weld line injection molding. 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. weld line injection molding

 
This study examines the impact of injection parameters on the weld line strength of the polyamide 6 and 30% fiberglass (PA6 + 30% FG) composite samplesweld line injection molding Injection Molding Glossary; Weld Lines; Weld Lines

These lines usually occur around holes or obstructions and cause locally weak areas in the molded part. Consequently, weld regions have been observed to have inferior mechanical properties compared to the bulk. J. Its appearance can be improved by adjusting parameters. <Mold> Increase (or decrease) the size of the runners and gates. 2-1. 2) Vents in an injection mold should let the air out, but not the liquid plastic. The possibility of the functional thin film for. Ozcelik studied the influence of the injection parameters and weld line on the mechanical properties of polypropylene (PP) during IM process via the design of experiment (DOE). With Ixef® PARA compounds, the strength of a weld line is typically 90 MPa (13,000 psi). The appearance quality of plastic parts in weld lines can be improved significantly through the rapid heating cycle molding (RHCM). as warpage, shrinkage and weld line of the plastic parts. 226-233. Learn more about ABS injection molding here. Weld lines appear as a result of the flow of molten plastic during the injection molding process. 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. Berikut beberapa di antaranya: 1. The gate vestige for injection molding is usually narrow. Weld lines can compromise the strength and aesthetics of the part, so it’s important to carefully design the mold and. They occur when melt flow fronts collide in a mold cavity. 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-line is a weak area. Int J Adv Manuf Technol 52:131–141. If weld lines are unavoidable due to multiple gates in a moulding, they should be positioned in the non-critical region. Weld line existence reduces the material strength; however, its demerit characteristics. Its properties make it possible to create thin-walled parts having close tolerances in fast cycles over long. 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 molded plastic part may also appear to be rust-colored. Weld line is formed when two different melt flows converge, as illustrated in Fig. 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. They can affect the strength and. A good weld typically occurs when the melt temperature where the weld line is formed is no more than 20°C below the injection temperature. 3. Injection molding is a highly versatile manufacturing process used to produce a wide range of plastic products with precision and efficiency. It is pos­si­ble to pre. th INTRODUCTION Injection molding is one of the most 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. Part design features may cause a material flow to split and rejoin as it flows around design features in a mold. Materials Science. Weld line Weld line dikatakan ketika dua atau lebih aliran lelehan depan. A meld line is defined as the re-merging of two flow fronts. ResourcesTo study the weld line formation of colliding flow fronts the filling of a mold cavity was simulated. 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. Munich, Germany: Carl Hanser Verlag, 1994. 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. First, an injection mold with triangular inserts was built to study the influence of meeting angles on material properties at the weld line. To increase the sustainability of the process, determinative parameters and their effects should be examined. For glass-filled grades, the thickness at the weld line can be slightly larger than the nominal value due to lower shrinkage associated with vertical fiber orientation at the weld line cross. In this study, the effects of injection temperature, injection pressure, and fiber cont. 809-814. In an injection molding process, a weld-line forms when two flow fronts meet each other. Alloys. Islyn Thomas summarized the need for a particular vent location better than I ever could. The weld-lines are undesirable from both aesthetic and functional points of view and their effect is different for. when two or more melt flow fronts contact each other immediately after the cooling process. This line does not normally impact the overall shape or dimensions of the item. • Move injection locations to make flow fronts meet more obliquely, turning the weld line into a meld line. The weld line length was selected as part of the quality index to investigate the effects of gate location on weld. 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. 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. Molding with weld line model Moldex3D was used for calculate the molding of lugs (figure 1). 5. A weld line region is typically filled at the end of an injection stroke or during the pressure phase. M. 9. Microsyst Technol, 14 (6) (2008), pp. [ 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. Weld lines represent the region where two separated melt fronts recombine. 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. poor flow fronts that are too cold, this can also lead to a deterioration in the mechanical properties. Weld lines form where two or more flow fronts come together and can create a cosmetic or structural problem. The. Weld or Knit lines are a plane or section in an injection molding part where the flow of molten plastics meets from different directions. 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. 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. 5. The thermo-rheological findings were used to investigate the sources of weld line weakness. 