In our DFM report, we will analyze the possible weld lines. The second technique, cascade injection moulding, can produce parts free from weld lines. [ 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. 1. This study focus on the formation of. In an injection molding process, a weld-line forms when two flow fronts meet each other. (2011) and Fig. In addition a weld line can be moved to an area where it is less visible. He said, “Vent cavities at weld lines or junction points where two or more material streams meet and fuse into a solid mass. INJECTION MOULDING DEFECTS 1 DEFECTS 1. Weld lines are a kind of Achilles heel of plastics. Failure may result due to the assembly torque, or end-use application loads (temperature, creep). The more gate points there are, the more weld lines will occur. Recently, the injection molding of fiber reinforced thermoplastics (FRTP) containing short fibers has been widely carried out to mass-produce molded products with complex shapes. 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. With Ixef® PARA compounds, the strength of a weld line is typically 90 MPa (13,000 psi). The goal is to create a uniform thickness and at the smallest (thinnest) level required. Weld lines are the unfavorable defect not only in normal injection molding process but in micro injection molding process. also utilized the co-injection molding technique to study the flow of polypropylene at the weld line behind an obstacle in injection molding; the weld line can be seen clearly from the Fig. 015 0. Weld lines not only affect the appearance and quality of products, but also cause negative influences on the mechanical properties [3,4,5]. Kobayashi et al. 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. In the first stage, the two part halves are injection molded and then, in a second process step outside of the molding machine, they are welded together. Weld lines appear as a result of the flow of molten plastic during the injection molding process. Weld lines can compromise the strength and aesthetics of the part, so it’s important to carefully design the mold. Sink Marks 2. Proceedings of ANTEC (2000), pp. Sequential valve gate technology. When the polymer resin is injected into a mold, it flows through all portions of the mold cavity. 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. As the injection process continues, the two separated melt fronts meet again along the longitudinal section of the plate forming a weld line. Flow Lines and Weld Lines. The weld line and the flow pattern of co-injection molding can be seen from Fig. The rule is, a higher pressure shall be required to push the material in the machine when there is excess mold. 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. Wavy lines are another feature of weld lines. The Solutions for Poor Welding Lines. 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. Weld lines often generate mechanically weak areas, because of the unfavorable perpendicular orientation of the macromolecules, fibers and/or other fillers to the direction of the main flow. Weld lines, knit lines, and meld lines are terminologies to describe the imperfections of finished parts in plastic injection. The main runner and sub-runner are too thin. The specific method is that when the product is just filled and filled in the cavity, the insert. 004 m, a characteristic velocity ν 0 =0. (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. 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 thin weld line is the result of weak material bonding, which lowers the strength of the part. The weld line degrades the. Causes: Weld lines are caused by the inadequate bonding of two or more flow fronts when there is partial solidification of the molten plastic. The impact behavior of weld-lines in injection molding. See moreEquipment. Azuddin / Procedia Engineering 184 ( 2017 ) 663 – 672 665 2. 1. 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. Weld-line, a common occurrence in plastic injection moulding, is a representative defect compromising mechanical qualities and product appearance [16]. 6. (1998) for clear photographs. Sink Marks Cause 1: Incorrect Melt Temperature. 3. In this study, epoxy molding compounds (EMC) filled with glass beads were fabricated with a twin-screw-extruder (TSE) and tempered before further processing to generate different degrees of cross-linking (0–15%) in the compounds. + Adjust injection speed. Voids and bubbles, 6. spelling: injection molding) is a manufacturing process for producing parts by injecting molten material into a mould, or mold. 3. These lines can occur at the gate location, where the plastic enters the mold, or anywhere along the flow path. 2) Vents in an injection mold should let the air out, but not the liquid plastic. The Problems & Solutions course is designed to train injection molding personnel in. This study presents an innovative approach to enhancing weld line strength in advanced polymer injection molding through applying gas-assisted mold. Experimental Setup 2. Shaofei Jiang. Too much injection molding pressure lost and increase the operation difficulty of the injection molding machine; 7. Injection molding can be performed with only one of these. A quantitative evaluation of the appearance quality of weld lines in RHCM parts. Features such as sharp corners or undercuts can. Fig 13:- Detailed view of weld lines. (1) Increase the injection pressure and prolong the injection time. Weld-line is a defect that arises in injection molding when two or more flow fronts collide. First, an injection mold with triangular inserts was built to study the influence of meeting angles on material properties at the weld line. 3. Weld lines typically appear in a part when an obstruction of some kind separates the melt flow and prevents it from "knitting" together. Flow marks in injection molding are defects that manifest as a line or series of lines forming a pattern different in color from the other parts of the molded material. 