Mechanical properties of the weld line defect in micro injection molding for various nano filled polypropylene composites. The flow of the material in the injection mould takes place through the gate. Mobile 0813; Shinko Sellbic Co. Adjust the position of the gate and include a venting slot. To determine the effect of the weld lines on tensile strength, tensile tests were conducted with the specimens fabricated with NORYL (amorphous blends of. In this way critical areas of the interface in regard to the lack of interdiffusion and the inappropriate molecular orientation were found to be placed near. A visual mold with variotherm system for weld line study in micro injection molding. In addition a weld line can be moved to an area where it is less visible. They can affect the strength and appearance of the part, depending on the temperature, pressure, speed, and mold design of the injection molding process. The gate is the critical bridge between the runners (the channels through which the molten plastic travels) and the actual mold. Materials Science. In some cases, a weld line can also cause a loss of strength and impact resistance. Table 2-Glass Fiber Glass Fiber Glass Fiber Glass Fiber A weld line refers to a line, notch or color change that is created on the molded part caused by the convergence of two separate flows of molten plastic. Try to gradually raise the mold temperature and barrel temperature. 3. The moldability validation and flow analysis tools enable you to iden-tify and correct potential injection molding problems as you design the product. Adjust Injection Molding Parameters: Optimizing injection speed, pressure, and temperature can help ensure better melt flow and reduce the likelihood of weld line formation. สาเหตุรองของการเกิดปัญหาการเกิดประกายเงิน (silver streak) 1. When an external load is applied to a weld line region, the part’s potential for mechanical failure is increased. A weld line is a visible seam where two areas of the molten plastic meet. This is expected to achieve maximum results while the pressure holding effect will also increase. Although this phenomenon occurs in almost all the commercially important polymer. To explore the formation of. If it only affects the appearance, it can change the position of the burn four to change the position of the weld line. In this paper, a weld line factor (W-L factor) was adopted to describe the. (1) make the mold vent larger at location with weld line; (2) Check if the mold vent is blocked or not or use vacuumized forming. 1. . Change the gate locations. Molding Equipment. Low mold temperatures are usually employed to decrease cycle molding time and final process costs; however, resulting surface defects include weld lines, sink. If you turn on the spigot to a garden hose, you will hear a hissing sound at the nozzle end for the first few seconds. Inadequate back pressure. 3. อุณหภูมิของพลาสติกเหลวสูงเกินไปจนก๊าซหรือความชื้นแยกตัวออกมาได้. T he decreased gloss level at the position of. Figure 1 below shows the development of a weld line. In the RHCM, the mold temperature profile plays a crucial. Known also as knit lines and weld marks, weld lines are difficult to eliminate completely, especially if your injection molded part requires holes. demanding injection molding and end-use requirements. • Reduce runner dimensions and maintain the same flow rate. Weld lines. The microstructure of weld lines is clearly observed from the micrographs. 3. For this purpose, the width of the weld line calculated by Sigmasoft is. This paper analyzes production data from injection molding processes to identify key interactions between the process variables from different material categories using the network inference method called “bagging conservative causal core network” (BC3net). This study presents an innovative approach to enhancing weld line strength in advanced polymer injection molding through applying gas-assisted mold. Our injection molding company is explaining what these imperfections are, why they can compromise. Interestingly, these materials have been shown to outperform long fiber thermoplastic (LFT) composites (in. The occurrence of a weld line means a significant problem both aesthetically and mechanically in the design of injection moulded parts. th INTRODUCTION Injection molding is one of the mostWeld lines have been one of the common defects puzzling the injection molding industry. Known methods to reduce weld-line effects are the optimization of injection molding parameters, enhanced tool temperature, and using special molding tool devices. 