Our weld line injection molding is essential for the best result of finished molded products. Neat polypropylene retains nearly 90% of its strength on a properly designed and molded weld line. In this paper, a weld line computer determination method based on filling simulation with surface model is proposed, from which the positions and lengths of the weld lines can be predicted. First, an injection mold with triangular inserts was built to study the influence of meeting angles on material properties at the weld line. T. In this study, one injection mold. The diameter of the hole is 12 mm. Sink Marks Cause 3: Improper Pack or Hold Pressure. Weld lines appear as a result of the flow of molten plastic during the injection molding process. 13 shows the best gate location for which the weld lines . Causes: Weld lines are caused by the inadequate bonding of two or more flow fronts when there is partial solidification of the molten plastic. Figure 1a illustrates how the weld line is produced when two melt streams merge during the final filling process. Munich, Germany: Carl Hanser Verlag, 1994. Weld line strength is influenced by the temperature at which the weld line is formed and the pressure exerted on the weld until the part freezes, (pressure is 0 at the weld line). + Move gate (to where it is not visible). com1. This results in a region of a different level of molecular entanglements than the bulk material. 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. Therefore, it is recommended to do a moldflow study prior to the mold being built. 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. Microsyst Technol. • Reduce runner dimensions and maintain the same flow rate. To increase the sustainability of the process, determinative parameters and their effects should be examined. Methodology. 1. In order to study the weld line developing process and its influence on mechanical properties in micro injection molding, a visual mold with variotherm system mold was designed and fabricated. 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. 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. Weld line formation in the injection molding process occurs. Shaofei Jiang. and most commonly, thermoplastic polymers are used. Weld line (also known as a knit line) is the line where two flow fronts meet when there is the inability of two or more flow fronts to “knit” together, or “weld,” during the molding process. Weld lines, knit lines, and meld lines are terminologies to describe the imperfections of finished parts in plastic injection molding processing. Causes. Insufficient plasticizing ability of injection molding machine. The flow of the material in the injection mould takes place through the gate. Tekanan yang kurang mampu untuk mendorong aliran dan kembali pada posisi semula dapat menimbulkan weld line. This defect occurs due to the temperature and pressure not being high enough, causing premature solidification. The impact behavior of weld-lines in injection molding. 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. Injection molding of large/complicated products are usually prepared by multiple compounds, which produces weldlines once the melt fronts are joined by impingement flow. Known methods to reduce weld-line effects are the optimization of injection molding parameters, enhanced tool temperature, and using special molding tool devices. Thoroughly clean molding machine cylinders. Weld lines are a common imperfection to be found in most plastic injected molded parts. Melt temperature does effect the weld. 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. – Use generous and even. Slow down injection speed. Molding with weld line model Moldex3D was used for calculate the molding of lugs (figure 1). Ada berbagai penyebab mengapa weld line bisa muncul pada permukaan produk plastik. 809-814. (1) Increase the injection pressure and prolong the injection time. Weld lines in injection molding are formed when two or more flow fronts of molten plastic material meet and merge during the molding process. 030 0. Amongst weld line. 1. Procedia Mater Sci 2014; 3: 2048–2053. We have various types and models available. The following are the reasons. Weld Lines and Fibers There are two basic types of weld lines: the stagnant and the flowing [1]. 2(a, b). Sink Marks Cause 2: Low Pack and Hold time. Weld or Knit lines are a plane or section in an injection molding part where the flow of molten plastics meets from different directions. As these flow fronts come together on the. Thus, it is important to understand (i) if the melt is able to fill the cavity up to the weld line location, (ii) where the weld line forms, and (iii) if the weld line is a cold or flowing one. Weld lines are visually undesirable and a plastic part is structurally weak at weld line positions. The impact behavior of weld-lines in injection molding. Below is one of the examples: !NOTE: if the weld lines is important to the cosmetic surface of your part, please bring this up to your mold maker during quoting phase. examined the relationship between the structural and mechanical qualities in HDPE/PA6 mixture which is molded with weld line and without weld line in plastic injections [6]. At a low volumetric injection flow rate of 33. S. Munich, Germany: Carl Hanser Verlag, 1994. Figure 1 a illustrates how the weld line is produced when two melt streams merge during the final filling process. Published 5 July 2019. 3 and 53. Mold vents should function the same way. This is expected to achieve maximum results while the pressure holding effect will also increase. 