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. Weld line and warping are two critical defects for injection-moulded part. Molding Equipment. 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. The weld line in injection molding is created when two melt streams connect, as shown in Figure 1. Weld lines are significant defects that affect injection molding quality, causing the poor appearance and low mechanical strength of injection‐molded parts. Flash. 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. There are several possible causes that need to be investigated to troubleshoot weld lines in injection molding. Melt temperature does effect the weld. Weld lines are significant defects that affect injection molding quality, causing the poor appearance and low mechanical strength of injection‐molded parts. Mold temperature controlInjection mold designers can alter the position of weld line by changing the gate locating. Weld lines. Plastic Injection Molding Process. The next type of injection molding defect is ‘Weld Lines’. 010 0. Root causes Many factors—including processing conditions, material, part design and mold design—can influence the visibility and strength of a weld line. One of the things that can compromise an injection molded part is a weld line, also called a knit line. This can allow the. There are several factors that can contribute to the formation of weld lines, including: Part design: The design of the part can impact the flow of the material and the likelihood of weld lines forming. Weld-line is a defect that arises in injection molding when two or more flow fronts collide. For example, filled resins and ABS are more likely to. You can choose material of low viscosity and can increase the injection pressure. Weld Lines-3 Ways for Detecting and Correcting. This month, in our FREE SimTech™ series of webinars, we will explore weld lines and how they develop. Weld Lines-3 Ways for Detecting and Correcting. 001 in . , less than 0. Typical injection molding processing temperatures of TPU materials are as follows: IM Zone 60A to 75A 80A to 90A 95A to 75D Rear 315 – 40 ºF45 -370 75 400The weld line in an injection molding product can significantly impact the strength and durability of the last part [12] [13][14][15]. A viscosity curve is developed using calculations of the fill time and plastic pressure at. Weld lines can. This can occur when a polymer flow splits to go around an interruption (e. 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. M. The melt stream is separated at the part’s cutout and reunited at the other end of the cutout. This occurs mainly in the presence of barriers that divide the melt flow in. Weld lines are a reality in the injection moulding of complex parts. 2017-01-0481. Poor mold spot Spot mold to ensure fit and vent depths at ~0 . Weld-line is a defect that arises in injection molding when two or more flow fronts collide. This reduced thickness of the frozen skin further enhances the visual appeal of the. It is normally at the meeting points of two flow fonts. Weld lines: Cold feedstock in the die: Increase injection speed, mold temperature, and feedstock temperature, enlarge gate opening, add venting channels or overflow wells near weld line locations, move gate location, redesign parts to avoid stream partition: Flow mark: Cold feedstock in the dieWeld lines are a common imperfection to be found in most plastic injected molded parts. 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. Injection molded plastic parts have comparatively less strength in the weld line section and they also have an impact on product aesthetics. 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. Second, depending on the size of the overflow well, you get a little bit of flow melding together, and that helps strength so that you have some intertwining of the polymer chains. Flow lines. After that, the compounds were injection-molded into tensile samples with and without weld lines to. 4. Weld line formation in the injection molding process occurs when two or more melt flow fronts contact each other immediately after the cooling process. Better weld line quality was obtained by Huang. Weld lines are visible lines or seams formed when molten plastic flow fronts meet and fuse together, often due to obstacles or flow interruptions in the. Short shots. Materials Science. Thereby creating localized pressure within the mold. Weld lines are formed when two or more flow fronts join, as the liquid polymer fills the. 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. View 08 DEFECTS & REMEDIES (61). The structure is more complex with longer molding cycle . 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 Line defect analysis, the most common of many defects in injection moulding products. Thus, it. The injection molding simulation software used offers a method for the detection of weld lines that has shown to be only reliable for the detection of stagnating weld lines. Effects of mold temperature and pressure on shrinkage 0. Specifically, injection-mold lines are often associated with poor mechanical strength. From Fig. Weld-line yield strength, yield strain, and failure strain of talc-filled polypropylene increase with increasing melt temperature and increasing hold pressure. 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. A meld line occurs when two moving melt fronts converge and flow parallel to each other. These are caused by the shot of molten plastic moving at different speeds throughout the injection. Conventional injection molding is widely used to produce plastic parts, mainly in the automotive industry, due to the high production ratios and quality of. Unless you are manufacturing an extremely simple part with one gate and a unidirectional flow front, your part will have weld lines. Thus, it is important to understand (i). 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. 