2023年1月3日 / by admin. Many works deal with weld lines and their dependence on processing parameters for conventional injection molding, but only a few works focus on the weld line in µIM. When this fails to happen correctly, a weld line defect occurs. A knit line in a plastic injection-molded part is created when two separate plastic flows meet within the mold and "resolidify" along their interface. Injection molding could be applied with many polymer materials, such as. This paper presents the. Injection molded plastic parts have comparatively less strength in the weld line section and they also have an impact on product aesthetics. The graph shows clearly how an increasing cavity temperature correlates with a reduction in the weld lines. Knit lines in injection molding are undesirable, especially when surface appearance and part strength are significant concerns. Bin-Xin Yang Ouyang Jie Supei Zheng Qiang Li Wen Zhou. Some of the common fixes for weld lines include: Increase the resin temperature to ensure both sides of the weld line are liquid when colliding. Effects of cavity surface temperature on mechanical properties of specimens with and without a weld line in rapid heat cycle. As the injection process continues, the two separated melt fronts meet again along the longitudinal section of the plate forming a weld line. In this mold, a visualization design and a rapid heating/cooling system were integrated, and specimens with different cross section. The impact behavior of weld-lines in injection molding. 2. It is a zone with reduced mechanical properties negatively influencing on the molding behavior in exploitation. The weld line is then created with a higher flow front temperature and is packed with more pressure. Expand. Change the gate locations. Effect of geometry and injection-molding parameters on weld-line strength. Learn how to avoid them and what injection molding companies do to prevent them. We'll show you how. Plastic Injection Molding Process. A tensile test specimen mold, which allows cavity thickness varying from 2. Fellahi et al. For glass-filled grades, the thickness at the weld line can be slightly larger than the nominal value due to lower shrinkage associated with vertical fiber orientation at the weld line cross. The wheel has to be gated at three places on the hub and. Insufficient plasticizing ability of injection molding machine. M. open access Abstract Micro weld lines are the common problem that occurs for plastic molded parts through injection molding process. Many researchers had emerged with several. and most commonly, thermoplastic polymers are used. Injection molding plate for mode I testing geometry. 2. These lines can occur due to variations in wall thickness, gate location, or the geometry of the part. This study describes how the weld line was formed on the part. 2. Which means engineers need to know how to account for this phenomenon in an efficient way. Nguyen-Chung. Thoroughly clean molding machine cylinders. In this regard, the plasticizing ability of the plastic injection moulding machine should be checked. Fracture Toughness of Weld Lines in Thermoplastic Injection Molding, Polymer Engineering and Science, 33(15): 996-1001. Injection molding. 005 0. They. 8. Failure may result due to the assembly torque, or end-use application loads (temperature, creep). Procedia Mater Sci 2014; 3: 2048–2053. ” Weld Lines in a plastic cover. Its design significantly impacts the final product’s appearance, strength, and functionality, making it crucial for manufacturers to understand its intricacies and variations thoroughly. A new kind of weld line was. In addition, its tensile strength and stiffness will be sharply decreased. + Increase mold temp, or materials’ temp, or holding pressure. Weld Lines. Its appearance can be improved by adjusting parameters. DescriptionThis insertion ensures the separation of the melt flow. 5. Mold flow analysis can predict the location of weld lines. Weld lines appear on the surface of a molded part where the molten material converges after splitting off into two or more directions in a mold. Injection molding is a highly versatile manufacturing process used to produce a wide range of plastic products with precision and efficiency. If the different flow fronts have cooled. Despite injection molding being recognized as a robust process for obtaining parts with high geometry accuracy, one last occurrence remains a challenge in micro-injection molding, especially when junctions are. Fracture behavior of weld lines in injection molded components loaded under real operating conditions. Islyn Thomas summarized the need for a particular vent location better than I ever could. 