Blow Moulding Research Articles

Modelling Stretch Blow Moulding of Poly (l-lactic acid) for the Manufacture of Bioresorbable Vascular Scaffold.

Stretch blow moulding (SBM) has been employed to manufacture bioresorbable vascular scaffold (BVS) from poly (l-lactic acid) (PLLA), whilst an experience-based method is used to develop the suitable processing conditions by trial-and-error. FEA modelling can be used to predict the forming process by the scientific understanding on the mechanical behaviour of PLLA materials above the glass transition temperature (Tg). The applicability of a constitutive model, the ‘glass-rubber’ (GR) model with material parameters from biaxial stretch was examined on PLLA sheets replicating the biaxial strain history of PLLA tubes during stretch blow moulding. The different stress–strain relationship of tubes and sheets under equivalent deformation suggested the need of re-calibration of the GR model for tubes. A FEA model was developed for PLLA tubes under different operation conditions, incorporating a virtual cap and rod to capture the suppression of axial stretch. The reliability of the FEA modelling on tube blowing was validated by comparing the shape evolution, strain history and stress–strain relationship from modelling to the results from the free stretch blow test.

Minimize Defects in 5 Liters Jerry Cans by Using Statistical Quality Control and Root Cause Analysis

PT. DS2 is one of the producers of household appliances, kitchen utensils, and children's toys to bottles and jerry cans, to produce 5 liters of jerry using 2 Blow Molding machines that can produce an average jerry of 6750 / plastic jerry per day. In the production process there are defects found in 5 liter jerry products. This study aims to determine the cause of defect, what factors cause defect. Method used in this research is SQC and RCA in an effort to determine the defect in the 5 liter jerry production process. From the results of research that has been done, the highest value of disability is PL bloom defect with 1686 pcs with a cumulative percentage of 41%. Based on the analysis using the control p chart that all percentages of defective pruduct are still in the control chart and declared safe.

FMEA tool to analysis of blow molding machine damage

Machine performance in industry has a vital role in the production floor. The machine operates smoothly will support the achievement of production targets. One sector produces packaging products made based on plastic experiencing a failure production process due to the frequent stopping of the Blow Molding Machine. Fishbone diagram and Failure Mode and Effect Analysis (FMEA) is used to find information about the factors cause the Blow Molding Machine to stop. Fishbone diagram is used to determine the factors cause the failure of the Blow Molding Machine in running the production process. FMEA is used to identify the factors causing loss and determine the priority level of risk based on the RPN value. The mold damage factor has the highest RPN value. Mold failure is most significant cause of Blow Molding Machine stops operating. The mold is damaged when stored in the spare part warehouse due to crushed by a material made of metal. Mold is stored in an unsuitable location. Analysis using a fishbone diagram to determine the root of the problem handled.

Infrared Heating Modeling of Recycled Pet Preforms in Injection Stretch Blow Molding Process

Infrared Heating Modeling of Recycled Pet Preforms in Injection Stretch Blow Molding Process

Evaluation of bonding integrity of hybrid-built AlSi10Mg-aluminium alloys parts using the powder bed fusion process

Recent advances in metal additive manufacturing (AM) technology enable complex conformal cooling channels to be fabricated for injection and blow mould inserts. However, high manufacturing costs hinder the technology being adopted in the mould-making industry. A cost-effective hybrid strategy was developed for the powder bed fusion (PBF) process in which powder materials get additively deposited onto pre-machined substrates as a practical cost-reduction solution. In this study, the interface bonding integrity, in terms of microstructure and mechanical properties, of powder AlSi10Mg and three types of substrate aluminium alloys were evaluated. Microstructure analysis revealed excellent powder-substrate fusion across the narrow interface of the three samples. All tensile specimens ruptured at least 5 mm away from the bonded interface, at the side where the material was of lower strength. Samples fabricated with AlSi10Mg-Alumec 89 alloys had the highest tensile strength of 481 MPa, about the same as standard as-built AlSi10Mg aluminium. Using the PBF-machined substrate hybrid AM strategy, Alumec 89, a high strength tooling-grade aluminium alloy, can be used as the base substrate for the fabrication of durable and high-performance aluminium injection and blow mould inserts.