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. injection molding. Strength measurements should be made to. 15 shows the frozen layer and weld lines at the end of mold filling. ”. The Influence of Knit-lines on the Tensile Properties of Injection Molded Parts, Polymer Engineering and Science, 23(10): 591-596. As the name implies, it is usually positioned along the edge of the workpiece, forming a visible mark at the demarcating line. ), with different mould surface finishes (polished, fine eroded, rough. The injection molding process can be optimized to maximize weld line strength by increasing mold and melt temperatures, and by increasing pack pressure at the weld line. This leads to a better molecular chain entanglement, which in turn creates a better weld. Or increase the number of gates. Proper venting is also required to ensure good weld-line quality. What is weld lines. Insufficient injection pressure and speed can cause weld lines. Plastic Injection Molding Process. Weld lines, knit lines, and meld lines are terminologies to describe the imperfections of finished parts in plastic injection molding processing. The edge gate is the most popular and straightforward injection mold gate design. This customary mark is caused by differential rates of cooling in the resin where. Mold Design Most conventional mold designs will work with TPU’s. When two or more strands of molten plastics meet in the mold, a weld line will be produced at the junction [1,2]. Weld lines are a common occurrence in injection molding that affects the overall quality and strength of a finished product. When two or more strands of molten plastics meet in the mold, a weld line will be produced at the junction [1,2]. Injection molding plate for mode I testing geometry. but the injection pressure will loss and injection molding pressure of this gate is bigger than that of direct gate. This paper presents the. Flow Lines. [ 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. 005 0. When the two such melt flows. Second, depending on the size of the overflow well, you get a little bit of flow melding together, and that helps strength so that you have some intertwining of the polymer chains. The relative weld-line strength is defined as the ratio of the strength of specimens with a weld line. 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. In this work, the residual strength of a fiber-reinforced injection molded part containing a hot weld line—or meld line—was evaluated. Injected plates were generated using a double-gated mold under four different process conditions. As a result this weld line will be a weak point in this part. Polyamide-6 (PA-66) was used as. Maintain a holding pressure that is no more than 1/2 the. 10 in Nguyen-Chung et al. Increase the injection speed to reduce the amount of cooling happening in the mold. Flow LinesThe most simple design modification for eliminating the weakening effect of a weld line is to increase the wall thickness in the weld line zone (Figure 4). In injection molding weld lines are formed whenever two flow fronts are joined. In this study, we apply the technique of SAW to explore the acoustic properties near injection-weld lines by comparing the velocity of (V R) in locations close to and locations distant from the weldAmong defects of injection molding parts, weld lines are the most common defect. (1) Increase the injection pressure and prolong the injection time. (1983). In injection molding weldlines are generated when two separate melt streams join either in multigated molds or as a consequence of flow around. Typical injection molding processing temperatures of TPU materials are as follows: IM ZONE 60A TO 75A 80A TO 90A 95A TO 75D REAR 315 – 340 °F 345 – 370 °F 375 – 400 °FTo study the weld line formation of colliding flow fronts the filling of a mold cavity was simulated. e. In this work, the residual strength of a fiber-reinforced injection molded part containing a hot weld line—or meld line—was evaluated. During the plastic injection molding process, one of the biggest challenges is. Micro weld lines are the common problem that occurs for plastic molded parts through injection molding process. Wu CH, Liang WJ (2005) Effects of geometry and injection-molding parameters on weld-line strength. The injection molding gate generates heat by dissipation. 1. Low mold temperatures are usually employed to decrease cycle molding time and final process costs; however, resulting surface defects include weld lines, sink marks,. Provide a gas vent. These potential causes include: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 process makes possible to produce a wide range of products with different sizes, shapes, and for varying applications. Flow front tracing simulation results for weld line developing process in micro injection molding with Comsol ® Multiphysics 3. Weld-line is a weak area which reduces the strength of the part locally. In this paper, a weld line factor (W-L factor) was adopted to describe the. 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. Redesign the mold to prevent the weld line. and Mosle, H. 5. Which means engineers need to know how to account for this phenomenon in an efficient way. They appear on the surface of injection molded parts like lines. Usually it’s a straight line, and often to be found radiating away from a hole, inclusion or other such part feature. Wolfgang Homes, head of the applications department of Eurotool, a manufacturer of hot runner systems, clarified the two methods for IMI, noting that. This injection molding defect appears as a black discoloration on the surface of the molded part. In spite of its cosmetic attributes, a bad knit line can significantly. 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. 