In-mold Decoration Research Articles

Barrel rifling node offset detection and subsequent optimization based on thin film in-mold decoration characteristics of the Johnson–Cook model

In this paper, a nodal detection method for the detection and optimization of barrel helix offsets is proposed. The barrel used in this experiment is a 6-helix barrel. Moreover, the special properties of the film of Polyetheretherketone (PEEK) material are used to cover the surface of the barrel helix with a virtual in-mold decoration (IMD) film, and the unique nature of the film die offset in the IMD is utilized to detect the position of the barrel helix. The area with a large die index is the area with a large helix offset in the barrel, and the IMD die index is introduced to quantify the data. The IMD die index is used to determine the helix offset of the damaged barrel. The novelty of this work is that each node can use the die index to efficiently detect the position of the barrel helix deviation, carry out subsequent optimization and repair work through the optimization of the injection molding parameters and the design optimization of the barrel and verify the experiment by comparing the results. Through the steady-state simulation research mode, different permutations and combinations of the two process parameters are simulated to study their effects. Quantitative reference indicators include but are not limited to dependent variables such as the fluid flow velocity, shear rate, temperature distribution and phase transition, and the shear heating process of the injection screw is taken into account in the mold flow analysis to ensure that the die index value is more accurate. It can be seen from the analysis results that the temperature of the barrel changes after the groove depth and groove width are changed, and the effect ratio of the groove depth is lower than that of the groove width in the same degree of size change.

Effect of Epoxy Conductive Adhesive on Film Deformation During the Thermoforming Process for In‐Mold Electronic Devices

AbstractIn‐Mold Electronics (IME) is an innovative technology that allows the creation of 3D‐shaped electronic surfaces by combining printed electronics and In‐Mold Decoration (IMD). During the manufacturing process, the materials that integrate these devices, such as adhesive, must endure the transformation conditions of thermoforming. However, the adhesive rigidity may influence the deformation of the film during this process. In this study, both printed and hybridized samples are compared regarding their stretching and thickness reduction during the thermoforming process. The results indicate that the deformation of the hybridized samples differs from the printed ones, resulting in less stretching in areas near the adhesive, with stretching increasing as it steps away from where it is deposited. Thickness values are also affected, being greater around the adhesive and decreasing farther away. Therefore, the presence of the adhesive significantly impacts the behavior of the film during processing, a factor that must be considered in the design of IME devices to maximize the number of functional devices.

Morphology and properties of PC/ABS notebook computer shell prepared by a combined in-mold decoration and microcellular injection molding process

In this paper, the PC/ABS notebook computer shells with PET film were prepared using a combined in-mold decoration and microcellular injection molding (IMD/MIM) process. Then the surface quality, morphology, impact toughness and wear resistance were investigated. The results shown that the surface quality is improved by IMD/MIM technology. The three dimensional surface roughness value (Sa) was about 1/3 of that of MIM parts. The cross-section of IMD/MIM samples have three layers. The first layer is a PET film decoration layer with about 132 µm thickness, followed by skin layer (about 22 µm) and foam layer. The range of thickness of the foam layer for the different specimens is about 7803 µm–7820 µm.The cell diameter is between 0.532 µm and 0.638 µm, which is about 2 times than that of MIM parts. Compared with MIM parts, the shape of the bubbles of IMD/MIM parts is ellipsoid with thinner wall. Moreover, the impact toughness of IMD/MIM parts are higher. The best impact toughness is 21.02 KJ/m2 within the scope of this experiment, which is 74% higher than the corresponding MIM part under the same foaming process. This may due to the PET film and micropores could block the initiation of the tip crack. Meanwhile, the IMD/MIM parts have excellent wear resistance property. In most cases, the wear rate of IMD/MIM parts is about 36.6% of MIM part under the same condition.

