Warping. Check runner and stem alignment. One of the most significant advantages of injection molding is the natural surface finish of molded parts. Injection molding process explained. D. Garrett MacKenzie | Mar 12, 2023 In the injection molding process, the. Tatjana Geminger, Stefan Jarka, in Specialized Injection Molding Techniques, 2016. Plastic injection molders – whether lacking the experience, adept knowledge or proper equipment – can produce defective products that don’t stand up to industry regulations, appearance requirements, and/or general client. Injection Molding Polypropylene: Polypropylene is a very useful plastic for injection molding and is typically available for this purpose in the form of pellets. The draft angle of the mold core is not big enough – increase the draft. As the plastic fills and pack the mold, part take shape and begin to cool. Excessive injection pressure creates stress that causes product warpage in the mold. Slip agents not only reduce the coefficient of friction (CoF) but also are used to reduce adhesion between the mold and injection molded polymer. Flow lines appear as a wavy pattern on the surface of your plastic. COMBINATION MOLD – See FAMILY MOLD. . 50,000 Stock items for Same Day Ship Out. 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. Avoid Drag in Molded Parts. Identifying your injection molded part defects is the first line of defense against wasting valuable molding machine time. Splay Silver-streaked appearance caused by gasses in. Appearance. Remedies: Pre-dry the plastic properly before molding. Haziness or cloudiness in molded parts is one of the most common injection molding defects. 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. splā (splay marks, silver streaking) n. Understanding your surface requirement is very important, as sometimes it’s. Take a look at five factors in the injection. Grippers for Injection Molding; Chemical for Injection Molding. While small gates may provide a nicer appearance. Some molds need to be textured. Molding Defect #1: Splay Molding Defect #2: Peel Molding Defect #3: Blush Troubleshooting Approach Start with Melt Temperature. Injection molding offers numerous advantages when it comes to producing HDPE parts, such as cost-effectiveness, high customization, and high malleability. Switch to a hot runner or reduce the size of the main channel. At the minimal pressure level for the second phase it is easy to inspect whether the part is a short shot at the end of first-stage injection. The three main causes of splay are heat, moisture, and shear. III. 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. Problem: Shear-sensitive material; gate land length much too long; and barrel temperatures, in an effort to eliminate gate blush, were raised too high. That’s the air escaping out of the nozzle until the hose is full of pressurized water. Injection molding is a process that utilizes a molten material that is forced into a mold to form a part. What is Splay? Silver or white streaks appearing on the surface of the part often indicate. 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. So what does the 140F mold temperature give us? The molding technician thought the 140F mold water was OK because the data sheet provided by the material supplier suggested mold temperatures from 75 to 180F. The presence of gloss and/or texture in the tool can make what would otherwise be an exact color match appear very different. Using a turnkey manufacturer, who also builds and maintains the mold, can help avoid any costly machining charges or mold replacement. Although, aluminum has been proven as a reliable mold material for production injection molding. 4% year-on. The following parameters should be evaluated for all projects when conducting a design for manufacturability evaluation in plastic injection molding: Maximum pressure: filling. What is Splay? Silver or white streaks appearing on the surface of the part often indicate splay in injection molding. 3 is a part tested 16 hr after molding. A cosmetic defect, it is often silvery in color and is sometimes called 'silver streak'. Depending on the material,. As more material enters the mold cavity, it. Wait 30 seconds and record temperature shown on the instrument. Randy Kerkstra and business partner Steve Brammer recently launched KB Molding Solutions, which offers training and consulting for the injection molding industry. com . [1] The most common cause of splay is moisture, which is caught in the resin inside the injection molding machine during the heating. Often times, the feedthroat is run at too cool a temperature, but it's also important that the feedthroat isn't so hot. It is a cosmetic defect typically appearing as an off-color streak, often silver in hue, along the surface of the molded part. Garrett MacKenzie is the