And What to Do About Them. 6 Successful Moldex3D Case Studies You Can t Miss

Transcription

1 5 Common Injection Molding Problems And What to Do About Them 6 Successful Moldex3D Case Studies You Can t Miss

2 CONTENTS CHALLENGE 1: WARPAGE CASE STUDY: Dr. Schneider Unternehmensgruppe CHALLENGE 2: WELD LINES AND FLOW MARKS CASE STUDY: Synventive CASE STUDY: Stanley Black & Decker CHALLENGE 3: AIR TRAPS CASE STUDY: TYC Brother Industrial Co., Ltd. CHALLENGE 4: INK WASH-OUT AND STRESS MARKS CASE STUDY: Acer CHALLENGE 5: SHORT SHOTS CASE STUDY: Extreme Tool and Engineering 2 /

3 CHALLENGE 1 WARPAGE Among so many challenges injection molders face, warpage may be one of the greatest. The most frequently asked question is what causes my parts to warp? In recent years, mold filling technology has been widely applied in the injection molding industry to help predict and diagnose the main causes of warpage. Based on the warp analysis results, plastic injection molders can virtually implement and validate preventive/corrective action to ensure product dimensional accuracy and assembly precision. 3 /

4 CHALLENGE 1 : WARPAGE Dr. Schneider Unternehmensgruppe CASE STUDY Dr. Schneider Unternehmensgruppe The Dr. Schneider Unternehmensgruppe is headquartered in the Upper Franconia region of Bavaria in the town of Kronach-Neuses. The Group has made itself a name as a specialist for first class products for automotive interiors from innovative ventilation systems and sophisticated modules for dashboards and center consoles to highly integrated panels and mechatronic components. As a flexible system coordinator and strategic business partner, Dr. Schneider is working on intelligent solutions for tomorrow s mobile world today. (Source) Industry: Automotive Website: 4 /

5 CHALLENGE 1 : WARPAGE Dr. Schneider Unternehmensgruppe BUSINESS NEEDS At Dr. Schneider, Moldex3D is now one of the most important and indispensable tools for engineers to use and perform feasibility studies on new parts to ensure part quality and manufacturability. In the past, however, Moldex3D plastic injection molding software was only viewed as additional reference information for part designers and was not used regularly at Dr. Schneider. As the company had to strike a balance between quality, quantity and process complexity, they realized that there was a real need for injection molding simulation and began to explore the possibilities and the potential of using Moldex3D software to meet the desired part performance requirements. 5 /

6 CHALLENGE 1 : WARPAGE Dr. Schneider Unternehmensgruppe THE SOLUTION Warpage_Volumetric Shrinkage [%] Moldex3D is chosen to assist Dr. Schneider engineers in the design and development process of plastic injection molded parts, from initial assessment for part feasibility to providing simulation-driven insights for optimizing shop floor production. For instance, in the case of an automotive fuel filler lever component, Dr. Schneider engineer used Moldex3D to perform a Warp analysis on the initial design. The simulation result showed the part had a total warpage displacement of mm in the critical area, which was not functional acceptable. The engineer further used Moldex3D to investigate the cause of warpage and found high shrinkage values in the problematic area. To minimize shrinkage, the engineer decided to minimize material consumption by reducing the wall thickness of the critical area from 2 mm to 1 mm The Volumetric shrinkage result showed high shrinkage values in the critical area 2 mm 1 mm SOLUTION USED Moldex3D Advanced Flow Cool Pack Warp Wall thickness was reduced by 50% to decrease volumetric shrinkage 6 /

7 CHALLENGE 1 : WARPAGE Dr. Schneider Unternehmensgruppe THE RESULTS Warpage_Total Displacement [mm] The simulation result of the improved design showed that the warpage amount was successfully reduced by 40%, from mm to mm. Through Moldex3D analysis, Dr. Schneider engineer was able to determine the cause of warpage and make informed design decisions. Nowadays at Dr. Schneider, every injection molded design must go through mold filling analysis. If something goes wrong, for example, when warpage values are unacceptable, Dr. Schneider s team will take immediate corrective action. In the end, Dr. Schneider is able to successfully solve manufacturing issues and optimize product and mold designs, which helps them efficiently reduce mold trials and mold modification costs before actual production Initial Design Total Warpage Displacement: mm Warpage_Total Displacement [mm] BENEFITS Reduced part warpage by 40% Obtained instant feedback on manufacturing feasibility Optimized Design Total Warpage Displacement: mm 7 /