Fabrication of lightweight polymer products with excellent mechanical properties using a novel double-sided in-mold decoration combined with fiber-reinforced microcellular injection molding process

This paper introduces a novel molding process known as the double-sided in-mold decoration combined with fiber-reinforced microcellular injection molding (DS-IMD/FR-MIM) process. This process utilizes supercritical fluids to grow a microcellular structure for a lightweight product and adds glass fibers into polymer particles to reinforce mechanical properties. Concurrently, double-sided in-mold decoration (DS-IMD) technique provides a symmetric temperature field for melts during filling stage and high surface quality for parts after cooling. Tensile splines are simulated and tested to examine the impacts of various in-mold decoration methods on the melt temperature, freezing layer fraction, fiber orientation, cellular morphology and distribution, and mechanical properties. Applied splines include undecorated and fiber-reinforced microcellular injection molding (FR-MIM) spline, single-sided in-mold decoration combined with fiber-reinforced microcellular injection molding (SS-IMD/FR-MIM) spline, and DS-IMD/FR-MIM spline. Additionally, a flexural spline is used to test its flexural strength and surface quality. The results show that DS-IMD/FR-MIM process provides slower freezing speed and better foaming effect than FR-MIM process. It also generates more symmetric cellular distribution and more orderly fiber distribution than SS-IMD/FR-MIM process. DS-IMD/FR-MIM splines have high surface quality on decorated surfaces and 10.2 % weight loss. By comparison with FR-MIM and SS-IMD/FR-MIM splines, DS-IMD/FR-MIM splines increase an elongation at break by 24.3 % and 14.8 %, respectively. This paper contributes a feasible approach and theoretical groundwork for the fabrication of lightweight products with excellent mechanical strength and appearance.

The Cellular Structure and Mechanical Properties of Polypropylene/Nano-CaCO3/Ethylene-propylene-diene-monomer Composites Prepared by an In-Mold-Decoration/Microcellular-Injection-Molding Process.

Polypropylene (PP)-composite foams were prepared by a combination process of microcellular injection molding (MIM) and in-mold decoration (IMD). The effect of ethylene propylene diene monomer (EPDM) on the crystallization properties, rheological properties, microstructure, and mechanical properties of PP-composite foams was studied. The effect of the additives on the strength and toughness of PP-composite foam as determined by the multiscale simulation method is discussed. The results showed that an appropriate amount of EPDM was beneficial to the cell growth and toughening of the PP blends. When the content of EPDM was 15 wt%, the PP-composite foams obtained the minimum cellular size, the maximum cellular density, and the best impact toughness. At the same time, the mesoscopic simulation shows that the stress concentration is the smallest, which indicates that 15 wt% EPDM has the best toughening effect in these composite materials.

Cellular distribution and warpage deformation in double-sided in-mold decoration combined with microcellular injection molding process

Cellular distribution and warpage deformation in double-sided in-mold decoration combined with microcellular injection molding process

Investigation of film–substrate interfacial characteristics of polymer parts fabricated via in-mold decoration and microcellular injection molding process

The appearance quality of foamed polymer parts can be improved by introducing high-appearance quality decorative films. However, the interfacial bonding characteristics of film that penetrated the surface of the substrate are few studied. In this paper, the foamed polypropylene (PP) parts with decoration films penetrated on the surface were prepared by the in-mold decoration and microcellular injection molding (IMD/MIM) process. The interfacial characteristics of the IMD/MIM parts were investigated experimentally through peeling tests and interfacial morphology. Based on the finite volume method, the coupled heat transfer model was established to calculate the temperature field in IMD/MIM process by taking into account the coupled heat transfer between polymer melt, film, and mold. The thermal response in the IMD/MIM process was numerically analyzed. The results show that the higher temperature on the polymer melt–film interface corresponds to relatively higher crystallinity and larger crystallite size and also favors the forming of the β-form crystal, which is beneficial to higher adhesion strength. The IMD/MIM parts can obtain a firm film–substrate adhesion and a uniformly strong bond between the film and the substrate.