owner/editor of plastic411. The splay that normally appears when wet polycarbonate is molded was. Splay (also called chicken tracks, tails, and hooks) is usually caused by a gas, usually water (steam), but can be caused by unmelt, dirt, chips, or flakes from three-plate molds, cold slugs, excessive volatile additives, air, and/or decompression. Silver Streak Analysis & Troubleshooting (1). In Figure 1 you can see the bubble; it looks like a gas bubble, right? Most would assume so. If the barrel temperature is too high or the heating is imbalanced, the barrel temperature should be lowered step by step. com and a consultant/trainer in plastic injection molding. Reporting to Shift Supervisor, the successful candidate will operate Molding presses and related equipment for the purposes of fittings production. “Incompatible materials” can be a number of things. mold damage → replace damaged parts or repair. Preventing Flash in Injection Molded Parts. However, even moisture levels of 0. sales@uninko. 3. They were processing gray rigid polyvinyl chloride (RPVC) with an 80mm 24:1 general purpose screw with a thread-on smear tip in a Demag injection molding machine. black specks and splay, process related problems such as filling related defects i. Splay. As a general rule, the amount of decompression should not exceed 1 ½ times the travel of the. Injection Molding The process of forming a material by forcing it from a heated cylinder, under pressure, through a spruce into a cavity of a confined mold. The forums offer a method to ask colleagues directly. They usually are a slightly different color than the rest of the piece, and typically occur on more narrow sections of the molded item. Reduce the screw speed and adjust the backpressure. 2) Vents in an injection mold should let the air out, but not the liquid plastic. Proper resin is a function of time/temperature. Our ISO Class 7 (10,000) clean room is equip. The injection molding companies must avoid any extra-thick bits of significant disparities in the thickness of the plastic component when constructing the mold. 0005''-0. Except for large parts, you are usually dealing with only a few extra grams. This allows the melt to keep enough velocity to ensure proper filing. 3. 3. 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. Figure 1 is the part before heating. DF is said to provide the most accurate control over packing, since pressure is sensed. All manufacturing. If you round up a bit, the viscosity at the fastest speed, a fill time of 0. 1. The mold maker may think that some minor defects are acceptable, or they may not even consider them from the beginning, which can cause problems when the injection mold is being manufactured. Its primary function—as the name suggests—is to act as a trap, or “well,” for the cold slug. If it’s a bubble, the wall stock will swell due to the gas inside expanding. Most often this problem occurs when parts are being made with colored, semi-transparent resins, or have. If the only solution is to use a spray, try our Tuff-Kote and Dri-Kote high-performance mold-release sprays. It usually appears at the gate where the plastic enters the mold. Drying of plastic resin can be a key step in the injection molding process, since too much moisture can cause a number of processing problems. Generally 70% to 90% of the energy necessary to melt the plastic comes from this compressing, friction, and screw-rotation combination. 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. Injection moulding (U. Melt decompression can lead to splay and other visual imperfections. 4. A compression ratio between 1. Figure 1 presents the shrinkage of polypropylene versus wall thickness in injection molded parts. To adjust injection parameter right Short shot Non-Fill/Short Mold Partial part Lack of material, injection speed or pressure too low To adjust injection parameter right Splay marks Splash Mark/Silver Streaks Circular pattern around gate caused by hot gas Moisture in the material, usually when resins are dried improperly To improve material drylyParts molded in ABS/PC tool: (top to bottom) 100% PP-based WPC; TPO/WPC blend with 20% wood; TPO/WPC blend with 10% wood. 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. Splay, a cosmetic defect in plastic injection molding, manifests as silver or white streaks on the surfaces of molded parts, as showcased in the accompanying image. 3) Friction and mold wall friction overheating. Vents should take up approximately 30% of the perimeter of the molded part. When purchasing plastic injection molded parts. This defect is caused when the polymer resin is injected into a mold and flows around a solid piece and forms when the resin collides back together without completely fusing back together. Controlling the switchover from first to. That degradation creates a gas, which is. The injection pressure is too high – adjust the parameters appropriately. The three main causes of splay are heat, moisture, and shear. 