Injection-molded Parts Research Articles

Design and Fabrication of Injection Molds to Manufacture Double Channel Laryngoscope for Effective Airway Management: Taguchi Method for Surface Roughness Optimization

The present work focuses on the mold design and production of the multifunctional device laryngoscope with surface quality through the injection molding process. A laryngoscope is a device used by anesthesiologists to lift the tongue that facilitates to fix the air pipe in the larynx. Demand still exists in the laryngoscope part to assist anesthesiologists to take care of the airway without causing chest compression and ensure visualization of vocal cords. Therefore, the present work aims at developing a laryngoscope with a double channeled device, wherein one for aligning the camera and another for the air pipe. The paper outlines the design parameters required for manufacturing a single cavity mold to produce a laryngoscope viz. injection molding machine. The mold has multiple plates with complex fluid channels which ensures effective thermal management in-mold system. The mold is manufactured using high-strength tool steel materials and the product laryngoscope (ABS: Acrylonitrile butadiene styrene) is fabricated from the designed mold. Taguchi L9 experimental array was used to determine the optimal conditions (injection pressure, injection velocity, mold and melt temperature) for desired surface finish in the laryngoscope parts. The designed mold and optimized injection molding conditions resulted in a lower surface roughness value equal to 0.214 µm. Thereby, injection-molded laryngoscope parts can be used for large-scale productions for the benefit of medical applications.

Plastic filling simulation comparison analysis of the gating system in injection moulding parameter

The paper is discussed the anticipation of the simulation software precision with the real moulding process by setting up the distinctive metering stroke separation. The Inventor CAD software was used to design the product experiment and perform the simulation by applying MoldFlow application to produce the processing parameter defining for the injection moulding machines. The results predicted by this filling simulation appears reasonable result as compared to the injected product. Prediction analysis given by the software is exceptionally valuable for the injection moulding parameter setting machines which can diminish the time of mould setup and can reduce the trial stage on the production line. The gating system is the most crucial part in injection moulding process and the limitation is to get the accurate filling time and injection pressure to ensure the cavity is fully filled before the material at the gate solidify. Gating system configurations are utilized to optimize the filling conditions of injection moulding parts. This important element was developed for achieving product quality. The utilize of simulation software is exceptionally supportive in the model designing stage to predict the quality and process capacity for the product. This paper presents the filling simulation of the side gate system to the injection moulding parameter.

Influence of Iron-Based Powder Additive on a Shape Accuracy of Injection Moulded Parts

Abstract This paper reviews the effects of iron-based powder on shape accuracy of injection moulded parts. Analysed specimens were produced on a micro injection moulding machine. At first, specimens of pure polypropylene (PP) were manufactured. Then specimens containing 1, 2 and 3 vol. % of iron powder additive were produced using the same process parameters. Subsequently, the samples were scanned using scanned using Zeiss METROTOM CT scanner. Results were analysed via CAE inspection tools. The main aim was to compare the shape and flatness of the scanned specimens to the nominal models. Results showed that iron-based additives of this vol.% had no significant effect on shape accuracy of produced parts. This paper is a partial result of the ongoing research focused on effect of iron and steel-based additives on material, magnetic and mechanical properties of polymers.

Comparison of Melting Processes for WPC and the Resulting Differences in Thermal Damage, Emissions and Mechanics.

The necessity for resource-efficient manufacturing technologies requires new developments within the field of plastic processing. Lightweight design using wood fibers as sustainable reinforcement for thermoplastics might be one solution. The processing of wood fibers requires special attention to the applied thermal load. Even at low processing temperatures, the influence of the dwell time, temperature and shear force is critical to ensure the structural integrity of fibers. Therefore, this article compares different compounding rates for polypropylene with wood fibers and highlights their effects on the olfactory, visual and mechanical properties of the injection-molded part. The study compares one-step processing, using an injection-molding compounder (IMC), with two-step processing, using a twin-scew-extruder (TSE), a heating/cooling mixer (HCM) and an internal mixer (IM) with subsequent injection molding. Although the highest fiber length was achieved by using the IMC, the best mechanical properties were achieved by the HCM and IM. The measured oxidation induction time and volatile organic compound content indicate that the lowest amount of thermal damage occurred when using the HCM and IM. The advantage of one-time melting was evened out by the dwell time. The reinforcement of thermoplastics by wood fibers depends more strongly on the structural integrity of the fibers compared to their length and homogeneity.

