As a result this weld line will be a weak point in this part. The optimal process condition is very likely to appear in this second part's fine-tune group. Weld line location. Mobile 0813; Shinko Sellbic Co. 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. 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. Maintain a holding pressure that is no more than 1/2 the. Weld lines in injection molding are a type of cosmetic defect that detracts from a plastic part’s appearance. The second technique, cascade injection moulding, can produce parts free from weld lines. 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. Sink Marks Cause 4: High Mold Temperature. Polym Eng Sci 45(7. + Improve vent inside the mold. He said, “Vent cavities at weld lines or junction points where two or more material streams meet and fuse into a solid mass. This reduced thickness of the frozen skin further enhances the visual appeal of the. • Reduce runner dimensions and maintain the same flow rate. These lines usually occur around holes or obstructions and cause locally weak areas in the molded part. This occurs mainly in the presence of barriers that divide the melt flow in. 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. Fig. Weld lines have been one of the common defects puzzling the injection molding industry. 3. This principle has been implemented on a complex component in the case of the spring-loaded cogwheel shown in Figure 5, for instance. are very minimum. Known also as knit lines and weld marks, weld lines are difficult to eliminate completely, especially if your injection molded part requires holes. Polym Eng Sci 45(7):1021–1030. An evaluation model based on artificial neural network method. 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. Plastic part design for injection molding – An introduction. As the plastic flows through the mold it. Adjust the design for the flow pattern to be a single source flow. Weld lines occur when melt flow fronts meet during the injection molding of plastic parts. 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. Microsyst Technol. 2012. Azuddin / Procedia Engineering 184 ( 2017 ) 663 – 672 Fig. 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. 2. In addition, its tensile strength and stiffness will be sharply decreased. Mechanical properties of the weld line defect in micro injection molding for various nano filled polypropylene composites. Insufficient plasticizing ability of injection molding machine. With Ixef® PARA compounds, the strength of a weld line is typically 90 MPa (13,000 psi). identi fy a s urface defect i n th e for m of a weld line, which occurs due to the two injection points at x = 5 mm and 34 mm ( see Fig. 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. This model provides the necessary information. Weld lines appear on the surface of a molded part where the molten material converges after splitting off into two or more directions in a mold. Weld or Knit lines are a plane or section in an injection molding part where the flow of molten plastics meets from different directions. Weld lines are a common defect generated in injection molding, which apparently affects the performance of final products, but the available reports on carbon fiber-reinforced thermoplastics are still rather few. The Influence of Knit-lines on the Tensile Properties of Injection Molded Parts, Polymer Engineering and Science, 23(10): 591-596. Injection molding could be applied with many polymer materials, such as. 3. 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. Injection-molding machine is the Negri Bossi VE210-1700 with screw. The weld line refers to the process in which the liquid material is divided into two or more flows in the cavity during the injection process and merged together after a period of time [51,77,78,79]. Molding Equipment. “I realized weld -line problems are a very common issue for injection molded parts,” Nicholson told Plastics Technology. 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]. 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. This gives a clue as to how it was formed. and most commonly, thermoplastic polymers are used. The choosing optimal gate location technique has been developed to set weld lines as far as possible from the region of maximum stresses. A weld line is a mark left on the surface of a plastic injected molded part. Still, it can be seen to varied degrees depending on mold. We recently had a few pieces (2-3%) crack after assembly, while in storage (not installed, still in the package). In this paper, a kind of polypropylene (PP) foam plastic parts with special weld lines were obtained by core-back foam injection molding with chemical blowing agent. These master batches and PP pellets were dry-blended by adjusting the ratio such that the fiber contents were 10, 20, and 30 wt%. Injection molding is nothing without molds. Weld Lines. Knit lines, weld lines, mold lines, or flow lines in injection molding are faint lines that become visible on certain plastic parts. 7 of the reference. [1] Kobayashi et al. Poor weld line quality can lead to short-term or long-term product failures, initiated at the weld line. The weld line’s strength is reduced when. Nozzle – The nozzle is at the end of the barrel and contacts the injection mold. The weld line is then created with a higher flow front temperature and is packed with more pressure. Increase the mold temperature. Bin-Xin Yang Ouyang Jie Supei Zheng Qiang Li Wen Zhou. J. 