{"id":107796,"date":"2025-04-28T11:10:09","date_gmt":"2025-04-28T09:10:09","guid":{"rendered":"https:\/\/xometry.pro\/articles\/injection-molding-defects\/"},"modified":"2025-08-08T14:29:03","modified_gmt":"2025-08-08T12:29:03","slug":"injection-molding-defects","status":"publish","type":"articles","link":"https:\/\/xometry.pro\/en\/articles\/injection-molding-defects\/","title":{"rendered":"16 Common Injection Molding Defects: Types, Causes, and Solutions"},"content":{"rendered":"<div role=\"navigation\" aria-label=\"Table of Contents\" class=\"simpletoc wp-block-simpletoc-toc\"><h2 class=\"simpletoc-title\">Table of Contents<\/h2>\n<ul class=\"simpletoc-list\">\n<li><a href=\"#h-quick-reference-defect-comparison-table-nbsp\">Quick-Reference Defect Comparison Table&nbsp;<\/a>\n\n<\/li>\n<li><a href=\"#h-injection-molding-defects-caused-by-mold-design\">Injection Molding Defects Caused By Mold Design<\/a>\n\n<\/li>\n<li><a href=\"#h-1-short-shots\">#1 Short Shots<\/a>\n\n<\/li>\n<li><a href=\"#h-2-flash\">#2 Flash<\/a>\n\n<\/li>\n<li><a href=\"#h-3-improper-parting-line-placement\">#3 Improper Parting Line Placement<\/a>\n\n<\/li>\n<li><a href=\"#h-4-bubbles-and-voids\">#4 Bubbles and Voids<\/a>\n\n<\/li>\n<li><a href=\"#h-5-gate-vestige\">#5 Gate Vestige<\/a>\n\n<\/li>\n<li><a href=\"#injection-molding-defects-caused-by-process\">Injection Molding Defects Caused By Process<\/a>\n\n<\/li>\n<li><a href=\"#h-6-flow-lines\">#6 Flow Lines<\/a>\n\n<\/li>\n<li><a href=\"#h-7-burn-marks\">#7 Burn Marks<\/a>\n\n<\/li>\n<li><a href=\"#h-8-sink-marks\">#8 Sink Marks<\/a>\n\n<\/li>\n<li><a href=\"#h-9-surface-delamination\">#9 Surface Delamination<\/a>\n\n<\/li>\n<li><a href=\"#h-10-weld-lines-knit-lines\">#10 Weld Lines (Knit Lines)<\/a>\n\n<\/li>\n<li><a href=\"#h-11-warping\">#11 Warping<\/a>\n\n<\/li>\n<li><a href=\"#h-12-jetting\">#12 Jetting<\/a>\n\n<\/li>\n<li><a href=\"#h-13-vacuum-voids\">#13 Vacuum Voids<\/a>\n\n<\/li>\n<li><a href=\"#h-14-discoloration\">#14 Discoloration<\/a>\n\n<\/li>\n<li><a href=\"#h-15-splay-marks-silver-streaking\">#15 Splay Marks (Silver Streaking)<\/a>\n\n<\/li>\n<li><a href=\"#h-16-contamination\">#16: Contamination<\/a>\n\n<\/li>\n<li><a href=\"#h-injection-molding-defects-by-severity-and-cost-impact\">Injection Molding Defects by Severity and Cost Impact<\/a>\n<\/li><\/ul><\/div>\n\n\n<p>By applying best practices in design, mold engineering, and process control, these defects are largely predictable and avoidable. This article identifies common injection molding defects, examines their underlying reasons, and offers practical solutions to help you achieve consistently high-quality molded parts.<\/p>\n\n\n<h2 class=\"wp-block-heading\" id=\"h-quick-reference-defect-comparison-table-nbsp\"><strong>Quick-Reference Defect Comparison Table <\/strong><\/h2>\n\n\n<p>The table below summarizes the various injection molding defect types and highlights their causes and possible design solution or prevention methods. More details are provided in the next section.<\/p>\n\n\n<div class=\"custom-table-block \" id=\"table-id-426\" >\r\n\t<div class=\"search-input-wrapper\">\r\n\t\t<svg width=\"16\" height=\"16\" viewBox=\"0 0 16 16\" fill=\"none\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\">\r\n\t\t\t<path d=\"M15.7812 13.833L12.6659 10.7177C12.5252 10.5771 12.3346 10.499 12.1347 10.499H11.6253C12.4877 9.39596 13.0002 8.00859 13.0002 6.49937C13.0002 2.90909 10.0911 0 6.50083 0C2.91056 0 0.00146484 2.90909 0.00146484 6.49937C0.00146484 10.0896 2.91056 12.9987 6.50083 12.9987C8.01006 12.9987 9.39742 12.4863 10.5004 11.6239V12.1332C10.5004 12.3332 10.5786 12.5238 10.7192 12.6644L13.8345 15.7797C14.1282 16.0734 14.6032 16.0734 14.8938 15.7797L15.778 14.8954C16.0718 14.6017 16.0718 14.1267 15.7812 13.833ZM6.50083 10.499C4.29167 10.499 2.50122 8.71165 2.50122 6.49937C2.50122 4.29021 4.28855 2.49976 6.50083 2.49976C8.70999 2.49976 10.5004 4.28708 10.5004 6.49937C10.5004 8.70852 8.71311 10.499 6.50083 10.499Z\" fill=\"#476175\"\/>\r\n\t\t<\/svg>\r\n\t\t<input type=\"search\" class=\"table-search-input\" id=\"table-search-426\" placeholder=\"Table search\">\r\n\t<\/div>\t\r\n\t<div class=\"table-wrapper\">\r\n\t\t<table style=\"width: 767px;\">\n<tbody>\n<tr>\n<td