943 µm to 0. A weld line region is typically filled at the end of an injection stroke or during the pressure phase. Redesign the mold to. Three terms that often get mixed up are weld, meld, and knit lines. Weld lines are a common imperfection to be found in most plastic injected molded parts. Weld lines are one of the typical quality issues of injection molded parts. Three terms that often get mixed up in injection molding are weld, meld and knit lines. Here’s how to decrease the chances of weld lines: Increase the temperature of the mold or the molten plastic. Weld lines can be caused by many reasons, which covers the various aspects of mold, process, raw materials and product design, etc. Don’t forget to eliminate entrapped air in the weld line injection molding; otherwise, it’ll create unfilled portions in your part design, causing more weakening. Sink Marks Cause 3: Improper Pack or Hold Pressure. A weld line (weld point, flow line or a knit line) forms when separate melt fronts travelling in opposite directions meet. The literature on the formation of weld lines, and their consequences, is more abundant on the area of injection molding [5-12] than on extrusion [13]. In some cases, a weld line can also cause a loss of strength and impact resistance. Weld lines occur when melt flow fronts meet during the injection molding of plastic parts. This special mould has changeable inserts to be able to inject with different gate types (standard, film, special-film, multi gates, etc. . Gambar 2. Blistering 4. 030 0. If the different flow fronts have cooled. These lines occur when two or more flow fronts meet and fuse together, resulting in a visible seam on the molded part. It can be determined by a visible line appearing on the surface of the plastic part where two flows of the plastic meet. + Improve vent inside the mold. 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 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 Solutions for Poor Welding Lines. In an injection molding process, a weld-line forms when two flow fronts meet each other. Injection pressures too high Reduce pressure . when two or more melt flow fronts contact each other immediately after the cooling process. According to the special features of micro injection molding process compared with normal injection molding process, the main related factors to weld line’s properties were classified as 3 group, named as processing conditions, mold design and structure, external process. when two or more melt flow fronts contact each other immediately after the cooling process. 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. The weld line’s strength is reduced when. Known methods to reduce weld-line effects are the optimization of injection molding parameters, enhanced tool temperature, and using special molding tool devices. During injection. A weld or meld line on plastic parts can cause structural problems and/or be visibly unacceptable. Weld Lines. Depending on the resin, resin temperature, mold temperature, and filling speed, knit lines can vary. Conventional injection molding is widely used to produce plastic parts, mainly in the automotive industry, due to the high production ratios and quality of injection parts. Weld line defects – also known as knit lines – is a defect that occurs when the injected plastic meets within a mold. The plaques are prepared out of 30% glass-filled Polyamide 6 material. Meanwhile, Using more advanced cooling method such as cyclic cooling or conformal cooling. Weld or knit lines occur when melt flow fronts collide in a mold cavity. If the plastic encounters a pin or other obstruction, the plastic flow front must split to form two flow fronts to go around the pin. The pressurized air restricts the flow of the plastic resin. Fisa et al. + Increase mold temp, or materials’ temp, or holding pressure. They are the result of fundamental physical effects taking place inside of the mold tool cavity. Islyn Thomas summarized the need for a particular vent location better than I ever could. (3-1) Increasing the Resin Temperature at the Weld Line Section. It is possible to pre. In this experiment, several ejector. Weld lines may occur depending on the product shape and gate positions. Prediction of the weld lines in injection molding process using neural networks. Except for a few injection molded parts with very simple geometry, weld lines occur in most injection molded parts (usually with one line or V-shaped groove), especially in large-scale complex products requiring multi gate mold and inserts. Weld lines can significantly reduce ultimate tensile strength (UTS) and fracture strain of talc filled polypropylene (PP). Weld-line is a weak area. Many studies were conducted to explain the weakness at the. 1 m/s, and a zero-shear-rate viscosity η 0 (T 0)=3760 Pas. When a product is produced through injection molding, a high-powered tool injects melted plastic into a custom, double-sided mold. When injection molding large products, molding is usually performed with multi-point gates, but weld lines can occur depending on the product shape and gate position. Increase the injection speed. 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. Heat/cool injection molding has a positive influence on the depth and visibility of weld lines. Weld-line is a weak area which reduces the strength of the part locally. 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. Gate location should set to avoid weld lines, keep clean of the important position of the products,. Weld lines form where two or more flow fronts come together and can create a cosmetic or structural problem. They decrease the. In this study, the effects of injection temperature, injection pressure, and fiber content on the mechanical properties of weld lines were studied for carbon fiber-reinforced nylon. The 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. Weld lines, generated during injection molding, can significantly reduce the mechanical performance of structures. Weld lines are formed when two orThe experiments were performed on an Arburg Allrounder 320C 600-250 injection moulding machine using a two cavity-injection mould (Fig. The melt stream is separated at the part’s cutout and reunited at the other end of the cutout. This principle has been implemented on a complex component in the case of the spring-loaded cogwheel shown in Figure 5, for instance. 