A weld line region is typically filled at the end of an injection stroke or during the pressure phase. The thermo-rheological findings were used to investigate the sources of weld line weakness. 2. Weld lines are visible lines or seams formed when molten plastic flow fronts meet and fuse together, often due to obstacles or flow interruptions in the. Weld lines not. In addition a weld line can be moved to an area where it is less visible. To explore the formation of weld lines in injection molding, a. 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. The literature on the formation of weld lines, and their consequences, is more abundant on the area of injection molding [5-12] than on extrusion [13]. If the different flow fronts have cooled. Increase the injection speed to reduce the amount of cooling happening in the mold. An excess mold release is a major cause of weld line due to two variables: high pressure and speed. Which means engineers need to know how to account for this phenomenon in an efficient way. This gives a clue as to how it was formed. 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. A quantitative evaluation of the appearance quality of weld lines in RHCM parts. 6. When the same pressure is maintained or lower than that, the drop in speed shall create the weld lines. enough to each other to avoid weld line issues. Blistering 4. 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 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 together? Avoid knit lines when designing a molded part to improve cosmetic appearance and functionality. ac. Weld lines are one of the typical quality issues of injection molded parts. 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. . Sink Marks Cause 1: Incorrect Melt Temperature. Recently hired at plastic injection molding simulation software provider Moldex3D, Nicholson was spurred to undertake the research study following a conversation with a customer experiencing weld-line woes. Weld lines are formed when there is an inability of two or more flow fronts to ‘knit’ or ‘weld,’ together during the molding process. Heat/cool injection molding has a positive influence on the depth and visibility of weld lines. 005 0. In this paper, a weld line factor (W-L factor) was adopted to. Wang. These lines. Weld-line is a defect that arises in injection molding when two or more flow fronts collide. 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. Part design features may cause a material flow to split and rejoin as it flows around design features in a mold. In an injection molding process, a weld-line forms when two flow fronts meet each other. This principle has been implemented on a complex component in the case of the spring-loaded cogwheel shown in Figure 5, for instance. 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. As compared to a weld line, the flow fronts come together at less than 135 degrees. Therefore, it is recommended to do a moldflow study prior to the mold being built. the meeting angle by optimizing variation over time in the cavity. 5. Tosello et al. Bubbles are caused by melting flow fronts colliding in a mold cavity. Valve. Multiple gating, splitting of the melt flow due to inserts in the cavity or through holes, as well as changes of thickness give rise to points within the structure where the flowing fronts will recombine and weld. Too high barrel temperature ( abnormal temperature control, deviation of material performance, and increasing cycle time); 8. The flow of the material in the injection mould takes place through the gate. Sink Marks 2. 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. Injection Molding Know How. For multiple gate and complex part, molding weld-lines are unavoidable, therefore mechanical behavior of the weld-line needs to be predicted. This is a video excerpt from our Problems & Solutions Course - Weldlines. Evaluate and optimize your part design The advantages of using the moldflow analysis to avoid potential defect like deformation, shrinkage, welding line etc, part designers can change the wall thickness or enhance the ribs to improve their part design. Neat polypropylene retains nearly 90% of its strength on a properly designed and molded weld line. Weld. Here are some ways to avoid. ), with different mould surface finishes (polished, fine eroded, rough. Kobayashi et al. If you adjust the ejection mechanism in the mold design, you also can reduce or eliminate your need for mold release agents. 4 at different time steps (legend scale is volume fraction of. Carefully consider all the relevant aspects of the mold design specification before. Weld lines are the most common defects in injection molded products. Weld lines: Cold feedstock in the die: Increase injection speed, mold temperature, and feedstock temperature, enlarge gate opening, add venting channels or overflow wells near weld line locations, move gate location, redesign parts to avoid stream partition: Flow mark: Cold feedstock in the dieWeld lines are a common imperfection to be found in most plastic injected molded parts. The most common and one of the most challenging injection molding defects are weld and knit lines. During injection. 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. Fellahi et al. injection molding. Wang, G. In the first, sequential injection moulding, the lines are displaced to noncritical areas of the moulding. 