style=\"width: 230px;\"><b>Injection Molding Defect<\/b><\/td>\n<td style=\"width: 290px;\"><b>Causes<\/b><\/td>\n<td style=\"width: 247px;\"><b>Quick Design Tips<\/b><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 230px;\"><b>Flash: <\/b>Thin plastic seepage along parting lines or ejectors<\/td>\n<td style=\"width: 290px;\">Overly tight radii near parting lines, inconsistent wall thickness, parting line in high-stress area, excess pressure, sharp corners, tool wear<\/td>\n<td style=\"width: 247px;\"><span style=\"font-weight: 400;\">\u2022 Place parting lines on low-visibility surfaces<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022 Avoid sharp corners near mold splits<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022 Maintain even wall thickness<\/span><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 230px;\"><b>Short Shots: <\/b>Incomplete fill; missing or thin sections<\/td>\n<td style=\"width: 290px;\">Thin walls, sharp transitions, complex flow paths, low pressure<\/td>\n<td style=\"width: 247px;\"><span style=\"font-weight: 400;\">\u2022 Keep walls &gt; 0.8 mm<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022 Avoid sharp turns<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022 Select low-viscosity resins<\/span><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 230px;\"><b>Gate Vestige: <\/b>Visible residue at gate after molding<\/td>\n<td style=\"width: 290px;\">Oversized gate, poor trimming, bad placement<\/td>\n<td style=\"width: 247px;\"><span style=\"font-weight: 400;\">\u2022 Use tunnel or sub-gates<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022<\/span><span style=\"font-weight: 400;\"> Place gates on hidden surfaces<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022 Confirm trimming during DFM<\/span><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 230px;\"><b>Improper Parting Line Placement: <\/b>Parting line crosses critical or visible areas<\/td>\n<td style=\"width: 290px;\">Poor mold alignment, unplanned geometry<\/td>\n<td style=\"width: 247px;\"><span style=\"font-weight: 400;\">\u2022 Place parting lines on natural edges<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022 Avoid logos or snap-fits<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022<\/span><span style=\"font-weight: 400;\"> Validate early in DFM<\/span><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 230px;\"><b>Bubbles and Void: <\/b>Internal or surface air pockets<\/td>\n<td style=\"width: 290px;\">Poor venting, moisture, uneven cooling<\/td>\n<td style=\"width: 247px;\"><span style=\"font-weight: 400;\">\u2022 Maintain even wall thickness<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022 Avoid thick-to-thin transitions<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022 Add ribs or venting channels<\/span><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 230px;\"><b>Flow Lines: <\/b>Wavy streaks or lines on surface<\/td>\n<td style=\"width: 290px;\">Low speed\/temperature, abrupt geometry<\/td>\n<td style=\"width: 247px;\"><span style=\"font-weight: 400;\">\u2022 Use smooth transitions and fillets<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022 Round off corners<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022 Gate into thicker areas<\/span><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 230px;\"><b>Burn Marks: <\/b>Dark or yellow marks near flow ends from trapped gases<\/td>\n<td style=\"width: 290px;\">High speed, poor venting, hot melt<\/td>\n<td style=\"width: 247px;\"><span style=\"font-weight: 400;\">\u2022 Add vent holes or ejector pins<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022 Reduce injection speed<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022 Avoid dead-end flow paths<\/span><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 230px;\"><b>Sink Marks: <\/b>Visible as depressions or surface dimples from uneven cooling<\/td>\n<td style=\"width: 290px;\">Improper mold design<\/p>\n<p>Thick areas, low packing, poor cooling<\/td>\n<td style=\"width: 247px;\"><span style=\"font-weight: 400;\">\u2022 Select appropriate materials like ABS, PC or PMMA<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022 Keep wall thickness uniform<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022 Follow rib-to-wall ratio (\u226460%)<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022 Core thick zones<\/span><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 230px;\"><b>Surface Delamination: <\/b>Peeling of the upper layer of the molded part, which exposes layers beneath.