Additive Surface Graining in Prototype Tooling for Injection Molding

Surface properties of injection molded parts have a strong effect on the visual and haptic perception of the parts by customers. Especially for injection molded automotive interior parts, grained surfaces can often be found. In conventional tooling, graining requires separate process steps. This makes the realization of grained injection molded prototype parts very complex. By additive manufacturing of injection molds in prototype tooling, it is possible to print micro structures into the mold surface in one printing operation. An injection mold with four different graining structures varying in depth and distance was designed and additively manufactured. The specification regarding the surface graining was analyzed by means of roughness measurements of the CAD model, injection mold and injection molded parts. Results show the feasibility of highly controllable additive surface graining.

Development and Characterization of Polylactide Blends with Improved Toughness by Reactive Extrusion with Lactic Acid Oligomers

In this work, we report the development and characterization of polylactide (PLA) blends with improved toughness by the addition of 10 wt.% lactic acid oligomers (OLA) and assess the feasibility of reactive extrusion (REX) and injection moulding to obtain high impact resistant injection moulded parts. To improve PLA/OLA interactions, two approaches are carried out. On the one hand, reactive extrusion of PLA/OLA with different dicumyl peroxide (DCP) concentrations is evaluated and, on the other hand, the effect of maleinized linseed oil (MLO) is studied. The effect of DCP and MLO content used in the reactive extrusion process is evaluated in terms of mechanical, thermal, dynamic mechanical, wetting and colour properties, as well as the morphology of the obtained materials. The impact strength of neat PLA (39.3 kJ/m2) was slightly improved up to 42.4 kJ/m2 with 10 wt.% OLA. Nevertheless, reactive extrusion with 0.3 phr DCP (parts by weight of DCP per 100 parts by weight of PLA–OLA base blend 90:10) led to a noticeable higher impact strength of 51.7 kJ/m2, while the reactive extrusion with 6 phr MLO gave an even higher impact strength of 59.5 kJ/m2, thus giving evidence of the feasibility of these two approaches to overcome the intrinsic brittleness of PLA. Therefore, despite MLO being able to provide the highest impact strength, reactive extrusion with DCP led to high transparency, which could be an interesting feature in food packaging, for example. In any case, these two approaches represent environmentally friendly strategies to improve PLA toughness.

Effect of Flax/PP pellets’ morphology on the mechanical properties of injection-molded parts

Flax and polypropylene (PP) pultrudates of 4.76 mm in diameter were produced using a multi-die pultrusion system. The flax content was 50 vol.%. Pultrusion conditions were varied to produce four porosity content between 4% and 22%. The pultrudates were pelletized into lengths of 6 and 15 mm, and injection-molded with pure PP to reduce the part flax content to 25 wt.%. Results showed that well consolidated pultrudates, having porosities up to 8%, were more resilient to the pelletizing process such that the pellets remained structurally intact after the process. These pellets went smoothly through the hopper into the injection molding machine screw. Pellets with void content higher than 8% lost integrity during pelletizing leading to uniform mixing. Exposed fibers segregated from the polymer in the hopper leading to ununiform mixing. The highest mechanical properties improvement compared to pure PP was using 15 mm pellets that had a prorosity of 8%. The tensile modulus doubled at 4652 ± 113 MPa. The impact strength increased by almost five times at 10.5 ± 0.7 [Formula: see text]. 15 mm pellets provided 1.7 times the impact strength of the 6 mm pellets. These improvement are attributed to low flax fiber thermal degradation and improved fiber dispersion.

Fabrication and Property Characterization of Long-Glass-Fiber-Reinforced Polypropylene Composites Processed Using a Three-Barrel Injection Molding Machine.

Processing equipment and parameters will highly influence the properties of long-fiber-reinforced injection-molded thermoplastic composites, leading to different fiber lengths and orientations. Thus, maintaining fiber length during the injection molding process is always a big challenge for engineers. This study uses long-glass-fiber-reinforced polypropylene with 25 mm fiber length and a special-built novel injection molding machine with a three-barrel injection unit, including a plasticizing screw, an injection plunger, and a packing plunger, to fabricate injection molding parts while retaining long fiber length. This study also discusses the influence of process parameters, such as back pressure, screw speed, melt temperature, and different flow paths, on the properties of long-glass-fiber-reinforced composites. The experiment results show that a higher screw speed and back pressure will reduce the fiber length in the injection-molded parts. However, using appropriate parameter settings can maintain the fiber length to more than 10 mm. It was found that by increasing the back pressure, the cross direction of the fiber orientation can be increased by up to 15% and the air trap volume fraction can be decreased by up to 86%. Setting appropriate back pressure under a low screw speed will increase the tensile strength. Finally, it was found that the single-edge-gate path results in a higher tensile strength than that of the single-sprue-gate path due to the retainment of longer fiber length in the injection-molded part.