8 CHALLENGE 2 WELD LINES AND FLOW MARKS Surface defects, such as flow marks and weld lines, are often found in plastic injection molded parts, especially larger sized parts, which are usually appearance parts and therefore require high quality surface finishes. Sequential valve gating (SVG) is a common technique that can give molders full control over the timing and the order of cavity fill pattern to prevent surface defects and improve part performance. To help molders reap the full benefits of sequential valve gating technique, Moldex3D is taking a step further by adding support for valve pin movement simulation, allowing molders to consider the influences of pin position and velocity to optimize their sequential valve gated hot runner systems. 8 /

9 CHALLENGE 2 : WELD LINES AND FLOW MARKS Synventive Molding Solutions CASE STUDY Synventive Molding Solutions Synventive is one of the world's leading manufacturers of hot runner systems for the plastics injection molding industry. With a dedication to providing the highest quality hot runner products and enabling technologies, Synventive is expanding what s possible in injection molding. (Source) Industry: Industrial Machinery & Equipment Website: 9 /

10 CHALLENGE 2 : WELD LINES AND FLOW MARKS Synventive Molding Solutions THE CHALLENGE With large injection molded parts, it is common to use sequential filling to eliminate weld lines. However, when molders use sequential valve gates, there is a possibility that some common defects will occur. These defects are pressure transition marks on unpainted parts, reflection marks after a paint drying process and hot spot marks opposite of a direct gated nozzle. These defects are a result of a change in pressures and the fact that polymer melt is compressible. Pressure Transition Marks on Unpainted Parts Synventive s activegate Technologies are a line of control systems that give molders using valve gated hot runner systems control beyond the on/off ability of conventional valve gates. The molder can control the stroke, velocity, and acceleration of the valve pins to prevent defects mentioned above. When the activegate control technology became available, there was no simulation tool at the time that could simulate the effects of controlling the stroke, velocity, and acceleration of the valve pins prior to building an actual mold and testing it. Thus, it was hard to identify potential defects and avoid them before the production. Reflection Marks After Paint Drying Process Hot Spot Marks Opposite Direct Gated Nozzles 10 /

11 CHALLENGE 2 : WELD LINES AND FLOW MARKS Synventive Molding Solutions THE SOLUTION First, Synventive ran a standard filling analysis with sequential valve gating in Moldex3D. After the flow front passed the second nozzle, the valve pin was opened. When this pin was opened, the material in the second nozzle, which is compressed and under high pressure, was released into the cavity. At that point few things happened. One, the flow front was pushed forward at a much faster rate than the flow from the first nozzle. This showed up as a large advancement, which can be seen as large distances between iso-contours, and can lead to pressure transition marks. Filling_Melt Front Time Time = EOF [sec] Uncontrolled Flow Front Two, some materials could flow backwards and create dense areas, which can be seen as smaller distances between iso-contours. When the part came out it looked acceptable, but if you paint these parts and then dry them in a dryer, the dense area can relax and there can be a reflection mark. Finally, material that was deposited on the wall can be re-melted by the high pressure melt entering the cavity, resulting in a hot spot. Flow Rate SOLUTION USED Moldex3D Advanced Flow Advanced Hot Runner 11 /

12 CHALLENGE 2 : WELD LINES AND FLOW MARKS Synventive Molding Solutions THE SOLUTION Next, Synventive ran a simulation using Moldex3D s Pin Movement Technology. The simulation is similar to the standard one but with the controlled opening speed and the acceleration of the pin in the second nozzle, which created small gaps that allowed the pressure in the second nozzle to equalize to the system. With an equal pressure, the material cannot advance the flow front, cannot push material backwards to create the dense areas, and cannot re-melt the material opposite of the gate. The simulation result showed that the iso-contours look uniform throughout the entire part. Filling_Melt Front Time Time = EOF [sec] Controlled Flow Front Flow Rate 12 /

13 CHALLENGE 2 : WELD LINES AND FLOW MARKS Synventive Molding Solutions THE RESULTS With Moldex3D, Synventive succeeded in identifying the injection molded parts that could potentially have defects under conventional sequential valve gating. Equally important, Moldex3D could simulate the advanced valve pin movement control that helped alter the characteristics of the melt front and eventually eliminate any defects that might have occurred. With that, molders could save time and money by scrapping fewer parts from the optimized sequential valve pin movement setting. Conventional sequential valve gating BENEFITS Early detection of common defects in injection molded parts that could be eliminated by activegate control technology Reduced manufacturing scrap and saved money Controlled sequential valve gating 13 /