<\/td>\n<td style=\"width: 290px;\">Incompatible materials, contamination<\/td>\n<td style=\"width: 247px;\"><span style=\"font-weight: 400;\">\u2022 Use single-material parts<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022 Confirm overmold compatibility<\/span><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 230px;\"><b>Weld Lines (Knit Lines): <\/b>Visible seams where melt fronts meet<\/td>\n<td style=\"width: 290px;\">Interrupted flow, low temp, poor venting<\/td>\n<td style=\"width: 247px;\"><span style=\"font-weight: 400;\">\u2022 Avoid sharp obstructions<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022 Add ribs near welds<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022<\/span><span style=\"font-weight: 400;\"> Optimize gate placement<\/span><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 230px;\"><b>Warping: <\/b>Distortion from uneven cooling or shrinkage<\/td>\n<td style=\"width: 290px;\">Varying wall thickness, poor material choice<\/td>\n<td style=\"width: 247px;\"><span style=\"font-weight: 400;\">\u2022 Use uniform walls<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022 Avoid large flat surfaces<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022<\/span><span style=\"font-weight: 400;\"> Add ribs for support<\/span><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 230px;\"><b>Jetting: <\/b>Snake-like lines from high-speed flow<\/td>\n<td style=\"width: 290px;\">Small gates, low mold temp, high speed<\/td>\n<td style=\"width: 247px;\"><span style=\"font-weight: 400;\">\u2022 Use fan or overlap gates<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022 Avoid sharp inlet transitions<\/span><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 230px;\"><b>Vacuum Voids: <\/b>Hidden internal voids from trapped air<\/td>\n<td style=\"width: 290px;\">Thick sections, trapped gas, low pressure<\/td>\n<td style=\"width: 247px;\"><span style=\"font-weight: 400;\">\u2022 Core thick areas<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022 Add cutouts<\/span><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 230px;\"><b>Discoloration: <\/b>Unwanted color variation on part surface<\/td>\n<td style=\"width: 290px;\">Resin degradation, contamination<\/td>\n<td style=\"width: 247px;\"><span style=\"font-weight: 400;\">\u2022 Specify color codes<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022<\/span><span style=\"font-weight: 400;\"> Avoid complex color transitions<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u2022 Use heat-stable pigments<\/span><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 230px;\"><b>Splay Marks (Silver Streaking): <\/b>Silvery streaks from moisture or contamination<\/td>\n<td style=\"width: 290px;\">Wet resin, high shear, poor drying<\/td>\n<td style=\"width: 247px;\"><span style=\"font-weight: 400;\">\u2022 Avoid sharp corners at gate<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\t<\/div>\r\n<\/div>\r\n<style>\r\n\t.custom-table-block table{\r\n\t\theight: initial!important;\r\n\t}\r\n\t.search-input-wrapper{\r\n\t\tposition: relative;\r\n\t\tmargin-bottom: 24px;\r\n\t}\r\n\t.search-input-wrapper svg{\r\n\t\tposition: absolute;\r\n\t\ttop:50%;\r\n\t\tleft:12px;\r\n\t\ttransform: 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0;\t\r\n\t}\r\n\t.custom-table-block .table-wrapper{\r\n\t\twidth: 100%;\r\n\t\toverflow-x: auto;\r\n\t}\r\n\t@media(max-width: 768px){\r\n\t\t\/* .custom-table-block tbody td{\r\n\t\t\twhite-space: nowrap;\r\n\t\t} *\/\r\n\t\t.custom-table-block .table-wrapper{\r\n\t\t\tmax-width: calc(100vw - 16px);\r\n\t\t}\r\n\t}\r\n<\/style>\r\n\n\n<h2 class=\"wp-block-heading\" id=\"h-injection-molding-defects-caused-by-mold-design\"><strong>Injection Molding Defects Caused By Mold Design<\/strong><\/h2>\n\n\n<p>Defects rooted in <a href=\"https:\/\/xometry.pro\/en\/articles\/injection-molding-design-tips\/\">mold design<\/a> usually emerge from improper initial tooling or inadequate mold maintenance. These often require extensive, costly, and time-consuming corrections, including significant mold modifications or complete retooling. Addressing mold-related issues through comprehensive Design for Manufacturing (DfM) analyses during the early design stage prevents costly production interruptions.