The most common of these methods are the hot air dryer, desiccant dryer, compressed air dryer, and vacuum dryer. Increase the injection speed. Advantages of HDPE as a Material. Grippers for Injection Molding; Chemical for Injection Molding. and T se-Hsi Chen [12. In any case, you’d prefer to create polycarbonate parts of different sizes; then this is the best technique that you need to use. splā n (splay marks, silver streaking) Scars or surface defects on injection molding arising from two main mechanisms. Bob Hatch is manager of technical service and customer support for Prime Alliance, the Des Moines-based resin distributor. In thermoplastic injection molding, the mold is always said to be “cold”—that is, relative to the temperature of the plastic melt. Usually, the rising temperature of the mold. Learn how to identify the. It also provided relief from splay and paint-adhesion problems. Olmsted, Martin Davis. Profiling injection is a great tool for establishing at what position a flow front is performing poorly, leading to a defect condition. Splay is a cosmetic defect so occurs in plastic vaccination molding, when color or white streaking appear on the surface of the part. Clamp tonnage / High pressure is too low. Take a good look at part design. CPT offers new & rebuilt injection mold machine replacement barrels, screws, & tips at competitive costs. Splay is a cosmetic defect that occurs in plastic injection molding, when silver or white streaks appear on the surface of the part. Splay: This is a common defect that shows up as shiny streaks on the part and. If you double the viscosity it would be 4000, five times the. Melt decompression can lead to splay and other visual imperfections. Under normal circumstances, the molten plastic fills the mold cavity in a “fountain flow” manner, as shown in Figure 2, which depicts the “fountain. April 5, 2017. Purchase Injection Molding Components now. The turbulent flow whips air into the polymer, creating micro bubbles. Splay caused by moisture. conventional injection molding equipment. Issues that can occur include splay marks. , a provider of training and consulting services to injection molders, including. With the machine on cycle, retract the injection unit, Purge. Splay is one cosmetic defect that occurs in plastic injection molding, although silver oder white streaks appear on the outside of the part. Maximum pressure: packing. 002'') pathways on the shutoff area of the cavity blocks. Splay can be a costly problem in the production of your molded components. 2. Take a look at five factors in the injection. A gas mark is a fault that grows in the direction that melt plastic flows on a product's surface resulting from gas interference during the filling process. Injection molding can be a real challenge if you don’t follow the “Five M’s”: Man, Mold, Machine, Material and Method. Appearance alone cannot tell you which type of splay is present. Flash can be caused by parting line mismatch in the tool. Bob Hatch is manager of technical service and customer support for Prime Alliance, the Des Moines-based resin distributor. advantages 8. Injection Profiling. MISUMI | Your Time, Our Priority. Get more about as to id and address splayHow to deal with splash marks. COCs low shrinkage, lubricated grades and mold. RESPONSIBILITIES: To run product produced by injection molding presses. See our Product List. The best way to avoid these part defects is to work with a plastic injection molder that has a great deal of experience with various resins and their applications. Splay is sometimes also called “silver streaks” because of the appearance of silvery scratches across the surface of the injection molded part. Too cold in the rearInjection Molding of Multimaterial Systems. Injection Molding Flash Remedies. This manual, A Guide to Polyolefin Injection Molding, contains general information concerning materials, methods and equipment for producing high quality, injection molded, polyolefin products at optimum production rates. Back Pressure in an injection molding process is often defined as “the resistance of the screw to recover as the metering section pumps molten plastic through the non-return valve to the. It's recommended that the minimum L/D used in injection molding be 20:1. COLD SLUG – The first material to enter an injection mold. Gas Marks Defined. plastic injection moulding 5. Source: Author jmoutoux. Unfortunately, fixing this injection molding defect often requires mold reformatting. splay,. Determine the time duration of the molten state. In addition, mold plumbing should be checked to ensure there are no. Office: +1. Tel: (60) 3 7890 6399 9am – 6pm (Mon. The faster the injection speed, the worse the jetting. Cleaner for Mold; Repair for Mold; Heating Items. 0005''-0. 