3. A flow mark is commonly referred to as a flow line occurs during the process of injection molding. A simulation process was conducted to determine the recommended setting of injection moulding parameters and the range of the variable. Fig. อุณหภูมิของพลาสติกเหลวสูงเกินไปจนก๊าซหรือความชื้นแยกตัวออกมาได้. . This principle has been implemented on a complex component in the case of the spring-loaded cogwheel shown in Figure 5, for instance. Zhao, X. Threadline gap in-between part due to improper gate location in complex design parts including excess of holes (multipoint. Weld lines can appear on the components when the molten plastics meet each other as they are flowing from two different parts of the mold. when two or more melt flow fronts contact each other immediately after the cooling process. Sink marks are a common type of injection molding defect. This study focuses on the effect of melt temperature on. In some cases, a weld line can also cause a loss of strength and impact resistance. org or visit 80-ton Victor injection molding machine, equipped with an accumulator capable of delivering maximum flow rate of 138 cm 3 /s and providing maximum injection pressure of 210 MPa, is utilized for experiments. Weld Lines. J. 4. Conclusion The formation of weld lines in micro injection molding of plastic depends on different parameters such as melt temperature, injection pressure and fabrication method. As the name implies, it is usually positioned along the edge of the workpiece, forming a visible mark at the demarcating line. Xie L, Zhu D, Ziegmann G, Steuernagel L (2016) Investigation on correlation between cold/hot weld line mechanical properties and micro injection molding processing parameters. Which means engineers need to know how to account for this phenomenon in an efficient way. The injection molding simulation software used offers a method for the detection of weld lines that has shown to be only reliable for the detection of stagnating weld lines. Weld lines can be caused by many reasons, which covers the various aspects of mold, process, raw materials and product design, etc. Avoid knit lines when designing a molded part to improve cosmetic appearance and functionality. Optimization of Injection Molding Process to Minimize Weld-line and Sink. [ 18 - 21 ] In addition, the effects. Weld lines are formed when two melt fronts come in contact with each other. After that, the compounds were injection-molded into tensile samples with and without weld lines to. 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. Weld lines not only affect the appearance and quality of products, but also cause negative influences on the mechanical properties. Wolfgang Homes, head of the applications department of Eurotool, a manufacturer of hot runner systems, clarified the two methods for IMI, noting that. As the injection process continues, the two separated melt fronts meet again along the longitudinal section of the plate forming a weld line. “I realized weld -line problems are a very common issue for injection molded parts,” Nicholson told Plastics Technology. With tighter heat controls, you can keep the material at the proper temperature to make sure the plastic keeps flowing and fills the mold cavity completely. Injection speed is too low. These lines are formed when two or more flowing molten plastic streams meet and fuse together, creating a visible line on the surface of the molded part. Miron MC, Major Z, Adachi T. Its appearance can be improved by adjusting parameters. Weld lines in injection molding occur when two flow fronts meet and create a visible line on the surface of the molded part. They are unavoidable even for moderate complex products. The weld line is an inevitable defect in the most injection molded components. Weld Line Phenomenon: Surface defect in which the weld, or the part where the flows of melted plastic meet inside the mold, shows up on the surface as a groove or pattern. 6. Jiquan Li, Taidong Li, +1 author. Weld lines form where two or more flow fronts come together and can create a cosmetic or structural problem. What causes them? The primary cause is weak bondage between two or more flow fronts. To prevent weld lines, increase the pressure and temperature. Gava and co-workers implemented an investigation devoted to the de-weld lines in injection molded thermoplastic composites. A family of short carbon fiber-reinforced thermoplastic (CFRTP) compounds specifically formulated for injection molding is being used to extend the capabilities of thermoplastic composites in a variety of part sizes and complexities. (1983). Fellahi et al. Weld line. Let’s review what causes meld and knit line imperfections, how they’re different, and how they affect part durability. II. Clamping Unit. Weld lines represent the region where two separated melt fronts recombine. Instead, a line that looks like a seam forms. Known methods to reduce weld-line effects are the optimization of injection molding parameters, enhanced tool temperature, and using special molding tool devices. Unfortunately, the 3D layering process creates ‘weld lines’ (an injection molding term) between layers which is essentially two layers of polymer that meet. Injection molding is a highly versatile manufacturing process used to produce a wide range of plastic products with precision and efficiency. (3-1) Increasing the Resin Temperature at the Weld Line Section. Wavy lines are another feature of weld lines. 3. In this experiment, several ejector. When an external load is applied to a weld line region, the part’s potential for mechanical failure is increased. Investigations on WLs in micro injection molded parts were performed in Refs. Knit lines, weld lines, mold lines, or flow lines in injection molding are faint lines that become visible on certain plastic parts. The optimal process condition is very likely to appear in this second part's fine-tune group. Weld lines in injection molding are frequently unavoidable. This can allow the. In the present study, Moldflow® software is applied to simulate the injection molding of automobile instrument light guide bracket and optimize the injection gate position. This method was adopted. Injection molded plastic parts have comparatively less strength in the weld line section and they also have an impact on product aesthetics. This study focus on the. (3-1) Increasing the Resin Temperature at the Weld Line Section. 