6. Weld line strength is important in blow molding as well as injection molding. 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. Fiber content dependence on. The thermo-rheological findings were used to investigate the sources of weld line weakness. 2011; 509 (2):226–233. 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. 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. Depending on the resin, resin temperature, mold temperature, and filling speed, knit lines can vary. Computer simulation packages of injection molding have had success in predicting filling behavior in extremely complicated geometries, capable of predicting weld lines’ location exactly. A simulation process was conducted to determine the recommended setting of injection moulding parameters and the range of the variable. In spite of its cosmetic attributes, a bad knit line can significantly. Mechanical properties of the weld line defect in micro injection molding for various nano filled polypropylene composites. 0 mm, is designed to conduct the. Weld lines are one of the typical quality issues of injection molded parts. The most common and one of the most challenging injection molding defects are weld and knit lines. reinforcement type and amount in nylon 6/6. Flash. Fig. These lines usually occur around holes or obstructions and cause locally weak areas in the molded part. 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. Weld Lines. 2002), the use of simulation approaches (Berti and. Xie L. The diameter of the hole is 12 mm. For multiple gate and complex part. For thick-walled parts, slow injection rates result in more uniform polymer distribution . Weld line usually is not allowed on some critical area, and weld line on the part also weaken the strength. Possible causes: Low temperature or fluidity of melted plastic during injection molding. In this mold, a visualization design and a rapid heating/cooling system were integrated, and specimens with different cross section. The. But none of the current packages can predict weld lines’ properties qualitatively. In narrow fields, a limited amount of molten liquid can solidify and block the flow. Gambar 2. Xie L, Ziegmann G (2008) A visual mold with variotherm system for weld line studying micro injection molding. That’s the air escaping out of the nozzle until the hose is full of pressurized water. Wu CH, Liang WJ (2005) Effects of geometry and injection-molding parameters on weld-line strength. A weld or meld line is a weakness or visible flaw created when two or more flow paths meet during the filling process. Unless you are manufacturing an extremely simple part with one gate and a unidirectional flow front, your part will have weld lines. Make the size of runner channel wider and/or shorter. Sink marks, 2. 2. When this fails to happen correctly, a weld line defect occurs. It is a zone with reduced mechanical properties negatively influencing on the molding behavior in exploitation. Clamping Unit. The weld line is an inevitable defect in the most injection molded components. Weld Line Factors for Thermoplastics. Compd. The resulting defects don’t stop at flash only. Processing OptimizationReduced frozen skin thickness: High injection speeds also contribute to a thinner frozen skin at the weld line. Procedia Mater Sci 2014; 3: 2048–2053. Figure 2. 000 0. For multiple gate and complex part, molding weld-lines are unavoidable, therefore mechanical behavior of the weld-line needs to be predicted. Let’s review what causes meld and knit line imperfections, how they’re different, and how they affect part durability. Plastics manufactured by injection molding are meant to be durable and reliable, able to hold up to heavy use, high temperatures, or adverse conditions. The following guidelines have. Effect of geometry and injection-molding parameters on weld-line strength. 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. Install an ultrared light inside the hopper. 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. The optimum injection molding parameters to manufacture the product was determined by . spelling: injection molding) is a manufacturing process for producing parts by injecting molten material into a mould, or mold. Thoroughly clean molding machine cylinders. To prevent weld lines, increase the pressure and temperature. An evaluation model based on artificial neural network method. Neat polypropylene retains nearly 90% of its strength on a properly designed and molded weld line. Article Google Scholar Deng YM, Zheng D, Lu XJ (2008) Injection moulding optimization of multi-class design variables using a PSO algorithm. In this study, we apply the technique of SAW to explore the acoustic properties near injection-weld lines by comparing the velocity of. The impact behavior of weld-lines in injection molding. 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. Strength at weld the line location and warpage problem in injection molding plastic component were not new problems in injection molding industries. These flow. Meld and knit lines are actually both different types of weld lines. Weld lines are among the most critical structural defects in parts made by the injection molding of fiber-reinforced thermoplastics, explained Sirmax in a press release. Our weld line injection molding is essential for the best result of finished molded products. Here is a look at the differences between them, the causes of meld and knit line imperfections, and their impact on part durability. 