Weld lines in injection molding are formed when two or more flow fronts of molten plastic material meet and merge during the molding process. Ada berbagai penyebab mengapa weld line bisa muncul pada permukaan produk plastik. This customary mark is caused by differential rates of cooling in the resin where. 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. These lines can occur at the gate location, where the plastic enters the mold, or anywhere along the flow path. Sink Marks Cause 3: Improper Pack or Hold Pressure. There are several possible causes that need to be investigated to troubleshoot weld lines in injection molding. 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. Flow-induced filler orientation and weld lines are un-avoidable facets of the injection molding process. Which means engineers need to know how to account for this phenomenon in an efficient way. Processing Optimization Reduced frozen skin thickness: High injection speeds also contribute to a thinner frozen skin at the weld line. Investigate for potential contamination. Berikut beberapa di antaranya: 1. 0 mm, is designed to conduct the. Threadline gap in-between part due to improper gate location in complex design parts including excess of holes (multipoint. Recently, injection molding process has generated growing interest, exhibiting great potential to easily fabricate unique polymeric materials for industrial applications. In this study, we apply the technique of SAW to explore the acoustic properties near injection-weld lines by comparing the velocity of. It is important to investigate the weld line because the weld line area can. box, along the region of weld line formation (wc, wm, we and wl) and away from the weld line, in a radial position along the flow direction (R), as shown in Figure 2. The weld line and the flow pattern of co-injection molding can be seen from Fig. If the different flow fronts have cooled. Ideally, the resin flow will split into two flow fronts to pass around the obstruction and then recombine into a single flow front. 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. Double push filling method. 18/06/2021. Minimize the use of release agent. Weld lines in injection molding are formed when two or more flow fronts of molten plastic material meet and merge during the molding process. This study focus on the. To determine the effect of the weld lines on tensile strength, tensile tests were conducted with the specimens fabricated with NORYL (amorphous blends of. Meld and knit lines are actually both different types of weld lines. Weld lines are a common imperfection to be found in most plastic injected molded parts. (1983). Consultant @ Effinno Technologies, BSME, MBA - Bridge between Plastics Injection Molding Knowledge and Practice. 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. 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. 5 mm, 1. Remedies: Raise the temperature of the mold or molten plastic. Remedies: Raise the temperature of the mold or molten plastic. (1) Increase the injection pressure and prolong the injection time. “I realized weld -line problems are a very common issue for injection molded parts,” Nicholson told Plastics Technology. Five injection molding process parameters, including mold temperature, melt temperature, packing pressure, injection. Procedia Mater Sci 2014; 3: 2048–2053. Try to gradually raise the mold temperature and barrel temperature. 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. To resolve this issue, rapid heat cycle molding (RHCM) has attracted attention as an innovative PIM technology. 2017-01-0481. Weld line formation in the injection molding process occurs when two or more melt flow fronts contact each other immediately after the cooling process. 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. Polyamide 6 (Lanxess, Durethan B 30 S 000000, non-reinforced, ISO 1874-PA 6, GR, 14-030, Cologne, Germany) was used for this experiment. For example, filled resins and ABS are more likely to. Figure 1 below shows the development of a weld line. This month, in our FREE SimTech™ series of webinars, we will explore weld lines and how they develop. It is possible to pre. – Use generous and even. The weld line in injection molding is created when two melt streams connect, as shown in Figure 1. In this study, we apply the technique of SAW to explore the acoustic properties near injection-weld lines by comparing the velocity of. Voids and bubbles, 6. Microsyst Technol, 14 (6) (2008), pp. The defects encountered could be caused by mechanical factors, such as poor mold design and mold manufacturing, or by processing related factors, such as incomplete kneading, inadequate molding pressure, injection. Figure 2. Just check out some of it on the above lists. Sink marks are a common type of injection molding defect. Since weldline in plastic injection molding (PIM) has an influence on not only the strength but also the surface appearance of a plastic product, it is preferable to reduce it as much as possible for high product quality. Avoid knit lines when designing a molded part to improve cosmetic appearance and functionality. when two or more melt flow fronts contact each other immediately after the cooling process. Injection molding could be applied with many polymer materials, such as. Weld line strength vs. Weld-line is a weak area which reduces the strength of the part locally. Redesign the mold to prevent the weld line. As the injection process continues, the two separated melt fronts meet again along the longitudinal section of the plate forming a weld line. injection molding, (b) weld line and meld line, and (c) injection sample size and shape. and Mosle, H. 