7. Date: October 23, 2019. Now, from the machine’s point of view, as the screw reaches the position of switchover, the controller, in something like 0. The solution to a Splay problem is, of course, to keep the plastic dry. Setting too high a temperature can prevent the gate from sealing properly and on time. In the process of injection. Office: +1. 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. Mis makan dapat menyebabkan materi dalam sekrup/barrel menjadi terlalu panas dan menjebak gas seperti yang didorong melalui zona kompresi yang akan menunjukkan di bagian sebagai lapisan perak/splay. However, the outsourcing injection molding within China has grown consistently. The defect detection tool then identifies any anomalous parts, detecting both functional and cosmetic defects. Low Gloss. 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. Increase gate size; 2. KS Plastics 2116 Farallon Drive San Leandro, CA 94577 Phone: 510-351-8230 sales@ksplastic. 008 to 0. This video helps to visually define the different properties of splay. . Participating in DFM and mold flow analysis is a good way to achieve this. In single-stage molding, overall heat is controlled by holding and cooling time while a change in injection speed can be used to change the temperature in the preform. Remedies: Vent the mold by grinding thin (0. Splay Can Holder; Mold Maintenance. Mixing Nozzles, Standard Nozzles, Insulated and Standard Heater Bands, Thermocouples, etc. Splay adjustments can be a simple fix, or several hours of babysitting a press and head scratching. 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. Paul Mastro is a plastics engineer with over 30 years of experience in the formulation, injection molding and. Packson had g. Watch the YouTube presentation below for information about Plastic411. Appearance alone cannot tell you which type of splay is present. The first way is to mold “by the book”. About Me Name: Mike Location: Redwood City, United States . Determine the time duration of the molten state. CYCLE TIME TOO SHORT. Located in the heart of Silicon Valley since 1974, we understand the performance expectations of cutting-edge companies delivering innovative technologies. Cosmetic Specifications of Injection Molded Parts, Revision A. 4. There are many "lookalike" defects, and more possible cause of splay, including excessive mold lubrication. Here are 3 common injection molding flaws and how to prevent them from happening in the future: Flow Lines. This line is known as the partingSplay is a cosmetic defect that occurs to plastic injection molding, for silver or white smears appear over the surface of the part. So I came across this defect which looks like splay. Barrel and Screw Measurement and Maintenance Programs. Most drying specifications for various resins are at temperatures where the resin will not agglomerate,If a balance tool is creating unequal short shots, make sure drops and tips are not contaminated from a previous run. On the other hand, with injection-molded products, various conditions—including the proportions and dispersion of material and additive contents, the temperature used to melt the plastic, the pressure, and the cooling time—significantly affect quality. Lets discuss moisture, as most of the time splay occurs because the resin has not been properly dried. Bernie A. Read our blog post here. 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. Olmsted, Martin Davis. Solution: Ensure the nylon is properly dried; increase dimensions in edge gate, sprue O-diameter, and nozzle orifice; relocate edge gate to the center. 5. Moisture and shear are the two primary causes of splay on an injection molded part. High-quality mold should be used in injection molding to avoid molding splay. If you have ever looked closely at a plastic object, you may have noticed a faint line running around its circumference. , a molder of thermoset and thermoplastic materials in Nashotah, WI. Gear to shape fittings comprises of a form and an injection molding press. One significant processes utilized to produce plastic pipe fittings is the injection molding. To decide on the likely cause(s), test each to prove/disprove whether it is causing the splay, then take the corrective action. Headquarters. proposed that surface defects, such as splay marks and silver streaks, are. The turbulent flow whips air into the polymer, creating micro bubbles. • Melt too hot Splay • Injection too fast • Gates too small • Barrel temperature profile wrong. Check out the numbers in the table accompanying the graph. R2:PET Preform Mold was damaged. A mold temperature of between 80-120℃ / 176-248℉ should be maintained to prevent sink marks. Figure 2 shows the part after testing, and you can now see a depression or sink. 3. A material that will undergo or has undergone a chemical reaction by the action of heat and pressure, catalysts, ultra-violet light, etc. Gloss should be considered in relation to both the mold and resin being processed, since some materials naturally have higher gloss. Air, water vapor, and decomposition gas are all components of gas, and the presence of gas is the primary cause of this mark. txt) or read online for free. Published by GMW on March 1, 2018. 