5. The schematic diagram of a weld line formation is illustrated in Figure 7, where is the welding angle of two melt fronts. Although they often cannot be avoided it’s possible to minimize their cosmetic effects to an acceptable degree through careful product design and. This can occur when a polymer flow splits to go around an interruption (e. To determine the effect of the weld lines on tensile strength, tensile tests were conducted with the specimens fabricated with NORYL (amorphous blends of. Micro injection molded polymeric parts coated with functional thin films/layers show off the promising applications in microsystems area. replication and poor weld line strength . technical ulletin SPECIALTY POLYME RS Design and Production of Injection Molding Tools. 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. Injection speed is too low. They decrease the. Plastic part design for injection molding – An introduction. The results showed that the tensile strength of PE remains unchanged in the presence of weld lines. Just check out some of it on the above lists. Flow marks in injection molding can be avoided if adequate measures are taken. The injection molding gate generates heat by dissipation. If the plasticizing ability of the plastics injection molding machine is insufficient, the plastic. Rapid heat and cool injection molding is an example of a measure to prevent the generation of weld lines. 21: Weld line failure caused by hoop stresses. ing weld line properties of injection molded thermo-. 13 shows the best gate location for which the weld lines . The following are the reasons. One common issue that frequently arises during injection molding is the formation of weld lines. Inadequate back pressure. Learn how to avoid them and what injection molding companies do to prevent them. When two or more strands of molten plastics meet in the mold, a weld line will be produced at the junction [1,2]. 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. In this regard, the plasticizing ability of the plastic injection moulding machine should be checked. Weld Lines. Gate position in injection mold. From Understanding Weld-line Integrity by Sabic Innovative Plastics, p. Injection molding weld lines where two or more flow fronts come together in the mold. Low mold temperatures are usually employed to decrease cycle molding time and final process costs; however, resulting surface defects include weld lines, sink. In some cases, a weld line can also cause a loss of strength and impact resistance. As the plastic flows through the mold it. 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. Weld lines are a common imperfection to be found in most plastic injected molded parts. Known methods to reduce weld-line effects are the optimization of injection molding parameters, enhanced tool temperature, and using special molding tool devices. Simulation of polymer molding filling process with an adaptive weld line capturing algorithm. Investigate for potential contamination. According to the weld line distribution map of six gate schemes shown in . 2. In our DFM report, we will analyze the possible weld lines. Weld lines create visible marks, but this type of injection molding defect can also reduce a part’s strength and durability. Penyebab Weld Line. Meld and knit lines are actually both different types of weld lines. A weld line is a mark left on the surface of a plastic injected molded part. 2. Still, it can be seen to varied degrees depending on mold. <Materials> Pre-dry thoroughly. Which means engineers need to know how to account for this phenomenon in an efficient way. Consultant @ Effinno Technologies, BSME, MBA - Bridge between Plastics Injection Molding Knowledge and Practice. Weld lines are significant defects that affect injection molding quality, causing the poor appearance and low mechanical strength of injection‐molded parts. Sink Marks Cause 5: Improper Part Geometry. 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. If there’s too much mold release, you may require a higher pressure to push it through the machine. The weld line in injection molding is created when two melt streams connect, as shown in Figure 1. Injection molding weld lines refer to a line on an injection molded part that is generated where the two halves of the mold come together. A weld line region is typically filled at the end of an injection stroke or during the pressure phase. 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. 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). Physics. Weld lines can. Here are some reasons why design is important for injection molding. Ada berbagai penyebab mengapa weld line bisa muncul pada permukaan produk plastik. Mold flow analysis can predict the location of weld lines. Many researchers had emerged with several. Mobile 0813; Shinko Sellbic Co. Weld lines often generate mechanically weak areas, because of the unfavorable perpendicular orientation of the macromolecules, fibers and/or other fillers to the direction of the main flow. According to the characteristics. A weld line occurs when two or more molten plastic flows meet and fuse during the injection molding process, resulting in a visible line on the surface of the molded part. Three terms that often get mixed up in injection molding are weld, meld and knit lines. 030 0. There are several possible causes that need to be investigated to troubleshoot weld lines in injection molding. Abstract. Weld lines. 1. In injection molded parts, there are 2 types of weld lines: The first type of weld mark is called cold-melt joints and is formed when the melt front enters the cavity with different gates. Wu CH, Liang WJ (2005) Effects of geometry and injection-molding parameters on weld-line strength. ac. A poor knit line. We recently had a few pieces (2-3%) crack after assembly, while in storage (not installed, still in the package). Weld lines in injection molding are frequently unavoidable. 