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. 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. 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. Weld lines can compromise the strength and aesthetics of the part, so it’s important to carefully design the mold and. + Increase mold temp, or materials’ temp, or holding pressure. Weld lines are significant defects that affect injection molding quality, causing the poor appearance and low mechanical strength of injection‐molded parts. During injection moulding, a weld-line occurs when two or more flow fronts collide in the hollow cavity. Weld lines can be a weak spot and have therefore to be taken into consideration in part design. 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. This leads to a better molecular chain entanglement, which in turn creates a better weld. A flat product case was considered as an example of a typical aircraft structural element. They decrease the. This failure causes the product to be damaged during use. This failure causes the product to be damaged during use. * Corresponding author, e-mail: fengsjpc@ku. Three terms that often get mixed up in injection molding are weld, meld and knit lines. Munich, Germany: Carl Hanser Verlag, 1994. 030 0. 2. The weld line’s strength is reduced when. สาเหตุรองของการเกิดปัญหาการเกิดประกายเงิน (silver streak) 1. Causes: Weld lines are caused by the inadequate bonding of two or more flow fronts when there is partial solidification of the molten plastic. A micro-photography study on the cross-section of the weld-line was also carried out. Weld line strength is important in blow molding as well as injection molding. From Understanding Weld-line Integrity by Sabic Innovative Plastics, p. 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. Article Google Scholar Deng YM, Zheng D, Lu XJ (2008) Injection moulding optimization of multi-class design variables using a PSO algorithm. (2) Causes & Countermeasures (See the table below) *Note: Flash also tends to occur when the injection pressure/speed are too high, but molding time is too long and mold temperature is too low. 2023年1月3日 / by admin. Flow front tracing simulation results for weld line developing process in micro injection molding with Comsol ® Multiphysics 3. The terahertz time-domain spectroscopy (THz-TDS) imaging technique was used to detect the weld line defect of an injection-moulded short glass fiber-reinforced composite. Insufficient plasticizing ability of injection molding machine. Weld lines, knit lines, and meld lines are terminologies to describe the imperfections of finished parts in plastic injection. Effects of cavity surface temperature on mechanical properties of specimens with and without a weld line in rapid heat cycle. 2012. An injection molding gate is the designed opening in a mold through which molten plastic is introduced into the mold cavity, initiating the process of taking the shape of the desired part. In the present work, the micro specimens were investigated. Microsyst Technol. Therefore, the length of flowing weld lines must be additionally defined. To explore the formation of. . This may require higher melt temperature or lower injection speed . This principle has been implemented on a complex component in the case of the spring-loaded cogwheel shown in Figure 5, for instance. 1. สาเหตุการเกิด weld line คือเมื่อการไหลของพลาสติกมาประสานกันนะจุดใดจุดหนึ่งและจุดนั้นเกิดความแตกต่างของอุณหภูมิในสองทิศทางการไหลจะทำให้เกิด. In order to reduce these weak points, a special ram technique for injection molding, which can be integrated into the mold, was investigated. Xie L. To increase the sustainability of the process, determinative parameters and their effects should be examined. Our injection molding company is explaining what these imperfections are, why they can compromise. A meld line occurs when two moving melt fronts converge and flow parallel to each other. Adjust Injection Molding Parameters: Optimizing injection speed, pressure, and temperature can help ensure better melt flow and reduce the likelihood of weld line formation. Proper venting is also required to ensure good weld-line quality. He said, “Vent cavities at weld lines or junction points where two or more material streams meet and fuse into a solid mass. Usually it’s a straight line, and often to be found radiating away from a hole, inclusion or other such part feature. Although this phenomenon occurs in almost all the commercially important polymer. 1, right). Compd. Polym Eng Sci 45(7):1021–1030. 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]. 3. 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. Weld lines, also known as knit lines, are a common defect in injection molding where two or more flow fronts of molten plastic meet but don’t properly fuse together. 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. Computer simulation packages of injection molding have had success in predicting filling behavior in extremely complicated geometries, capable of predicting weld lines’ location exactly. 010 0. 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. Bin-Xin Yang Ouyang Jie Supei Zheng Qiang Li Wen Zhou. Weld lines are visually undesirable and a plastic part is structurally weak at weld line positions. demanding injection molding and end-use requirements. 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. Crack growth behavior. Weld line. A new kind of weld line was. Strength measurements should be made to. , 47 (2008. Fig 13:- Detailed view of weld lines. replication and poor weld line strength . 