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. In this study, polypropylene (PP) was compounded respectively with carbon nano fibers (CNFs) and TiO 2 nano particles at various weight fractions (10, 20, 30, 35. This weld line can act as a weak spot in the material. In some cases, a weld line can also cause a loss of strength and impact resistance. Weld-line, a common occurrence in plastic injection moulding, is a representative defect compromising mechanical qualities and product appearance [16]. 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. 298 µm and the weld line on the heated region was almost eliminated with the aid of induction heating. During injection. C. 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 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. The appearance quality of plastic parts in weld lines can be improved significantly through the rapid heating cycle molding (RHCM). The flow of the material in the injection mould takes place through the gate. In an injection molding process, a weld-line forms when two flow fronts meet each other. 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. 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. He now teaches courses in injection molding and plastic part design at the Polymers Center of Excellence and UNC-Charlotte in Charlotte, N. Article Google Scholar Deng YM, Zheng D, Lu XJ (2008) Injection moulding optimization of multi-class design variables using a PSO algorithm. Thoroughly clean molding machine cylinders. Controlling injection molding weld lines with good design and process control. Save. Meld and knit lines are actually both different types of weld lines. 666 Azieatul Azrin Dzulkipli and M. Depending on the resin, resin temperature, mold temperature, and filling speed, knit lines can vary. Weld lines may appear like seams or scratches, but that is not what they are. When two or more strands of molten plastics meet in the mold, a weld line will be produced at the junction [1,2]. (1) Increase the injection pressure and prolong the injection time. The Problems & Solutions course is designed to train injection molding personnel in. These lines can occur at the gate location, where the plastic enters the mold, or anywhere along the flow path. For multiple gate and complex part, molding weld-lines are unavoidable, therefore mechanical behavior of the weld-line needs to be predicted. Weld-line, a common occurrence in plastic injection moulding, is a representative defect compromising mechanical qualities and product appearance [16]. 4 at different time steps (legend scale is volume fraction of. , 509 (2) (2011), pp. ชิ้นงานเกิดเป็นเส้นรอยประสาน Weld line. Yes, it does help, for two reasons: Often the weld line traps air and the ‘dump’ acts as a vent to allow the air to escape. 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. Proper venting is also required to ensure good weld-line quality. The definition of weld lines: When multiple plastic flow fronts meet in the cavity after encountering inserts, holes, or areas with inconsistent flow rates or interrupted melt flows, or in the case of gate injection filling, the inability of two or more flow fronts to fully “knit” together will cause the linear weld marks. 025 100 120 140 160 180 200 220 240 Mold Temperature (F) LDPE PPEffects of mold temperature and pressure on shrinkage 0. Injection molding is a manufacturing process that involves injecting molten plastic into a mold cavity to create a specific shape or design. 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. When this fails to happen correctly, a weld line defect occurs. Star Rapid offers tips and tricks to improve your prototypes and production parts. In order to prepare the weld line specimen by micro injection molding, a mould integrated with visual system and variotherm system was designed and constructed, shown as Fig. Plast. Figure 1 below shows the development of a weld line. Compd. 809-814. Weld lines, knit lines, and meld lines are terminologies to describe the imperfections of finished parts in plastic injection molding processing. Weld lines form where two or more flow fronts come together and can create a cosmetic or structural problem. ” Another. Miron MC, Major Z, Adachi T. 3. The tensile stresses of the weld lines with ultrasonic functions are 8. Wavy lines are another feature of weld lines. 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. 015 0. For thick-walled parts, slow injection rates result in more uniform polymer distribution . Let’s review what causes meld and knit line imperfections, how they’re different, and how they affect part durability. 1 Prediction of weld lines with injection molding simulation softwareWeld lines in design for manufacture. Molding with weld line model Moldex3D was used for calculate the molding of lugs (figure 1). To respond to poor plasticization and uneven melt temperature, the molding cycle can be extended to make. Instead, a line that looks like a seam forms. 3 cc/sec, the weld lines are no longer perceivable above 130 C. The welding angle can be used to differentiate weld lines and meld lines. The melt stream is separated at the part’s cutout and reunited at the other end of the cutout. This consequently produces weld lines. 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. Effect of geometry and injection-molding parameters on weld-line strength. Weld line formation in the injection molding process occurs. Weld line formation in the injection molding process occurs when two or more melt flow fronts contact each other immediately after the cooling process. Fisa et al. 