<\/p>\n\n\n\n<p>The primary mold design-related defects include:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Short Shots<\/strong><\/li>\n\n\n\n<li><strong>Flash<\/strong><\/li>\n\n\n\n<li><strong>Bubbles and Voids<\/strong><\/li>\n\n\n\n<li><strong>Gate Vestige<\/strong><\/li>\n\n\n\n<li><strong>Improper Parting Line Placement<\/strong><\/li>\n<\/ul>\n\n\n    <aside class=\"article-content-aside\">\r\n        <a href=\"https:\/\/xometry.pro\/en\/articles\/injection-molding-design-tips\/\" class=\"aside-image sidebar__aside-image\"><img decoding=\"async\" src=\"https:\/\/xometry.pro\/wp-content\/uploads\/2023\/12\/injection-moulding-draft-angles-1440x584-1.webp\" alt=\"\"><\/a><a href=\"https:\/\/xometry.pro\/en\/articles\/injection-molding-design-tips\/\" class=\"aside-link\">Design Tips for Injection Molding<\/a>    <\/aside>\r\n    \n\n    <aside class=\"article-content-aside\">\r\n        <a href=\"https:\/\/xometry.pro\/en\/articles\/injection-moulding-overview\/\" class=\"aside-image sidebar__aside-image\"><img decoding=\"async\" src=\"https:\/\/xometry.pro\/wp-content\/uploads\/2023\/07\/injection-moulding-parts.jpg\" alt=\"Injection molded parts\"><\/a><a href=\"https:\/\/xometry.pro\/en\/articles\/injection-moulding-overview\/\" class=\"aside-link\">Injection Molding Technology Overview<\/a>    <\/aside>\r\n    \n\n<h2 class=\"wp-block-heading\" id=\"h-1-short-shots\"><strong>#1 Short Shots<\/strong><\/h2>\n\n\n<figure class=\"wp-block-image size-large\"><div class=\"wp-block-image__wrap\"><img decoding=\"async\" width=\"1024\" height=\"421\" src=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/short-shots-1-1024x421.png\" alt=\"A comparison of simulation and experimental results highlighting a short shot defect\" class=\"wp-image-119528\" srcset=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/short-shots-1-1024x421.png 1024w, https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/short-shots-1-300x123.png 300w, https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/short-shots-1-768x315.png 768w, https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/short-shots-1.png 1422w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><a class=\"wp-block-image__fancy-box-button\" href=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/short-shots-1.png\" data-fancybox=\"gallery-107796\" data-caption=\"A comparison of simulation and experimental results highlighting a short shot defect. Source: ResearchGate\" aria-label=\"Open full image\"><img src=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/short-shots-1.png\" class=\"wp-block-image__fancy-box-button-thumbnail wp-post-image\" alt=\"\" loading=\"lazy\" decoding=\"async\"><svg class=\"wp-block-image__fancy-box-button-icon\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"18\" height=\"18\" viewBox=\"0 0 18 18\" fill=\"none\" aria-hidden=\"true\">\r\n               <path d=\"M0 2V6H2V2H6V0H2C0.895 0 0 0.895 0 2ZM2 12H0V16C0 17.105 0.895 18 2 18H6V16H2V12ZM16 16H12V18H16C17.105 18 18 17.105 18 16V12H16V16ZM16 0H12V2H16V6H18V2C18 0.895 17.105 0 16 0Z\" fill=\"#092C47\"\/>\r\n             <\/svg><\/a><\/div><figcaption class=\"wp-element-caption\"><em>A comparison of simulation and experimental results highlighting a short shot defect. Source: <a class=\"\" href=\"https:\/\/www.researchgate.net\/figure\/Illustrative-example-of-short-shot-for-target-product_fig5_393913292\">ResearchGate<\/a><\/em><\/figcaption><\/figure>\n\n\n\n<p>Short shots occur when the mold cavity isn\u2019t fully filled, leaving incomplete sections or missing features. This typically affects thin-walled or distant areas and results in scrapped parts.