This study focus on the. The effects of these two injection molding process parameters are explained in terms of their influence on the skin-core morphology observed on the fracture surfaces in the weld zone. The parts are molded flat and are slightly stressed once installed in an arced position, but not excessively. Weld-line is a weak area which reduces the strength of the part locally. A weld line region is typically filled at the end of an injection stroke or during the pressure phase. Weld lines occur when melt flow fronts meet during the injection molding of plastic parts. The position, length, and angle of weld lines are dependent on the. 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. 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. Three terms that often get mixed up in injection molding are weld, meld and knit lines. But the unfavorable and unavoidable defect of weld line in micro injection molding part leads to detrimental mechanical and surface properties. Flow-induced filler orientation manifests in higher tensile prop-erties in the direction of flow compared to those normal to the direction of flow. Meld and knit lines are actually both different types of weld lines. In this study the polycarbonate (PC) and carbon fiber (CF) are used as the experimental materials to investigate the impact of injection molding process parameters on tensile strength of weld line. 22 shows how the weld lines are formed when the melt splits around core pins during the injection molding process. Optimization of Injection Molding Process to Minimize Weld-line and Sink. 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. They decrease the. Weld-line is a defect that arises in injection molding when two or more flow fronts collide. NX Mold Flow Analysis. Nozzle – The nozzle is at the end of the barrel and contacts the injection mold. 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 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. This will produce parts with aExperimental results show that the weld-line strength from a standard test is not applicable in microinjection molding. 3. Investigations on WLs in micro injection molded parts were performed in Refs. C. Avoid knit lines when designing a molded part to improve cosmetic appearance and functionality. The melt stream is separated at the part’s cutout and reunited at the other end of the cutout. According to the weld line distribution map of six gate schemes shown in . This failure causes the product to be damaged during use. Polyamide-6 (PA-66) was used as. injection molded pipe-fittings with and without weld line. 2 mm to 1. <Materials> Pre-dry thoroughly. These lines usually occur around holes or obstructions and cause locally weak areas in the molded part. As the weld line can significantly lower the mechanical strength of µIM parts, it is relevant to clarify the position of weld. 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. 5. Xie L, Zhu D, Ziegmann G, Steuernagel L (2016) Investigation on correlation between cold/hot weld line mechanical properties and micro injection molding processing parameters. Miron MC, Major Z, Adachi T. 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. The. The optimal process condition is very likely to appear in this second part's fine-tune group. 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. Weld Lines are formed when two or more molten polymer flows meet during the injection molding process. Description Knit lines, weld lines, mold lines, or flow lines in injection molding are faint lines that become visible on certain plastic parts. Threadline gap in-between part due to improper gate location in complex design parts including excess of holes (multipoint. . Increase the injection speed. (3-1) Increasing the Resin Temperature at the Weld Line Section. 000 0. Increase the injection speed. 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. Published 5 July 2019. Kondisi ini juga bisa menandakan bahwa mesin injection. th e use of design of e xperiment techniq ue. 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. Injection molding is a highly versatile manufacturing process used to produce a wide range of plastic products with precision and efficiency. Insufficient clamp tonnage Increase clamp pressure or move to machine with more tonnage . open access Abstract Micro weld lines are the common problem that occurs for plastic molded parts through injection molding process. The design of the mold, as well as the part being molded, has a significant impact on the success of the process. The schematic diagram of a weld line formation is illustrated in Figure 7, where is the welding angle of two melt fronts. Try to gradually raise the mold temperature and barrel temperature. M. Weld lines. Wolfgang Homes, head of the applications department of Eurotool, a manufacturer of hot runner systems, clarified the two methods for IMI, noting that. Therefore, the length of flowing weld lines must be additionally defined. 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. This thermal field was transferred to an injection molding flow solver to compare simulations and experimental results from the high speed video, both with and without the effect of induction heating. 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. 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. 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. 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. Injection molding plate for mode I testing geometry. 