14 CHALLENGE 2 : WELD LINES AND FLOW MARKS Stanley Black & Decker CASE STUDY Stanley Black & Decker Stanley Black & Decker is a $13 billion revenue, $20+ billion market capitalization, purpose-driven industrial organization. Stanley Black & Decker has 58,000 employees in more than 60 countries and operates the world s largest tools and storage business, the world s second largest commercial electronic security company, a leading engineered fastening business as well as Oil & Gas and Infrastructure businesses. (Source) Industry: Hardware Website: 14 /

15 CHALLENGE 2 : WELD LINES AND FLOW MARKS Stanley Black & Decker THE CHALLENGE Model_Shaded Model Stanley Black & Decker engineers faced a challenge with a hand tool part that formed weld lines that were difficult to accurately locate. From their historical testing, the part would crack near the screw boss if a weld line exists. In addition, the use of bi-material (ABS and TPE) for improving comfort, grip, and visual appeal of the hand tool was difficult to achieve good bonding without testing in actual mold. Following the vendor s experience and suggestions sometimes still could not resolve the issue which resulted in the need of costly tool fixing and delayed project schedules. 15 /

16 CHALLENGE 2 : WELD LINES AND FLOW MARKS Stanley Black & Decker THE SOLUTION Moldex3D allowed Stanley Black & Decker engineers to predict the location of weld lines in the hand tool. Therefore, the team could know how to modify the inner structure to change the weld line position to attain the structural strength required to pass the drop test without having costly design changes. Moldex3D also enabled engineers to predict the ABS and TPE bonding temperature and molding conditions. Thus, it helped them optimize the molding conditions to achieve the best bonding before the tooling started. Filling_Melt Front Time Melt Front at sec Time = EOF x10-1 [sec] Weld Line Initial Design: Weld line was predicted in critical area of the part SOLUTION USED Moldex3D Advanced Flow Cool MCM Pack Warp 16 /

17 CHALLENGE 2 : WELD LINES AND FLOW MARKS Stanley Black & Decker THE RESULTS Model_Shaded Model Based on the simulation results, Stanley Black & Decker engineers addressed the weld line problem by changing the internal structure of the part. The application demonstrated how Stanley Black & Decker can deliver high quality products by utilizing Moldex3D mold filling simulation software to avoid costly mistakes that might occur in final production. BENEFITS Changed weld line position to pass the drop test Optimized molding conditions to have best ABS and TPE bonding Reduced tooling time and cost Filling_Melt Front Time Melt Front at sec Time = EOF x10-1 [sec] Weld Line Revised Design: After changing the part design, the weld line was successfully moved to areas that have less effect on strength 17 /

18 CHALLENGE 3 AIR TRAPS Air traps are likely to occur in areas that are improperly filled and lack required vents. Trapped air will cause bubbles or voids in the injection molded parts and further lead to cosmetic issues. The racetrack effect is another major cause of air traps that are mainly due to large variations in wall thickness. Moldex3D Air Trap result can help visualize possible air trap locations in advance, so injection molders can modify the filling pattern or the venting locations to better tackle the potential air trap problem and reduce its occurrence on the part. 18 /

19 CHALLENGE 3 : AIR TRAPS TYC Brother Industrial Co., Ltd. CASE STUDY TYC Brother Industrial Co., Ltd. TYC Brother Industrial Co., Ltd. (TYC) is one of the world s largest manufacturers of automotive, motorcycle, truck and bus lighting products. It is a worldwide supplier of lighting products for all functions to both original equipment manufacturer (OEM) and automotive part replacement markets in North America, Europe, Asia-Pacific, Africa and Middle East. (Source) Industry: Automotive Website: 19 /

20 CHALLENGE 3 : AIR TRAPS TYC Brother Industrial Co., Ltd. 1 st shot 1 st shot THE CHALLENGE Valve Gate Multi-shot molding is widely used in manufacturing automotive lighting components. In this case, TYC was tasked with designing an automotive light cover using two-shot molding process. However, the racetrack effect, caused by the large difference in part thickness, occurred as the molten plastic flowed through the cavity at the second shot, resulting in air traps and weld lines at undesired locations. 2 nd shot Adding another valve gate for the second shot would be costly, and there was not enough space for this. The proper venting locations for the air traps to escape also had to be at the region where the air was not blocked by the part insert injected from the first shot. Therefore, the current air trap locations at the second shot must be moved to different regions, farther from the gate. 20 /

