Therefore, it is recommended to do a moldflow study prior to the mold being built. These processing changes will increase chain. S. As the unfavorable defect in micro injection molding parts, weld line brings reduced mechanical and physical properties, especially for nano filled composites. In spite of its cosmetic attributes, a bad knit line can significantly compromise a part. Although they often cannot be avoided it’s possible to minimize their cosmetic effects to an acceptable degree through careful product design and. The three parameters affecting operation were called injection pressure, injection time, and packing pressure which influence the quality of weld line. This occurs either due to injection through multiple gates or as a conse-รอยประสานของเนื้อพลาสติก Weld line ตอนที่1. The main types of injection molding defects are: 1. [1-2] investigated the weld line zone of injection molded glass-fiber-filled polypropylene (PP) composites. Ghazanfarpour. Sink marks. Its appearance can be improved by adjusting parameters. A knit line, also called a weld line, occurs when the liquid plastic moves through the mold and hits more melted plastic and they don’t flow or fuse together. Mold vents should function the same way. (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. In this lesson we will focus on the meld and weld lines. It forces out trapped air pockets and can prevent a vacuum void from occurring. (3-1) Increasing the Resin Temperature at the Weld Line Section. 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 of weld-line, etc. Consultant @ Effinno Technologies, BSME, MBA - Bridge between Plastics Injection Molding Knowledge and Practice. but the injection pressure will loss and injection molding pressure of this gate is bigger than that of direct gate. Injection Molding defect:molding weld_and_meld_line. Injection molding, polypropylene, talc. To explore the formation of weld lines in injection molding, a. They are the result of fundamental physical effects taking place inside of the mold tool cavity. Another way to eliminate weld lines in plastic injection molding is to adjust the molding conditions. The hair-like weld line is the. Weld line and warping are two critical defects for injection-moulded part. 2-1. As the name implies, it is usually positioned along the edge of the workpiece, forming a visible mark at the demarcating line. [ 18 - 21 ] In addition, the effects. In order to increase the quality of the products manufactured by injection molding, RTC technology can be used to achieve higher mold temperatures. Weld line formation in the injection molding process occurs. 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. In this case the two flow fronts will meet and there will be very little molecular orientation across the weld. Don’t forget to eliminate entrapped air in the weld line injection molding; otherwise, it’ll create unfilled portions in your part design, causing more weakening. 4. 020 0. 015 0. 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. In the sense that the weld line is better formed before the resin. The parts are molded flat and are slightly stressed once installed in an arced position, but not excessively. Weld Line defect analysis, the most common of many defects in injection moulding products. Proceedings of ANTEC (2000), pp. The hair-like weld line is the result of weak. Three terms that often get mixed up are weld, meld, and knit lines. The need to minimize fiber breakage, plus the higher viscosity of materials with. 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]. This is where the melt fronts divided by an insert, such as a pin or a. Weld lines occur when melt flow fronts meet during the injection molding of plastic parts. 025 mm (0 . Mold temperature controlInjection mold designers can alter the position of weld line by changing the gate locating. 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. th INTRODUCTION Injection molding is one of the mostWeld Lines in a plastic cover. That helps. Stop using mold parting agents. Preventing sink marks of injection molded parts using CAE analysis. Weld. 15 shows the frozen layer and weld lines at the end of mold filling. g. This customary mark is caused by differential rates of cooling in the resin where. • Reduce runner dimensions and maintain the same flow rate. An evaluation model based on artificial neural network method. + Improve vent inside the mold. Weld-line is a weak area which reduces the strength of the part locally. Micro weld lines are the common problem that occurs for plastic molded parts through injection molding process. 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. Figure 1 a illustrates how the weld line is produced when two melt streams merge during the final filling process. Email him at jhenz. 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. Wolfgang Homes, head of the applications department of Eurotool, a manufacturer of hot runner systems, clarified the two methods for IMI, noting that. Increase the injection speed to reduce the amount of cooling happening in the mold. Another relevant topic in injection molding is the presence of weld lines (WLs) and their properties, which could lead to part weakness through surface disturbances, optical issues and reduced bonding [21, 22]. Edge Gates. Weld lines can significantly reduce ultimate tensile strength (UTS) and fracture strain of talc filled polypropylene (PP). Many studies were conducted to explain the weakness at the. Provide a gas vent. Redesign the mold to prevent the weld line. 9 – Over Packing. 1 m/s, and a zero-shear-rate viscosity η 0 (T 0)=3760 Pas. EasyFill Advanced provides the weld-line temperature distribution and meeting angle prediction. Weld-line, a common occurrence in plastic injection moulding, is a representative defect compromising mechanical qualities and product appearance [16]. 