1 Prediction of weld lines with injection molding simulation softwareWeld lines in design for manufacture. Except for a few very simple injection molded parts, they occur on most injection molded parts (typically in the form of a line or V-groove), especially large complex items that require use of multi-gate molds and inserts. The thermo-rheological findings were used to investigate the sources of weld line weakness. However, research about the computer determination of weld lines in injection molding remains scarce. When molten plastic flows, it forms a smooth continuous flow until it meets an obstruction. These potential causes include:Known methods to reduce weld-line effects are the optimization of injection molding parameters, enhanced tool temperature, and using special molding tool devices. A meld line occurs when two moving melt fronts converge and flow parallel to each other. Meddad and Fisa [3] found that the weld line is a zone between 2 and 8 mm wide extending throughout the thickness in which the fibers are oriented almost. weld lines in infill analysis of injection molding simulation was observed [5]. Jiquan Li, Taidong Li, +1 author. In this study the polycarbonate (PC) and carbon fiber (CF) are used as the experimental materials to investigate the impact of injection molding process parameters on tensile strength of weld line. Published 5 July 2019. Weld lines are a kind of Achilles heel of plastics. Joe Henz is a chemical engineer with 30 years of experience in the plastics industry, primarily with GE. Wu CY, Ku CC, Pai HY (2011) Injection molding optimization with weld line design constraint using distributed multi-population genetic algorithm. Procedia Mater Sci 2014; 3: 2048–2053. This failure causes the product to be damaged during use. 2. Unless you are manufacturing an extremely simple part with one gate and a unidirectional flow front, your part will have weld lines. Meld lines are formed when two separate flow fronts meets. Therefore, the investigation on the developing process of weld line would be a significant issue for improving the quality of micro injection molded parts. They. Weld lines can be caused by material flowing around holes or inserts in the part, multiple injection gates or variable wall thickness where hesitation or "race tracking" can occur. This paper presents the. 4. DYNAPLAST Tbk. For multiple gate and complex part, molding weld-lines are unavoidable, therefore mechanical behavior of the weld-line needs to be predicted. Ideally, the resin flow will split into two flow fronts to pass around the obstruction and then recombine into a single flow front. Injection molding is a complex multi-variable, nonlinear and time-varying unsteady process, which makes it more difficult to optimize the process parameters. (2) Adjust the injection speed: high speed allows the melt to reach the confluence without cooling down, and low speed allows time for the air in the cavity to be discharged. Weld line and warping are two critical defects for injection-moulded part. (1) Flash: Extra plastic material in the shape of films or burrs, which appears on the parting surface, around the runner or in the insert crevice. Weld and meld lines are generally caused by holes or inserts in the part, multiple gates, variable wall thickness or hesitation and. As a result, the portion has a faint, perhaps undetectable line. NX Mold Flow Analysis. The weld lines in injection molded parts arise as a result of the collision of two fronts of the flowing material, which fills the mold cavity and are sometimes unavoidable [1][2][3] [4]. In. A flow mark is commonly referred to as a flow line occurs during the process of injection molding. Its appearance can be improved by adjusting parameters. Numerical results show that weld lines can be predicted accurately, and the formation and evolution processes of weld line can be shown more clearly by co-injection molding technique. ”Weld Lines in a plastic cover. Weld lines in injection molding are a type of cosmetic defect that detracts from a plastic part’s appearance. Melt temperature does effect the weld. 1. 298 µm and the weld line on the heated region was almost eliminated with the aid of induction heating. Weld lines in injection molding occur when two flow fronts meet and create a visible line on the surface of the molded part. For multiple gate and complex part. 2012. In the sense that the weld line is better formed before the resin temperature. A weld line occurs when two or more molten plastic flows meet and fuse during the injection molding process, resulting in a visible line on the surface of the molded part. Flash. Re-balancing entire manufacturing lines may be required to effectively deliver and sustain SMED excellence. [ 18 - 21 ] In addition, the effects. Designers can easily set up and perform analysis with only a few clicks. Polymer Engineering and Science (2005) There are more references available in the full text version of this article. , 47 (2008. % glass fibers – PA6 Aramid SV 30-1ETM (figure 1b). Sink Marks Cause 3: Improper Pack or Hold Pressure. Processing OptimizationReduced frozen skin thickness: High injection speeds