11 ref. Preventing Flash in Injection Molded Parts. injection molding process was carried out by varying important processing parameters of mold temperature, injection speed, packing pressure and melt. 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. This type of injection plastic defect occurs as small depressions or recesses. «Splay» Meaning of splay in the English dictionary with examples of use. To lay open the end of a tubular structure by making a longitudinal incision to increase its potential diameter. 00. Purge the barrel amply, to allow the barrel time to heat soak. He is the technical director at Dickten & Masch Mfg. 2. Answer: The trapped gas ignites from the heat generated by pressure. Splay Defects in Plastic Injection. Preventing the polymer surface from instantaneously freezing during filling allows the material to. 5mm (0. S. If you double the viscosity it would be 4000, five times the. 6 sec instead of the typical 7 sec for ABS/PC. Injection molding is particularly rough on polymers because in addition to the barrel temperatures required to soften the material, there can be significant shearing forces applied to the material to move it rapidly through the machine nozzle and into the mold cavities. 02% moisture. Tool: Single-cavity, cold runner. conventional injection molding equipment. 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. To determine the cause of your issue, first determine where. Splay A defect in the surface of a molded part that is usually small in size, shiny, and may have the appearance of a lightly tinted or silver streaks. The main types of injection molding defects are: 1. The Plastic is Cooling Too Quickly: The presence of jetting might mean you have another issue: plastic is cooling too quickly within the mold. He has provided process-engineering expertise to many top. This article continues our series of troubleshooting reports from one of the leading on-the-spot problem solvers in the molding industry. Verify that the process itself has been decoupled first, yielding a 95-98% full part with no hold or pack added. Pressure creates heat and eventually the gas reaches a point where it ignites burning the plastic in the mold. Injection Molding. ContaminationBrentwood offers a manufacturing environment of over 30,000 square feet to support our medical device customers. Fill pattern animation. This extra effort ensures that their injection molding process is smooth and free of splay defects, resulting in high-quality finished parts. Allows you to accommodate a variety of part sizes. We have over 40 years of injection mold experience. Medical utensils often. Run capacity has increased from 1,000-1,500 parts to 24,000 parts before having to reapply, with a 45-second cycle time. The speed in which the plastic is injected into the mold (known as the ram speed) may be too high. The most common: incompatible materials. metal injection moulding 7. 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. Splay is a cosmetic defect that occurs when moisture gets into the resin during the heating process of the injection molding machine. Solution: Ensure the nylon is properly dried; increase dimensions in edge gate, sprue O-diameter, and nozzle orifice; relocate edge gate to the center. Its primary function—as the name suggests—is to act as a trap, or “well,” for the cold slug. +86 186-6535-2868. remove the plate suction tube damaged → replace the damaged suction tube or repair. , leading to a relatively infusible state. Michael Sepe is our analyst and author. Remedies: Vent the mold by grinding thin (0. Slower, controlled speeds allow for smoother laminar flow that prevents air entrapment. Plastic411 Overview. A good comparison would be the difference between molasses and water. Clean the molding cylinder thoroughly; 3. The usual injection of molten plastic is assisted by. Injection Molding: How to Set Second. Moisture and shear are the two primary. Injection moulding can be performed with a host of materials mainly including metals (for which the process is called die-casting ), glasses, elastomers, confections, and most commonly thermoplastic and. The chart below shows recommended wall thicknesses for common injection molding resins. With the machine on cycle, retract the injection unit, Purge. Molten polymer moves through the barrel of the machine and forced in to a steel mold. Many defects can occur in injection molding. These data were obtained from many and Splay can be a costly problem in the production of your molded components. 