Effect of Gas Counter Pressure on the Surface Roughness, Morphology, and Tensile Strength between Microcellular and Conventional Injection-Molded PP Parts.

Microcellular injection-molded parts have surface defect problems. Gas counter pressure (GCP) is one of the methods to reduce surface defects. This study investigated the effect of GCP on the surface roughness, morphology, and tensile strength of foamed and conventional injection-molded polypropylene (PP) products. GCP is generated by filling up the mold cavity with nitrogen during the injection-molding (IM) process. It can delay foaming and affect flow characteristics of microcellular and conventional injection-molding, which cause changes in the tensile strength, flow length, cell morphology, and surface quality of molded parts. The mechanism was investigated through a series of experiments including tuning of GCP and pressure holding duration. Surface roughness of the molded parts decreased with the increase in GCP and pressure holding duration. Compared to microcellular IM, GCP-assisted foaming exhibited much better surface quality and controllable skin layer thickness.

Properties of Liquid Crystal Injection Mouldings

Abstract The suitability of liquid crystal polymers for the injection moulding process was pointed out at the time of their discovery. However, up to now, it has been assumed that the unmodified liquid crystal polymers were less suited to processing by injection moulding due to their distinct anisotropies. The direction of developments in the application of liquid crystal polymers was done mainly in another direction. We, however, have been concerned for more than four years now with this subject [3, 4, 5], even when our practical experiments could not be as comprehensive as we would wish, due to the limited availability of the raw materials. We have also been able to use this time to develop CAE programs which support the constructor in the design of injection moulds, whereby these programs enable the flow process to be simulated and therefore enabling the orientation to be seen at every point in the injection moulded part [6]. This is naturally particularly important for those materials in which the orientation of the molecules plays such a large part for the respective properties, as these are caused by the direction of the flows in the flow process. A changed runner position causes other orientations. More details should therefore be reported about our investigations to date.

Surface Defects of TPO Injected Foam Parts for Automotive Applications

Abstract Benefits of reduced vehicle weight can have an important environmental impact since there is a 6 to 8% improvement in fuel efficiency for every 10% in weight reduction. In this work, foaming technology is used to produce injection molded TPO parts (thermoplastic olefin compounds) for the automotive industry with a minimum of 20% weight reduction while retaining a glossy surface quality. It was found by Guo et al. (2006, 2007) that the best strategy to raise the surface quality was to decrease the shot size, the cycling time and the temperature of the injected melt. However, the targeted objective of a minimum of 20% weight reduction was not achieved in these preliminary experiments. Therefore, in this work a blend of TPO and maleic anhydride modified polypropylene (PP-g-MA) was used in order to promote TPO foamability and improve the surface quality of injected parts. Under these conditions, we managed to produce injected molded TPO samples with a 24% weight reduction and good surface quality. Moreover, we investigated the effect of PP-g-MA in the TPO system by performing rheological measurements and photoacoustic Fourier transform infrared (PA-FTIR) analysis to characterize the PP-g-MA physico-chemical interactions with TPO.

UCsim2: two-dimensionally structured illumination microscopy using UC2.

State-of-the-art microscopy techniques enable the imaging of sub-diffraction barrier biological structures at the price of high costs or a lack of transparency. We try to reduce some of these barriers by presenting a super-resolution upgrade to our recently presented open-source optical toolbox UC2. Our new injection moulded parts allow larger builds with higher precision. The 4× lower manufacturing tolerance compared to three-dimensional printing makes assemblies more reproducible. By adding consumer-grade available open-source hardware such as digital mirror devices and laser projectors, we demonstrate a compact three-dimensional multimodal setup that combines image scanning microscopy and structured illumination microscopy. We demonstrate a gain in resolution and optical sectioning using the two different modes compared to the widefield limit by imaging Alexa Fluor ® 647- and Silicon Rhodamine-stained HeLa cells. We compare different objective lenses and by sharing the designs and manuals of our setup, we make super-resolution imaging available to everyone. This article is part of the Theo Murphy meeting issue 'Super-resolution structured illumination microscopy (part 2)'.