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). Mechanical properties of the weld line defect in micro injection molding for various nano filled polypropylene composites. Gate Placement: Properly positioning the gate can direct the melt flow to minimize weld lines or relocate the weld line to non-visible areas of the part. This type of injection molding resolves any trouble caused by undesired welding lines. To explore the formation of. 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. 2012. Adjust Injection Molding Parameters: Optimizing injection speed, pressure, and temperature can help ensure better melt flow and reduce the likelihood of weld line formation. Weld-line, a common occurrence in plastic injection moulding, is a representative defect compromising mechanical qualities and product appearance [16]. Short Shot Short Shot adalah suatu kondisi dimana, plastik leleh yang akan diinjeksikan kedalam cavity tidak mencapai kapasitas yang ideal atau sesuai settingan mesin. The weld line in an injection molding product can significantly impact the strength and durability of the last part [12] [13][14][15]. Weld lines in injection molding are formed when two or more flow fronts of molten plastic material meet and merge during the molding process. 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. We recently had a few pieces (2-3%) crack after assembly, while in storage (not installed, still in the package). The possibility of the functional thin film for. (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. 226-233. Re-balancing entire manufacturing lines may be required to effectively deliver and sustain SMED excellence. 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. Abstract. Weld lines may appear like seams or scratches, but that is not what they are. Reposition gates and runners to allow resin to flow around the obstruction from a. However, even with advanced technologies and precise control, the process is not without its challenges. 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. Weld line and warping are two critical defects for injection-moulded part. This article will introduce you the usage, types, and advantages of the Sequence Injection Timer. 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. The melt stream is separated at the part’s cutout and reunited at the other end of the cutout. This failure causes the product to be damaged during use. Install an ultrared light inside the hopper. Change the gate locations. This model provides the necessary information. Save. Weld line formation in the injection molding process occurs when two or more melt flow fronts contact each other immediately after the cooling process. injection molding, (b) weld line and meld line, and (c) injection sample size and shape. The weld line in injection molding is created when two melt streams connect, as shown in Figure 1. Remember, by avoiding weld lines, you can lessen operations cost. Xie L, Ziegmann G (2008) A visual mold with variotherm system for weld line studying micro injection molding. It provides scientific basis for designers toWeld lines are significant defects that affect injection molding quality, causing the poor appearance and low mechanical strength of injection‐molded parts. Flow marks in injection molding are defects that manifest as a line or series of lines forming a pattern different in color from the other parts of the molded material. An injection molding gate is a critical component in mold design, acting as the passage through which molten plastic travels from the runners into the mold cavity. Try to gradually raise the mold temperature and barrel temperature. These flow fronts occur when the molten plastic material encounters obstacles, such as inserts, ribs, or other features within the mold cavity. Simulation of polymer molding filling process with an adaptive weld line capturing algorithm. When a product is produced through injection molding, a high-powered tool injects melted plastic into a custom, double-sided mold. Causes: Weld lines are caused by the inadequate bonding of two or more flow fronts when there is partial solidification of the molten plastic. Unless you are manufacturing an extremely simple part with one gate and a unidirectional flow front, your part will have weld lines. 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. Weld line location. This will produce parts with aExperimental results show that the weld-line strength from a standard test is not applicable in microinjection molding. In this study, one injection mold. Redesign the mold to prevent the weld line. Micro-injection molding (µIM) is a widespread process for the production of plastic parts with at least one dimension, or feature, in the microscale (conventionally below 500 µm). Wu CY, Ku CC, Pai HY (2011) Injection molding optimization with weld line design constraint using distributed multi-population genetic algorithm. a) Multi-fiber connector micro injection molding simulation b) 3D simulation of micro gear with 150µm diameter for weld line position prediction c) 3D micro injection molding filling simulation of micro gear with 180µm diameter Fig. Miron MC, Major Z, Adachi T. These weld lines occur usually around holes or at the material flow joint area in the injeciton molded part, some welding lins is very small, specially if. If there’s too much mold release, you may require a higher pressure to push it through the machine. The thermo-rheological findings were used to investigate the sources of weld line weakness. Depending on the resin, resin temperature, mold temperature, and filling speed, knit lines can vary. 2. A visible weld line is observed, due to a combina-The Weld line result itself has a scale associated with the placement of the weld line that is directly relative to how severe the weld line will be based on the angle in which the two flow fronts meet. In recent years, researchers have. Increase the injection speed to reduce the amount of cooling happening in the mold. when two or more melt flow fronts contact each other immediately after the cooling process. If the plasticizing ability of the plastics injection molding machine is insufficient, the plastic cannot be fully plasticized, resulting in weld lines when filling the mold. 2. 