375 inch; shorten the gate land to no. Inconsistencies in the injection molding or extrusion process caused by the fluctuations in viscosity of the resin which is a major factor in injection molding / extrusion. Custom Plastic Injection Molding Process - Basic Defect Identification and Troubleshooting . Too cool a melt. The moisture and volatile content in the raw material is. Here are a few of the most common defects that may occur in plastic injection molding — and how product teams can avoid them. Purpose. When a rust preventative is over-applied, it can cause grease to break down in certain areas of the mold, leading to bleeding. Pressure creates heat and eventually the gas reaches a point where it ignites burning the plastic in the mold. Using a turnkey manufacturer, who also builds and maintains the mold, can help avoid any costly machining charges or mold replacement. Zap-Ox saves the customer hours of cleaning time that had previously been spent on excessive buildup. Usually oblong, silvery surface streaks which are open in the shapre of a U counter to the direction of flow. The shape is a part metal square (typically steel or hardened steel) that is machined to frame the depressions in the square. R4:The position of the take-up plate is not correct. Moisture. Using a turnkey manufacturer, who also builds and maintains the mold, can help avoid any costly machining charges or mold replacement. Maksud splay dalam kamus Corsica dengan contoh kegunaan. He is a highly respected writer and educator in the area of plastics processing. Learn the causes of common problems such as injection molding splay. If there is flash on the short shot, we can focus on parameters affecting first-stage injection. Its primary function—as the name suggests—is to act as a trap, or “well,” for the cold slug. These data were obtained from many and Splay can be a costly problem in the production of your molded components. Splay is a cosmetic defect that appear in plastic injection moulding, when white instead white streaks appear on an surface of the part. How can valve gated molds improve cycle time and part quality in injection. The higher requirement on the surface finish of the part, the longer effort and time spent during the production of the mold, hence it will lead to higher cost on your overall cost. Place the heated probe into the melt puddle (Purging mass). Randy Kerkstra and business partner Steve Brammer recently launched KB Molding Solutions, which offers training and consulting for the injection molding industry. applications. An opening in the mold where the injection-molded material enters the mold to create the intended plastic part. Speaking the same “language” on the production floor, streamlines communications between employees and between shifts. If you turn on the spigot to a garden hose, you will hear a hissing sound at the nozzle end for the first few seconds. The material supplier is the best source for this information. इस वीडियो में इंजेक्शन मोल्डिंग से सम्बंधित एक डिफेक्ट silver mark/streaks के बारे में. Injection molding continues to be a complex manufacturing process that requires perfect harmony of part design, mold design, material selection, and the molding process itself. This process is fast, cheap, and helps create vast volumes of identical objects. 1 Caused By The Quality of Injection Mold. There are many "lookalike" errors, and many possible causes of splay, including immoderate molding lubrication. Splay is a term used in the manufacture of injection molded plastics to refer to off-colored streaking that occurs when moisture is caught in the material feed, or if the material degrades during processing. Unfortunately, getting it correct out the gate can be extremely difficult to accomplish on the first attempt, which is why it's important to partner with an experienced. 572. One of the most common defects in plastic injection is splay. 5. Located in the heart of Silicon Valley since 1974, we understand the performance expectations of cutting-edge companies delivering innovative technologies. Moisture and shear are the two primary. Material- ABS Barrel Temperature- ~240 Celsius Pre-drying- 80-90 C for 3 hours The streaks do not come over whole part but only at a single location at the end of fill each time. MISUMI | Your Time, Our Priority. Mixed raw materials or poor thermal stability. It will also profile key analysis. Slip agents not only reduce the coefficient of friction (CoF) but also are used to reduce adhesion between the mold and injection molded polymer. Increase size of the vents. Moisture is a major. A desiccant drier should be used to dry the polycarbonate products to less than 0. This type of injection plastic defect occurs as small depressions or recesses. Injection molding moisture steaks or splay marks solution. Now, from the machine’s point of view, as the screw reaches the position of switchover, the controller, in something like 0. The material temperature is too high, which causes decomposition. Splay is defined here to include any defects that appear as smeared material or bubbles on the part surface, usually oriented in the flow direction. January-October 2022, exports of plastic products amounted to $89. Whereas conventional injection molding uses velocity control during the filling stage and then switches over to pressure control for final filling and packing, DF uses pressure control only. Splay is defined here to include any defects that appear as smeared material or bubbles on the part surface, usually oriented in the flow direction. There’s a good reason burns are also