also contribute to a thinner frozen skin at the weld line. The weld line’s strength is reduced when. Insufficient plasticizing ability of injection molding machine. The result is part defects such as weld lines, poor finish, or discoloration. ing weld line properties of injection molded thermo-. In this study, one injection mold. Microsyst Technol. Weld Line defect analysis, the most common of many defects in injection moulding products. It is possible to pre. C. In this study the polycarbonate (PC) and carbon fiber (CF) are used as the experimental materials to investigate the impact of injection molding process parameters on tensile strength of weld line. 0 mm, is designed to conduct the. Depending on the resin, resin temperature, mold temperature, and filling speed, knit lines can vary. This reduced thickness of the frozen skin further enhances the visual appeal of the. The weld-lines are undesirable from both aesthetic and functional points of view and their effect is different for varied materials, process conditions, loadings, forms. Weld lines, generated during injection molding, can significantly reduce the mechanical performance of structures. As such, optimizing mold designs should always be incorporated in your production model. The weld-lines are undesirable from both aesthetic and functional points of view and their effect is different for varied materials, process conditions, loadings, forms. 2. In this way critical areas of the interface in regard to the lack of interdiffusion and the inappropriate molecular orientation were found to be placed near. Depending on the resin, resin temperature, mold temperature, and filling speed, knit lines can vary. and Mosle, H. Increase the mold temperature. Methodology. In this study, we apply the technique of SAW to explore the acoustic properties near injection-weld lines by comparing the velocity of. Here are a few of the most common defects that may occur in plastic injection molding — and how product teams can avoid them. Weld lines have been one of the common defects puzzling the injection molding industry. Plastic part design for injection molding – An introduction. From Understanding Weld-line Integrity by Sabic Innovative Plastics, p. They decrease the. Controlling the mold’s temperature could also minimize the weld line’s effects. The Problems & Solutions course is designed to train injection molding personnel in. Its properties make it possible to create thin-walled parts having close tolerances in fast cycles over long. The weld line is an inevitable defect in the most injection molded components. Increase the injection speed. Therefore, it is recommended to do a moldflow study prior to the mold being built. A weld line can also be called a knit line. Complexities in the design and intricate pathways in the mold can also create flash in injection molded parts. This happens when the molten plastic is injected into the mold cavity and flows around an obstacle such as a pin, hole, or protrusion, and then comes back together. To respond to poor plasticization and uneven melt temperature, the molding cycle can be extended to make. Weld lines are one of the typical quality issues of injection molded parts. This study focus on the. The weld line and the flow pattern of co-injection molding can be seen from Fig. 6. The thermo. Here are some strategies. This line does not normally impact the overall shape or dimensions of the item. 2-1. Avoid knit lines when designing a molded part to improve cosmetic appearance and functionality. Weld line formation in the injection molding process occurs. The formation of weld line in the injection molding method is caused by the product and mold design that is one of the common mistakes. For multiple gate and complex part, molding weld-lines are unavoidable, therefore mechanical behavior of the weld-line needs to be predicted. Crack growth behavior. (2) Causes & Countermeasures (See the table below) *Note: Flash also tends to occur when the injection pressure/speed are too high, but molding time is too long and mold temperature is too low. Slow down injection speed. Here we are looking at most common part defect that can come from injection molding called weld line. 1. 2. (2) Causes & Countermeasures (See the table below) *Note: Flash also tends to occur when the injection pressure/speed are too high, but molding time is too long and mold temperature is too low. In an injection molding process, a weld-line forms when two flow fronts meet each other. 