Parameter identification of transport PDE/nonlinear ODE cascade model for polymer extrusion with varying die gap

AbstractA new transport PDE/nonlinear ODE cascade model is proposed to simulate extrudate thickness for polymer extrusion with varying die gap. The model is developed to simulate extrusion in extrusion blow moulding. A finite element method simulator is used as a reference for the proposed model to replicate its time dependent extrudate thickness profile. The parameters of the proposed model are identified by minimizing the response error between the proposed model and the finite element method simulator due to step inputs. The novel model is computationally cheap, suitable for controller design, and effective in simulating the extrudate thickness.

Numerical and experimental validation of an explicit meshfree method: With applications to material forming

Meshfree methods were introduced twenty-five years ago to overcome a range of issues faced by mesh-based methods, which predominately relate to the issues of mesh-entanglement, which can result in poor accuracy. Although meshfree methods have progressed significantly over these years, the application of these techniques to real-world material forming problems is limited, despite the potential benefits they can provide over traditional mesh-based methods. This paper is concerned with the meshfree simulation of the stretch blow moulding process, which is the primary manufacturing process used to produce polymer bottles. Traditionally, the finite element method has been used to simulate this process, however, difficulties are often encountered during these simulations, which can cause reduced accuracy. In this paper, a nodally integration explicit element-free Galerkin method is formulated. Firstly, the formulation is validated through several numerical problems, which display the accuracy, and computational efficiency of the proposed method. Following this, the experimental characterisation of the stretch blow moulding process is discussed. Finally, the developed formulation is utilised to construct a validated simulation of the stretch blow moulding process. The accuracy obtained in the stretch blow moulding simulations highlights the capability of the explicit meshfree formulation, which has the potential to be applied to a wide range of large deformation phenomena.

Effect of infill pattern on mechanical properties of 3D printed PLA and cPLA

PLA are the most sustainable alternatives and can fit in a wide-range of applications of electronics, nonwoven fabrics and food packaging. With these PLA’s adaptability and suitability in many techniques of production such as injection moulding, extrusion, and blow moulding, PLA has become high interest in the production process. Besides, PLA as a thermoplastic polyester that mostly obtained from renewable materials [1]. Infill patterns can affect the mechanical properties of 3D printed PLA and cPLA. PLA with zig zag infill pattern has higher tensile strength of 23.409 MPa compared to PLA with grid and concentric infill pattern. Meanwhile, cPLA with grid infill pattern has higher tensile strength of 30.5638 MPa compared to cPLA with concentric and zig zag infill pattern. By using the suitable infill pattern parameter, the 3D printed PLA and cPLA can have good mechanical properties and can be applied in packaging, pharmaceuticals, textiles, automotive, biomedical and tissue engineering. It has been widely investigated for biomedical applications due to its biodegradability and biocompatibility.

Blowing Kinetics, Pressure Resistance, Thermal Stability, and Relaxation of the Amorphous Phase of the PET Container in the SBM Process with Hot and Cold Mold. Part II: Statistical Analysis and Interpretation of Tests.

The technology of filling drinks without preservatives (such as fresh juices, iced tea drinks, and vitaminized drinks) is carried out using hot filling. Mainly due to the production costs and lower carbon footprint, polyethylene terephthalate (PET) bottles are increasingly used in this technology. In this paper, the main aim is to describe and interpret the results of statistical analysis of the influence of the temperature of the blow mold in the SBM (stretch blow molding) process and the method of hot filling on the macroscopic and microscopic bottle properties. The macroscopic bottle properties were defined by the thickness profile, pressure resistance, thermal stability, and the coefficients of blowing kinetics. In addition, the influence of the SBM process on the microscopic PET material properties (in the bottle) relative to the microscopic preform properties was analyzed. The microscopic properties were defined by the degree of crystallite, density, and relaxation of the amorphous phase of the PET material. For this purpose, response surface experiments were performed for the two analyzed factors, i.e., the temperature of the blow mold and the method of hot filling. The sample size was investigated to determine the minimum number of repetitions (number of bottles in the measurement series) required to achieve acceptable measurement uncertainty. The research conducted shows that, despite fulfilling the postulate of acceptable measurement uncertainty, in terms of the power of ANOVA (analysis of variance) in DOE (design of experiment), the accepted number of bottles in the measurement series is too small. The tests of the bottle material density, material crystallite, and relaxation of amorphous phase relative to the preform material density, material crystallite, and relaxation of amorphous phase show that microcavity effects occur during the deformation of the PET material, and that these are associated with the orientation of the microstructure. The blow kinetics study shows that there is a gradient of flow of the bottle material over the thickness of the bottle wall during blowing, and it has been deduced that the air temperature between the blow mold and the wall of the blown bottle has an impact on the kinetics of blowing the bottle.