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. Poor weld line quality can lead to short-term or long-term product failures, initiated at the weld line. The utility model relates to a mold structure capable of eliminating the appearance of weld lines of a hole. Lesson 6: Meld and Weld Lines (Processing) When plastic flows into an injection mold, the internal flow pattern depends on the part design, mold design, and processing factors. 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). Plastic Injection Molding Process. Three terms that often get mixed up in the plastic injection molding industry are weld, meld, and knit lines. 1. Criens, R. The. The weld line is an inevitable defect in the most injection molded components. They. Polym. As such, optimizing mold designs should always be incorporated in your production model. Silver Streak. Part design features may cause a material flow to split and rejoin as it flows around design features in a 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]. For this purpose, the width of the weld line calculated by Sigmasoft is. Vertical Plastic Injection Molding Machine [10, 11, 12] 2. In recent years, researchers have. In this experiment, several ejector. S. Miron MC, Major Z, Adachi T. CrossRef View in Scopus Google Scholar [17] G. Weld line is formed when two different melt flows converge, as illustrated in Fig. The. This reduced thickness of the frozen skin further enhances the visual appeal of the. 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]. Here are some reasons why design is important for injection molding. 000 0. 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. The design of the mold, as well as the part being molded, has a significant impact on the success of the process. Remember, by avoiding weld lines, you can lessen operations cost. We have various types and models available. C. But the unfavorable and unavoidable defect of weld line in micro injection molding part leads to detrimental mechanical and surface properties. Injection Molding Glossary; Weld Lines; Weld Lines. Weld-line is a defect that arises in injection molding when two or more flow fronts collide. Weld lines. An injection molding gate is a critical component in mold design, acting as the passage through which molten plastic travels from the runners into the mold cavity. Siemens PLM Software. ). If the different flow fronts have cooled. Weld lines form where two or more flow fronts come together and can create a cosmetic or structural problem. . 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. 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. 025 100 120 140 160 180 200 220 240 Mold Temperature (F) LDPE PPEffects of mold temperature and pressure on shrinkage 0. 3 Materials Polypropylene (PP) and. The Solutions for Poor Welding Lines. Fiber content dependence on. This reduced thickness of the frozen skin further enhances the visual appeal of the. Mechanical properties of the weld line defect in micro injection molding for various nano filled polypropylene composites. Weld lines occur when melt flow fronts meet during the injection molding of plastic parts. Sink Marks Cause 1: Incorrect Melt Temperature. 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. The optimal process condition is very likely to appear in this second part's fine-tune group. Weld line is one of the plastic injection molding defects. Int J Adv Manuf Technol:1–11In addition to the weld line, the exposure of fibers on the molded product surface results in a rough surface, which degrades the appearance of the product. As a result, the portion has a faint, perhaps undetectable line. The moldability validation and flow analysis tools enable you to iden-tify and correct potential injection molding problems as you design the product. 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. Injection molding is a highly versatile manufacturing process used to produce a wide range of plastic products with precision and efficiency. 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. 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. In this experiment, several ejector. Save. Weld line, 5. Depending on the resin, resin temperature, mold temperature, and filling speed, knit lines can vary. Plastic part design for injection molding – An introduction. In a weld line, reinforcement fibers adopt an orthogonal orientation with respect to the filling direction, which results in a significant reduction in the strength and. In the end, the total amount of time that running a complete Taguchi DOE (L18) to occupy an injection. Weld Lines are formed when two or more molten polymer flows meet during the injection molding process. When two or more strands of molten plastics meet in the mold, a weld. The following are the reasons. 3 and 53. Therefore, the investigation on the developing process of weld line would be a significant issue for improving the quality of micro injection molded parts. (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 line defects are a common part defect that occurs when the injected plastic flows around a solid piece of the mold and does not knit back together. Weld lines can be caused by many reasons, which covers the various aspects of mold, process, raw materials and product design, etc. It occupies a major part in the plastics industry ranking second to plastic extrusion in terms of production and the utilization of both thermoplastic and thermosetting plastic materials. A weld or meld line is a weakness or visible flaw created when two or more flow paths meet during the filling process. อุณหภูมิของพลาสติกเหลวสูงเกินไปจนก๊าซหรือความชื้นแยกตัวออกมาได้. A weld line region is typically filled at the end of an injection stroke or during the pressure phase. In our DFM report, we will analyze the possible weld lines. Weld line existence reduces the material