Introducing surface functionality on thermoformed polymeric films

We present a fabrication process for the production of 3-dimensional micro-structured polymeric films. The microstructures are fabricated in a single step using thermal nanoimprint lithography as patterning technique. The micro-structured polymer films are then transformed into a 3D shape by means of a plug-assisted thermoforming process, while keeping the functionality of the micro-patterned areas. The preserved functionality is characterized by water contact angle measurements, while the deformation of the micro-structured topographies due to the thermoforming process is analyzed using confocal microscopy and Digital Image Correlation (DIC) techniques. This combined fabrication process represents a promising solution to complement in-mold decoration approaches, enabling the production of new functional surfaces. As the microstructures are fabricated by means of a mechanical modification of the surface, without the need of chemical treatments or coatings, the presented technique represents a promising, simple and green solution, suitable for the industrial fabrication of 3D nonplanar shaped functional surfaces. • A method to produce 3-dimensional micro-structured polymeric films by combination of nanoimprint lithography and thermoforming is presented • The surface microstructures defined by Nanoimprint Lithography induce surface hydrophobicity which is maintained after the thermoforming process. The microstructures defined by nanoimprint induce surface hydrophobicity which is maintained after the thermoforming process. • The strain induced by the thermoforming process deforms the microstructure, affecting the functional properties. • This combined process complement in-mold decoration approaches with the introduction of new functional surfaces.

Investigation on Film-Substrate Interfacial Characteristics of Parts Fabricated Via a Novel Integrated In-Mold Decoration and Microcellular Injection Molding Process

Investigation on Film-Substrate Interfacial Characteristics of Parts Fabricated Via a Novel Integrated In-Mold Decoration and Microcellular Injection Molding Process

Effect of film types on thermal response, cellular structure, forming defects and mechanical properties of combined in-mold decoration and microcellular injection molding parts

Different types of polymer films were used in the combined in-mold decoration and microcellular injection molding (IMD/MIM) process. The multiphase fluid-solid coupled heat transfer model was established to study the thermal response at the melt filling stage in the IMD/MIM process. It was found that the temperature distributed asymmetrically along the thickness direction due to the changed heat transfer coefficient of the melt on the film side. When polyethylene terephthalate (PET) films were applied, the temperature of the melt-film interface increased faster and to be higher at the end of melt filling stage in comparison with the application of polycarbonate (PC) and thermoplastic polyurethane (TPU) films. And the effects of film types on the cellular structure, forming defects and mechanical properties of IMD/MIM parts were also studied experimentally. The results showed that the film types had no obvious effect on the cells size in the transition layer and the mechanical properties of the parts. Under certain film thickness, the offset distance of core layer was the largest with PET film used, while the offset distance was the smallest with TPU film used. And similar results were found for the warpage of the parts. However, an exactly opposite change occurred for the thickness of film-side transition layer and the bubble marks on the surface of the parts.

Effect of POE on mechanical properties and cellular structure of PP/Nano-CaCO3 composites in IMD/MIM process

Nano-CaCO3 can effectively improve the strength of foamed Polypropylene (PP), ethylene-octene copolymer (POE) can greatly enhance the toughness of PP, and PP-g-MAH can improve the compatibility of Nano-CaCO3 with PP. The supercritical fluid-nitrogen (N2) was used as physical foaming agent, and the PET film was selected to study the effect of POE content on the mechanical properties and cellular structure of PP/nano-CaCO3 blends during combined in-mold decoration and microcellular injection molding (IMD/MIM) process. The results showed that the addition of POE did improve the impact strength of PP/nano-CaCO3 composites, while the tensile strength and flexural strength decreased. On account of the characteristics of POE, the melt strength change of PP/nano-CaCO3 blend system after POE’s addition was studied. The melt strength of the blend system decreased at first and then increased. It can be found that POE distributed uniformly in PP, and POE particle size decreased with the increase of POE content. Besides, it was revealed that POE could improve the cellular structure of the vertical section and the parallel section. The mechanical properties and cellular structure were optimized when 10% POE was added.

