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. To explore the formation of weld lines in injection molding, a. 3. and most commonly, thermoplastic polymers are used. 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. Burn Marks. Sink Marks Cause 1: Incorrect Melt Temperature. The weld line’s strength is reduced when. Controlling injection molding weld lines with good design and process control. In this paper, two different injection molding tests were completed. Flash. In the present work, the micro specimens were investigated. Meld and knit lines are actually both different types of weld lines. It occurs when melting plastic material is injected into a mold, it flows through all parts of th. Wu CH, Liang WJ (2005) Effects of geometry and injection-molding parameters on weld-line strength. 1. For multiple gate and complex part, molding weld-lines are unavoidable, therefore mechanical behavior of the weld-line needs to be predicted. Fracture Toughness of Weld Lines in Thermoplastic Injection Molding, Polymer Engineering and Science, 33(15): 996-1001. Here we are looking at most common part defect that can come from injection molding called weld line. Molding with weld line model Moldex3D was used for calculate the molding of lugs (figure 1). A weld line refers to a line, notch or color change that is created on the molded part caused by the convergence of two separate flows of molten plastic. Our weld line injection molding is essential for the best result of finished molded products. The choosing optimal gate location technique has been developed to set weld lines as far as possible from the region of maximum stresses. weld lines in infill analysis of injection molding simulation was observed [5]. Make the size of runner channel wider and/or shorter. 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. In the sense that the weld line is better formed before the resin. However, research about the computer determination of weld lines in injection molding remains scarce. 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 lines may appear like seams or scratches, but that is not what they are. Gambar 2. Weld lines can lower the integrity of the part. When two or more strands of molten plastics meet in the mold, a weld. 3. Fellahi et al. Figure 1 a illustrates how the weld line is produced when two melt streams merge during the final filling process. This is a video excerpt from our Problems & Solutions Course - Weldlines. Reduce the amount of release agents. A simulation of mold filling with multi-inlets or an insert in the cavity is pursued with an improved Level Set Method. Three terms that often get mixed up in injection molding are weld, meld and knit lines. Inadequate back pressure. Int J Adv Manuf Technol 52:131–141. Weld-line is a weak area which reduces the strength of the part locally. ” Another. Weld lines may appear like seams or scratches, but that is not what they are. 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 second technique, cascade injection moulding, can produce parts free from weld lines. They can affect the strength and appearance of the part, depending on the temperature, pressure, speed, and mold design of the injection molding process. T he decreased gloss level at the position of. สาเหตุรองของการเกิดปัญหาการเกิดประกายเงิน (silver streak) 1. They are the result of fundamental physical effects taking place inside of the mold tool cavity. reinforcement type and amount in nylon 6/6. Avient’s Zachary Alderman shares practical tips on designing and injection molding parts utilizing short-fiber reinforcements. Thus, it is important to understand (i) if the melt is able to fill the cavity up to the weld line location, (ii) where the weld line forms, and (iii) if the weld line is a cold or flowing one. A visual mold with variotherm system for weld line study in micro injection molding. 2. Penyebab Weld Line. Weld line existence reduces the material strength; however, its. The gate location should enable the two flow fronts to merge easily and continue to flow beyond the weld line. Weld lines are one of the typical quality issues of injection molded parts. 1, right). 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. 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. Failure may result due to the assembly torque, or end-use application loads (temperature, creep). To increase the sustainability of the process, determinative parameters and their effects should be examined. 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. 2017-01-0481. The Influence of Knit-lines on the Tensile Properties of Injection Molded Parts, Polymer Engineering and Science, 23(10): 591-596. As the weld line can significantly lower the mechanical strength of µIM parts, it is relevant to clarify the position of weld. That’s the air escaping out of the nozzle until the hose is full of pressurized water. . Berikut beberapa di antaranya: 1. Knit lines, weld lines, mold lines, or flow lines in injection molding are faint lines that become visible on certain plastic parts. ” Weld Lines in a plastic cover. Insufficient plasticizing ability of injection molding machine. It can be determined by a visible line appearing on the surface of the plastic part where two flows of the plastic meet. Injection molded plastic parts have comparatively less strength in the weld line section and they also have an impact on product aesthetics. The effects of fiber concentration has been studied in detail. 