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 and meld lines are generally caused by holes or inserts in the part, multiple gates, variable wall thickness or hesitation and. 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. About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features NFL Sunday Ticket Press Copyright. Weld-line is a weak area which reduces the strength of the part locally. The structure is more complex with longer molding cycle . 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. 2) Vents in an injection mold should let the air out, but not the liquid plastic. Wu CH, Liang WJ (2005) Effects of geometry and injection-molding parameters on weld-line strength. Weld lines are a common imperfection to be found in most plastic injected molded parts. Adjust the design for the flow pattern to be a single source flow. My polymer material selection courses 👉 Find Out About Plastics Blog👉 ht. Ni. It forces out trapped air pockets and can prevent a vacuum void from occurring. A simulation process was conducted to determine the recommended setting of injection moulding parameters and the range of the variable. Weld-line is a defect that arises in injection molding when two or more flow fronts collide. 3. The gate location should enable the two flow fronts to merge easily and continue to flow beyond the weld line. The weld line and the flow pattern of co-injection molding can be seen from Fig. They appear on the surface of injection molded parts like lines. If the large molded product is. 2. A meld line occurs when two moving melt fronts converge and flow parallel to each other. It is not always easy to completely eliminate weld lines by simply adjusting the relevant injection mold design or the molding conditions. , a post that forms a hole) and then rejoins, or when polymer melt fronts meet, from multiple injection points. weld lines in infill analysis of injection molding simulation was observed [5]. ). , less than 0. The Influence of Knit-lines on the Tensile Properties of Injection Molded Parts, Polymer Engineering and Science, 23(10): 591-596. (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 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. Weld lines have been one of the common defects puzzling the injection molding industry. Too much injection molding pressure lost and increase the operation difficulty of the injection molding machine; 7. (a) (b) Figure 1. Abstract. In the present work, the micro specimens were investigated. To elimi- nate weld lines, you can enlarge shrinkage. Google Scholar [10] S. In order to reduce these weak points, a special ram technique for injection molding, which can be integrated into the mold, was investigated. 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]. Effects of mold temperature and pressure on shrinkage 0. The thermo. Definition: A seam that appears where two areas of molten plastics meet. . the three-plate mold often adopt this kind of gate. Specifically, injection-mold lines are often associated with poor mechanical strength. Steven. One common issue that frequently arises during injection molding is the formation of weld lines. In this regard, the plasticizing ability of the plastic injection moulding machine should be checked. 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. The injection molding temperature and the mold temperature were fixed respectively at 230 °C and 50 °C. 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. The edge gate is the most popular and straightforward injection mold gate design. After that, the compounds were injection-molded into tensile samples with and without weld lines to. They are unavoidable even for moderate complex products. Mostly, this happens when two or more flow fronts do not “knit” during the injection molding process. This occurs either due to injection through multiple gates or as a conse-รอยประสานของเนื้อพลาสติก Weld line ตอนที่1. Raising the mold temperature will keep the material molten longer, resulting in stronger weld lines and even elimination of weld lines. Published 5 July 2019. Redesign the mold to prevent the weld line. But none of the current packages can predict weld lines’ properties qualitatively. Besides, possibly it would be. Specifically, injection-mold lines are often associated with poor mechanical strength. The goal is to create a uniform thickness and at the smallest (thinnest) level required. Sink marks are a common type of injection molding defect. 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. Stop using mold parting agents. Jiquan Li, Taidong Li, +1 author. GlossFlow-induced fiber orientation and weld lines are com-mon features of the injection molding process. They decrease the. Ghazanfarpour. Streaks 3. 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. Our injection molding company is explaining what these imperfections are, why they can compromise. The weld line degrades the. 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. Thereby creating localized pressure within the mold. 5. 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 this study, the effects of injection temperature, injection pressure, and fiber content on the mechanical properties of weld lines were studied for carbon fiber-reinforced nylon. 13 shows the best gate location for which the weld lines . 