2. To study the weld line formation of colliding flow fronts the filling of a mold cavity was simulated. In the RHCM, the mold temperature profile plays a crucial. The line where two resin flows “knit” or “weld” together during injection molding is called a weld or knit line. 943 µm to 0. 10(a) (please see Fig. Procedia Mater Sci 2014; 3: 2048–2053. poor flow fronts that are too cold, this can also lead to a deterioration in the mechanical properties. The flow of the material in the injection mould takes place through the gate. Flow analysis of the weld line formation during injection mold filling of thermoplastics. Meld Lines. Knit lines, weld lines, mold lines, or flow lines in injection molding are faint lines that become visible on certain plastic parts. The weld lines that occur in injection mouldings are critical areas on which depends on the strength of the mouldings. Polyamide 6 (Lanxess, Durethan B 30 S 000000, non-reinforced, ISO 1874-PA 6, GR, 14-030, Cologne, Germany) was used for this experiment. Co-injection molding technique is a useful way to study weld lines, which can offer more detailed information of the. That helps. The type of resin used during injection molding plays a large role in whether or not a knit line will be present. Weld lines are formed when two melt fronts come in contact with each other. Three terms that often get mixed up in the plastic injection molding industry are weld, meld, and knit lines. 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. Materials Science. 4 at different time steps (legend scale is volume fraction of. A weld or meld line is a weakness or visible flaw created when two or more flow paths meet during the filling process. Injection-molding machine is the Negri Bossi VE210-1700 with screw. The edge gate is the most popular and straightforward injection mold gate design. 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. However, research about the computer determination of weld lines in injection molding remains scarce. This consequently produces weld lines. When molten plastic flows, it forms a smooth continuous flow until it meets an obstruction. 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. Fisa et al. (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. 3. Information about PA6/PA66 (Nylon) Injection Molding. Increase the injection speed to reduce the amount of cooling happening in the mold. One of the factors that determines the quality of injection molded parts is the weld line [50,75,76]. A weld line (weld point, flow line or a knit line) forms when separate melt fronts travelling in opposite directions meet. As the weld line can significantly lower the mechanical strength of µIM parts, it is relevant to clarify the position of weld. Injection molding is nothing without molds. In spite of the symmetry of the molding the formed weld line was not straight, due to a slight unbalance of the two injection gates. The relative weld-line strength is defined as the ratio of the strength of specimens with a weld line and a comparable sample with the same geometry but without the weld line, and this measure mainly depends on the molding conditions, such as melt temperature, mold temperature, and injection pressure [8]. He now teaches courses in injection molding and plastic part design at the Polymers Center of Excellence and UNC-Charlotte in Charlotte, N. This principle has been implemented on a complex component in the case of the spring-loaded cogwheel shown in Figure 5, for instance. 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. Sink Marks Cause 2: Low Pack and Hold time. In an injection molding process, a weld-line forms when two flow fronts meet each other. 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. But add 30% glass and weld-line strength retention drops to only 34% as high as the compound with no weld. , Ltd. A weld line is a visible seam where two areas of the molten plastic meet. Weld lines can be caused by several different problems: Low temperature of injection moulding machine barrel. 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. It is important to investigate the weld line because the weld line area can induce potential failure of structural application. Weld lines are a common occurrence in injection molding that affects the overall quality and strength of a finished product. 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. Visualization analysis of flow behavior during weld-line formation in injection molding process. Therefore, it is recommended to do a moldflow study prior to the mold being built. This consequently produces weld lines. Weld-Line in an injection molded part develops when two or more melt fronts are converged together. In the 1947 book, Injection Molding of Plastics, the late Dr. In the heating step, the heatingOverview of the injection molding process. Investigate for potential contamination. 020 0. 2017-01-0481. Some of the approaches include the application of machine learning methods (Chen 2008; Manjunath and Krishna 2012; Kuo et al. The result is part defects such as weld lines, poor finish, or discoloration. + Adjust injection speed. The welding angle can be used to differentiate weld lines and meld lines. Clamping unit berfungsi untuk memegang dan mengatur gerakan mold unit, serta gerakan ejector saat melepas benda dari molding unit, pada clamping unit lah kita bisa mengatur berapa panjang gerakan molding saat dibuka dan seberapa panjang ejector harus bergerak. The microstructure of weld lines is clearly observed from the micrographs. Bociaga and Jaruga (2007) investigated flowing weld line in injection process by injection molding machine, which the part surface was observed in reflected light using the optimal microscope and. 8. From Understanding Weld-line Integrity by Sabic Innovative Plastics, p. Weld line and warping are two critical defects for injection-moulded part. Weld-line is a weak area which reduces the strength of the part locally. Weld lines in injection molding are formed when two or more flow fronts of molten plastic material meet and merge during the molding process. 