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). This failure causes the product to be damaged during use. Poor weld line Ⅰ. Many researchers had emerged with several. Flow analysis of the weld line formation during injection mold filling of thermoplastics. 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. It can be determined by a visible line appearing on the surface of the plastic part where two flows of the plastic meet. 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. 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. Munich, Germany: Carl Hanser Verlag, 1994. One of the factors that determines the quality of injection molded parts is the weld line [50,75,76]. Remedies: Raise the temperature of the mold or molten plastic. The following are the conclusion drawn from the present research: 1. Optimization of Injection Molding Process to Minimize Weld-line and Sink. ” Weld Lines in a plastic cover. Poor weld line Ⅰ. 2017-01-0481. When molten plastic flows, it forms a smooth continuous flow until it meets an obstruction. Flow marks in injection molding can be avoided if adequate measures are taken. Meld Lines. The following are the reasons. 4. 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 in injection molding are formed when two or more flow fronts of molten plastic material meet and merge during the molding process. Causes: Weld lines are caused by the inadequate bonding of two or more flow fronts when there is partial solidification of the molten plastic. They occur when melt flow fronts collide in a mold cavity. The melt stream is separated at the part’s cutout and reunited at the other end of the cutout. Gava and co-workers implemented an investigation devoted to the de-weld lines in injection molded thermoplastic composites. 943 µm to 0. Thereby creating localized pressure within the mold. Increase the melting temperature. Polymers 2023, 15, 2440 3 of 21. Our injection molding company is explaining what these imperfections are, why they can compromise. 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]. Weld lines not only affect the appearance and quality of products, but also cause negative influences on the mechanical properties. 22: Weld line formation when melt splits around core pins. A weld line develops when two or more flow fronts come together but do not meld completely because of partial solidification. Figure 1 below shows the development of a weld line. Flow-induced filler orientation manifests in higher tensile prop-erties in the direction of flow compared to those normal to the direction of flow. Sink marks, 2. Valve gates also make weld lines less of. Weld line is formed when two different melt flows converge, as illustrated in Fig. A knit line may be unnoticeable or may look like a crack. Weld lines are formed when two melt fronts come in contact with each other. In an injection molding process, a weld-line forms when two flow fronts meet each other. In addition a weld line can be moved to an area where it is less visible. 5. This study addresses the effects of injection molding weld line on the fatigue crack resistance of commercial CPVC in the temperature range of −10 to 70 °C. One solution is to prevent the weld lines from forming in regions that are. Edge Gates. Here are some strategies. 2. Alloys. In an injection molding process, a weld-line forms when two flow fronts meet each other. Figure 2. Information about PA6/PA66 (Nylon) Injection Molding. Just check out some of it on the above lists. Adjust the design for the flow pattern to be a single source flow. However, research about the computer determination of weld lines in injection molding remains scarce. These flow fronts occur when the molten plastic material encounters obstacles, such as inserts, ribs, or other features within the mold cavity. Weld or knit lines are perhaps the most common and difficult injection molding defect to eliminate. 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. 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. We'll show you how. 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. 1. [ 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. 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. T he decreased gloss level at the position of. Usually it’s a straight line, and often to be found radiating away from a hole, inclusion or other such part feature. A poor knit line. C. A weld line develops when two or more flow fronts come together but do not meld completely because of partial solidification. 5. Weld-line is a weak area which reduces the strength of the part locally. It provides scientific basis for designers toWeld lines are significant defects that affect injection molding quality, causing the poor appearance and low mechanical strength of injection‐molded parts. 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. You will have to confirm them before tooling. 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. Wang. (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 this lesson we will focus on the meld and weld lines. In addition a weld line can be moved to an area where it is less visible. But add 30% glass and weld-line strength retention drops to only 34% as high as the compound with no weld. This paper presents the. 