21: Weld line failure caused by hoop stresses. Improper fusion of two fluid flows, a state before weld line. 005 0. This customary mark is caused by differential rates of cooling in the resin where. Weld Lines. Meld and knit lines are actually both different types of 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. Effects of cavity surface temperature on mechanical properties of specimens with and without a weld line in rapid heat cycle. ac. Below is one of the examples: !NOTE: if the weld lines is important to the cosmetic surface of your part, please bring this up to your mold maker during quoting phase. These master batches and PP pellets were dry-blended by adjusting the ratio such that the fiber contents were 10, 20, and 30 wt%. Moldflow is computer software that is widely used across the plastic injection molding industry to predict and optimize the injection molding process and assist with mold design. 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. oped which factors the weld lines into the virtual design of chopped-strand-rein-forced thermoplastic parts. Weld lines are a kind of Achilles heel of plastics. Micro injection molded polymeric parts coated with functional thin films/layers show off the promising applications in microsystems area. 020 0. on conventional reciprocating screw injection molding machines using molding practices standard for filled engineering thermoplastics . When two or more strands of molten plastics meet in the mold, a weld line will be produced at the junction [1,2]. 22 shows how the weld lines are formed when the melt splits around core pins during the injection molding process. Tekanan. Known also as knit lines and. Gate blush, 4. They. 015 0. In addition, its tensile strength and stiffness will be sharply decreased. When this fails to happen correctly, a weld line defect occurs. 13 shows the best gate location for which the weld lines . Google Scholar | Crossref | ISI. 1. Lesson 6: Meld and Weld Lines (Processing) When plastic flows into an injection mold, the internal flow pattern depends on the part design, mold design, and processing factors. Again, consult with professionals as to how you could improve mold designs. 1. 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]. Joe Henz is a chemical engineer with 30 years of experience in the plastics industry, primarily with GE. Mold flow analysis can predict the location of weld lines. The results showed that the tensile strength of PE remains unchanged in the presence of weld lines. “I realized weld -line problems are a very common issue for injection molded parts,” Nicholson told Plastics Technology. Weld line formation in the injection molding process occurs. Co-injection molding technique is a useful way to study weld lines, which can offer more detailed information of the. Try to gradually raise the mold temperature and barrel temperature. 809-814. In injection molding, it is often important to maintain consistent color throughout the part. [ 18 - 21 ] In addition, the effects. Cited by (41) Effect of mould surface roughness adjustments to increase the flow path length in the injection moulding process. when two or more melt flow fronts contact each other immediately after the cooling process. Sequential valve gate technology. For this purpose, the width of the weld line calculated by Sigmasoft is. Facebook. 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. This month, in our FREE SimTech™ series of webinars, we will explore weld lines and how they develop. This may require higher melt temperature or lower injection speed . 0 mm, is designed to conduct the. Processing OptimizationReduced frozen skin thickness: High injection speeds also contribute to a thinner frozen skin at the weld line. Weld lines have been one of the common defects puzzling the injection molding industry. Weld Lines. Let’s review what causes meld and knit line imperfections, how they’re different, and how they affect part durability. 6. 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. Increase the injection speed. A meld line is defined as the re-merging of two flow fronts. From: Polylactic Acid (Second Edition), 2019. Insufficient plasticizing ability of injection molding machine. Thereby creating localized pressure within the mold. To resolve this issue, rapid heat cycle molding (RHCM) has attracted attention as an innovative PIM technology. Munich, Germany: Carl Hanser Verlag, 1994. This defect occurs due to the temperature and pressure not being high enough, causing premature solidification. Known methods to reduce weld-line effects are the optimization of injection molding parameters, enhanced tool temperature, and using special molding tool devices. The resulting defects don’t stop at flash only. Weld lines not only affect the appearance and quality of products, but also cause negative influences on the mechanical properties. Weld Line defect analysis, the most common of many defects in injection moulding products. A weld line is a visible seam where two areas of the molten plastic meet. Expand. Weld line, 5. Weld line is formed when two different melt flows converge, as illustrated in Fig. 2(a, b). 5. Weld lines represent the region where two separated melt fronts recombine. 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. In the sense that the weld line is better formed before the resin temperature. 