5. Meld and knit lines are actually both different types of weld lines. A weld line develops when two or more flow fronts come together but do not meld completely because of partial solidification. Lesson 6: Meld and Weld Lines (Processing) When plastic flows into an injection mold, the internal flow pattern depends on the part design, mold design, and processing factors. Again, consult with professionals as to how you could improve mold designs. Effect of geometry and injection-molding parameters on weld-line strength. 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-reinforced thermoplastics are still rather few. 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 cracking was always located in the weld/knit line and therefore caused by weakness in the bonding of the plastic at. Burn Marks. These lines usually occur around holes or obstructions and cause locally weak areas in the molded part. In addition, its tensile strength and stiffness will be sharply decreased. Ideally, the resin flow will split into two flow fronts to pass around the obstruction and then recombine into a single flow front. ResourcesTo study the weld line formation of colliding flow fronts the filling of a mold cavity was simulated. 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-reinforced thermoplastics are. Increase the mold temperature. 2. Materials Science. In this paper, a kind of polypropylene (PP) foam plastic parts with special weld lines were obtained by core-back foam injection molding with chemical blowing agent. 4. Since weldline in plastic injection molding (PIM) has an influence on not only the strength but also the surface appearance of a plastic product, it is preferable to reduce it as much as possible for high product quality. And how to use the 3 modes of the sequential controller correctly to prevent burn marks, weld line, short shot, and other part defects in injection molding. Polym Eng Sci 45(7):1021–1030. Key words: weld line strength, thermoplastic composites, injection molding, wall thickness, skin and core layers Department of Materials Engineering, Faculty of Engineering, Kasetsart University, Bangkok 10900, Thailand. [ 18 - 21 ] In addition, the effects of flow behavior of the polymer melt due to the optimal process parameters for the minimization of weld-line effects are an important consideration. The present work focuses on studying the effect of packing pressure on strength of stagnation weld-line. Wang. (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. Therefore, the investigation on the developing process of weld line would be a significant issue for improving the quality of micro injection molded parts. In the 1947 book, Injection Molding of Plastics, the late Dr. Knit lines in injection molding are undesirable, especially when surface appearance and part strength are significant concerns. Flashes, 3. Plastic Rapid Injection Molding is popular not only in low volume manufacturing but also in large quantities molding, it is the most common way to manufacture plastic parts. Flow-induced filler orientation manifests in higher tensile prop-erties in the direction of flow compared to those normal to the direction of flow. 1. 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. This study presents an innovative approach to enhancing weld line strength in advanced polymer injection molding through applying gas-assisted mold. In our DFM report, we will analyze the possible weld lines. When two or more streams of plastic meet and fuse together, a visible line or weakness is formed on the surface of the finished product. The flow disruptor is a small insert introduced inside the injection molding cavity, in the weld line area, and its objective is to mix the melt and disrupt fountain flow in order to blur and. 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. on conventional reciprocating screw injection molding machines using molding practices standard for filled engineering thermoplastics . 2 mm to 1. of micro injection molding process simulation by technology update and progress. Weld-line is a defect that arises in injection molding when two or more flow fronts collide. <1> As illustrated in Figure 4, the existence of. Rapid heat and cool injection molding is an example of a measure to prevent the generation of weld lines. Weld or knit lines result wherever two or more polymer flow fronts unite. 005 0. A weld line develops when two or more flow fronts come together but do not meld completely because of partial solidification. Unless you are manufacturing an extremely simple part with one gate and a unidirectional flow front, your part will have weld lines. Conventional injection molding is widely used to produce plastic parts, mainly in the automotive industry, due to the high production ratios and quality of. The formation of weld lines and their location along the flow path is a well-studied phenomenon in conventional injection molding; however, only a few papers are devoted to micro-injection molding [11,13,14,15,16]. Processing OptimizationReduced frozen skin thickness: High injection speeds also contribute to a thinner frozen skin at the weld line. reinforcement type and amount in nylon 6/6. Weld lines can significantly reduce ultimate tensile strength (UTS) and fracture strain of talc filled polypropylene (PP). But add 30% glass and weld-line strength retention drops to only 34% as high as the compound with no weld. In the present work, the micro specimens were investigated. The Factors that Cause Weld Line in Injection molding Pressure. With Ixef® PARA compounds, the strength of a weld line is typically 90 MPa (13,000 psi). This