire study, postural assessment tools, computer aided design, digital human modeling and simulation, and basic work study techniques were used. Plastic processing industry is highly fragmented, consisting of small, medium scale enterprises with tremendous growth potential. Occupational design ergonomics research in the injection molding plastic furniture manufacturing shop-floor workstations is very scarce in industrially developing countries. Shop-floor workers are affected by prevalent awkward working postures and consequent body part discomforts. Useful and easily implementable accessories/fixtures with convenient design features were conceptualized. Virtual ergonomics evaluation of the workstation with proposed accessories/fixtures showed significant reduction of awkward working postures. Physical prototypes of the proposed fixtures were constructed and real human trials were performed in the factories. Time study indicated reduction in operator cycle time when compared with time taken before design modifications. Research methodology, results and design solutions described from an ergonomics perspective would definitely serve as a helpful guide for existing as well as upcoming factories in the injection molded plastic furniture manufacturing industry of industrially developing countries and further similar research endeavors.

FDM Modeled Polymer Tooling for Plastic Injection Molding

FDM Modeled Polymer Tooling for Plastic Injection Molding

Design of Conformal Porous Structures for the Cooling System of an Injection Mold Fabricated by Additive Manufacturing Process

Abstract The cooling system of plastic injection mold plays a critical role during the injection molding process. It not only affects part quality but also its cycle time. Traditionally, due to the limitations of conventional drilling methods, the cooling system of the injection mold usually consists of simple paralleled straight channels. It seriously limits the mobility of cooling fluid, which leads to the low cooling efficiency for the parts with complex free-form surfaces. In this research, an innovative design method for the cooling system of an injection mold is proposed by using conformal porous structures. The size and shape of each cell in the conformal porous structure are varied according to the shape of an injection molded part. Design cases are provided at the end of this paper to further illustrate the efficiency of the proposed method. Compared with those existing design methods for the uniform porous structures, the proposed method can further reduce the nonuniformity of the mold surface temperature distribution and decrease the pressure drop of the cooling system.

The Effect of Processing on The Surface and Subsurface Characteristic of Plastic Injection Mold Steel

AISI P20 is prehardened mold steel that is commonly used to manufacture plastic injection molding. The surface characteristics of molds play crucial role to control plastic injected molds parts. Besides, the characteristic of molds is mainly influenced by machining process, the manufacturing process to produce molds. This study presents the extensive experimental work focusing on the machining processing conditions on the surface characteristics of Plastic Injection mold steels. The input parameters are cutting speeds, feed rates and cutting inserts’ geometry (wiper and non-wiper). The measured output parameters are subsurface hardness of machined parts and phase transformation induced from cutting process. Experimental results show that wiper insert significantly helps to improve surface quality of components. Besides, microhardness measurement shows that thermal softening occurs resulting from machining of this alloy. XRD data illustrates peak broadening and increased intensity with machined samples.

Advancements in Design And Fabrication of Conformal Cooling Channels for Improvement in Plastic Injection Molding Process

Advancements in Design And Fabrication of Conformal Cooling Channels for Improvement in Plastic Injection Molding Process

Effect of Melt Temperature on Weld Line Strength

This article deals with the influence of the melt temperature on weld line strength in injection-molded plastic parts. A special mold was created for this investigation to make specimens with a central weld line. The experimental material was polypropylene Sabic PP 90910. Its stress at break is around 16 MPa and its melting temperature is between 200°C and 260°C. In general, the presence of weld lines has a negative impact on mechanical properties. This investigation showed that the strength depends on the melt temperature (160–260°C in this case). Strength was measured using mechanical testing. It was found to increase with the melt temperature, up to 210°C. Above 210°C, degradation of the plastic led to decreasing strengths. A melt temperature range of 190–210°C is therefore optimal for this application. Shear forces and friction were found to play a great role, as they raise the melt temperature during molding. This was confirmed by mold-flow analysis. The melt temperature during molding was up to 18% higher than the initial melt temperature. This investigation has important consequences for the plastic industry. It is relevant to evaluations of the polymer matrix strength in composite materials and the strength of 3D printed parts with multiple weld lines.