Blowing Kinetics, Pressure Resistance, Thermal Stability, and Relaxation of the Amorphous Phase of the PET Container in the SBM Process with Hot and Cold Mold. Part I: Research Methodology and Results.

The technology of filling drinks without preservatives (such as fresh juices, iced tea drinks, vitaminized drinks) is carried out using hot filling. Mainly due to the production costs and lower carbon footprint, polyethylene terephthalate bottles, commonly called PET, are increasingly used in this technology. In this paper, the main aim is to describe the statistical analysis methodology of the influence of the temperature of the blow mold in the SBM process and the method of hot filling on the macroscopic and microscopic bottle properties. The macroscopic bottle properties were defined by the thickness profile, pressure resistance, thermal stability, and the coefficients of blowing kinetics. Moreover, the influence of the SBM (stretch blow moulding) process on the microscopic PET material properties (in the bottle) relative to the microscopic preform properties was analyzed. The microscopic properties were defined by the degree of crystallite, density, and relaxation of the amorphous phase of the PET material. For this purpose, response surface experiments were performed for the two analyzed factors (independent variables), i.e., the temperature of the blow mold and the method of hot filling. The sample size was investigated to determine the minimum number of repetitions (number of bottles in the measurement series) required to achieve acceptable measurement uncertainty. The research conducted shows that despite fulfilling the postulate of acceptable measurement uncertainty, in terms of the power of ANOVA (analysis of variance) in DOE (design of experiment) the accepted number of bottles in the measurement series is too small. The tests of the bottle material density, material crystallite, and relaxation of amorphous phase relative to the preform material density, material crystallite, and relaxation of amorphous phase show that the microcavity effects occur during the deformation of the PET material, and that these are associated with the orientation of the microstructure. The blow kinetics study shows that there is a gradient of flow of the bottle material over the thickness of the bottle wall during blowing, and it has been deduced that the air temperature between the blow mold and the wall of the blown bottle has an impact on the kinetics of blowing the bottle.

Prototipado rápido en la fabricación de moldes impresos en 3D para soplado de plástico

En la industria salvadoreña pueden encontrarse empresarios y microempresarios que no tienen los recursos para fabricar botellas de plástico con diseños estilizados que los diferencien de otras marcas y productos, lo que les impide escalar a otros segmentos de mercado o mercados internacionales, frenando el crecimiento de sus negocios. Una posible causa es que la fabricación de moldes de soplado requiere una inversión inicial muy costosa. Sin embargo, existen alternativas como la fabricación de moldes de bajo rendimiento, que tienen una resolución más baja y un tiempo de vida más corto, pero, al mismo tiempo, ofrecen como beneficio un menor costo de fabricación y, por lo tanto, un menor costo de adquisición para el empresario, posibilitando la producción de botellas estilizadas a conveniencia. Entre las diversas formas de fabricar moldes de bajo rendimiento está la técnica de ingeniería inversa, que requiere un equipo de creación rápida de prototipos. Este artículo describe el procedimiento de ingeniería inversa para generar el molde para soplado. Con el diseño disponible se imprimió el molde necesario y con esto se fabricaron las botellas, que se escanearon para verificar con el programa de computadora sus dimensiones comparándolas con el archivo original del molde. Simultáneamente, los contenedores se verificaron en el laboratorio de metrología industrial para validar los resultados de la computadora, estos resultados se presentan en el documento.