called gas traps in injection molding: they’re caused by trapped gases. Remedies: Mold design: (1) Add an exhaust system to a place where the exhaust gas is easily generated. The simplest cause can be contamination resulting from equipment that has not been properly cleaned, resulting in dust contaminating the resin, but some other common culprits include: High Barrel or Nozzle Temperature: If the temperature of the. Weld lines are injection molding defects that can be mitigated by a number of tactics that depend on your part design. Most drying specifications for various resins are at temperatures where the resin will not. Explore our injection molding troubleshooting guide! Web here are 11 common needle mold defects, what the. Take a good look at part design. If you were to pour water and molasses at the same time, water would flow much easier than the molasses. 1. If the grease breaks down on the slides and lifters, it could become tacky, causing them. Learn other about wie to identify and address splayOn this channel you can get more information about injection moulding machine and processingInjection molding moisture steaks or splay marks solution. While the. Participating in DFM and mold flow analysis is a good way to achieve this. It usually appears at the gate where the plastic enters the mold. Moisture and shear are the two primary causes of splay on an injection molded part. Splay Marks. Splay 1 3 – 2 – 5 – 4 – Short shots. Injection Molding Process. The maximum weight reduction which can be achieved greatly depends on the individual mold shape. This approach will assume you have developed a basic understanding of the injection. Splay can be a costly problem in the production of your molded components. Check runner and stem alignment. Injection molding moisture steak. Just like most injection-molding defects, delamination can be caused by one or more of several potential issues. Understanding your surface requirement is very important, as sometimes it’s. Our quality software enables us to provide the molders with data on the specific defects and where we are seeing them on the parts so they can make adjustments to their processes and/or modifications to the molds themselves to solve the problems. profile extrusion, for example, may require a lower moisture content than. This is an excerpt from Lesson #6 in Paulson's Injection Molded Part Problems and Solutions training progam - Splay (or Silver Streaks) and how to fix them. Injection Molding Know How. In addition, it is important to note that nylon is not only affected by poor drying/ moisture conditions. D. There are many "lookalike" defects, and many possible causes is splay, included excessive mold lubrication. . A gas mark is a fault that grows in the direction that melt plastic flows on a product's surface resulting from gas interference during the filling process. Some materials are hydroscopic. “Incompatible materials” can be a number of things. Stiff materials can utilize deeper vents. 4% year-on. Moisture and off-gases can be a cause of splay. Inlet pressure curve. Remedies: Increase the injection fill speed in small increments (two percent of total) until the delamination tendency disappears. The material pumped out of the cylinder is foamed and shows blisters on the injection molding parts surface. KS Plastics 2116 Farallon Drive San Leandro, CA 94577 Phone: 510-351-8230 sales@ksplastic. How do you reduce splay in injection molding? A large drop in temperature when material enters the mold from nozzle can lead to beginning-of-fill splay. Flow lines appear as a wavy pattern on the surface of your plastic parts. Search for: Search SearchSplay is defined here to include any defects that appear as smeared material or bubbles on the part surface, usually oriented in the flow direction. A good comparison would be the difference between molasses and water. Available for Subscriptions. How to Prevent Common Failure Modes in Injection Molding. Use care when reducing barrel temperature, while maintaining proper shear to provide proper melt and mixing. He is a well-known columnist for magazines covering this area. 2. Steve Brammer is Molding Technical Manager at Lacks Trim Systems. The cost of injection molding is in three places, cycle time, mold construction, and setup costs. It is because a higher temperature results in prematurely expelling the injection-molded components. Gear to shape fittings comprises of a form and an injection molding press. Molasses is thick, and flows slowly. When purchasing plastic injection molded parts. These are cosmetic blemishes on the part’s surface. Dyi-Cheng Chen. A cosmetic defect, it is often silvery in color and is sometimes called ‘silver streak’s. Splay can be caused by a variety of variables, and recognizing these sources is critical for resolving and preventing the issue. Valve gate nozzles leave a small witness mark on the part—the same size as the gate diameter. Grippers for Injection Molding; Chemical for Injection Molding. Purchase Splay Can Holder, Factory Automation parts, Die & Mold parts, industrial tools and consumables. Znaczenie słowa splay w słowniku w słowniku wraz z przykładami użycia. Sliver