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. 22: Weld line formation when melt splits around core pins. Abstract. Adjust the position of the gate and include a venting slot. In. . Facebook. JENIS-JENIS DEFECT (CACAT) PADA PRODUK INJECTION MOLDING PT. 3. A knit line may be unnoticeable or may look like a crack. For multiple gate and complex part, molding weld-lines are unavoidable, therefore mechanical behavior of the weld-line needs to be predicted. 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). 015 0. Munich, Germany: Carl Hanser Verlag, 1994. 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. 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. [1] Kobayashi et al. During the plastic injection molding process, one of the biggest challenges is. Unless you are manufacturing an extremely simple part with one gate and a unidirectional flow front, your part will have weld lines. <Mold> Increase (or decrease) the size of the runners and gates. The graph shows clearly how an increasing cavity temperature correlates with a reduction in the weld lines. Mold vents should function the same way. Maintain a holding pressure that is no more than 1/2 the. 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. 666 Azieatul Azrin Dzulkipli and M. 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. + Optimize holding pressure time. Weld-line is a weak area which reduces the strength of the part locally. The second technique, cascade injection moulding, can produce parts free from weld lines. This paper evaluates the shrinkage and strength of weld line using Design of Experiment and Response Surface Methodology in multi-objective optimisation utilising the injection moulding parameters. 2. 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]. 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. Weld lines Weld lines are weak areas formed by converging flows of plastic that can lead to mechanical part failure if not properly accounted for in the part design. 9 – Over Packing. Injection pressures too high Reduce pressure . Examples of such failure are shown in Figure 1. Silver Streak. Joe Henz is a chemical engineer with 30 years of experience in the plastics industry, primarily with GE. In this work, the weldline strength of injection molded short-glass-fiber reinforced polycarbonate was derived by an analytical method of modified rule-of-mixtures as a function of the area fraction between skin and core layers. Injection Molding Glossary; Weld Lines; Weld Lines. The Problems & Solutions course is designed to train injection molding personnel in. Insufficient injection pressure and speed can cause weld lines. 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. In this paper, a weld line factor (W-L factor) was adopted to describe the. Weld-line, a common occurrence in plastic injection moulding, is a representative defect compromising mechanical qualities and product appearance [16]. 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. Remember, by avoiding weld lines, you can lessen operations cost. In injection molding, it is often important to maintain consistent color throughout the part. Park et al. . A quantitative evaluation of the appearance quality of weld lines in RHCM parts. If the injection molding speed is too slow, however, there may be an insufficient filling of the mold. Weld lines can be a weak spot and have therefore to be taken into consideration in part design. Weld lines Weld lines are weak areas formed by converging flows of plastic that can lead to mechanical part failure if not properly accounted for in the part design. The design of the mold, as well as the part being molded, has a significant impact on the success of the process. Here are a few of the most common defects that may occur in plastic injection molding — and how product teams can avoid them. As a defect of micro injection molding parts, weld line is unfavorable since it will influence the surface quality and mechanical properties of micro parts. , 509 (2) (2011), pp. G. Weld Lines. 2. Ideally, the resin flow will split into two flow fronts to pass around the obstruction and then recombine into a single flow front. Plastic Injection Molding Process. Weld lines not only affect the appearance and quality of products, but also cause negative influences on the mechanical properties. Thus, it is important to understand (i). , a post that forms a hole) and then rejoins, or when polymer melt fronts meet, from multiple injection points. J. Wang. 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. Polym. In. Usually it’s a straight line, and often to be found radiating away from a hole, inclusion or other such part feature. 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. In this study, one injection mold. 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. 2007; Lotti et al. Weld Line Factors for Thermoplastics. Thus, a right gate design raises polymer temperature to prevent the formation of weld lines and flow marks. Weld lines are a kind of Achilles heel of plastics. Double push filling method. As a result, the portion has a faint, perhaps undetectable line.