Investigation on Foamed PP/Nano-CaCO3 Composites in a Combined in-Mold Decoration and Microcellular Injection Molding Process.

A combined in-mold decoration and microcellular injection molding (IMD/MIM) method has been used in this paper. The foamed PP/nano-CaCO3 composites were prepared to investigate their mechanical properties, cellular structure, and surface quality. The content of nano-CaCO3 varied from 0 to 10 wt %. The results showed that nano-CaCO3 acted as a reinforcing phase and nucleating agent, which help to improve the mechanical properties of foamed composites. The cellular structure and mechanical properties were optimum when the nano-CaCO3 content was 6 wt %. In the vertical section, the cell size and density of transition layer on the film side was bigger than that on the non-film side. In the parallel section, the cell ratio of length to diameter of transition layer on the film side was smaller than that on the non-film side, and the cell tile angle was larger than that on the non-film side. With nano-CaCO3 content increasing, the surface quality showed a trend of decreasing first and then increasing.

Investigation on forming defects and crystallization of plastic parts in combined in-mold decoration and microcellular injection molding based on a multiphase flow-solid coupled heat transfer model

Microcellular injection molding (MIM) combined with in-mold decoration (IMD) method can produce foamed parts with improved surface appearance by changing the heat transfer in the MIM mold. The temperature field has a significant effect on the forming defects and crystallization of the foamed parts. Based on finite volume method, a multiphase flow-solid coupled heat transfer model was established to calculate the temperature field in IMD/MIM process, and the implicit domain coupling algorithm (IDCA) was used to calculate the temperature field by taking the coupled heat transfer between the mold and the polymer melt into account. Compared with the experimental results, it is found that the established model can accurately predict the temperature field. The thermal response in IMD/MIM process was further analyzed. The effect of film on the forming defects of parts molded by IMD/MIM process was discovered by combining the simulation results with the experimental surface topography and warpage results, and the effect of film on the crystallization of parts molded by IMD/MIM process was also revealed.

Mechanism of Bubble Formation in a Combined In-Mold Decoration and Microcellular Foaming Injection Molding Process

A combined in-mold decoration and microcellular foaming injection molding process (IMD/Mucell) is proposed to improve the surface quality of foamed parts. Through theoretical inference, the mathematical models of temperature field, velocity profile and forces on bubble were established with combining traditional mathematical models and the different heat transfer coefficient of the mold inner surface. The effects of the non-isothermal mold on the bubble structure and forming process of inter bubble were investigated with experiments and numerical simulation. Results showed that the critical pressure of the cavity existed in the melt filling and bubble expanding stage, and it affected the cells structure obviously at the filling stage. The lift force took the bubbles to the film side based on the velocity profile of viscous fluid, and maximal bubble was closer to the transition layer with film due to higher temperature. In the combined process, the evolution rule of superficial bubbles was analyzed, and results showed that the surface quality was improved in the film side.

A Combined In-Mold Decoration and Microcellular Injection Molding Method for Preparing Foamed Products with Improved Surface Appearance.

A combined in-mold decoration and microcellular injection molding (IMD/MIM) method by integrating in-mold decoration injection molding (IMD) with microcellular injection molding (MIM) was proposed in this paper. To verify the effectiveness of the IMD/MIM method, comparisons of in-mold decoration injection molding (IMD), conventional injection molding (CIM), IMD/MIM and microcellular injection molding (MIM) simulations and experiments were performed. The results show that compared with MIM, the film flattens the bubbles that have not been cooled and turned to the surface, thus improving the surface quality of the parts. The existence of the film results in an asymmetrical temperature distribution along the thickness of the sample, and the higher temperature on the film side leads the cell to move toward it, thus obtaining a cell-offset part. However, the mechanical properties of the IMD/MIM splines are degraded due to the presence of cells, while specific mechanical properties similar to their solid counterparts are maintained. Besides, the existence of the film reduces the heat transfer coefficient of the film side so that the sides of the part are cooled asymmetrically, causing warpage.