2 mm and a ring movement of at least 4. 12515 NE 95th Street , Vancouver, WA 98682. 5. [1] The most common cause of splay is moisture, which is caught in the resin inside the injection molding machine. The shape is a part metal square (typically steel or hardened steel) that is machined to frame the depressions in the square. Znaczenie słowa splay w słowniku w słowniku wraz z przykładami użycia. Grippers for Injection Molding; Chemical for Injection Molding. On injection molded parts, the biggest problems are splay, flash, knit lines and gouges. 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. Select a better surface material for the mold cavity, to reduce shrinkage. . Moisture and off-gases can be a cause of splay. It provides a clear, free-flowing path for plastic granules, powders, and liquids (such as liquid color) into the feed section of the screw. In fact, viscosity is influenced more by shear rate—injection speed—than temperature or even resin lot variations. Troubleshoot molding machines to bring parts into specifications for size, appearance, flash, splay, cycle time, etc. If burning or flashing occurs, the injection speed is too high and delamination is being caused by other factors. spe western sections annual pacific technical conference and technical displays/1979/costa mesa ca; usa; da. If it’s a void, the wall stock will collapse and show a sink. Molding Problems Trouble Shooter. The molecules bond together as desired and splay is eliminated. When two materials can’t bond together, it results in separation that very quickly becomes delamination. This article continues our series of troubleshooting reports from one of the leading on-the-spot problem solvers in the molding industry. Sink marks usually occur when there’s a shrinking of a molded component’s inner part. 1. Midstate Mold & Engineering. Air flow may become erratic due to moisture in the molding system and this can be a source of trouble. A purge compound can be a great solution before pulling the tool. The molecules bond together as desired and splay is eliminated. To prevent parting line mismatch: Clean off any plastic, dirt, or contaminants that could keep the mold from closing correctly, especially behind slides and inside the leader pin bushings. How to Prevent Common Failure Modes in Injection Molding. The faster the injection speed, the worse the jetting. Issues that can occur include splay marks. Some materials are hydroscopic. The most common cause of blisters resulting from material issues is that the material is not dry enough when it goes into the melting process. SPLAY Splay: Moisture is the primary causes of splay on an injection molded part. There are many "lookalike" defects, plus many conceivable causes of splay, including excessive mold lubrication. Injection molding moisture steaks or splay marks solution. 4. Proper resin is a function of time/temperature. 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. Let’s first discuss moisture, as most of the time splay occurs because the resin has not been properly dried. Divide the required shot size by 5, creating 5 stages of injection. 2. 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. Expand the gate (*a) 5. There are three ways to mold. Moisture. 375 inch; shorten the gate land to no. This. The pressures used to inject molten plastic is tremendous. Valve gate nozzles leave a small witness mark on the part—the same size as the gate diameter. For specific questions or more information, please email. The inject speed needs to be reduced on the molding machine. In addition, mold plumbing should be checked to ensure there are no. View my complete profile. CPT offers new & rebuilt injection mold machine replacement barrels, screws, & tips at competitive costs. When possible, a plastic injection molding machine with a relatively large barrel can also be used to improve the plasticization of the melt. 2. The material pumped out of the cylinder is foamed and shows blisters on the injection molding parts surface. Splay is a cosmetic defect that occurs in plastic injection molding,. RESPONSIBILITIES: To run product produced by injection molding presses. What's SPLAY in molding & how to fix it. 4. Gloss should be considered in relation to both the mold and resin being processed, since some materials naturally have higher gloss. Learn about 10 common plastic injection molding defects, find out why they occur, and get tips to fix them. 30-30 Melt temperature Rule Procedure: Spray the probe with mold release Heat the probe 30 F above the front zone temperature. Splay can be more obvious on black