is a video excerpt from our Problems & Solutions Course - Weldlines. In an injection molding process, a weld-line forms when two flow fronts meet each other. Weld-line strength for plastics can vary from 20% to nearly 100% of the strength of the plastic itself. This study presents an innovative approach to enhancing weld line strength in advanced polymer injection molding through applying gas-assisted mold temperature control, significantly increasing mold temperature beyond typical values observed in conventional processes. Avient’s Zachary Alderman shares practical tips on designing and injection molding parts utilizing short-fiber reinforcements. In. Weld lines. Remedies: Raise the temperature of the mold or molten plastic. Thereby creating localized pressure within the mold. During the plastic injection molding process, one of the biggest challenges is. The quality of the weld line can be improved through optimized processing conditions, increased mold and melt temperatures, and increased injection speed to reduce the viscosity of the polymer. These master batches and PP pellets were dry-blended by adjusting the ratio such that the fiber contents were 10, 20, and 30 wt%. This defect occurs due to the temperature and pressure not being high enough, causing premature solidification. Increase the injection speed. Flow marks in injection molding can be avoided if adequate measures are taken. th INTRODUCTION Injection molding is one of the mostWeld lines have been one of the common defects puzzling the injection molding industry. 1007/s00397-003-0339-2 ORIGINAL CONTRIBUTIONCauses and Remedies of Sink Marks In Injection Molding. 2. How Are They Formed? Molten plastic resin is injected into a mold cavity through an opening known as a gate. Weld-line is a weak area which reduces the strength of the part locally. The Solutions for Poor Welding Lines. + Optimize holding pressure time. 3 cc/sec, the weld lines are no longer perceivable above 130 C. . Int J Adv Manuf Technol 52:131–141. The main runner and sub-runner are too thin or too long. 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. Weld lines can impact the strength and appearance of the final part, and are often considered a defect. Let’s review what causes meld and knit line imperfections, how they’re different, and how they affect part durability. The effects of these two injection molding process parameters are explained in terms of their influence on the skin-core morphology observed on the fracture surfaces in the weld zone. Usually it’s a straight line, and often to be found radiating away from a hole, inclusion or other such part feature. A new kind of weld line was. The next type of injection molding defect is ‘Weld Lines’. 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. The most simple design modification for eliminating the weakening effect of a weld line is to increase the wall thickness in the weld line zone (Figure 4). However, research about the computer determination of weld lines in injection molding remains scarce. Figure 2. The strength of the weld-line area can be increased by optimizing injection molding process parameters like melt temperature, injection speed, packing pressure, changing gate type and location, etc. As the weld line can significantly lower the mechanical strength of µIM parts, it is relevant to clarify the position of weld. 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. To study the weld line formation of colliding flow fronts the filling of a mold cavity was simulated. It is not always easy to completely eliminate weld lines by simply adjusting the relevant injection mold design or the molding conditions. A meld line occurs when two moving melt fronts converge and flow parallel to each other. The. The wheel has to be gated at three places on the hub and. Mold flow analysis is widely employed in mold making industry, utilizing data simulation software, the injection molding process can be simulated and presented on the computer,. Increase the injection speed to reduce the amount of cooling happening in the mold. T he decreased gloss level at the position of. 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. Valve gates also make weld lines less of. Still, it can be seen to varied degrees depending on mold. Effect of process parameters on the relative weld line strength From injection molding practice and literature, 1, 3,4 it is generally accepted that: if a weld line forms before the filling is. Here we are looking at most common part defect that can come from injection molding called weld line. Weld lines are formed when two orAbout Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features NFL Sunday Ticket Press Copyright. 2004; To study the weld line formation of colliding flow fronts the filling of a mold cavity was simulated. The problem with ‘weld lines. Sink marks, 2. Weld lines occur when melt flow fronts meet during the injection molding of plastic parts. Increase the mold temperature. A quantitative evaluation of the appearance quality of weld lines in RHCM parts. 4. 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. A poor knit line. Gate blush, 4. (2011) and Fig. Many researchers had emerged with several. The weld lines that occur in injection mouldings are critical areas on which depends on the strength of the mouldings. of micro injection molding process simulation by technology update and progress. In this case the two flow fronts will meet and there will be very little molecular orientation across the weld. In a meld line, the plastic comes together at an angle greater than 135 degrees. Weld lines in injection molding are a type of cosmetic defect that detracts from a plastic part’s appearance. Here are some reasons why design is important for injection molding. Increase the injection speed. J. You will have to confirm them before tooling. Some of the approaches include the application of machine learning methods (Chen 2008; Manjunath and Krishna 2012; Kuo et al. .