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. Bubbles are caused by melting flow fronts colliding in a mold cavity. As the unfavorable defect in micro injection molding parts, weld line brings reduced mechanical and physical properties, especially for nano filled composites. In an injection molding process, a weld-line forms when two flow fronts meet each other. Injection speed is too low. (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. As a result, the portion has a faint, perhaps undetectable line. The thermo-rheological findings were used to investigate the sources of weld line weakness. 3 cc/sec, the weld lines decrease over temperatures up to 150 C, while at higher volumetric injection flow rates of 43. 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. Remedies: Raise the temperature of the mold or molten plastic. The microstructure of weld lines is clearly observed from the micrographs. Three terms that often get mixed up are weld, meld, and knit lines. Information about PA6/PA66 (Nylon) Injection Molding. It is a zone with reduced mechanical properties negatively influencing on the molding behavior in exploitation. The weld line and the flow pattern of co-injection molding can be seen from Fig. 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. Weld-line, a common occurrence in plastic injection moulding, is a representative defect compromising mechanical qualities and product appearance [16]. Conclusion The formation of weld lines in micro injection molding of plastic depends on different parameters such as melt temperature, injection pressure and fabrication method. The Solutions for Poor Welding Lines. Weld line location. Because of the ever-increasing requirements for parts performance, lots of researchers have perf. Unless you are manufacturing an extremely simple part with one gate and a unidirectional flow front, your part will have weld lines. Melt temperature is 250°C, mold temperature is 110°C. 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, knit lines, and meld lines are terminologies to describe the imperfections of finished parts in plastic injection. <Materials> Pre-dry thoroughly. An injection molding processor who can analyze the process from the plastics point of view, can quickly solve any molding problem, regardless of the machine or plastic type. This defect occurs due to the temperature and pressure not being high enough, causing premature solidification. 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. This type of injection molding resolves any trouble caused by undesired welding lines. Thoroughly clean molding machine cylinders. Depending on the resin, resin temperature, mold temperature, and filling speed, knit lines can vary. Miron MC, Major Z, Adachi T. 5. (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. In a meld line, the plastic comes together at an angle greater than 135 degrees. The schematic diagram of a weld line formation is illustrated in Figure 7, where is the welding angle of two melt fronts. 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. Polym. The Solutions for Poor Welding Lines. Three terms that often get mixed up in the plastic injection molding industry are weld, meld, and knit lines. 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. Remedies: Raise the temperature of the mold or molten plastic. Siemens PLM Software. When two or more strands of molten plastics meet in the mold, a weld line will be produced at the junction [1,2]. 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. 2. Rapid heat and cool injection molding is an example of a measure to prevent the generation of weld lines. We investigate the effects of various heating times and. 1. Shaofei Jiang. 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. Xie L, Ziegmann G (2008) A visual mold with variotherm system for weld line studying micro injection molding. Its appearance can be improved by adjusting parameters. Flow marks in injection molding can be avoided if adequate measures are taken. Mold vents should function the same way. The optimum injection molding parameters to manufacture the product was determined by . Reposition gates and runners to allow resin to flow around the obstruction from a. C. G. Weld Lines and Fibers There are two basic types of weld lines: the stagnant and the flowing [1]. The parts are molded flat and are slightly stressed once installed in an arced position, but not excessively. The. In. Its design significantly impacts the final product’s appearance, strength, and functionality, making it crucial for manufacturers to understand its intricacies and variations thoroughly. Weld line reduction is one of the major concerns in plastic injection molding (PIM) that results in high surface appearance and high strength of a plastic product. As these flow fronts come together on the. Participating in DFM and mold flow analysis is a good way to achieve this. Injection molding can be performed with only one of these materials like glass, plastics, etc. This paper presents the. 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. Procedia Mater Sci 2014; 3: 2048–2053. 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. Injection Molding Glossary; Weld Lines; Weld Lines. Article Google Scholar Deng YM, Zheng D, Lu XJ (2008) Injection moulding optimization of multi-class design variables using a PSO algorithm. Miron MC, Major Z, Adachi T. (2) Adjust the injection speed: high speed allows the melt to reach the confluence without cooling down, and low speed allows time for the air in the cavity to be discharged. 