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. From Fig. Sink marks are a common type of injection molding defect. In this lesson we will focus on the meld and weld lines. 005 0. 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. During injection moulding, a weld-line occurs when two or more flow fronts collide in the hollow cavity. The injection molding gate generates heat by dissipation. Weld lines appear as a result of the flow of molten plastic during the injection molding process. They have their origins in material choice, part design, tooling, and processingIncrease the mold temperature and smooth out any sharp corners or turns in the mold to facilitate even melt flow. The weld line’s strength is reduced when. Injection molds: (a) mold type A, (b) fixed plate of the mold type B, and (c) moving plate of mold type B The second mold (mo ld type B) was used for the ISO D2 specimen, as shown in Figure 2b,c . Unless you are manufacturing an extremely simple part with one gate and a unidirectional flow front, your part will have weld lines. Weld lines not only affect the appearance and quality of products, but also cause negative influences on the mechanical properties. Here are some ways to avoid. In the above diagram, the converging flow fronts (indicated by red arrows. Except for a few injection molded parts with very simple geometry, they occur on most injection molding parts (the shape is usually a line or V-shaped groove), especially Large complex items requiring the use of multi-gate molds and inserts. Polymers 2023, 15, 2440 3 of 21. Flow lines are lines, waves, or ring patterns that appear on the surface of a part, noted by their slightly different color from the rest of the piece. Figure 1a illustrates how the weld line is produced when. 2) show that the weld line is formed as expected from the middle of the cavity towards the wall. Weld lines are significant defects that affect injection molding quality, causing the poor appearance and low mechanical strength of injection‐molded parts. Gava and co-workers implemented an investigation devoted to the de-Injection-mold weld lines may or may not be easily identified by naked eye or straightforward optical microscopy. Failure may result due to the assembly torque, or end-use application loads (temperature, creep). Weld Lines-3 Ways for Detecting and Correcting. Besides, possibly it would be. What is weld lines. This paper presents the. The micro tensile part was prepared by the double gate injection. Weld lines create visible marks, but this type of injection molding defect can also reduce a part’s strength and durability. with a characteristic length χ 0 =0. Weld Lines. Weld lines can be a weak spot and have therefore to be taken into consideration in part design. “I realized weld -line problems are a very common issue for injection molded parts,” Nicholson told Plastics Technology. The Difference Between Knit and Meld Lines–and Why It Matters. Weld line. Try to gradually raise the mold temperature and barrel temperature. 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. Ejector System (Pötsch, 1995) . The Influence of Knit-lines on the Tensile Properties of Injection Molded Parts, Polymer Engineering and Science, 23(10): 591-596. They are unavoidable even for moderate complex products. A viscosity curve is developed using calculations of the fill time and plastic pressure at. 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. 004 m, a characteristic velocity ν 0 =0. Weld lines in injection molding are frequently unavoidable. Co-injection molding technique is a useful way to study weld lines, which can offer more detailed information of the. 1. The schematic diagram of a weld line formation is illustrated in Figure 7, where is the welding angle of two melt fronts. Heating and cooling mould systems, which cost extremely high, are a typical technology to prevent the weld-line. The melt stream is separated at the part’s cutout and reunited at the other end of the cutout. Five injection molding process parameters, including mold temperature, melt temperature, packing pressure, injection. The weld line is then created with a higher flow front temperature and is packed with more pressure. Remedies: Reduce packing and fill rates by adjusting until the part is properly filled with minimum stresses. It is possible to pre. To explore the formation of weld lines in injection molding, a flow model based on viscoelastic constitutive equation is presented in this article to predict and evaluate of weld lines location and properties, in which Rolie. In this study, we apply the technique of SAW to explore the acoustic properties near injection-weld lines by comparing the velocity of (V R) in locations close to and locations distant from the weldSince 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. poor flow fronts that are too cold, this can also lead to a deterioration in the mechanical properties. Bubbles are caused by melting flow fronts colliding in a mold cavity. When injection molding large products, molding is usually performed with multi-point gates, but weld lines can occur depending on the product shape and gate position. One common issue that frequently arises during injection molding is the formation of weld lines. The four sets of plaques are produced by changing the magnitude of packing pressure equal to 60% of filling pressure, with increment of 20% up to 120% of filling pressure. In this experiment, several ejector. The plaques are prepared out of 30% glass-filled Polyamide 6 material. Steven. Meld and knit lines are actually both different types of weld lines. When molten plastic flows, it forms a smooth continuous flow until it meets an obstruction. Weld line existence reduces the material strength; however, its demerit characteristics. distribution [4]. A weld-line is known as a representative defect in the field