strength; however, its demerit characteristics. spelling: injection molding) is a manufacturing process for producing parts by injecting molten material into a mould, or mold. The weld line is then created with a higher flow front temperature and is packed with more pressure. Tekanan yang kurang mampu untuk mendorong aliran dan kembali pada posisi semula dapat menimbulkan weld line. Joe Henz is a chemical engineer with 30 years of experience in the plastics industry, primarily with GE. This can occur when a polymer flow splits to go around an interruption (e. The quality of the weld line can be improved through optimized processing conditions, increased mold and melt temperatures, and increased injection speed to reduce the viscosity of the polymer. It has larger cross-sectional regions that allow sufficient molten plastic flow into the cavity. Weld lines in injection molding are a type of cosmetic defect that detracts from a plastic part’s appearance. as warpage, shrinkage and weld line of the plastic parts. 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. The edge gate is the most popular and straightforward injection mold gate design. To respond to poor plasticization and uneven melt temperature, the molding cycle can be extended to make. Weld lines create visible marks, but this type of injection molding defect can also reduce a part’s strength and durability. Abstract. Injection-molding machine is the Negri Bossi VE210-1700 with screw. Co-injection molding technique is a useful way to study weld lines, which can offer more detailed information of the. Complexities in the design and intricate pathways in the mold can also create flash in injection molded parts. You will have to confirm them before tooling. Thus, a right gate design raises polymer temperature to prevent the formation of weld lines and flow marks. Five industry pros with more than 200 years of combined molding experience provide step-by-step best practices on mounting a mold in a horizontal injection molding machine. The present work focuses on studying the effect of packing pressure on strength of stagnation weld-line. 2. Wu CH, Liang WJ (2005) Effects of geometry and injection-molding parameters on weld-line strength. 2011; 509 (2):226–233. 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. A visual mold with variotherm system for weld line study in micro injection molding. The cracking was always located in the weld/knit line and therefore caused by weakness in the bonding of the plastic at. Weld Lines and Fibers There are two basic types of weld lines: the stagnant and the flowing [1]. Instead, a line that looks like a seam forms. Weld lines, generated during injection molding, can significantly reduce the mechanical performance of structures. [ 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. JENIS-JENIS DEFECT (CACAT) PADA PRODUK INJECTION MOLDING PT. + Optimize holding pressure time. In a weld line, reinforcement fibers adopt an orthogonal orientation with respect to the filling direction, which results in a significant reduction in the strength and. The tensile stresses of the weld lines with ultrasonic functions are 8. The injection molding process can be optimized to maximize weld line strength by increasing. Participating in DFM and mold flow analysis is a good way to achieve this. 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). In. For multiple gate and complex part. Known methods to reduce weld-line effects are the optimization of injection molding parameters, enhanced tool temperature, and using special molding tool devices. Polymers 2023, 15, 2440 3 of 21. Injection molding of large/complicated products are usually prepared by multiple compounds, which produces weldlines once the melt fronts are joined by impingement flow. Weld-line is a weak area which reduces the strength of the part locally. When an external load is applied to a weld line region, the part’s potential for mechanical failure is increased. In this study, the effects of injection temperature, injection pressure, and fiber cont. 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. Amongst weld line. What causes them? The primary cause is weak bondage between two or more flow fronts. C. The flow of the material in the injection mould takes place through the gate. (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. Its appearance can be improved by adjusting parameters. Weld lines are a kind of Achilles heel of plastics. 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. A weld line develops when two or more flow fronts come together but do not meld completely because of partial solidification. A poor knit line can cause only cosmetic blemishes or it can significantly weaken the structural integrity of a part. The choosing optimal gate location technique has been developed to set weld lines as far as possible from the region of maximum stresses. 020 0. Munich, Germany: Carl Hanser Verlag, 1994. Edge Gates. 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. Weld lines are formed when two melt fronts come in contact with each other. According to the characteristics. Munich, Germany: Carl Hanser Verlag, 1994. Weld lines occur when melt flow fronts meet during the injection molding of plastic parts. If the injection molding speed is too slow, however, there may be an insufficient filling of the mold. Investigations on WLs in micro injection molded parts were performed in Refs. In an injection molding process, a weld-line forms when two flow fronts meet each other. This injection molding defect appears as a black discoloration on the surface of the molded part. The microstructure of weld lines is clearly observed from the micrographs. It can be determined by a visible line appearing on the surface of the plastic part where two flows of the plastic meet. This study focuses on the effect of melt temperature on. If there’s too much mold release, you may require a higher pressure to push it through the machine. The formation of weld lines and their location along the flow path is a well-studied phenomenon in conventional injection molding; however, only a few papers are devoted to micro-injection molding [11,13,14,15,16]. Figure 1 a illustrates how the weld line is produced when two melt streams merge during the final filling process. Meld lines are formed when two separate flow fronts meets. 