5. The parting line in injection molding is which one of the following: (a) the lines formed where polymer melt meets after flowing around a core in the mold, (b) the narrow gate sections where the parts are separated from the runner, (c) where the clamping unit is joined to the injection unit in the molding machine, or (d) where the two mold halves come. Weld-line is a defect that arises in injection molding when two or more flow fronts collide. Sink Marks Cause 2: Low Pack and Hold time. The most common and one of the most challenging injection molding defects are weld and knit lines. They decrease the. Weld lines appear as a result of the flow of molten plastic during the injection molding process. Reduce the amount of release agents. Possible causes: Low temperature or fluidity of melted plastic during injection molding. T. 2. box, along the region of weld line formation (wc, wm, we and wl) and away from the weld line, in a radial position along the flow direction (R), as shown in Figure 2. Weld lines represent the region where two separated melt fronts recombine. . Munich, Germany: Carl Hanser Verlag, 1994. Melt temperature is 250°C, mold temperature is 110°C. In injection molding of thermosoftening plastics, an important aspect having a bearing on the quality of articles is the appearance of weld lines that are formed when there are inserts, barriers, molding signs, reinforcements, etc. Weld Line Factors for Thermoplastics. Except for a few very simple injection molded parts, they occur on most injection molded parts (typically in the form of a line or V-groove), especially large complex items that require use of multi-gate molds and inserts. Clamping unit berfungsi untuk memegang dan mengatur gerakan mold unit, serta gerakan ejector saat melepas benda dari molding unit, pada clamping unit lah kita bisa mengatur berapa panjang gerakan molding saat dibuka dan seberapa panjang ejector harus bergerak. To resolve this issue, rapid heat cycle molding (RHCM) has attracted attention as an innovative PIM technology. Injection speed is too low. Article Google Scholar Xie L, Ziegmann G (2009) Influence of processing parameters on micro injection molded weld line mechanical properties of polypropylene (PP). 3. Weld lines have been one of the common defects puzzling the injection molding industry. When two or more strands of molten plastics meet in the mold, a weld line will be produced at the junction [1,2]. Simulation of polymer molding filling process with an adaptive weld line capturing algorithm. Weld-line is a weak area which reduces the strength of the part locally. If you have critical requirements for strength of knit lines, please call a Protolabs applications engineer at 877-479-3680 to discuss, or email at [email protected]. The weld lines in injection moulded parts arise as a result of the collision of two fronts of the flowing material, which fills the mould cavity and are sometimes unavoidable. Alloys. In order to prepare the weld line specimen by micro injection molding, a mould integrated with visual system and variotherm system was designed and constructed, shown as Fig. That’s the air escaping out of the nozzle until the hose is full of pressurized water. Int J Adv Manuf Technol:1–11In addition to the weld line, the exposure of fibers on the molded product surface results in a rough surface, which degrades the appearance of the product. Weld line defects are a common part defect that occurs when the injected plastic flows around a solid piece of the mold and does not knit back together. This study examines the impact of injection parameters on the weld line strength of the polyamide 6 and 30% fiberglass (PA6 + 30% FG) composite samples. The default weld line result recognizes 135º as the maximum angle of collision and as that angle decreases, the severity increases as it. 3 cc/sec, the weld lines are no longer perceivable above 130 C. com1. A weld line is a mark left on the surface of a plastic injected molded part. Fracture behavior of weld lines in injection molded components loaded under real operating conditions. Molding with weld line model Moldex3D was used for calculate the molding of lugs (figure 1). Weld-line yield strength, yield strain, and failure strain of talc-filled polypropylene increase with increasing melt temperature and increasing hold pressure. 025 100 120 140 160 180 200 220 240 Mold Temperature (F) LDPE PPEffects of mold temperature and pressure on shrinkage 0. If the different flow fronts have cooled. Weld Line Factors for Thermoplastics. Weld-line strength for plastics can vary from 20% to nearly 100% of the strength of the plastic itself. 