of plastic injection moulding, and also as a cause of inferior mechanical propensities and poor appearance. The next type of injection molding defect is ‘Weld Lines’. Raising the mold temperature will keep the material molten longer, resulting in stronger weld lines and even elimination of weld lines. The difference between a weld and meld line is simply determined by the angle at which the converging flow fronts meet. One solution is to prevent the weld lines from forming in regions that are. Injected plates were generated using a double-gated mold under four different process conditions. Typical injection molding processing temperatures of TPU materials are as follows: IM ZONE 60A TO 75A 80A TO 90A 95A TO 75D REAR 315 – 340 °F 345 – 370 °F 375 – 400 °FTo study the weld line formation of colliding flow fronts the filling of a mold cavity was simulated. Meld lines are formed when two separate flow fronts meets. By the reflection method and a high speed camera, the visual system can be used to record and observe the forming process of micro weld lines during the. Adjust the design for the flow pattern to be a single source flow. Reduce the amount of release agents. Weld line formations can be weak if they fall in areas that will bear stress or impact. 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. Weld line defects in injection molding is a line or lines on the part surface that caused the part looking ugly or cuased part lifetime, or even broken easily. + Move gate (to where it is not visible). Or increase the number of gates. 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. Weld line is formed when two different melt flows converge, as illustrated in Fig. In injection molding, it is often important to maintain consistent color throughout the part. “I realized weld -line problems are a very common issue for injection molded parts,” Nicholson told Plastics Technology. As the polymer resin is injected into a mold, it flows through all parts of the 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. 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 utility model relates to a mold structure capable of eliminating the appearance of weld lines of a hole-shaped injection molded product. Sink MarksWeld 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. When the two such melt flows. Vacuum voids. The second technique, cascade injection moulding, can produce parts free from weld lines. To explore the formation of weld lines in injection molding, a. (3) Adjust the temperature of the barrel and nozzle: the viscosity. 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. Prediction of the weld lines in injection molding process using neural networks. If the injection gate is not properly designed, it can cause the formation of defects like sink-mark, warpage, short shot, weld-line, air traps, and other faults [15]. In injection molding, a V-notch-shaped weld line is generated in the melt front meeting area. Sink Marks Cause 1: Incorrect Melt Temperature. 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. When two or more strands of molten plastics meet in the mold, a weld line will be produced at the junction [1,2]. Weld-line is a weak area which reduces the strength of the part locally. Weld lines can appear on the surface of a molded part where the molten material has converged after splitting off in a mold. Conventional injection molding is widely used to produce plastic parts, mainly in the automotive industry, due to the high production ratios and quality of. In some cases, a weld line can also cause a loss of strength and impact resistance. Weld lines. Increase the melting temperature. Meld and knit lines are actually both different types of weld lines. Short shots can occur in this case because the air in the mold cavity has nowhere to go while the plastic is entering. Controlling the mold’s temperature could also minimize the weld line’s effects. The default weld line result recognizes 135º as the maximum angle of collision and as that angle decreases, the severity increases as it. gasket seal leakage where the weld line crosses a gasket. Its appearance can be improved by adjusting parameters. analyzed the heat transfer during heating and cooling phases of RHCM process. Google Scholar [10] S. 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). The simulated cold weld line length is consistent with the experimental one when a 115 °C mold temperature is adopted; with lower mold temperatures, the simulated lengths are smaller than the experimental ones—in accordance with the literature on the conventional injection molding process [26,27]—probably because of the definition adopted. Criens, R. Adjust Injection Molding Parameters: Optimizing injection speed, pressure, and temperature can help ensure better melt flow and reduce the likelihood of weld line formation. Polym Eng Sci 45(7. A weld line is often unavoidable. Jiquan Li, Taidong Li, +1 author. Gate blush, 4. Increase the injection speed to reduce the amount of cooling happening in the mold. About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features NFL Sunday Ticket Press Copyright. 2. In this case the two flow fronts will meet and. For multiple gate and complex part. (3) Adjust the temperature of the barrel and nozzle: the viscosity. Weld Line defect analysis, the most common of many defects in injection moulding products. Known methods to reduce weld-line effects are the optimization of injection molding parameters, enhanced tool temperature, and using special molding tool devices. avoid weld lines, and facilitate smooth. When this fails to happen correctly, a weld line defect occurs. Abstract. Weld or Knit lines are a plane or section in an injection molding part where the flow of molten plastics meets from different directions. 