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. That helps. Weld line location. Injection molding could be applied with many polymer materials, such as. 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. Weld lines are a common occurrence in injection molding that affects the overall quality and strength of a finished product. 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. ac. The appearance quality of plastic parts in weld lines can be improved significantly through the rapid heating cycle molding (RHCM). Injection molding can be performed with only one of these materials like glass, plastics, etc. 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. This article will introduce you the usage, types, and advantages of the Sequence Injection Timer. Five injection molding process parameters, including mold temperature, melt temperature, packing pressure, injection. <Mold> Increase (or decrease) the size of the runners and gates. Install an ultrared light inside the hopper. Weld line formation in the injection molding process occurs. Weld line existence reduces the material strength; however, its. 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. Article Google Scholar Deng YM, Zheng D, Lu XJ (2008) Injection moulding optimization of multi-class design variables using a PSO algorithm. The results showed that the tensile strength of PE remains unchanged in the presence of weld lines. Let’s review what causes meld and knit line imperfections, how they’re different, and how they affect part durability. The weld line’s strength is reduced when. The utility model relates to a mold structure capable of eliminating the appearance of weld lines of a hole. 7 in Kobayashi et al. Despite injection molding being recognized as a robust process for obtaining parts with high geometry accuracy, one last occurrence remains a challenge in micro-injection molding, especially when junctions are. Weld 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. 1. This study describes how the weld line was formed on the part. Make the size of runner channel wider and/or shorter. Bubbles are caused by melting flow fronts colliding in a mold cavity. In an injection molding process, a weld-line forms when two flow fronts meet each other. “I realized weld -line problems are a very common issue for injection molded parts,” Nicholson told Plastics Technology. Weld lines can be a weak spot and have therefore to be taken into consideration in part design. It is important to investigate the weld line because the weld line area can. This reduced thickness of the frozen skin further enhances the visual appeal of the. Facebook. 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. 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. 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. 3. Change the gate locations. 2002), the use of simulation approaches (Berti and. , 47 (2008. une, 13: 15. In addition a weld line can be moved to an area where it is less visible. 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. Materials Science. Weld lines create visible marks, but this type of injection molding defect can also reduce a part’s strength and durability. 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. Rapid heat and cool injection molding is an example of a measure to prevent the generation of weld lines. They are unavoidable even for moderate complex products. Machine Shot Capacity – The maximum volume of resin that can be injected in a single stroke of the injection machine. Compd. If weld lines are unavoidable due to multiple gates in a moulding, they should be positioned in the non-critical region. Figure 1 below shows the development of a weld line. Alloys. Injection Molding Glossary; Weld Lines; Weld Lines. 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. 5. Failure may result due to the assembly torque, or end-use application loads (temperature, creep). Weld Line defect analysis, the most common of many defects in injection moulding products. 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. Poor weld line quality can lead to short-term or long-term product failures, initiated at the weld line. 3. Weld lines are one of the typical quality issues of injection molded parts. Bociaga and Jaruga (2007) investigated flowing weld line in injection process by injection molding machine, which the part surface was observed in reflected light using the optimal microscope and. (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. If not, the speed will drop, and it could create weld lines. 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 gate vestige for injection molding is usually narrow. In injection molding, it is often important to maintain consistent color throughout the part. Conventional injection molding is widely used to produce plastic parts, mainly in the automotive industry, due to the high production ratios and quality of. 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. Weld-line is a weak area which reduces the strength of the part locally. Therefore, it is recommended to do a moldflow study prior to the mold being built. Plastic part design for injection molding – An introduction. Weld lines are injection molding defects that can be mitigated by a number of tactics that depend on your part design. This is a video excerpt from our Problems & Solutions Course - Weldlines. High-density PE was also moulded in the same conditions but in a lower temperature range (145 to 220°C). 13 shows the best gate location for which the weld lines . Alloys. 