Design of the printing pattern on film for three‐dimensional molded interconnect devices

AbstractThis article discusses the application of an in‐mold decoration (IMD) technology for the development of three‐dimensional molded interconnect devices (3D‐MID). The 3D‐MID process uses the film printing technology to print the circuit pattern on a plastic film, and then deform it to the shape of the component by thermoforming. Then, the plastic film is placed inside the mold cavity for injection molding, and is attached to the surface of the component after molding. Experiments were performed for the 3D‐MID process using a semisphere shape. A simple geometric model was also proposed to correlate the printed film patterns before and after the thermoforming. The geometric model will be used to design the required printing pattern on a 2D film for a given 3D pattern on a component.

The Future Looks Bright for In‐Mold Labeling

Plastics EngineeringVolume 73, Issue 5 p. 28-30 Printing & Decorating The Future Looks Bright for In-Mold Labeling IML decoration expands into new materials, markets and processes, including thermoforming Nancy D. Lamontagne, Nancy D. LamontagneSearch for more papers by this author Nancy D. Lamontagne, Nancy D. LamontagneSearch for more papers by this author First published: 01 May 2017 https://doi.org/10.1002/j.1941-9635.2017.tb01710.xAboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume73, Issue5May 2017Pages 28-30 RelatedInformation

Effect of asymmetric cooling system on in-mold roller injection molded part warpage

In-mold decoration (IMD) injection molding has been the most promising surface decoration technique in recent years, with the in-mold roller (IMR) injection molding being the most automated production process. During the IMR process, heat transfer in the cavity surface is significantly retarded because of the low thermal conductivity of film. As a result of the asymmetric melt and mold temperature, thermal-induced part warpage easily occurs. To understand the variation in the temperature field of the core and cavity caused by the plastic film, this research uses simulation and experiments to investigate the influence of the mold's (core-and-cavity) asymmetric cooling system temperature on product warpage, and examines the impact of the film's heat retardation effect on the crystallinity, tensile strength, and surface roughness of the treated products. Our results show that the film causes a higher contact temperature between the hot melt and mold during the molding process, resulting in asymmetric temperature in the mold (core and cavity), increasing the crystallinity of the cavity and consequently increasing product warpage. In plastic, the warpage increase is from 0.03mm to 0.62mm when the film thickness is 0.175mm and the temperatures of the mold and hot melt are 50°C and 230°C, respectively, a great increase than with steel (P20). With the asymmetric cooling system design, in which the cavity temperature is 50°C and the core temperature is 65°C, the warpage can be reduced by 53%. For crystallinity and crystalline size, the film heat retardation effect of the IMR process increases the crystallinity of the cavity by 16%, and the crystallite size by 12%, along with some increase in tensile strength. In addition, the IMR process can also increase the smoothness of the product surface, reducing the surface roughness by 50%.

The application of carbon black and printing ink technology in molded interconnect devices

Abstract In this article, the processing of molded interconnect devices (MIDs) was studied via in-mold decoration (IMD) molding technology. A screen printing process using carbon black and printing ink was proposed in the study. For comparison, various conductivity materials such as copper powder, iron powder, carbon black and silver composite were studied with the screen printing method. The results show that there is no electrical conductivity for the ink containing copper or iron powder up to 90% concentration. The low cost carbon black with printing ink was shown to be successful for the IMD process.

Mechanical Behaviors and Thermoforming Features of PMMA Used In-Mold Decoration

Mechanical behaviors and thermoforming features of plastic material PMMA-IRK-304 used in-mold decoration are studied in this paper. Dynamic mechanical analysis experiments, uniaxial tension tests at several high temperatures and different stretching velocity were carried out to analysis and explain the phenomenon of yielding, strain softening and strain hardening. Results showed that the glass transition temperature range of PMMA-IRK-304 films was suitable for thermoforming of in-mold decoration.