1. M. Process. Weld lines are the result of fundamental physical effects taking place inside of the mold tool cavity, they are common imperfection to be found in most plastic injection molded parts. These are preferred over weld lines as they will normally result in improved cosmetics and structure. 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. The impact behavior of weld-lines in injection molding. The specific method is that when the product is just filled and filled in the cavity, the insert. How Are They Formed? Molten plastic resin is injected into a mold cavity through an opening known as a gate. This is expected to achieve maximum results while the pressure holding effect will also increase. The resulting defects don’t stop at flash only. Since it is often impossible to avoid weld lines as well as a limited possibility to increase the weld line strength by adjusting the injection molding parameters, a method to predict the weld line strength in the product development process is shown below. The melt stream is separated at the part’s cutout and reunited at the other end of the cutout. Weld lines in injection molding are a type of cosmetic defect that detracts from a plastic part’s appearance. 1 Mold In order to study the formation of weld lines, the mold cavities has been. The main runner and sub-runner are too thin. Cracks in Corners – When cracks appear in the corners of plastic parts, the cause is too much plastic shrinkage onto the mold core in that corner. 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 lines are an integral part of plastic injection molding and can seldom be prevented, even by specifically planning the mold with inserts for holes or the like. 10. 15 shows the frozen layer and weld lines at the end of mold filling. Sequential valve gate technology. Instead, a line that looks like a seam forms. The weld line in injection molding is created when two melt streams connect, as shown in Figure 1. Provide a gas vent. 2017-01-0481. Design. Azuddin / Procedia Engineering 184 ( 2017 ) 663 – 672 665 2. In a meld line, the plastic comes together at an angle greater than 135 degrees. As a result this weld line will be a weak point in this part. Weld lines can significantly reduce ultimate tensile strength (UTS) and fracture strain of talc filled polypropylene (PP). As these flow fronts come together. Weld-line is a weak area which reduces the strength of the part locally. Weld Lines. injection molding is followed by the welding. 080 inches. Injection molded plastic parts have comparatively less strength in the weld line section and they also have an impact on product aesthetics. Weld lines can be a weak spot and have therefore to be taken into consideration in 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. The Problems & Solutions course is designed to train injection molding personnel in. Weld line additionally called as knit line, is a defect that occurs when the injected plastic meets within a mold. 3. For multiple gate and complex part. Its appearance can be improved by adjusting parameters. also utilized the co-injection molding technique to study the flow of polypropylene at the weld line behind an obstacle in injection molding; the. Islyn Thomas summarized the need for a particular vent location better than I ever could. (1998) for clear photographs. In the sense that the weld line is better formed before the resin temperature. Polymers 2023, 15, 2440 3 of 21. Another way to eliminate weld lines in plastic injection molding is to adjust the molding conditions. 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. Figure 1 a illustrates how the weld line is produced when two melt streams merge during the final filling process. They. 1. 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. 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. Molding calculation in Moldex3D: (а) melt front and weld line, (b). Move injection locations to make weld lines form closer to the gates. The thin weld line is the result of weak material bonding, which lowers the strength of the part. 025 mm (0 . The special injection mold is designed and fabricated to produce plaques having stagnation weld-line. Amongst weld line. In spite of its cosmetic attributes, a bad knit line can significantly compromise a part. poor flow fronts that are too cold, this can also lead to a deterioration in the mechanical properties. Azieatul Azrin Dzulkipli and M. While there are many situations where they are barely perceptible, weldlines represent a potential source of weakness in molded parts. • Move injection locations to make flow fronts meet more obliquely, turning the weld line into a meld line. The hair-like weld line is the. Weld lines are a common issue in injection molding, and occur when two flow fronts meet and fuse together as the material cools and solidifies. Failure may result due to the assembly torque, or end-use application loads (temperature, creep). g. For the production of these weld-line specimens, a special mold was used and injection molding parameters were systematically varied, tensile (ISO 527-2) and impact (ISO 179-1/1eU) properties were measured, and statistical analyses were performed to gain insight on the correlation between melt flow rate and weld-line behavior. Oil lines and reservoirs are typical examples for hollow composite parts which are conventionally produced using a multi-stage process. Weld-line is a defect that arises in injection molding when two or more flow fronts collide. 