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. ”Weld Lines in a plastic cover. 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]. When an external load is applied to a weld line region, the part’s potential for mechanical failure is increased. Miron MC, Major Z, Adachi T. 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. on conventional reciprocating screw injection molding machines using molding practices standard for filled engineering thermoplastics . 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. Wu CY, Ku CC, Pai HY (2011) Injection molding optimization with weld line design constraint using distributed multi-population genetic algorithm. In the 1947 book, Injection Molding of Plastics, the late Dr. Again, consult with professionals as to how you could improve mold designs. “I realized weld -line problems are a very common issue for injection molded parts,” Nicholson told Plastics Technology. We recently had a few pieces (2-3%) crack after assembly, while in storage (not installed, still in the package). CrossRef View in Scopus Google Scholar [17] G. Consequently, it causes viscous dissipation which leads to the generation of heat. 2004; To study the weld line formation of colliding flow fronts the filling of a mold cavity was simulated. This paper presents the. 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. Here are a few of the most common defects that may occur in plastic injection molding — and how product teams can avoid them. The result is part defects such as weld lines, poor finish, or discoloration. Ideally, the resin flow will split into two flow fronts to pass around the obstruction and then recombine into a single flow front. A visual mold with variotherm system for weld line study in micro injection molding. The weld lines in blow molding occur wherever the pari son knits together in the head, mold tacking areas and mold parting pinch-off region. These lines can occur at the gate location, where the plastic enters the mold, or anywhere along the flow path. These flow fronts occur when the molten plastic material encounters obstacles, such as inserts, ribs, or other features within the mold cavity. reinforcement type and amount in nylon 6/6. Figure 1 below shows the development of a weld line. warpage, and weld line. Weld line formation in the injection molding process occurs. This remains as a challenge for control engineers. 2-1. Unless you are manufacturing an extremely simple part with one gate and a unidirectional flow front, your part will have weld lines. Weld-Line in an injection molded part develops when two or more melt fronts are converged together. In spite of its cosmetic attributes, a bad knit line can significantly. Sequential valve gate technology. 9. Flash. 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]. Sink Marks Cause 1: Incorrect Melt Temperature. Knit lines in injection molding are undesirable, especially when surface appearance and part strength are significant concerns. When two or more strands of molten plastics meet in the mold, a weld line will be produced at the junction [1,2]. demanding injection molding and end-use requirements. 2. 2021年4月23日 / by admin. 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 several different problems: Low temperature of injection moulding machine barrel. 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. Although this phenomenon occurs in almost all the commercially important polymer. Weld-line is a defect that arises in injection molding when two or more flow fronts collide. Insufficient injection pressure and speed can cause weld lines. Fracture Toughness of Weld Lines in Thermoplastic Injection Molding, Polymer Engineering and Science, 33(15): 996-1001. + Improve vent inside the mold. This reduced thickness of the frozen skin further enhances the visual appeal of the. 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. (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. Fig 13:- Detailed view of weld lines. Tekanan. Weld line is one of the plastic injection molding defects. Instead, a line that looks like a seam forms. วัตถุดิบ พลาสติก PMPA ( อะคริลิก ) เกรด A. 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. 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. * Corresponding author, e-mail: [email protected] an injection molding process, a weld-line forms when two flow fronts meet each other. 1. This defect occurs due to the temperature and pressure not being high enough, causing premature solidification. Fortunately, there are several. This may require higher melt temperature or lower injection speed . Weld-line, a common occurrence in plastic injection moulding, is a representative defect compromising mechanical qualities and product appearance [16]. Weld lines not only affect the appearance and quality of products, but also cause negative influences on the mechanical properties. A weld line can also be called a knit line. A flow mark is commonly referred to as a flow line occurs during the process of injection molding. 1. Emerging Materials Research. To determine the effect of the weld lines on tensile strength, tensile tests were conducted with the specimens fabricated with NORYL (amorphous blends of. When a product is produced through injection molding, a high-powered tool injects melted plastic into a custom, double-sided mold. The Influence of Knit-lines on the Tensile Properties of Injection Molded Parts, Polymer Engineering and Science, 23(10): 591-596. 