2. . Here is a look at the differences between them, the causes of meld and knit line imperfections, and their impact on part durability. 025 100 120 140 160 180 200 220 240 Mold Temperature (F) LDPE PPAbstract. The Problems & Solutions course is designed to train injection molding personnel in. Weld line location. Although they often cannot be avoided it’s possible to minimize their cosmetic effects to an acceptable degree through careful product design and. “I realized weld -line problems are a very common issue for injection molded parts,” Nicholson told Plastics Technology. warpage, and weld line. Furthermore, injection molding was applied by filling these pellets into a micro-injection molding machine (C. [ 18 - 21 ] In addition, the effects. Increase the mold temperature. Physics. 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. 7 of the reference. As the plastic flows through the mold it. 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. 1. In spite of its cosmetic attributes, a bad knit line can significantly. 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. Let’s review what causes meld and knit line imperfections, how they’re different, and how they affect part durability. Gate blush, 4. Flashes, 3. Weld lines in injection molding are frequently unavoidable. In the plastic injection molding industry, we work with materials that are byproducts of oil refinement and molds made of metal casting, so our terminology is bound to be at least slightly confusing. * Corresponding author, e-mail: [email protected] an injection molding process, a weld-line forms when two flow fronts meet each other. A weld line is a visible seam where two areas of the molten plastic meet. Unless you are manufacturing an extremely simple part with one gate and a unidirectional flow front, your part will have weld lines. With unchangeable and fixed requirements for the final product, their avoidance often proves difficult. 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. The schematic diagram of a weld line formation is illustrated in Figure 7, where is the welding angle of two melt fronts. 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. Wu CH, Liang WJ (2005) Effects of geometry and injection-molding parameters on weld-line strength. 2. In injection molding, it is often important to maintain consistent color throughout the part. The weld line’s strength is reduced when. Weld line formation in the injection molding process occurs. The molded plastic part may also appear to be rust-colored. In some cases, a weld line can also cause a loss of strength and impact resistance. <1> As illustrated in Figure 4, the existence of. During the plastic injection molding process, one of the biggest challenges is. This paper analyzes production data from injection molding processes to identify key interactions between the process variables from different material categories using the network inference method called “bagging conservative causal core network” (BC3net). ชิ้นงานเกิดเป็นเส้นรอยประสาน Weld line. Insufficient plasticizing ability of injection molding machine. A weld line is often unavoidable. 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 following are the conclusion drawn from the present research: 1. 2. In injection molding, it is often important to maintain consistent color throughout the part. The impact behavior of weld-lines in injection molding. Melt temperature is 250°C, mold temperature is 110°C. Weld lines can impact the strength and appearance of the final part, and are often considered a defect. The weld line in an injection molding product can significantly impact the strength and durability of the last part [12] [13][14][15]. Bubbles are caused by melting flow fronts colliding in a mold cavity. In the injection molding process, weld line regions occur when a molten polymer flow front is first separated and then rejoined. Weld or knit lines are perhaps the most common and difficult injection molding defect to eliminate. Weld line section presents notch or gloss difference. 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 type of resin used during injection molding plays a large role in whether or not a knit line will be present. Injection molding plate for mode I testing geometry. Fatigue crack growth (FCG) tests were conducted on SEN specimens prepared from 100 mm. Known also as knit lines and weld marks, weld lines are difficult to eliminate completely, especially if your injection molded part requires holes. (3-1) Increasing the Resin Temperature at the Weld Line Section. Weld-line is a defect that arises in injection molding when two or more flow fronts collide. The formation of weld lines and their location along the flow path is a well-studied phenomenon in conventional injection molding; however, only a few papers are devoted to micro-injection molding [11,13,14,15,16]. In a meld line, the plastic comes together at an angle greater than 135 degrees. These are preferred over weld lines as they will normally result in improved cosmetics and structure. Change the gate locations.