parts, but this plastic molding defect can be found in pretty much any injection molding material, any color. These features occur on flat and consistent surfaces of molded parts. It requires a significant capital investment and a relatively long lead time to machine the tools. building; 35 molding machines;Injection molding Troubleshooting guide. One of the most common injection molding defects is Splay, also referred to as “silver streaks” or “jetting”. Adjust the thickness (1t-2t) 6. The Plastic Injection Molder’s Guide to Defect-Free Parts. , sink marks and voids, and post. It causes silvery streaks on the surface of the molded part. Splay can be a costly problem in the production of your molded components. Just like most injection-molding defects, delamination can be caused by one or more of several potential issues. Contamination can be defined as an imperfection in a molded part caused by the presence of a foreign object or material that is not part of the original molding compound. 14 billion, up 12. Bob Hatch is manager of technical service and customer support for Prime Alliance, the Des Moines-based resin distributor. This can be avoided by running the resin through a dryer prior to molding. Splay is a aesthetic defect that occurs in plastic injection molding, when gray or white streaking pop at the surface of the part. Splay can be caused by a variety of variables, and recognizing these sources is critical for resolving and preventing the issue. Splay is a cosmetic defect that occurs in plastic injection molding, when black or white streaks appear on the surface of this part. Ensure Machine Purging: In injection molding, purging refers to cleaning the molding machine of one material or color. Bob Hatch is manager of technical service and customer support for Prime Alliance, the Des Moines-based resin distributor. Explanation: Excessive moisture does not belong in the molding compound. Splay caused by moisture. Particularly in injection molding, a typical method of forming plastic, care must be. Midstate Mold & Engineering. Texture. Gate size. 21 Splay Three types of splay are often encountered in injection molding. Part/material: 33% glass-filled nylon 6/6 disk used in an assembly. Air, water vapor, and decomposition gas are all components of gas, and the presence of gas is the primary cause of this mark. High nozzle temperatures can promote the formation of thermal splay marks from keeping the. Source: Author jmoutoux. Splay: This is a common defect that shows up as shiny streaks on the part and. Plastics processors are responsible for making process corrections when defects affect their scrap rate. 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. While the. 3. To decide on the likely cause(s), test each to prove/disprove whether it is causing the splay, then take the corrective action. Scribd is the world's largest social reading and publishing site. This specification addresses the cosmetic quality of molded plastic parts and related post molding activities. A Guide To Polyolefin Injection Molding Introduction Polyolefins are the most widely used plastics for injection molding. Switch to a hot runner or reduce the size of the main channel. Mixed raw materials or poor thermal stability. Injection Molding Problems and Solutions (14/17) – Splay Marks. See our Product List. Place the heated probe into the melt puddle (Purging mass). Find the most up-to-date version of SPI AQ-103 at GlobalSpec. 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. There have countless "lookalike" defects, and many possible causes of splay, including excessive mold lubrication. One of the most common defects in plastic injection is splay. To decide on the likely cause(s), test each to prove/disprove. Many people think the. When purchasing plastic injection molded parts. Specific attention to processing details will enhance quality and productivity . Identifying splay can be challenging, as its appearance may resemble other defects such as surface scratches, scuffs, flow lines, contamination-related delamination, or flaking, all. The gate restricts flow as the part fills. This article will help to identify various. Possible Causes & Remedies: Machine Cause. What is Splay? Silver or white streaks appearing on the surface of the part often indicate splay in injection molding. 508-520-0011 Fax: +1. 002'') pathways on the shutoff area of the cavity blocks. By contrast, a slow injection speed will give you a matte finish and a cold mold, such as 50F, will give you a more flexible part. 3. Thermoplastic resins fall into two distinct categories, each with their own advantages and disadvantages. 102-106; bibl. Then I give you some troubleshooting tips that might help fix. . Splay happens during the injection molding process due to the presence of gas or vapor within the molten plastic.