7 of the reference. Sink marks are a common type of injection molding defect. They found that the weld line is a zone between 2 and 8 mm wide extending throughout the thickness in whichTo investigate the effect of hot gas heating in injection molding on the weld line appearance, an experiment was conducted with the molding parameters listed in Table 2. (1)Injection Machine Poor plasticization and non-uniform melt temperature – appropriately extend the injection molding cycle, to ensure thorough plasticization, and change for a machine with a larger. injection molding. With unchangeable and fixed requirements for the final product, their avoidance often proves difficult. Sink Marks Cause 5: Improper Part Geometry. The effects of filling time, packing time, packing pressure, melt temperature, and mold temperature on the ultimate tensile strength (UTS) and the elongation value of the weld. In the 1947 book, Injection Molding of Plastics, the late Dr. Remedies: Reduce packing and fill rates by adjusting until the part is properly filled with minimum stresses. 000 0. This month, in our FREE SimTech™ series of webinars, we will explore weld lines and how they develop. After that, the compounds were injection-molded into tensile samples with and without weld lines to. As a result this. To prevent knit lines, injection molders can increase the temperature of the molten resin to prevent solidification from starting too soon, and increasing injection speeds and pressure are also potential solutions. The next type of injection molding defect is ‘Weld Lines’. Additionally, you can get our free Design Cube, which will provide a physical aid to help understand how knit lines form as well as other injection molding design considerations. An evaluation model based on artificial neural network method. This failure causes the product to be damaged during use. 2007; Lotti et al. The effects of fiber concentration has been studied in detail. Weld lines represent the region where two separated melt fronts recombine. 000 0. This principle has been implemented on a complex component in the case of the spring-loaded cogwheel shown in Figure 5, for instance. Figure 2. Weld-line is a weak area which reduces the strength of the part locally. Install an ultrared light inside the hopper. Weld line section presents notch or gloss difference. 2011; 509 (2):226–233. Unfortunately, the 3D layering process creates ‘weld lines’ (an injection molding term) between layers which is essentially two layers of polymer that meet. In the case of PC, the model predicts satisfactorily the weld-line strength as a function of injection temperature. Fortunately, there are several. Weld lines, knit lines, and meld lines are terminologies to describe the imperfections of finished parts in plastic injection. Moldflow is computer software that is widely used across the plastic injection molding industry to predict and optimize the injection molding process and assist with mold design. In this study, polypropylene (PP) was compounded respectively with carbon nano fibers (CNFs) and TiO 2 nano particles at various weight fractions (10, 20, 30, 35. Flow front tracing simulation results for weld line developing process in micro injection molding with Comsol ® Multiphysics 3. Keywords: Flow behavior , Injection molding , Particle tracking , Visualization , Weld-line Article MetricsSimulations and experiments were conducted with gas temperatures of 200–400 °C to investigate the impact of external gas-assisted mold temperature control (Ex-GMTC) on the quality of weld line of molding products. In an injection molding process, a weld-line forms when two flow fronts meet each other. (1) Increase the injection pressure and prolong the injection time. A meld line is defined as the re-merging of two flow fronts. Technol. Weld lines, also known as knit lines, are a common defect in injection molding where two or more flow fronts of molten plastic meet but don’t properly fuse together. It occurs when melting plastic material is injected into a mold, it flows through all parts of th. Improper fusion of two fluid flows, a state before weld line. Weld lines occur when melt flow fronts meet during the injection molding of plastic parts. Weld lines may appear like seams or scratches, but that is not what they are. 1. This occurs wherever there is a hole, notch, or any other feature on a part which divides the flow of plastic into 2 separate “flow fronts. Polym. The melt stream is separated at the part’s cutout and reunited at the other end of the cutout. Weld lines are a common defect generated in injection molding, which apparently affects the performance of final products, but the available reports on carbon fiber. To increase the sustainability of the process, determinative parameters and their effects should be examined. 2. The terahertz time-domain spectroscopy (THz-TDS) imaging technique was used to detect the weld line defect of an injection-moulded short glass fiber-reinforced composite. 