Numerical simulation of self heating during stretch blow moulding of PET: viscohyperelastic modelling versus experimental results

During the stretch blow moulding (SBM) process of polyethylene terephthalate (PET) bottle, high viscous dissipation generates self heating phenomena. Since the influence of temperature on polymer’s behavior is important, it is necessary to evaluate the self heating values in order to manage accurately the simulation of the process. An anisotropic visco-hyperelastic model has been developed to manage numerical simulations of free blowing. The model takes into account the anisotropy and the effect of the temperature. It has been computed in a user-interface VUMAT implemented in the software ABAQUS/Explicit. The identification of the model is based on experimental data of biaxial tension tests. We identified the characteristics taking into account the self-heating effect by a semi analytical process followed by an adjustment using finite element. For sake of validation, PET preforms have been blown from different initial temperature and followed using a thermal camera. The increase of temperature is measured by comparing initial temperature and final temperature. Comparison between the experimental and numerical simulations is discussed and influence of initial temperature or blowing pressure is highlighted in a large numerical investigation.

Risk Factors Identification of Fire Incidents in 2017-2018

Introduction: The massive development of the industrial sector leads to an increase in the risk of fire incidents. A company is obligated to prevent, reduce, and extinguish fire incidents by providing training and facilitating supporting tools to avoid fire incidents in the workplace. PT. ARPS is a Surabaya-based manufacturing company that produces plastic packaging and has a potential danger of medium to high levels. By applying the case study design, as an observational study, this study aims to identify the factors that influence and trigger the fire incidents at PT. ARPS during 2017-2018. Methods: The population of this study is the workers of the Assembly Decoration 1 (AD1) and the Blow Molding (DM) production areas. The collected data are analyzed and presented descriptively through tables and narration. Results: The data show that the first fire incident occurred on 10 February 2017 to the KK6 machine in the AD1 area, followed by the second incident that occurred on 18 March 2018 to the VK4 machine in the BM area, and the third incident (30 March 2018) to the KKS6 machine in the AD1 area. Conclusion: It can be stated that the three fire incidents at PT. ARPS that occurred from 2017 until March 2018 are caused by unsafe actions that are the negligence of the human resources, and unsafe conditions, which comprise the unstable machines. Other factors, such as supervision, maintenance, work instruction, and managerial, are identified as the upholding factors to the fire incidents at PR. ARPS. Keywords: factor identification, fire incident, unsafe action, unsafe condition

Study on the Effect of Gas Pressure on Bottle Wall Thickness in the Blow Molding Process

Study on the Effect of Gas Pressure on Bottle Wall Thickness in the Blow Molding Process

Pet Şişe Şişirme Makinelerinde Fırın Optimizasyonu

In this study, we have consulted the information of Pet Bottle Machine manufacturers and end users; Located in a limited number of Pet Bottle Blowing Machines in Turkey has been conducted on ovens. After the preform moves around its axis since it enters the machine and reaches the required heat by passing through the oven sections, bottles are obtained by giving 40 bar high pressure in the blowing unit. The quality of the obtained bottles is very important. The reason for this is that the labeling, filling and palletizing machines are also included in the continuation of Pet Bottle Blowing Machines. If the bottles are of poor quality, the entire line stops. The most important way to ensure that the bottles are produced in a robust manner is the efficient heating of the preforms, the raw material of the bottle. This study provided more efficient application of heat treatments of prefoms. In the heat treatment of the preform, to optimize the oven zone; PLC, HMI, temperature controls, thermal heat meter, thermocupl and thermal camera are used. The instantaneous temperature values obtained from the thermal heat meter, thermocupl and temperature controls are processed to the PLC as a reference and necessary adjustments are made available to the user via HMI. The reference values imported to PLC were developed using ST language in Codesys based software. In this study, instant values are shown on the panel. By using these data, heat optimization of infrared lamps in Pet Bottle Blow Molding Machines despite variable weather conditions is provided. The heat taken from the oven, the preform which is the raw material of the bottle, which has been optimized by the software, is observed with the thermal camera; The results were compared with the standard oven. In the context of the data obtained, it was observed that the software positively affected the preform and caused the production of bottles of better quality and cost-effective which are not affected by the changing climate conditions.