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. They. Venting at Weld Lines. The effects of fiber concentration has been studied in detail. + Increase mold temp, or materials’ temp, or holding pressure. Remedies: Raise the temperature of the mold or molten plastic. This leads to a better molecular chain entanglement, which in turn creates a better weld. Injection molded plastic parts have comparatively less strength in the weld line section and they also have an impact on product aesthetics. 3 and 53. The following are the conclusion drawn from the present research: 1. The weld line’s strength is reduced when. They are the result of fundamental physical effects taking place inside of the mold tool cavity. In this paper, a weld line factor (W-L factor) was adopted to describe the. Weld lines are a kind of Achilles heel of plastics. [ 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. Processing OptimizationReduced frozen skin thickness: High injection speeds also contribute to a thinner frozen skin at the weld line. 2. Int J Adv Manuf Technol 52:131–141. These lines can occur due to variations in wall thickness, gate location, or the geometry of the part. According to the characteristics. However, even with advanced technologies and precise control, the process is not without its challenges. It can be determined by a visible line appearing on the surface of the plastic part where two flows of the plastic meet. • Reduce runner dimensions and maintain the same flow rate. 18 ชิ้นงานเกิดเป็นเส้นรอยประสาน Weld line. This month, in our FREE SimTech™ series of webinars, we will explore weld lines and how they develop. This study presents an innovative approach to enhancing weld line strength in advanced polymer injection molding through applying gas-assisted mold temperature control, significantly increasing mold temperature beyond typical values observed in conventional processes. 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. Amongst weld line. In this study, one injection mold. 1. We have various types and models available. Weld lines in injection molding are formed when two or more flow fronts of molten plastic material meet and merge during the molding process. Fiber content dependence on. A weld line is often unavoidable. Learn more about ABS injection molding here. 2-1. replication and poor weld line strength . Inadequate back pressure. Injection molding is one of the most established and well-known methods of plastic processing. A simulation process was conducted to determine the recommended setting of injection moulding parameters and the range of the variable. A weld line is a mark left on the surface of a plastic injected molded part. 1. Steven. Ideally, the resin flow will split into two flow fronts to pass around the obstruction and then recombine into a single flow front. 2. Possible causes: Low temperature or fluidity of melted plastic during injection molding. It is important to investigate the weld line because the weld line area can induce potential failure of structural application. Microsyst Technol, 14 (6) (2008), pp. If it only affects the appearance, it can change the position of the burn four to change the position of the weld line. A weld or meld line is a weakness or visible flaw created when two or more flow paths meet during the filling process. Injection molding is nothing without molds. 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. Increase the injection speed to reduce the amount of cooling happening in the mold. In this regard, the plasticizing ability of the plastic injection moulding machine should be checked. 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]. This can allow the. To respond to poor plasticization and uneven melt temperature, the molding cycle can be extended to make. 2012. The edge gate is the most popular and straightforward injection mold gate design. , Ziegmann G. In some cases, a weld line can also cause a loss of strength and impact resistance. If the injection molding speed is too slow, however, there may be an insufficient filling of the mold. It is not always easy to completely eliminate weld lines by simply adjusting the relevant injection mold design or the molding conditions. Flow Lines. It occurs when melting plastic material is injected into a mold, it flows through all parts of th. Molding Equipment. poor flow fronts that are too cold, this can also lead to a deterioration in the mechanical properties. Clamping unit berfungsi untuk memegang dan mengatur gerakan mold unit, serta gerakan ejector saat melepas benda dari molding unit, pada clamping unit lah kita bisa mengatur berapa panjang gerakan molding saat dibuka dan seberapa panjang ejector harus bergerak. The gate is the critical bridge between the runners (the channels through which the molten plastic travels) and the actual mold. One common issue that frequently arises during injection molding is the formation of weld lines. Weld lines can. This happens when the molten plastic is injected into the mold cavity and flows around an obstacle such as a pin, hole, or protrusion, and then comes back together. 6. 010 0. Increase the injection speed to reduce the amount of cooling happening in the mold. 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. Increase the melting temperature. When this fails to happen correctly, a weld line defect occurs. Kagitci YC, Tarakcioglu N (2015) The effect of weld line on tensile strength in a polymer composite part. The occurrence of a weld line means a significant problem both aesthetically and mechanically in the design of injection moulded parts. Adding vents, using overflows, or using porous metal. Injection pressures too high Reduce pressure . Weld line formation in the injection molding process occurs when two or more melt flow fronts contact each other immediately after the cooling process. Install an ultrared light inside the hopper. Thus, a right gate design raises polymer temperature to prevent the formation of weld lines and flow marks. Email him at jhenz@polymer-center. 