An Investigation to Reduce the Effect of Moisture on Injection-Molded Parts through Optimization of Plasticization Parameters

Plastic materials can absorb moisture from the atmosphere even after drying. This absorbed moisture can cause many defects in the molding process. Conventionally, a dryer is used to reduce the moisture content. However, the use of a drying unit involves huge daily power consumption and is also time-consuming. Therefore, this study proposed a new method to reduce the impact of moisture on molded product part quality through the optimization of plasticization parameters while reducing drying time. Two plastic materials, polyurethane (TPU) and polycarbonate (PC), were used for the experimental verification. Key plasticization parameters, including back pressure, screw rotation speed, and barrel temperature were chosen; their influence was investigated by the design of experiments (DOE). Moisture-induced defects, such as air bubble area, part surface gloss, and appearance were measured and correlated with the plasticization parameters. It was found, after optimization via a three-level DOE and factorial design multivariate statistical analysis using TPU, that the gloss (GU) of the PC part without drying was very close to that (98.4 GU) of the fully dried PC. The proposed methodology may help molders to improve production efficiency and achieve cost savings.

On-demand forklift hailing system for Intralogistics 4.0

The shift to I4.0 is happening. While large companies have a range of solutions to implement that change, small and medium-sized enterprises (SME) fall short on solutions tailored for their specific needs. To support SMEs in their transformation toward I4.0, we propose a lightweight system to hail forklifts in a production facility of a medium-sized enterprise.Existing shop floor workflows are implemented within the system and allow machine operators to hail forklift drivers using an embedded or a web-based client. Forklift drivers receive driving instructions on their smartphones. Shift managers can monitor intralogistic activities on a dashboard. Management can extract relevant production and forklift KPIs from the system.In a two-week evaluation phase, we installed our system in a production facility for injection moulded plastic parts. We equipped 12 machines and two forklifts and registered a total of 690 jobs. We found half of the jobs were picked up in 4:05 min and 80% of all jobs were completed in less than 40:02 min.

Study on Algorithms for the Virtual Assembly and Best Combinations of In-line Measured Injection-Molded Parts

Geometrical deviations of manufactured parts affect the quality of the resulting product. In an assembly, deviations accumulate so that the functional requirements may no longer be met. Therefore, the compliance of geometrical interfaces is of great importance in order to achieve a high-quality product. Modern 3D sensors capture dense point clouds of manufactured parts and thus enable creating a part’s geometrical digital twin. However, there are no suitable registration techniques that allow computing the assembly of the measured parts. With the knowledge of the assembly configuration, the geometrical accumulation can be determined, ultimately allowing the prediction of the quality of the final product. In the authors preceding work, the virtual assembly registration technique was presented methodologically. This paper focusses on the implementation of a dedicated use case. As real-world problem, the assembly of injection-molded covers and housings is examined. The data acquisition is fully integrated into an in-line measurement process. Therefore, a fringe projection system is used for capturing 3D data. Specific segmentation approaches are presented in order to detect the part and to segment assembly-relevant geometries in the measurement data. Due to possible artefacts in the point clouds, strategies for increasing the robustness are discussed. Finally, the developed quality prediction is embedded in the production context. In order to achieve time, cost, and quality benefits, a selective assembly strategy is applied that reduces the number of scrap parts by a factor of two and more.

Use of a digital image correlation method for full-field shrinkage measurement in injection molding

An original methodology using Digital Image Correlation (DIC) has been designed to precisely measure full-field shrinkages of injection molded polymer plates and then to give the opportunity to compare quantitatively extensive numerical simulations to experiments. The principle of the methodology is based on the full-field strain determination between a reference image of the mold and that of injection-molded parts, which are 275 × 100 × 2.2 mm3 plates. To allow for DIC calculation, 50 µm-depth engravings were machined by electro-discharge process at the surface of the mold. The result of the analysis is a 2D full-field shrinkage map over the whole plate surface (i.e. flow and transverse), with a standard deviation of 0.03%. The marking density has been shown to have a roughly linear influence on the precision of shrinkage measurement. This methodology allows the quantification of the effect of several injection parameters on in-plane shrinkage fields: holding pressure, injection flow rate and direction, geometry of injection gates, or geometrical constraints. Once the best set of parameters of material constitutive laws is identified for the simulation of polymer plates, the simulation procedure is ready to be applied on more complex 3D geometries.