21 CHALLENGE 3 : AIR TRAPS TYC Brother Industrial Co., Ltd. THE SOLUTION Filling_Melt Front Time Time = EOF [sec] Gate location 2 Too fast 1 Air Trap Weld Line To resolve the race-tracking issue, TYC used Moldex3D to evaluate Too slow wall thickness, leading to unbalanced flow. Moldex3D Flow analysis was performed to help TYC engineers identify unbalanced flow paths in the part. The Flow analysis result showed that path 1 and path 7 are longer than other flow paths. To achieve balanced flow and eliminate air traps, TYC engineers modified the wall thickness and then used Moldex3D to analyze filling patterns. The simulation results showed that an increase in thickness of the central region and adding additional flow restrictors balanced fill pattern. SOLUTION USED Moldex3D Advanced Flow Warp Pack MCM Cool Venting Analysis Model_Thickness [mm] Too fast Add additional flow-restricting zones Increase wall thickness Add additional flow-restricting zones 21 /

22 CHALLENGE 3 : AIR TRAPS TYC Brother Industrial Co., Ltd. Filling 10% Filling 30% Filling 40% THE RESULTS The simulation results showed that the air trap locations could be altered towards the desired locations that could let the air escape. The weld lines could also be minimized at the shifted locations. Equally important, the filling pattern was optimized to achieve balanced filling. More uniform filling temperature inside the part cross section could also be observed in the revised design. In addition, the experimental result and simulation result for the validation of the filling pattern were in a good agreement. Filling 80% Filling 85% BENEFITS Optimized part design Resolved air traps and weld line issues Achieved balanced filling Reduced cost and time spent on mold revisions 22 /

23 CHALLENGE 4 INK WASH-OUT AND STRESS MARKS Ink washout is caused by high shear stress between the film and the melt. An ink-wash index is used in the simulation tool to predict the occurrence of ink washout. Usually, areas near the gate or with extreme thickness variations have a higher ink washout index value. With Moldex3D, injection molders can avoid ink washout and surface defects by validating and optimizing part/mold designs and process parameters, including melt temperature and injection speed in the early development phase. 23 /

24 CHALLENGE 4 : INK WASH-OUT AND STRESS MARKS Acer CASE STUDY Acer Founded in 1976, today Acer is one of the world s top ICT companies and has a presence in over 160 countries. As Acer looks into the future, it is focused on enabling a world where hardware, software and services will infuse with one another to open up new possibilities for consumers and businesses alike. From service-oriented technologies to the Internet of Things to gaming and virtual reality, Acer s 7,000+ employees are dedicated to the research, design, marketing, sale, and support of products and solutions that break barriers between people and technology. (Source) Industry: Consumer Electronics Website: 24 /

25 CHALLENGE 4 : INK WASH-OUT AND STRESS MARKS Acer THE CHALLENGE Consumer electronic devices continue to get slimmer and lighter. The use of fiber-reinforced materials (PC+GF) allows the production of thinner parts while maintaining the desired strength and stiffness. In-mold Roller (IMR) technology is widely used in manufacturing ultrabook cases, which can provide scratch-resistance and design flexibility advantages. However, the flow of glass fibers tend to cause ink washout during the in-mold roller molding process. The Acer engineers were tasked to solve the ink washout and the visible defects in the gate area of an ultrabook base cover part. Moreover, they were challenged to meet stringent wall thickness specifications, which required the base case part to maintain a wall thickness of 8 mm. Filling_Shear Rate Time = EOF x10 2 [1/sec] Node 1 Node 11 Initial Design Shear Rate Node 1 Node 2 Node 3 Node 4 Node 5 Node 6 Node 7 Node 8 Node 9 Node 10 Node /