streaking or yellowing of PET preform. Headquarters. Garrett MacKenzie is the owner/editor of plastic411. Simplified diagram of the process. Date: October 23, 2019. To lay open the end of a tubular structure by making a longitudinal incision to increase its potential diameter. . Here are some common fixes for injection molding splay: Moisture-related: Ensuring that all material is thoroughly dry before beginning the injection mold process is crucial. To fix it, you can try increasing the injection speed, adjusting the temperature of the barrel, increasing the back pressure, or using a different type of plastic material. When possible, a plastic injection molding machine with a relatively large barrel can also be used to improve the plasticization of the melt. Molding Defect #1: Splay Molding Defect #2: Peel Molding Defect #3: Blush Troubleshooting Approach Start with Melt Temperature. Many people think the. Splay adjustments can be a simple fix, or several hours of babysitting a press and head scratching. Solution: Ensure the nylon is properly dried; increase dimensions in edge gate, sprue O-diameter, and nozzle orifice; relocate edge gate to the center. Hubs offers any type of SPI surface finish, such as A-1, D-2 or D-3. XIAOLIN Plastic Industry Co. The cold slug well received that plug of solidified plastic on the next shot. Symptoms/problem: Swirls and gloss on the part’s surface. Figure 2 is a part tested a few minutes after molding and Fig. Hollows in. The Troubleshooter’s notebook. Remedies: Establish a cushion of at least 1/8'' and not more than 1/4''. It may not necessarily produce visible splay, as the water is consumed in the hydrolysis reaction. This specification addresses the cosmetic quality of molded plastic parts and related post molding activities. com. This causes splay, which is a visual defect, but also creates a weak part due to brittleness. Remedies: Raise the mold temperature in increments of 10 degrees F until the bubbles disappear. Find the most up-to-date version of SPI AQ-103 at GlobalSpec. See Product Details. This can result in bubbles or splay in the molded part. Studying read about how in identifies and address splayWeldlines Splay Jetting Burn Marks Warpage. . To fix it, you can try increasing the injection speed, adjusting the temperature of the barrel, increasing the back pressure, or using a different type of plastic material. Typical of the plastics in the thermosetting family are the aminos (melamine and urea), most polyesters, alkyds, epoxies, and phenolics. Injection molding problems MOISTURE RELATED DEFECTS Splay Irregular Moldings Brittleness Bubbles Sink Marks There are several methods for drying resins which utilize industrial drying systems prior to injection molding. This can be avoided by running the resin through a dryer prior to molding. It offers ways to identify splay causesm and gives solutions on how to correct splay c. The liquid plastic goes through a dryer, if necessary (as moisture in the plastic might cause splay or hydrolysis in the finished product). 4. Source: Author jmoutoux. Scientific molding practices optimize gate velocity for bubble-free filling. com and a consultant/trainer in plastic injection molding. This cosmetic defect occurs in plastic injection molding, when silver or white streaks appear on the surface of the part face due to air, contamination, heat, moisture, or shear issues. black specks and splay, process related problems such as filling related defects i. Gas will mix with plastic melt if the high. The molecules bond together as desired and splay is eliminated. If the only solution is to use a spray, try our Tuff-Kote and Dri-Kote high-performance mold-release sprays. Leading the growth and advancement of technology and innovation in plastics machinery for over 50 years, JSW provides a full line of all-electric injection molding machines, ranging from 30-3000 metric tonnes and offers ease of operation, safety, and environment-friendly improvements such as energy and space-saving features. Packson had g. In Figure 1 you can see the bubble; it looks like a gas bubble, right? Most would assume so. Method of switchover from first to second stage. Splay can be caused by a variety of variables, and recognizing these sources is critical for resolving and preventing the issue. 3. Remedies: Use an injection screw with the proper compression ratio. Splay – Contamination – Cold Slugs (discontinuities where injected material was inconsistent)Causes & Solutions for this injection molding defects: 1. Warping. These are molding defects that can occur in the manufacturing process of plastic injection molding. The three main causes of splay are heat, moisture, and shear, with heat being a primary culprit. Reporting to Shift Supervisor, the successful candidate will operate Molding presses and related equipment for the purposes of fittings production. Practical Injection Molding. Injection Molding Extrusion Blow Molding Molds & Tooling Manufacturing Recycling Additive Manufacturing Features Thermoforming Compounding Rotomolding. Synonimy słowa splay i jego tłumaczenie na 25 języków. Machines with fill speed programming capability are recommended. Advertisement. As