1, right). This leads to a better molecular chain entanglement, which in turn creates a better weld. Weld-Line in an injection molded part develops when two or more melt fronts are converged together. Star Rapid offers tips and tricks to improve your prototypes and production parts. Instead of using flow leaders and deflectors to control the locations of the weld lines, this paper presents an approach to specify the locations of the weld. [23, 24]. Strength measurements should be made to. reinforcement type and amount in nylon 6/6. Weld lines are formed when there is an inability of two or more flow fronts to ‘knit’ or ‘weld,’ together during the molding process. It is important to investigate the weld line because the weld line area can induce potential failure of structural application. Yes, it does help, for two reasons: Often the weld line traps air and the ‘dump’ acts as a vent to allow the air to escape. Weld lines have been one of the common defects puzzling the injection molding industry. The effects of filling time, packing time, packing pressure, melt temperature, and mold temperature on the ultimate tensile strength (UTS) and the elongation value of the weld. Weld lines can be caused by many reasons, which covers the various aspects of mold, process, raw materials and product design, etc. Weld-line is a defect that arises in injection molding when two or more flow fronts collide. The definition of weld lines: When multiple plastic flow fronts meet in the cavity after encountering inserts, holes, or areas with inconsistent flow rates or interrupted melt flows, or in the case of gate injection filling, the inability of two or more flow fronts to fully “knit” together will cause the linear weld marks. 2(a, b). Weld line existence reduces the material strength; however, its. (1983). * Corresponding author, e-mail: fengsjpc@ku. Raising the mold temperature will keep the material molten longer, resulting in stronger weld lines and even elimination of weld lines. 1. Tekanan. Remedies: Raise the temperature of the mold or molten plastic. <1> As illustrated in Figure 4, the existence of. JENIS-JENIS DEFECT (CACAT) PADA PRODUK INJECTION MOLDING PT. also utilized the co-injection molding technique to study the flow of polypropylene at the weld line behind an obstacle in injection molding; the weld line can be seen clearly from the Fig. The position, length, and angle of weld lines are dependent on the. Polyamide 6 (Lanxess, Durethan B 30 S 000000, non-reinforced, ISO 1874-PA 6, GR, 14-030, Cologne, Germany) was used for this experiment. Weld lines in injection molding are formed when two or more flow fronts of molten plastic material meet and merge during the molding process. This customary mark is caused by differential rates of cooling in the resin where. In a meld line, the plastic comes together at an angle greater than 135 degrees. The tensile stresses of the weld lines with ultrasonic functions are 8. Neat polypropylene retains nearly 90% of its strength on a properly designed and molded weld line. Weld line formation in the injection molding process occurs. Voids and bubbles, 6. Just check out some of it on the above lists. From: Polylactic Acid (Second Edition), 2019. Miron MC, Major Z, Adachi T. An injection molding gate is the designed opening in a mold through which molten plastic is introduced into the mold cavity, initiating the process of taking the shape of the desired part. Weld lines are significant defects that affect injection molding quality, causing the poor appearance and low mechanical strength of injection‐molded parts. In this paper, a weld line factor (W-L factor) was adopted to. Threadline gap in-between part due to improper gate location in complex design parts including excess of holes (multipoint. Weld or knit lines result wherever two or more polymer flow fronts unite. Emerging Materials Research. Weld line strength is important in blow molding as well as injection molding. In this paper, aiming at the problem of weld line defects in the injec- tion process of a key phone panel, the injection process is optimized by using Moldflow and drop simulation. Effects of mold temperature and pressure on shrinkage 0. Weld lines Weld lines are weak areas formed by converging flows of plastic that can lead to mechanical part failure if not properly accounted for in the part design. Weld line problem which occurs in polymer parts produced by plastic injection method and affects appearance and strength on a large scale was researched in this paper. 030 0. A poor knit line. Weld Line defect analysis, the most common of many defects in injection moulding products. The formation of weld line in the injection molding method is caused by the product and mold design that is one of the common mistakes. วัตถุดิบ พลาสติก PMPA ( อะคริลิก ) เกรด A. The need to minimize fiber breakage, plus the higher viscosity of materials with. Injection molding is one of the most established and well-known methods of plastic processing. 943 µm to 0. The gate vestige for injection molding is usually narrow. Weld lines are a kind of Achilles heel of plastics.