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. Fatigue crack growth (FCG) tests were conducted on SEN specimens prepared from 100 mm. To prevent weld lines, increase the pressure and temperature. Gate position in injection mold. Fig 13:- Detailed view of weld lines. Mold flow analysis can predict the location of weld lines. Flow front tracing simulation results for weld line developing process in micro injection molding with Comsol ® Multiphysics 3. 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. When two or more strands of molten plastics meet in the mold, a weld. A quantitative evaluation of the appearance quality of weld lines in RHCM parts. 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. Sink Marks Cause 5: Improper Part Geometry. Injection molding is one of the most established and well-known methods of plastic processing. Joe Henz is a chemical engineer with 30 years of experience in the plastics industry, primarily with GE. Weld Line defect analysis, the most common of many defects in injection moulding products. Effects of fillers and/or reinforcements on weld-line strength of nylon 6/6. Vibration assisted injection molding. The three parameters affecting operation were called injection pressure, injection time, and packing pressure which influence the quality of weld line. A simulation of mold filling with multi-inlets or an insert in the cavity is pursued with an improved Level Set Method. Zhao, X. Although they often cannot be avoided it’s possible to minimize their cosmetic effects to an acceptable degree through careful product design and. The main runner and sub-runner are too thin or too long. Weld-line is a weak area which reduces the strength of the part locally. From Understanding Weld-line Integrity by Sabic Innovative Plastics, p. Plastic Injection Molding Process. Weld Line Factors for Thermoplastics. Processing Optimization Reduced frozen skin thickness: High injection speeds also contribute to a thinner frozen skin at the weld line. Fellahi et al. Investigate for potential contamination. of micro injection molding process simulation by technology update and progress. 2021年4月23日 / by admin. The weld lines are an integral part of plastic injection molding and can seldom be prevented, even by specifically planning the mold with inserts for holes or the like. In the heating step, the heatingOverview of the injection molding process. Weld and meld lines are generally caused by holes or inserts in the part, multiple gates, variable wall thickness or hesitation and. 2 mm to 1. 3. Weld-line strength for plastics can vary from 20% to nearly 100% of the strength of the plastic itself. Weld lines form where two or more flow fronts come together and can create a cosmetic or structural problem. Make the size of runner channel wider and/or shorter. % glass fibers – PA6 Aramid SV 30-1ETM (figure 1b). Weld lines appear as a result of the flow of molten plastic during the injection molding process. In this study, we apply the technique of SAW to explore the acoustic properties near injection-weld lines by comparing the velocity of. [ 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. Melt temperature does effect the weld. Adding vents, using overflows, or using porous metal. Weld lines can lower the integrity of the part. [8,9] It is capable of. They can affect the strength and appearance of the part, depending on the temperature, pressure, speed, and mold design of the injection molding process. of micro injection molding process simulation by technology update and progress. Its design significantly impacts the final product’s appearance, strength, and functionality, making it crucial for manufacturers to understand its intricacies and variations thoroughly. 1. une, 13: 15. 226-233. Weld line strength is important in blow molding as well as injection molding. When two or more strands of molten plastics meet in the mold, a weld line will be produced at the junction [1,2]. In this paper, two different injection molding tests were completed. Because of the ever-increasing requirements for parts performance, lots of researchers have perf. Gate blush, 4. Flash. Some of the approaches include the application of machine learning methods (Chen 2008; Manjunath and Krishna 2012; Kuo et al. 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. oped which factors the weld lines into the virtual design of chopped-strand-rein-forced thermoplastic parts. Vertical Plastic Injection Molding Machine [10, 11, 12] 2. Wu CH, Liang WJ (2005) Effects of geometry and injection-molding parameters on weld-line strength. In injection molding, it is often important to maintain consistent color throughout the part. When two or more strands of molten plastics meet in the mold, a weld line will be produced at the junction [1,2]. Threadline gap in-between part due to improper gate location in complex design parts including excess of holes (multipoint. Weld Lines-3 Ways for Detecting and Correcting. 1. 020 0. Voids and bubbles, 6. Injection speed is too low. 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. (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. th INTRODUCTION Injection molding is one of the mostWeld lines have been one of the common defects puzzling the injection molding industry. Depending on the resin, resin temperature, mold temperature, and filling speed, knit lines can vary. Causes: Weld lines are caused by the inadequate bonding of two or more flow fronts when there is partial solidification of the molten plastic. 