a raw material for injection molding, HDPE is an excellent choice. An injection molding manufacturer in western Europe producing industrial products was challenged with splay appearing in their product, resulting in an undesirable 20% scrap rate. 7 Million Products, 2,000 Brands. These injection mold coatings are applied either in your tool room or on the press and give exceptional release characteristics to the part in the mold, allowing it to eject without sticking and thereby eliminating any pin push marks. If the only solution is to use a spray, try our Tuff-Kote and Dri-Kote high-performance mold-release sprays. FIG. Injection molding offers numerous advantages when it comes to producing HDPE parts, such as cost-effectiveness, high customization, and high malleability. SPLAY Splay: Moisture is the primary causes of splay on an injection molded part. Possible Causes & Remedies: Machine Cause. Step 1 – Develop a Scientific Molding Process. Allow 10 cycles for each 10-degree adjustment (up or down) for the mold temperature to stabilize. Dri-Kote™. 21 Splay Three types of splay are often encountered in injection molding. COMBINATION MOLD – See FAMILY MOLD. 375 Victoria Road Austintown, OH 44515 USA (330) 726-4000. Divide the required shot size by 5, creating 5 stages of injection. Place vents at last place to fill and at converging flow fronts. Though it is only visible once plated, it is caused my molding issues; trapped moisture in the plastic can come to the surface during. Splay. FIG. As more material enters the mold cavity, it. I give you 4 different variables that can cause splay. What Are Silver Streaks in Injection Molding? A silver streak, also known as a splay mark, is a cosmetic defect that is typically visible on plastic parts with a smooth surface. Increase the injection speeds: Lower injection speeds cause premature cooling. Reduce Splay Defects and White Streaks in Your Injection Molded Parts MOS Plastics is a division of KS Group and specializes in high-precision prototyping, injection molding, contract manufacture, and assembly for Healthcare and electronic OEMs. Don't forget to take a step back and take a look at what's going on with your injection molding machine as a whole. Trapped air, inadequate drying, high temperatures, and contamination can. The Plastic Injection Molder’s Guide to Defect-Free Parts. The most common: incompatible materials. The most common: incompatible materials. Participants are also presented with information and practices on how to best process, document and maintain a reliable scientific injection molding process. First-stage injection fills 92% to 99. You can purchase the book on Amazon: Injection Molding – Advanced Troubleshooting Guide: The 4M Approach. He is the technical director at Dickten & Masch Mfg. Texture. As a raw material for injection molding, HDPE is an excellent choice. Follow Us:Although injection molding is one of the most cost-effective manufacturing options, it does have one drawback. 3. That’s the air escaping out of the nozzle until the hose is full of pressurized water. Learn more about how to identify and deal splayCalculate melt residence time by formula in molding guides . It provides a clear, free-flowing path for plastic granules, powders, and liquids (such as liquid color) into the feed section of the screw. Improve injection time. Jetting can be defined as a "snake-like" pattern on the surface of a molded part, usually emanating from the gate area. The revolutionary low constant pressure injection molding platform works with virtually any plastic injection machine, material, and mold. It owns the name silver streak. Adjust the thickness (1t-2t) 6. from sticking or clumping together (often called “bridging”) in the feed throat. Answer: The trapped gas ignites from the heat generated by pressure. Increase injection pressure. The melt holds enough temperature to maintain a low enough viscosity. txt) or read online for free. and has burn marks. $34. Moisture turns to steam when heated in the injection unit, and these steam pockets interfere with molecular bonding of the plastic. Splay (moisture or trapped air) Haze, blush, and poor gloss; Orange peel and surface ripples; Gate blush and gate splay;There are three general guidelines for selection of the screw for an injection molding machine to be used with PC/ABS resins: 1. Quick drying Dri-Kote mold release spray is a dry mold release, which has the advantage of being difficult to over apply. Plastic injection defects can lead to large scrap events and lost profits, and splay is one of the more frequent defects a processor must correct. Learn how to identify the root cause of splay and how to correct it with various solutions. Splay is defined here to include any defects that appear as smeared material or bubbles on the part surface, usually oriented in the flow direction. Valve gate nozzles leave a small witness mark on the part—the same size as the gate diameter. The cure for splash marks is，therefore to eliminate all volatile matter. If you round up a bit, the viscosity at the fastest speed, a fill time of 0. Our ISO Class 7 (10,000) clean room is equip. ) Check Your Machine. Plastic decomposition. Time also plays a factor: molten resin must be able to reach all points of the mold before it starts to harden. Ejection temperature is too high. So I came across this defect which looks like splay. A reduction of 10 – 25% is usually achieved in. Splay is a term used in the manufacture of injection molded plastics to refer to off. Usually oblong, silvery surface streaks which are open in the shapre of a U counter to the direction of flow. Injection Molding. The chart below shows recommended wall thicknesses for common injection molding resins. The wall thicknesses of an injection molded part generally range from 2mm – 4mm (0. Here is a look at a few more surface finish considerations for making better molds. Content Provider. 