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. Weld line formation in the injection molding process occurs. Weld lines can be caused by many reasons, which covers the various aspects of mold, process, raw materials and product design, etc. ppt from SCIENCE 101 at Symbiosis International University. Weld-line is a defect that arises in injection molding when two or more flow fronts collide. Weld lines may occur on a molded part’s surface where, after breaking off into two or more directions in a mold, the molten material has converged. These lines usually appear on the narrowest portion of the part, and appear to originate from the mold’s gates, where the molten resin flows into the mold to form. Try to gradually raise the mold temperature and barrel temperature. Weld lines, created in the areas of collision of two flow fronts of plastic in the injection mold cavity, are the reason of lower mechanical properties and a worse surface condition of molded parts. In this study, the effects of injection temperature, injection pressure, and fiber cont. Shaofei Jiang. Weld lines are formed when two orThe experiments were performed on an Arburg Allrounder 320C 600-250 injection moulding machine using a two cavity-injection mould (Fig. The weld lines that occur in injection mouldings are critical areas on which depends on the strength of the mouldings. This customary mark is caused by differential rates of cooling in the resin where. Weld lines can compromise the strength and aesthetics of the part, so it’s important to carefully design the mold. Adjust Injection Molding Parameters: Optimizing injection speed, pressure, and temperature can help ensure better melt flow and reduce the likelihood of weld line formation. Second, depending on the size of the overflow well, you get a little bit of flow melding together, and that helps strength so that you have some intertwining of the polymer chains. Steven. Known methods to reduce weld-line effects are the optimization of injection molding parameters, enhanced tool temperature, and using special molding tool devices. investigated the impact of injection molding parameters on weld line formation and strength reduction. Unless you are manufacturing an extremely simple part with one gate and a unidirectional flow front, your part will have weld lines. To determine the effect of the weld lines on tensile strength, tensile tests were conducted with the specimens fabricated with NORYL (amorphous blends of. Weld line and warping are two critical defects for injection-moulded part. 004 m, a characteristic velocity ν 0 =0. In the sense that the weld line is better formed before the resin. That’s the air escaping out of the nozzle until the hose is full of pressurized water. The Solutions for Poor Welding Lines. This is expected to achieve maximum results while the pressure holding effect will also increase. distribution [4]. . If the melt temperature is low or the injection speed and pressure are low, you may end up with a more pronounced weld line. If you are familiar with any form of scientific injection molding, regardless of the name, then you know one of the first steps is performing a viscosity curve study. Known also as knit lines and weld marks, weld lines are difficult to eliminate completely, especially if your injection molded part requires holes. 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. A simulation of mold filling with multi-inlets or an insert in the cavity is pursued with an improved Level Set Method. Remedies: Raise the temperature of the mold or molten plastic. Increase the melting temperature. Meanwhile, Using more advanced cooling method such as cyclic cooling or conformal cooling. Introduction Weld lines are formed during mold filling whenever two separated melt streams recombine. If the plastic encounters a pin or other obstruction, the plastic flow front must split to form two flow fronts to go around the pin. The weld lines in blow molding occur wherever the pari son knits together in the head, mold tacking areas and mold parting pinch-off region. 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. 010 0. The micro tensile part was prepared by the double gate injection. When two or more strands of molten plastics meet in the mold, a weld line will be produced at the junction [1,2]. Molding Equipment. 943 µm to 0. 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. 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. 1. The Factors that Cause Weld Line in Injection molding Pressure. Sink Marks Cause 5: Improper Part Geometry. Weld lines in injection molding occur when two flow fronts meet and create a visible line on the surface of the molded part. Weld line formation in the injection molding process occurs. Weld-line strength for plastics can vary from 20% to nearly 100% of the strength of the plastic itself. 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. 2(a, b). Weld lines are where two flow. Remedies: Raise the temperature of the mold or molten plastic. When two or more strands of molten plastics meet in the mold, a weld line will be produced at the junction [1,2]. 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. 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. 