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. Abstract and Figures. They. 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. As these flow fronts come together on the. Weld lines can lower the integrity of the part. The wheel has to be gated at three places on the hub and. Figure 2. Gate position in injection mold. The weld line is an inevitable defect in the most injection molded components. 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. 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]. Gava and co-workers implemented an investigation devoted to the de-weld lines in injection molded thermoplastic composites. Int J Adv Manuf Technol 52:131–141. 2017-01-0481. The choosing optimal gate location technique has been developed to set weld lines as far as possible from the region of maximum stresses. 2(a, b). Weld line usually is not allowed on some critical area, and weld line on the part also weaken the strength. Abstract. Let’s review what causes meld and knit line imperfections, how they’re different, and how they affect part durability. A micro-photography study on the cross-section of the weld-line was also carried out. 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. Poor weld line Ⅰ. A weld or meld line is a weakness or visible flaw created when two or more flow paths meet during the filling process. Weld-line is a weak area which reduces the strength of the part locally. Visualization analysis of flow behavior during weld-line formation in injection molding process. The need to minimize fiber breakage, plus the higher viscosity of materials with. From Understanding Weld-line Integrity by Sabic Innovative Plastics, p. These lines can weaken the strength of the part, and they can also be unsightly. Fracture behavior of weld lines in injection molded components loaded under real operating conditions. This is expected to achieve maximum results while the pressure holding effect will also increase. So today we are going to take a look at the five most common defects in injection molding and their solutions. Ejector System (Pötsch, 1995) . Weld Line Factors for Thermoplastics. 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. Sink marks are a common type of injection molding defect. Weld lines are a common imperfection to be found in most plastic injected molded parts. Introduction. Except for a few very simple injection molded parts, they occur on most injection molded parts (typically in the form of a line or V-groove), especially large complex items that require use of multi-gate molds and inserts. 2. Investigate for potential contamination. อุณหภูมิของพลาสติกเหลวสูงเกินไปจนก๊าซหรือความชื้นแยกตัวออกมาได้. A weld line is a mark left on the surface of a plastic injected molded part. when two or more melt flow fronts contact each other immediately after the cooling process. T he decreased gloss level at the position of. 1. Sink Marks Cause 3: Improper Pack or Hold Pressure. 3. 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. Poor weld line Ⅰ. They can affect the strength and. Injection molding. Raising the mold temperature will keep the material molten longer, resulting in stronger weld lines and even elimination of weld lines. Here are some reasons why design is important for injection molding. 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. Munich, Germany: Carl Hanser Verlag, 1994. Article Google Scholar Xie L, Ziegmann G (2009) Influence of processing parameters on micro injection molded weld line mechanical properties of polypropylene (PP). Mold flow analysis is widely employed in mold making industry, utilizing data simulation software, the injection molding process can be simulated and presented on the computer,. 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 simulation of mold filling with multi-inlets or an insert in the cavity is pursued with an improved Level Set Method. Adjust Injection Molding Parameters: Optimizing injection speed, pressure, and temperature can help ensure better melt flow and reduce the likelihood of weld line formation. Injection molding is a complex multi-variable, nonlinear and time-varying unsteady process, which makes it more difficult to optimize the process parameters. 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. In recent years new methods for quality prediction and optimization of the injection molding process have been proposed and applied. Vertical Plastic Injection Molding Machine [10, 11, 12] 2. 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]. (1998) for clear photographs. 1% higher than the ones without ultrasonic assistant, which indicates that the weld line strength in micro injection molding can be well reinforced by the ultrasonic oscillation due to the fact that ultrasonic oscillation induces better diffusion among the melting. Designers can easily set up and perform analysis with only a few clicks. Jiquan Li, Taidong Li, +1 author. Weld lines are a kind of Achilles heel of plastics. The impact behavior of weld-lines in injection molding. However, research about the computer determination of weld lines in injection molding remains scarce. 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.