2. Gas will mix with plastic melt if the high. To determine whether you’re looking at bubbles or voids, slowly heat the area with a torch or heat gun. Solution: Open the sprue O diameter to at least . Once you have a cool shell formed the rest of the mold entering absorbs heat from the layer next to the wall. Several other defects, like scuffs, flow lines, surface scratches, delamination from contamination and flaking, can resemble splay, so it’s important to determine the cause of the streaks as the first step in troubleshooting. Then I give you some troubleshooting tips that might help fix. 375 inch; shorten the gate land to no. The slip agents have exactly the same effect on metallization and reduce adhesion. For example, if operators are making a mold of a medical part—like an endoscope, which a surgeon needs to hold with gloves—they will need to develop a uniform texture for gripping. Splay. 508-520-0011 Fax: +1. Voids are instances of plastic shrink that creates a vacuum in the plastic wall stock. Here are some common fixes for injection molding splay: Moisture. Many companies worldwide continue to purchase China injection molding services; some are placing large orders, and some even set up their own sourcing office in China. Viscosity: Definition Viscosity as it relates to plastic injection is the measurement of how thick or thin a material flows. Knit / Weld Lines. 8 : 1 and 2. Preventing Flash in Injection Molded Parts. Splay Defects in Plastic Injection. A Plastic Injection Molding Process Problem – Troubleshooting Methods . What's SPLAY in molding & how to fix it. The defect detection tool trains on a set of images of a range of defect-free plastic parts. Use of a slip-ring type non-return valve with clearances of at least 3. A desiccant drier should be used to dry the polycarbonate products to less than 0. At this temperature,. Please call 814-898-6103 or email [email protected]. 2. In addition, ABS provides a colorfast, high-gloss surface finish. At times the part may also shatter. If the barrel temperature is too high or the heating is imbalanced, the barrel temperature should be lowered step by step. It usually appears at the gate where the plastic enters the mold. Increase gate size; 2. This manual, A Guide to Polyolefin Injection Molding, contains general information concerning materials, methods and equipment for producing high quality, injection molded, polyolefin products at optimum production rates. • Estimated clamp tonnage of 5. Since the cavity is more than 90% full, not much more plastic is needed. Set it longer for the cooling time. If you round up a bit, the viscosity at the fastest speed, a fill time of 0. Air, water vapor, and decomposition gas are all components of gas, and the presence of gas is the primary cause of this mark. Plastics Processing || Class - 44 ||🔷 इंजेक्शन मोल्ड़िंग में Silver Streak और Splay Mark Defect क्या होता है?🔷 Silver Streak. Source: Google. It is indicative of an undesirable turbulence and splitting of the flow front. It is these steam bubbles that you see as Splay. To decide on the likely cause(s), test each to prove/disprove. . This helps prevent mold release buildup, especially in the problem areas of a mold, which in turn mitigates gas build up. 14 billion, up 12. Injection moulding process explained with key elements. Setting too high a temperature can prevent the gate from sealing properly and on time. The pressures used to inject molten plastic is tremendous. Splay happens during the injection molding process due to the presence of gas or vapor within the molten plastic. To decide on the likely cause(s), test each to prove/disprove whether it is causing the splay, then take the corrective action. Custom Plastic Injection Molding - Troubleshooting Techniques - For this part of this series, we will start out with a very basic injection molding problem and some possible ways of solving it. 4. PRECISION PLASTIC INJECTION MOLDERS 20 Liberty Way Franklin, MA 02038 USA. Garrett MacKenzie is the owner/editor of plastic411. Control injection speed to avoid material shearing and splay. Injection molding Troubleshooting guide Eastman copolyesters. Increase stock temperature by increasing back pressure. Figure 2 shows the part after testing, and you can now see a depression or sink. Plastic injection defects can lead to large scrap events and lost profits, and splay is one of the more frequent defects a processor must correct.