2017-01-0481. technical ulletin SPECIALTY POLYME RS Design and Production of Injection Molding ToolsWeld lines have been one of the common defects puzzling the injection molding industry. According to the characteristics. 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. Weld lines are formed when two melt fronts come in contact with each other. Proper venting is also required to ensure good weld-line quality. 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. Figure 1. Zhao, X. Weld-line yield strength, yield strain, and failure strain of talc-filled polypropylene increase with increasing melt temperature and increasing hold pressure. They decrease the. Weld or knit lines are perhaps the most common and difficult injection molding defect to eliminate. Again, consult with professionals as to how you could improve mold designs. 2021年4月23日 / by admin. If so, look for an alternative resin. [ 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. . 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]. Flow lines arise when at least two melt fronts meet at an acute an-Weld line is aesthetically unpleasant and affects the mechanical strength of injection molded parts. Poor weld line quality can lead to short-term or long-term product failures, initiated at the weld line. Figure 2. Technol. + Adjust injection speed. + Move gate (to where it is not visible). In this study, the effects of injection temperature, injection pressure, and fiber cont. Abstract. Increase the mold temperature. To study the weld line formation of colliding flow fronts the filling of a mold cavity was simulated. 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 injected. Table 2-Glass Fiber Glass Fiber Glass Fiber Glass Fiber 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 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. The weld line length was selected as part of the quality index to investigate the effects of gate location on weld. In manufacturing, the Weld line or Knit line or Meld line is the line where two flow fronts meet when there is the inability of two or more flow fronts to "knit" together, or "weld", during the molding process. 3. Weld Lines. At a low volumetric injection flow rate of 33. For thick-walled parts, slow injection rates result in more uniform polymer distribution . 2-1. Injection pressure or. One of the factors that determines the quality of injection molded parts is the weld line [50,75,76]. In the heating step, the heatingOverview of the injection molding process. Nozzle – The nozzle is at the end of the barrel and contacts the injection mold. Weld line and warping are two critical defects for injection-moulded part. Weld line is one of the plastic injection molding defects. Processing Optimization Reduced frozen skin thickness: High injection speeds also contribute to a thinner frozen skin at the weld line. 3 Materials Polypropylene (PP) and. <Materials> Pre-dry thoroughly. 010 0. A new kind of weld line was. Weld-line is a weak area which reduces the strength of the part locally. Gava and co-workers implemented an investigation devoted to the de-weld lines in injection molded thermoplastic composites. The melt stream is separated at the part’s cutout and reunited at the other end of the cutout. C. 10(a) (please see Fig. อุณหภูมิของพลาสติกเหลวสูงเกินไปจนก๊าซหรือความชื้นแยกตัวออกมาได้. Plastic Injection Molding Process. open access Abstract Micro weld lines are the common problem that occurs for plastic molded parts through injection molding process. Install an ultrared light inside the hopper. The welding angle can be used to differentiate weld lines and meld lines. This is expected to achieve maximum results while the pressure holding effect will also increase. This principle has been implemented on a complex component in the case of the spring-loaded cogwheel shown in Figure 5, for instance. Boost time too long Shorten boost time, lower boost pressure, or move transfer to an earlier position . 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. Therefore, the investigation on the developing process of weld line would be a significant issue for improving the quality of micro injection molded parts. Learn more about ABS injection molding here. Bin-Xin Yang Ouyang Jie Supei Zheng Qiang Li Wen Zhou. 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. High-density PE was also moulded in the same conditions but in a lower temperature range (145 to 220°C). If the plasticizing ability of the plastics injection molding machine is insufficient, the plastic cannot be fully plasticized, resulting in weld lines when filling the mold. Insufficient injection pressure and speed can cause weld lines. 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. This consequently produces weld lines. As the plastic flows through the mold it. 666 Azieatul Azrin Dzulkipli and M. 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. Redesign the mold to prevent the weld line. Fortunately, there are several. Weld lines are visually undesirable and a plastic part is structurally weak at weld line positions. <Mold> Increase (or decrease) the size of the runners and gates. 