Overcoming geometric limitations in metallic glasses through stretch blow molding

Bulk metallic glasses (BMGs) exhibit remarkable mechanical properties, such as high strength and elasticity, which is often paired with fracture toughness. Their supercooled liquid region gives rise to plastic-like processing and suggests parts and shapes that can otherwise not be obtained for crystalline metals. However, current processing techniques only allow for limited options in terms of geometry, thicknesses uniformity, and shape complexity. Here we introduce a new processing technique, “stretch blow molding,” to expand the range of possible parts and increase the available geometries that can be fabricated with BMGs. Additionally, a model is derived that allows for the quantification and prediction of stretch blow molding and provides insight into its potential use and limitations. We demonstrate that with stretch blow molding overall strains exceeding 2000% are achievable, compared to the previously reported ∼150% of blow molding. With the ability to stretch blow mold shapes that were previously unachievable with any other metal fabrication technique in a fast and economical manner, and the superb properties of BMGs, we look forward to a broad commercial adaptation of this technique.

Experimental characterisation on the behaviour of PLLA for stretch blowing moulding of bioresorbable vascular scaffolds

Processing tubes from poly (l-lactic acid) (PLLA) by stretch blow moulding (SBM) is used in the manufacture of bioresorbable vascular scaffolds (BVS) to improve their mechanical performance. To better understand this processing technique, a novel experimental setup by free stretch blow inside a water bath was developed to visualise the tube forming process and analyse the deformation behaviour. PLLA tubes were heated, stretched and blown with no mould present inside a temperature-controlled water bath whilst recording the processing parameters (axial force, inflation pressure). The onset of pressure activation relative to the axial stretch was controlled deliberately to produce a simultaneous (SIM) or sequential (SEQ) mode of deformation. Real-time images of the tube during forming were captured using high speed cameras and the surface strain of the patterned tube was extracted using digital image correlation (DIC). The deformation characteristics of PLLA tubes in SBM was quantified by analysis of shape evolution, strain history and stress-strain relationship.

Influence of Initial Value of Transient Time Step on Numerical Simulation of Blow Molding Balloon

The correlation between the initial time value of transient iterative parameters and the blowing pressure in the numerical simulation process of blowing balloon is investigated by POLYFLOW. The results show that: 1) As the blow molding pressure increases, the boundary value of the iterative time step decreases rapidly at first and then slowly. At the end of the first step of iterative calculation for each boundary value, the balloon parison is in the mold core cavity. 2) If the initial time value of transient iterative parameters is smaller than the boundary value of the iterative time step, the balloon parison is still in the mold core cavity at the end of the first iteration. However, if the iterative calculation continues, the calculation process may be interrupted when the time step is smaller than the initial time value of the transient iterative parameters, which makes the blow molding simulation of balloon unable to continue. 3) It is suggested that the initial time value of transient iterative parameters is one order of magnitude smaller than the boundary value of the iterative time step to complete smoothly the simulation of blow molding balloon.

Experimental characterisation and modelling of polyethylene terephthalate preform for injection stretch blow moulding

Polyethylene terephthalate (PET) is a widely used polymer in the production of bottles by injection stretch blow moulding (ISBM). In this work, we present a characterisation method to identify material properties directly from a preform, considering temperature and stress-relaxation effects related to its viscoelastic response. A customised oven and gripping system were designed to perform uniaxial tests in a proper temperature range on tubular specimens obtained from preforms. A visco-hyperelastic model is then proposed: a Marlow-type strain energy function coupled with a Prony series and William-Landel-Ferry equation to include time and temperature dependency. Finally, a case study of ISBM process is implemented in a finite element code considering this constitutive model. Strain maps and predicted thickness of the bottle wall were evaluated as process quality indicators. Simulation results showed good agreement with measurements on the real processed bottle, confirming the usefulness of the approach for product or process parameters optimisation.

Predictive Modeling for Quality Assurance of Extrusion Blow Molding

Predictive Modeling for Quality Assurance of Extrusion Blow Molding