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. It can be determined by a visible line appearing on the surface of the plastic part where two flows of the plastic meet. 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. Use a less viscous plastic. Too much injection molding pressure lost and increase the operation difficulty of the injection molding machine; 7. The part becomes partially solidified and won’t sufficiently bond where the two halves meet, resulting in. 2004; To study the weld line formation of colliding flow fronts the filling of a mold cavity was simulated. For multiple gate and complex part, molding weld-lines are unavoidable, therefore mechanical behavior of the weld-line needs to be predicted. Mold Design Most conventional mold designs will work with TPU’s. Avient’s Zachary Alderman shares practical tips on designing and injection molding parts utilizing short-fiber reinforcements. In the injection molding process, weld line regions occur when a molten polymer flow front is first separated and then rejoined. Known methods to reduce weld-line effects are the optimization of injection molding parameters, enhanced tool temperature, and using special molding tool devices. In a weld line, reinforcement fibers. Insufficient plasticizing ability of injection molding machine. Runner Type Venting Plastic melt and mold temperature Injection speed and pressure Learn how to troubleshoot weld lines in injection molding. 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. It is a zone with reduced mechanical properties negatively influencing on the molding behavior in exploitation. ), with different mould surface finishes (polished, fine eroded, rough. A knit line may be unnoticeable or may look like a crack. The weld line in injection molding is created when two melt streams connect, as shown in Figure 1. 943 µm to 0. This occurs mainly in the presence of barriers that divide the melt flow in. Weld Lines. (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. The weld line’s strength is reduced when. 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]. Weld-line is a weak area. Weld lines are a reality in the injection moulding of complex parts. Weld lines represent the region where two separated melt fronts recombine. The weld lines that occur in injection mouldings are critical areas on which depends on the strength of the mouldings. In weak material bonding, they will appear as hair-like weld lines. Weld or knit lines are perhaps the most common and difficult injection molding defect to eliminate. In this regard, the plasticizing ability of the plastic injection moulding machine should be checked. Download : Download high-res image (856KB) Download : Download full-size image; Fig. 22: Weld line formation when melt splits around core pins. Wavy lines are another feature of weld lines. 4 at different time steps (legend scale is volume fraction of. Weld lines not only affect the appearance and quality of products, but also cause negative influences on the mechanical properties [3,4,5]. 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. This is particularly true if the wall thickness in the weld is thin – i. According to the studies, the most important factor to reduce weld lines is increasing the mold temperature. Weld lines are visible to varying degrees on any molded part depending on gate location, flow length, melt/mold temperature, cavityA 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. Thus, it is important to understand (i). As the polymer. Injected plates were generated using a double-gated mold under four different process conditions. Boost time too long Shorten boost time, lower boost pressure, or move transfer to an earlier position . Optimizing the injection parameters through combination of adjusting the molding temperature, varying the gate pressure, and increasing the dwell time. and Mosle, H. Mold flow marks, also known as flow lines or weld lines, are often caused by variations in the flow of molten plastic material during the injection molding process. The weld line can either be a minor cosmetic issue or potentially bad enough to negatively impact the part's strength. Amongst weld line. A poor knit line can cause only cosmetic blemishes or it can significantly weaken the structural integrity of a part. 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. Kobayashi et al. Weld lines not only detract from an injection-molded part’s surface quality, but also significantly reduce its mechanical strength. weld lines in infill analysis of injection molding simulation was observed [5]. , a post that forms a hole) and then rejoins, or when polymer melt fronts meet, from multiple injection points. injection molding. Flow-in-duced fiber orientation manifests in higher tensile properties in the direction of flow compared to normal to the direction of flow [13–15]. Figure 2. When the same pressure is maintained or lower than that, the drop in speed shall create the weld lines. Try to gradually raise the mold temperature and barrel temperature. , 190°C mass and 20°C mold temperature, as well as. Ni. , 2 (3–4) (1988. A weld line (weld point, flow line or a knit line) forms when separate melt fronts travelling in opposite directions meet. 