The Effects of Injection Parameters and Foaming Agent on Dimensional Accuracy of Produced Parts in Plastic Injection Molding

The Effects of Injection Parameters and Foaming Agent on Dimensional Accuracy of Produced Parts in Plastic Injection Molding

Optimization of Process Parameters of Plastic Injection Molding Machine by using Taguchi Method

Optimization of Process Parameters of Plastic Injection Molding Machine by using Taguchi Method

Impact of human resources on remanufacturing process, internal complexity, perceived quality of core, numerosity, and key process indicators

• Managers must pay special attention to retain specialized personnel; indirect effects from human resources are significant. • Experience is the most important element of remanufacturing process and it´s required personnel to stay in the company. • Because of a bad perception of quality core, cost of spare partes and engineering changes will increase. • Because of a bad perception of quality core, total cost, energy consumption and processing time will increase. This article assesses the impact of human resources experience and its training level on key process indicators, perceived quality of core, and internal complexity of remanufactured metal-mechanic products. These five elements were integrated as latent variables composed of 13 observed variables and associated through seven hypotheses. Data was gathered from six remanufacturing companies located in the Northern Border of Mexico, including 480 different metal-mechanic remanufactured products such as auto parts, molds for plastic injection molding, and turbine components. Hypotheses were validated using a Structural Equation Model and partial least square. Results indicate that the experience and training of human resources has a positive impact on the perceived quality of core and key process indicators, but not on internal complexity of the remanufacturing process; however, these variables are indirectly associated through perceived quality of core and key process indicators.

Optimization of mold temperature profile and process parameters for weld line reduction and short cycle time in rapid heat cycle molding

Weld line reduction is one of the major concerns in plastic injection molding (PIM) that results in high surface appearance and high strength of a plastic product. To resolve this issue, rapid heat cycle molding (RHCM) has attracted attention as an innovative PIM technology. In the RHCM, the mold temperature profile plays a crucial role in weld line reduction. On the other hand, high productivity as well as high surface appearance is also required in the PIM, and the trade-off between them will be observed. To achieve weld line reduction and high productivity simultaneously, it is important to adjust both the mold temperature profile and other process parameters in RHCM. A trial and error method is so widely used to adjust them, but it is much time-consuming task. In this paper, the mold temperature profile and several process parameters are optimized for the weld line reduction and the short cycle time. Therefore, multi-objective design optimization is performed. Numerical simulation in PIM is so intensive that a sequential approximate optimization using radial basis function is adopted to identify the Pareto frontier with a small number of simulations. The trade-off between the weld line reduction and the cycle time is clarified through the numerical result. Based on the numerical result, the experiment using a PIM machine (GL100, Sodick) is carried out. It has been confirmed through the numerical and experimental result that the proposed approach in RHCM is valid for the weld line reduction and the short cycle time.

A Study on the Characteristics of Plastic Injection Molding Using Core in Core Cooling Technology

A Study on the Characteristics of Plastic Injection Molding Using Core in Core Cooling Technology

An experimental investigation to optimise injection moulding process parameters for plastic parts by using Taguchi method and multi-objective genetic algorithm

Plastic injection moulding is a useful method to produce plastic parts with high-quality surface finish. Improper process parameter settings can cause many production troubles namely defective products, reduce dimensional precision and scrap. Thus, determining the optimal processing parameters is regularly performed in injection moulding industry. In this paper, to determine the initial range of process parameters steady state experiments were performed. Taguchi method and multi objective genetic algorithm are used to optimise the process parameters of electric meter box and to reduce its shrinkage and warpage and to enhance its impact strength. For this purpose L27 orthogonal array was used. The modified linear graph was used with the line separation method to assign the parameters and interactions to various columns of the orthogonal array. The confirmation experiments show that the errors associated with prediction of shrinkage, warpage and impact strength are 5.11%, 5.91% and 1.171% respectively.

Continuous improvement of injection moulding using Six Sigma: case study

Plastic injection moulding is considered as one of the very challenging processes to obtain output with a good quality and low cost. This paper presents a case study of the deployment of Six Sigma in plastic injection moulding to improve the quality of the final product by eliminating major defects occurred using cost effective methods. The main objective is to identify the major quality problems and to eliminate root causes by adopting Six Sigma define, measure, analyse, improve and control (DMAIC) methodology. The proposed Six Sigma approach effectively integrates quantitative and qualitative tools such as statistical process control (SPC) charts, Pareto chart, histogram, Ishikawa diagram, measurement system analysis, hypothesis test and checklist to achieve the desired goal. The results reveal that the implementation of the proposed Six Sigma approach can reduce the rejection rate significantly. It is found that the quality of the final products is substantially improved in terms of sigma level which increased from 4.06 to 4.5 and the cost of poor quality (COPQ) is reduced by 45%.