26 CHALLENGE 4 : INK WASH-OUT AND STRESS MARKS Acer THE SOLUTION Control Factor Mesh Order Level 1 a-1 Level 2 Level 3 Level 4 d-3 e-2 f-2 Melt Temp. ( C) With Moldex3D, Acer engineers were able to set sensor nodes on the gate to diagnose the cause of ink washout and the stress mark. The results showed that the problematic areas have higher shear rate. In order to reduce the shear stress, Acer team performed Moldex3D DOE analysis to analyze the different types of meshes and gates and set two quality factors, which are the shear rate and the sprue pressure, during the filling as smaller-the-better. Based on the DOE analysis results, Acer team was able to identify the main control factors of the ink washout and the best run, which consists of the optimum processing parameters. Mold Temp. ( C) 45 Max. Flow Rate (%) 20 Mesh Worst Run f-1 Best Run d-3 Melt Temp. Mold Temp Max. Flow Rate Shear Stress (MPa) Sprue Injection Pressure Value(MPa) By comparing the best and the worst run, Acer found that in the worst run, the shear rate curve of the gate area is very steep while the curve of the best run is relatively smooth. As a result, Acer changed the gate design and then reworked the design, successfully solving the ink washout problem. Shear Rate Initial Design Optimized Design Node 1 Node 2 Node 3 Node 4 Node 5 Node 6 Node 7 Node 8 Node 9 Node 10 Node 11 SOLUTION USED Moldex3D edesign Flow Pack DOE 26 /

27 CHALLENGE 4 : INK WASH-OUT AND STRESS MARKS Acer THE RESULTS Moldex3D helped Acer eliminate visible defects around the gate area and obtain optimal mold designs in the shortest time possible. With the help of Moldex3D, Acer was able to reap the full benefits of fiber reinforcement materials, reducing the product weight and thickness to meet even the most demanding product specifications. Packing_Shear Stress Time = EOF x10 0 [MPa] Initial Design: Higher shear stress was found in the gate region Packing_Shear Stress Time = EOF x10 0 [MPa] BENEFITS Identified the best gate type to reduce shear stress and avoid ink washout Significantly reduced wall thickness by 48% Reduced product weight by 40% Optimized Design: Shear stress was significantly reduced 27 /

28 CHALLENGE 5 SHORT SHOTS Short shots usually occur when a molded part is not filled completely. There are many factors that can lead to short shots. These include gate, runner, thin wall, insufficient injection speed or pressure, improper venting, etc. Moldex3D allows injection molders to investigate the main causes of short shots by taking into account possible factors and easily change these factors to see the effects of the fill pattern to avoid short shots. 28 /

29 CHALLENGE 5 : SHORT SHOTS Extreme Tool and Engineering CASE STUDY Extreme Tool and Engineering Extreme Tool & Engineering is an ISO 9001:2015 certified premier injection molding and tool building facility located in Wakefield, Michigan. Extreme is a premier mold maker and injection molder with the vision to bring plastics to life with innovative and progressive solutions within the medical, packaging-consumer goods and automotive industries. (Source) Industry: Mold Making Website: 29 /

30 CHALLENGE 5 : SHORT SHOTS Extreme Tool and Engineering THE CHALLENGE There were a lot of uncertainties surrounding Extreme s molding process before they used Moldex3D What will the fill time be? Can our press generate the needed sprue pressure? How much clamp force will we need? Is the shot size appropriate for the barrel? To reduce these uncertainties, Extreme decided to leverage Moldex3D s simulation solutions to can help provide greater confidence prior to actual manufacturing. Warpage_X-Displacement x10-3 [in] /

31 CHALLENGE 5 : SHORT SHOTS Extreme Tool and Engineering THE SOLUTION Extreme chose Moldex3D to help eliminate uncertainties arising from the molding process. They would like to utilize Moldex3D to find the area where additional air venting is required, the press needed, the maximum clamp force, reasonable filling time and predict product warpage before the mold trials. In this case, Extreme used Moldex3D to simulate melt front and predict the end of fill. SOLUTION USED Moldex3D Advanced Flow Warp Pack MCM Cool 31 /

32 CHALLENGE 5 : SHORT SHOTS Extreme Tool and Engineering THE RESULTS Moldex3D simulation result of the melt front matched well with the actual molded result and showed that short shots occurred on the opposite sides of the part. Extreme then applied this knowledge into tool design to add vent inserts. Moldex3D helped Extreme make educated decision as to where to vent and also drive the tool design right from the start. Thus, they didn t have to wait until short shots occur in the first sample to make adjustments or corrections. Based on the simulation result, Extreme selected suitable locations to add vent inserts. BENEFITS Accurately predicted short shots Avoided costly mold repair and rework Used simulation to guide future design and make educated decisions 32 /

33 About Moldex3D Moldex3D is the world leading CAE product for the plastic injection molding industry. With the best-in-class analysis technology, Moldex3D can help you carry out in-depth simulation of the widest range of injection molding processes and to optimize product designs and manufacturability. In addition, our high compatibility and adaptability have provided users with instant connection to mainstream CAD systems, generating a flexible simulation-driven design platform. For more information, please visit Request A Demo Get A Trial Follow us on 33 /

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