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. (1) Increase the injection pressure and prolong the injection time. Root causes Many factors—including processing conditions, material, part design and mold design—can influence the visibility and strength of a weld line. In the feeding system of injection molding, the flow of plastic melt begins from the nozzle of the injection molding machine, traverses through the sprue and runners, and ultimately reaches the mold gate(you can call it the injection molding gate as well)—the entry point to the mold cavity. Therefore, more studies covering this subject are required in order to improve the insight regarding the mechanism involved in the formation of weld lines in extrusion and,From the so-produced materials, specimens with weld lines were produced according to the first test series, but varying the injection molding parameters only twice, between the best and worst settings found in the previous study with the polypropylene types with MFR 8 g/10 min, i. Multiple gates are acceptable as long as they are close enough to each other to avoid weld line issues. Knit lines, weld lines, mold lines, or flow lines in injection molding are faint lines that become visible on certain plastic parts. Weld lines have been one of the common defects puzzling the injection molding industry. The most common and one of the most challenging injection molding defects are weld and knit lines. It is not always easy to completely eliminate weld lines by simply adjusting the relevant injection mold design or the molding conditions. A weld line region is typically filled at the end of an injection stroke or during the pressure phase. Recently, the injection molding of fiber reinforced thermoplastics (FRTP) containing short fibers has been widely carried out to mass-produce molded products with complex shapes. Controlling the mold’s temperature could also minimize the weld line’s effects. Known methods to reduce weld-line effects are the optimization of injection molding parameters, enhanced tool temperature, and using special molding tool devices. Valve. You can expect a mold shrinkage percentage of. Adding vents, using overflows, or using porous metal. Published 5 July 2019. GlossFlow-induced fiber orientation and weld lines are com-mon features of the injection molding process. 2020-01-1306. Weld lines are one of the typical quality issues of injection molded parts. In this study, we apply the technique of SAW to explore the acoustic properties near injection-weld lines by comparing the velocity of (V R) in locations close to and locations distant from the weldAmong defects of injection molding parts, weld lines are the most common defect. When two or more strands of molten plastics meet in the mold, a weld line will be produced at the junction [1,2]. Increase the injection speed and mold/operational temperature to prevent fracture or surface breakdown. Abstract. 7 of the reference. If the melt temperature is low or the injection speed and pressure are low, you may end up with a more pronounced weld line. 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 manufacturing, the Weld line or Knit line or Meld 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. The weld line in injection molding is created when two melt streams connect, as shown in Figure 1. Weld Lines-3 Ways for Detecting and Correcting. Weld Lines. Materials Science. Weld Lines. An excess mold release is a major cause of weld line due to two variables: high pressure and speed. Depending on the resin, resin temperature, mold temperature, and filling speed, knit lines can vary. The Solutions for Poor Welding Lines. The wheel has to be gated at three places on the hub and. 2) Vents in an injection mold should let the air out, but not the liquid plastic. the meeting angle by optimizing variation over time in the cavity. Azieatul Azrin Dzulkipli and M. These lines. Weld lines not only affect the appearance and quality of products, but also cause negative influences on the mechanical properties. This special mould has changeable inserts to be able to inject with different gate types (standard, film, special-film, multi gates, etc. The four sets of plaques are produced by changing the magnitude of packing pressure equal to 60% of filling pressure, with increment of 20% up to 120% of filling. 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. consideration in gate location. Change the gate locations. This is where the melt fronts divided by an insert, such as a pin or a block, in a mold cavity rejoin each other downstream of the insert. Effect of the processing conditions on the variations of the bulk temperature, T b , at the end of mold filling at the two locations: in (left) and away (right) from the weld-line (T w , T inj. 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. A visual mold with variotherm system for weld line study in micro injection molding. Process. the three-plate mold often adopt this kind of gate. 13 shows the best gate location for which the weld lines . Wang, G. These are caused by the shot of molten plastic moving at different speeds throughout the injection. 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. In this work, the residual strength of a fiber-reinforced injection molded part containing a hot weld line—or meld line—was evaluated. A flat product case was considered as an example of a typical aircraft structural element. Optimizing the Injection Parameters. Weld or knit lines occur when melt flow fronts collide in a mold cavity. สาเหตุหลักชิ้นงานพลาสติกเกิดรอยเชื่อมประสาน (weld line) คือ การประสานหรือการรวมตัวกันของพลาสติกเหลวไม่ดีเท่าที่ควรThis insertion ensures the separation of the melt flow. Injection-molding machine is the Negri Bossi VE210-1700 with screw diameter 60 mm. Features such as sharp corners or undercuts can. 1. e. Simulation of polymer molding filling process with an adaptive weld line capturing algorithm. An obstruction such as a core pin or holes will split the material flow and cause a weld line issue to form on the other side. Injection molding is an efficient manufacturing process for mass-producing parts with complicated geometry. This gives a clue as to how it was formed. The Injection Moulding Process is a manufacturing process used for producing parts or components by injecting molten material into the mold cavity. Wang. During injection. In an injection molding process, a weld-line forms when two flow fronts meet each other. Too high barrel temperature ( abnormal temperature control, deviation of material performance, and increasing cycle time); 8.