Measured and simulated examination of the propagation paths of structure‐borne sound using the structural intensity for fibre reinforced injection moulded thermoplastic parts

AbstractIn product development e.g. electromobility, engineers need to place special emphasis on acoustics. A large number of automotive interior components consist of injection‐moulded thermoplastic parts. If required these lightweight components are reinforced with fibres or fillings. This reinforcement leads to a higher vibration sensitivity and higher natural frequencies. Due to the fact that the auditory threshold decreases with a rising excitation frequency, a conflict of objective between acoustics and lightweight components exists. In order to influence the acoustic behaviour in early development stages, the structure‐borne sound including its source and propagation paths have to be analysed. An appropriate parameter by which to visualise these pieces is the structural intensity (STI) which is calculated by the product of velocity and stress. Previous investigations have mainly focused on the behaviour of isotropic materials e.g. steel calculated using FEM. An experimental determination of the STI is a challenge since the stress of a vibrating structure cannot be directly measured. Furthermore the experimental determination is limited to the surface of the structure. First investigations using FEM were carried out to examine composite materials with a unidirectional fibre orientation and revealed a high potential to influence the structural behaviour in acoustic matters, i.e. the transmission of structure‐borne sound. Therefore a current research project deals with the opportunities to influence the vibro‐acoustic behaviour of injection moulded parts using the structural intensity. In this paper a method is presented to examine the influence of fibres, fillings and geometric modifications on the STI for injection moulded parts using FEM. A method to measure the STI for orthotropic parts is also presented. In addition to a comparison between the measured and the simulated results, a look‐ahead at planned future investigations in the research project is given.

Reducing the Burn Marks on Injection-Molded Parts by External Gas-Assisted Injection Molding.

A burn mark is a sort of serious surface defect on injection-molded parts. In some cases, it can be difficult to reduce the burn marks by traditional methods. In this study, external gas-assisted injection molding (EGAIM) was introduced to reduce the burn marks, as EGAIM has been reported to reduce the holding pressure. The parts with different severities of burn marks were produced by EGAIM and conventional injection molding (CIM) with the same molding parameters but different gas parameters. The burn marks were quantified by an image processing method and the quantitative method was introduced to discuss the influence of the gas parameters on burn marks. The results show that the burn marks can be eliminated by EGAIM without changing the structure of the part or the mold, and the severity of the burn marks changed from 4.98% with CIM to 0% with EGAIM. Additionally, the gas delay time is the most important gas parameter affecting the burn marks.

Fabrication of Micro-Groove on the Surface of CFRP to Enhance the Connection Strength of Composite Part.

Carbon fiber-reinforced plastic (CFRP) has the advantages of being light weight, high strength, and corrosion resistant. At present, it is widely used in the lightweight design of automobile parts. The manufacturing of lightweight parts inevitably involves the connection between CFRP and the polymer material. The connection strength between CFRP and the polymer material significantly affects the service life of the composite parts. Taking CFRP and polyamide 6 (PA6) injection-molded composite parts as an example, this paper proposed a technological method to enhance the connection strength between CFRP and PA6. The proposed method was to fabricate micro-groove structures on the CFRP surface by compression molding. These micro-groove structures effectively increased the injection-molding area of the composite parts, thus enhancing the connection strength between CFRP and PA6. This paper presented a detailed study on the compression-molding process of micro-grooves on the CFRP surface, and successfully obtained the appropriate parameters. Finally, PA6 was used for injection molding on the CFRP with micro-grooves at an injection pressure of 8 MPa, an injection temperature of 240 °C, a holding pressure of 5 MPa, and a holding time of 2.5 s. The experimental results show that the micro-groove array structures on the CFRP surface could effectively improve the tensile strength of the connection interface in the composite parts. Compared with the composite part without micro-grooves, the tensile strength of the composite part with micro-grooves was increased by 80.93%. The composite parts prepared in this paper are mainly used in automobile interiors and the research results of this paper meet the actual needs of the enterprise.

Investigation on surface roughness of injection molded polypropylene parts with 3D optical metrology

Investigation on surface roughness of injection molded polypropylene parts with 3D optical metrology