Human-robot collaborative reconfigurable platform for surface finishing processes

Surface polishing can be counted among the most challenging manufacturing operations, especially when high qualitative levels in terms of surface texture characteristics are requested, such as in the case of polishing operations for plastic injection moulds. Robot-based solutions for surface polishing and quality assessment operations have been proposed at the state of the art, but it still is required the involvement of skilled workers for process supervision and final tuning operations. The introduction of human-machine collaborative solutions opens new opportunities, as the use of symbiotic polishing approaches, where both the humans and the machines capabilities can be shared to improve process effectiveness. The current work proposes a human-robot collaborative approach for surface polishing processes that integrates state of the art robot-based polishing and surface quality assessment technologies in a human-safe shared working environment. As a proof of approach feasibility, the paper presents the prototype of a reconfigurable platform designed to implement a flexible human-robot collaborative scenario for execution of polishing and quality assessment operations. Preliminary demonstrative polishing sessions on simple and complex components validate the system effectiveness with respect to manufacturing efficiency and reconfigurability capabilities. The results obtained provide a first positive response that symbiotic approach can objectively improve the polishing processes.

A Hierarchical Approach for Solving Simultaneous Lot Sizing and Scheduling Problem with Secondary Resources

This study represents a decomposition heuristic approach for simultaneous lot sizing and scheduling problem for multiple product, multiple parallel machines with secondary resources. The motivation of the study comes from the real-world instance of a plastic injection plant at Vestel Electronics. The plastic injection plant requires plastic injection molds at the planner’s disposal, in order to produce variations of products, by the compatible plastic injection machines. The variations on the molds and the mold changes on the machines bring out sequence dependent major and minor setups. Since each machine requires an operator, we have extended the formulation with workforce and shift planning. Results show that proposed heuristic yields comparable solutions to that of exact model for small and medium size instances; and provides schedules for the large size instances, for which exact model cannot find a feasible solution in the allotted time.

An experimental investigation to optimise injection moulding process parameters for plastic parts by using Taguchi method and multi-objective genetic algorithm

Plastic injection moulding is a useful method to produce plastic parts with high-quality surface finish. Improper process parameter settings can cause many production troubles namely defective products, reduce dimensional precision and scrap. Thus, determining the optimal processing parameters is regularly performed in injection moulding industry. In this paper, to determine the initial range of process parameters steady state experiments were performed. Taguchi method and multi objective genetic algorithm are used to optimise the process parameters of electric meter box and to reduce its shrinkage and warpage and to enhance its impact strength. For this purpose L27 orthogonal array was used. The modified linear graph was used with the line separation method to assign the parameters and interactions to various columns of the orthogonal array. The confirmation experiments show that the errors associated with prediction of shrinkage, warpage and impact strength are 5.11%, 5.91% and 1.171% respectively.

Thermo-fluid Topology Optimization and Experimental Study of Conformal Cooling Channels for 3D Printed Plastic Injection Molds

Abstract With the advent of additive manufacturing, innovative design methods, such as network-based techniques, and structural topology optimization have been used to generate complex and highly efficient cooling systems in recent years. However, methods that incorporate coupled thermal and fluid analysis remain scarce. In this paper, a coupled thermal-fluid topology optimization algorithm is introduced for the design of conformal cooling channels. The problem is formulated based on a coupling of Navier- Stokes equations and convection-diffusion equation. The problem is solved by gradient-based optimization after analytical sensitivity derived using adjoint method. With this method, the channel position problem is replaced to a material distribution problem. The material distribution directly depends on the effect of flow resistance, heat conduction, natural and forced convection. The algorithm leads to a two-dimensional conceptual design having optimal heat transfer and balanced flow, which is further transformed into three-dimensional cooling channel design. Here, a comprehensive study is presented, starting from design, simulation, 3D printing process and experimental testing of an injection mold with conformal cooling channels in industrial production environment. A traditional mold model is provided by an industrial collaborator. To enhance the overall thermo-fluid performance of the mold and improve final product quality, a redesign of this mold core is done with conformal cooling channels inside. The final design is 3D printed in pre-alloyed tool-steel powder Maraging Steel using Truprint 3000 metal 3D printing machine. The printed core required some heat treatment and finishing processes and added features to be incorporated to make it production ready. Once all the preparation was complete, the core was tested experimentally in a multicavity injection molding machine in real industrial environment at our industrial partner’s production facility. This paper describes all the steps starting from design, analysis, die 3D printing and finally ending at final experimental testing, as well as recommendations for tool designer and injection molding industry to implement additive manufacturing for their benefit. This paper is not just focused on a specific aspect such as design, simulation or manufacturing, but rather a comprehensive paper presenting a case study on implementation of topology optimization and additive manufacturing in real life industrial production scenario.

Optimization of Nozzle Section in Plastic Injection Moulding Process

Optimization of Nozzle Section in Plastic Injection Moulding Process