6. are very minimum. 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. To study the weld line formation of colliding flow fronts the filling of a mold cavity was simulated. 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. Which means engineers need to know how to account for this phenomenon in an efficient way. Other possible causes include: Low mold or material temperature; Insufficient holding time or. The performance of weld lines in talc filled polypropylene box moldings produced with a. The simulated cold weld line length is consistent with the experimental one when a 115 °C mold temperature is adopted; with lower mold temperatures, the simulated lengths are smaller than the experimental ones—in accordance with the literature on the conventional injection molding process [26,27]—probably because of the definition adopted. Weld lines have been one of the common defects puzzling the injection molding industry. The default weld line result recognizes 135º as the maximum angle of collision and as that angle decreases, the severity increases as it. 000 0. 2. Remedies: Reduce packing and fill rates by adjusting until the part is properly filled with minimum stresses. . Email him at jhenz. demanding injection molding and end-use requirements. The effects of fiber concentration has been studied in detail. Design. [ 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. Steven. Weld Line defect analysis, the most common of many defects in injection moulding products. Try to gradually raise the mold temperature and barrel temperature. Meld and knit lines are actually both different types of weld lines. 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. Weld or Knit lines are a plane or section in an injection molding part where the flow of molten plastics meets from different directions. Ghazanfarpour. They are unavoidable even for moderate complex products. Google Scholar [10] S. Injection molding could be applied with many polymer materials, such as. This paper presents the. In the above diagram, the converging flow fronts (indicated by red arrows. Weld lines in design for manufacture. 48 applied high-frequency induction heating to eliminate weld lines in an injection-molded plastic part, and experimental observation indicated that weld depth was reduced from 2. The hair-like weld line is the result of weak. Unless you are manufacturing an extremely simple part with one gate and a unidirectional flow front, your part will have weld lines. In this paper, two different injection molding tests were completed. It has larger cross-sectional regions that allow sufficient molten plastic flow into the cavity. Multiple gating, splitting of the melt flow due to inserts in the cavity or through holes, as well as changes of thickness give rise to points within the structure where the flowing fronts will recombine and weld. ac. The weld line is an inevitable defect in the most injection molded components. 2. Preventing sink marks of injection molded parts using CAE analysis. Microsyst Technol, 14 (6) (2008), pp. 2. 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. + Move gate (to where it is not visible). technical ulletin SPECIALTY POLYME RS Design and Production of Injection Molding ToolsIncrease the injection speed in order to fill the mold more quickly and ensure the material does not prematurely cool down; in addition, when the speed is adjusted the flow fronts may meet at a different spot and move the weld line location. The Injection Moulding Process is a manufacturing process used for producing parts or components by injecting molten material into the mold cavity. 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]. This model provides the necessary information. 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. These lines usually appear on the narrowest portion of the part, and appear to originate from the mold’s gates, where the molten resin flows into the mold to form. ac. Abstract. 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. ). 1. In Fig. Wu CY, Ku CC, Pai HY (2011) Injection molding optimization with weld line design constraint using distributed multi-population genetic algorithm. Neat polypropylene retains nearly 90% of its strength on a properly designed and molded weld line. Additionally, you can get our free Design Cube, which will provide a physical aid to help understand how knit lines form as well as other injection molding design considerations. Additionally, you can get our free Design Cube, which will provide a physical aid to help understand how knit lines form as well as other injection molding design considerations. poor flow fronts that are too cold, this can also lead to a deterioration in the mechanical properties. Reduce the amount of release agents. The flow fronts at different times (Fig. 7 in Kobayashi et al. การแก้ไข ชิ้นงานจุดที่เกิดความอ่อนแอบริเวณ weld line คือต้องใช้ความเร็วในการฉีดต่ำในจุด. If you adjust the ejection mechanism in the mold design, you also can reduce or eliminate your need for mold release agents. The holding pressure was set as approximately equal to the maximum injection pressure obtained at the time of filling the resin. Weld lines form where two or more flow fronts come together and can create a cosmetic or structural problem. 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. The thermo-rheological findings were used to investigate the sources of weld line weakness. 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. 298 µm and the weld line on the heated region was almost eliminated with the aid of induction heating. Definition: A seam that appears where two areas of molten plastics meet. The micro tensile part was prepared by the double gate injection.