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. Knit lines, weld lines, mold lines, or flow lines in injection molding are faint lines that become visible on certain plastic parts. Thus, a right gate design raises polymer temperature to prevent the formation of weld lines and flow marks. It is possible to pre. Problem: Weld lines are formed when plastic resin is forced around an obstruction in a mold tool and reforms on the side opposite the gate. To respond to poor plasticization and uneven melt temperature,. Lesson 7: Meld and Weld Lines (Part Design) When plastic flows into an injection mold, the internal flow pattern depends on the part design, mold design, and processing factors. Reduce the amount of release agents. 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. Many researchers had emerged with several. 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. Weld Lines-3 Ways for Detecting and Correcting. Mold Design. Boost time too long Shorten boost time, lower boost pressure, or move transfer to an earlier position . The part becomes partially solidified and won’t sufficiently bond where the two halves meet, resulting in. 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. Avient’s Zachary Alderman shares practical tips on designing and injection molding parts utilizing short-fiber reinforcements. <Materials>Injection moulding (U. A knit line may be unnoticeable or may look like a crack. Weld line formation in the injection molding process occurs when two or more melt flow fronts contact each other immediately after the cooling process. Maintain a holding pressure that is no more than 1/2 the. + Increase mold temp, or materials’ temp, or holding pressure. Redesign the mold to prevent the weld line. Sink marks, 2. The molded plastic part may also appear to be rust-colored. Download : Download high-res image (856KB) Download : Download full-size image; Fig. 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. when two or more melt flow fronts contact each other immediately after the cooling process. Weld line, 5. wall thickness, gate and runner designs and re-validate the result. Weld line existence reduces the material strength; however, its demerit characteristics. Ideally, the resin flow will split into two flow fronts to pass around the obstruction and then recombine into a single flow front. Plastics manufactured by injection molding are meant to be durable and reliable, able to hold up to heavy use, high temperatures, or adverse conditions. This model provides the necessary information. Root causes Many factors—including processing conditions, material, part design and mold design—can influence the visibility and strength of a weld line. 22 shows how the weld lines are formed when the melt splits around core pins during the injection molding process. Injection pressures too high Reduce pressure . Ejector System (Pötsch, 1995) . For the production of these weld‐line specimens, a special mold was used and injection molding parameters were systematically varied, tensile (ISO 527‐2) and impact (ISO 179‐1/1eU. M. Figure 1a illustrates how the weld line is produced when. analyzed the heat transfer during heating and cooling phases of RHCM process. In this study, polypropylene (PP) was chosen as the processing material and a micro dog-bone tensile test sample was selected as the objective part. There are several possible causes that need to be investigated to troubleshoot weld lines in injection molding. Injected plates were generated using a double-gated mold under four different process conditions. 1. This is particularly true if the wall thickness in the weld is thin – i. Weld lines are a surface defect caused when two or more flow fronts come together during the injection process. gas, which can cause blistering, as well as poor weld lines, warpage and the formation of cold slugs that affect filling and part mechanical properties. Weld lines form where two or more flow fronts come together and can create a cosmetic or structural problem. In a weld line, reinforcement fibers. Edge Gates. Figure 2. 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. Thus, it is important to understand (i). Weld lines have been one of the common defects puzzling the injection molding industry. Weld lines represent the region where two separated melt fronts recombine. These processing changes will increase chain. In some cases, a weld line can also cause a loss of strength and impact resistance. Introduction. In this experiment, several ejector. Figure 2. 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. Weld lines not only detract from an injection-molded part’s surface quality, but also significantly reduce its mechanical strength. Injected plates were generated using a double-gated mold under four different process conditions. The weld line is an inevitable defect in the most injection molded components. Flow-induced filler orientation manifests in higher tensile prop-erties in the direction of flow compared to those normal to the direction of flow. demanding injection molding and end-use requirements. Injection molding of large/complicated products are usually prepared by multiple compounds, which produces weldlines once the melt fronts are joined by impingement flow. 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. Conventional injection molding is widely used to produce plastic parts, mainly in the automotive industry, due to the high production ratios and quality of.