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. In this mold, a visualization design and a rapid heating/cooling system were integrated, and specimens with different cross section. Fracture behavior of weld lines in injection molded components loaded under real operating conditions. This article will introduce you the usage, types, and advantages of the Sequence Injection Timer. . This can occur when a polymer flow splits to go around an interruption (e. Sink marks are a common type of injection molding defect. Known methods to reduce weld-line effects are the optimization of injection molding parameters, enhanced tool temperature, and using special molding tool devices. 025 100 120 140 160 180 200 220 240 Mold Temperature (F) LDPE PPAbstract. Weld Line defect analysis, the most common of many defects in injection moulding products. Weld lines. injection molding, (b) weld line and meld line, and (c) injection sample size and shape. Weld lines, generated during injection molding, can significantly reduce the mechanical performance of structures. <Materials> Pre-dry thoroughly. Weld line section presents notch or gloss difference. molding Æ Thermoplastics Æ Weld line Æ Simulation Rheol Acta (2004) 43: 240–245 DOI 10. 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. Insufficient plasticizing ability of injection molding machine. It is not always easy to completely eliminate weld lines by simply adjusting the relevant injection mold design or the molding conditions. 005 0. Complexities in the design and intricate pathways in the mold can also create flash in injection molded parts. 3 Materials Polypropylene (PP) and. To position weld-line to avoid critical areas for the sake of aesthetics or mechanical strength is the key to the success of bi-injection molding. (3) Adjust the temperature of the barrel and nozzle: the viscosity. Miron MC, Major Z, Adachi T. 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. 1, right). Weld lines are a common imperfection to be found in most plastic injected molded parts. Try to gradually raise the mold temperature and barrel temperature. org or visit 80-ton Victor injection molding machine, equipped with an accumulator capable of delivering maximum flow rate of 138 cm 3 /s and providing maximum injection pressure of 210 MPa, is utilized for experiments. Venting at Weld Lines. Polyamide 6 (Lanxess, Durethan B 30 S 000000, non-reinforced, ISO 1874-PA 6, GR, 14-030, Cologne, Germany) was used for this experiment. This study examines the impact of injection parameters on the weld line strength of the polyamide 6 and 30% fiberglass (PA6 + 30% FG) composite samples. The edge gate is the most popular and straightforward injection mold gate design. To resolve this issue, rapid heat cycle molding (RHCM) has attracted attention as an innovative PIM technology. A poor knit line can cause only cosmetic blemishes or it can significantly weaken the structural integrity of a part. Increase the injection speed to reduce the amount of cooling happening in the mold. They decrease the. th e use of design of e xperiment techniq ue. 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. 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. Weld Line Factors for Thermoplastics. Figure 1. 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]. Again, consult with professionals as to how you could improve mold designs. 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. Sink Marks Cause 1: Incorrect Melt Temperature. Weld lines create visible marks, but this type of injection molding defect can also reduce a part’s strength and durability. From: Polylactic Acid (Second Edition), 2019. • Optimize the design of the runner system. 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. Materials Science. The design of the mold, as well as the part being molded, has a significant impact on the success of the process. Three terms that often get mixed up in the plastic injection molding industry are weld, meld, and knit lines. In this paper, aiming at the problem of weld line defects in the injec- tion process of a key phone panel, the injection process is optimized by using Moldflow and drop simulation. Designers can easily set up and perform analysis with only a few clicks. If there’s too much mold release, you may require a higher pressure to push it through the machine. 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. The microstructure of weld lines is clearly observed from the micrographs. Tekanan. 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. As a result, the portion has a faint, perhaps undetectable line. A flow mark is commonly referred to as a flow line occurs during the process of injection molding. According to the characteristics. (2011) and Fig. In this study, the effects of injection temperature, injection pressure, and fiber cont. Therefore, it is recommended to do a moldflow study prior to the mold being built. This paper presents the. To prevent knit lines, injection molders can increase the temperature of the molten resin to prevent solidification from starting too soon, and increasing injection speeds and pressure are also potential solutions. 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. CrossRef View in Scopus Google Scholar [17] G. 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 narrow fields, a limited amount of molten liquid can solidify and block the flow. The thermo-rheological findings were used to investigate the sources of weld line weakness.