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]. A quantitative evaluation of the appearance quality of weld lines in RHCM parts. Poor weld line Ⅰ. 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. Therefore, it is recommended to do a moldflow study prior to the mold being built. 025 100 120 140 160 180 200 220 240 Mold Temperature (F) LDPE PPAbstract. 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. Known also as knit lines and weld marks, weld lines are difficult to eliminate completely, especially if your injection molded part requires holes. Figure 2. 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]. The following guidelines have. 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. Depending on the resin, resin temperature, mold temperature, and filling speed, knit lines can vary. Weld lines can be caused by many reasons, which covers the various aspects of mold, process, raw materials and product design, etc. 2-1. industry, to deliver intuitive injection mold-ing simulations embedded in NX. 6. Various measures are taken at production sites to address these problems. In addition a weld line can be moved to an area where it is less visible. Equipment. A weld line (weld point, flow line or a knit line) forms when separate melt fronts travelling in opposite directions meet. Weld line formation in the injection molding process occurs. Consultant @ Effinno Technologies, BSME, MBA - Bridge between Plastics Injection Molding Knowledge and Practice. Weld lines not only affect the appearance and quality of products, but also cause negative influences on the mechanical properties. 5. We have various types and models available. 2012. 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. 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. Characteristic: Basically, there are PA6 AND PA66(Nylon 6 or Nylon 66), Nylon has tenacious and wearable, self-lubricious and smooth characteristics with non-toxic and antibiosis and high water absorbability. Computer simulation packages of injection molding have had success in predicting filling behavior in extremely complicated geometries, capable of predicting weld lines’ location exactly. 3 cc/sec, the weld lines are no longer perceivable above 130 C. 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. 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. , 509 (2) (2011), pp. In injection molding weld lines are formed whenever two flow fronts are joined. As the injection process continues, the two separated melt fronts meet again along the longitudinal section of the plate forming a weld line. JENIS-JENIS DEFECT (CACAT) PADA PRODUK INJECTION MOLDING PT. Sink Marks Cause 2: Low Pack and Hold time. The diameter of the hole is 12 mm. They occur when melt flow fronts collide in a mold cavity. Knit lines in injection molding are undesirable, especially when surface appearance and part strength are significant concerns. molding Æ Thermoplastics Æ Weld line Æ Simulation Rheol Acta (2004) 43: 240–245 DOI 10. See moreIncreasing the temperature of the mold or plastic material. 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. If you have critical requirements for strength of knit lines, please call a Protolabs applications engineer at 877-479-3680 to discuss, or email at [email protected]. une, 13: 15. Flow-induced filler orientation manifests in higher tensile prop-erties in the direction of flow compared to those normal to the direction of flow. The type of resin used during injection molding plays a large role in whether or not a knit line will be present. Weld lines appear as a result of the flow of molten plastic during the injection molding process. 1. Slow down injection speed. S. 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. 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. Adjust Injection Molding Parameters: Optimizing injection speed, pressure, and temperature can help ensure better melt flow and reduce the likelihood of weld line formation. In injection molding of thermosoftening plastics, an important aspect having a bearing on the quality of articles is the appearance of weld lines that are formed when there are inserts, barriers, molding signs, reinforcements, etc. in the cavity of the injection mold. Neat polypropylene retains nearly 90% of its strength on a properly designed and molded weld line. Weld lines in injection molding are a type of cosmetic defect that detracts from a plastic part’s appearance. 18 ชิ้นงานเกิดเป็นเส้นรอยประสาน Weld line. Weld lines can impact the strength and appearance of the final part, and are often considered a defect. 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. + Increase mold temp, or materials’ temp, or holding pressure. 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. 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. 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. 8. 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. The cracking was always located in the weld/knit line and therefore caused by weakness in the bonding of the plastic at. (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. 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 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. That helps. 1. 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) 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. Alloys. Set up the process overflow and use it as the place where the weld line is generated, and then cut off and remove it after forming.