<\/p>\n\n\n    <aside class=\"article-content-aside\">\r\n        <a href=\"https:\/\/xometry.pro\/en\/articles\/injection-molding-materials\/\" class=\"aside-image sidebar__aside-image\"><img decoding=\"async\" src=\"https:\/\/xometry.pro\/wp-content\/uploads\/2023\/12\/Mix-Plastic-pellets.webp\" alt=\"Mix Plastic pellets\"><\/a><a href=\"https:\/\/xometry.pro\/en\/articles\/injection-molding-materials\/\" class=\"aside-link\">Injection Molding Materials: Comprehensive Overview<\/a>    <\/aside>\r\n    \n\n\n<p><strong>Root Causes<\/strong>: Thin or narrow sections, abrupt transitions, long flow paths, poor gate placement, low injection pressure, rapid cooling.<\/p>\n\n\n\n<p><strong>Design Fixes:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Keep wall thickness consistent and \u22650.8 mm unless your resin supports thinner walls.<\/li>\n\n\n\n<li>Use radii and smooth transitions instead of sharp corners to maintain flow.<\/li>\n\n\n\n<li>Avoid long, narrow paths\u2014add flow leaders or adjust gate placement to reduce travel distance.<\/li>\n\n\n\n<li>Simulate flow with MoldFlow or equivalent tools during design validation.<\/li>\n\n\n\n<li>Design ribs and bosses with proper fill ratios; rib thickness should be ~60% of adjacent wall thickness.<\/li>\n<\/ul>\n\n\n    <section class=\"article-author-block\">\r\n        <div class=\"article-content-wrapper\">\r\n            <div class=\"author-block\">\r\n                            <\/div>\r\n                <div class=\"quote-block\" style=\"border-color: #0E6AED;\">\r\n                    <p><strong>Pro Tip<\/strong>: For parts with thin walls or intricate features, selecting low-viscosity resins can help ensure better flow into complex geometries and reduce the risk of short shots.<\/p>\n                <\/div>\r\n        <\/div>\r\n    <\/section>\r\n\n\n<h2 class=\"wp-block-heading\" id=\"h-2-flash\"><strong>#2 Flash<\/strong><\/h2>\n\n\n<p>Flash forms when plastic seeps into mold gaps, creating thin fins along parting lines, ejector pins, or gates.&nbsp;<\/p>\n\n\n\n<p>It\u2019s often cosmetic but may require post-processing or lead to tolerance issues if excessive.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><div class=\"wp-block-image__wrap\"><img decoding=\"async\" width=\"1024\" height=\"660\" src=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/flash-1-1024x660.png\" alt=\"Examples of defect types: short shots, flash, and sink marks\" class=\"wp-image-119541\" srcset=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/flash-1-1024x660.png 1024w, https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/flash-1-300x193.png 300w, https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/flash-1-768x495.png 768w, https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/flash-1.png 1360w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><a class=\"wp-block-image__fancy-box-button\" href=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/flash-1.png\" data-fancybox=\"gallery-107796\" data-caption=\"Examples of defect types: short shots, flash, and sink marks. Source: ResearchGate\" aria-label=\"Open full image\"><img src=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/flash-1.png\" class=\"wp-block-image__fancy-box-button-thumbnail wp-post-image\" alt=\"\" loading=\"lazy\" decoding=\"async\"><svg class=\"wp-block-image__fancy-box-button-icon\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"18\" height=\"18\" viewBox=\"0 0 18 18\" fill=\"none\" aria-hidden=\"true\">\r\n               <path d=\"M0 2V6H2V2H6V0H2C0.895 0 0 0.895 0 2ZM2 12H0V16C0 17.105 0.895 18 2 18H6V16H2V12ZM16 16H12V18H16C17.105 18 18 17.105 18 16V12H16V16ZM16 0H12V2H16V6H18V2C18 0.895 17.105 0 16 0Z\" fill=\"#092C47\"\/>\r\n             <\/svg><\/a><\/div><figcaption class=\"wp-element-caption\"><em>Examples of defect types: short shots, flash, and sink marks. Source: <a href=\"https:\/\/www.researchgate.net\/figure\/Examples-of-defect-types-short-shot-flash-and-sink-marks_fig2_372735033\">ResearchGate<\/a><\/em><\/figcaption><\/figure>\n\n\n\n<p><strong>Root Causes<\/strong>: Excessive injection pressure, poor mold fit, worn tooling, sharp transitions at shut-offs, overly complex parting geometry, tolerance stacking.<\/p>\n\n\n\n<p><strong>Design Fixes:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Place parting lines away from sharp corners and cosmetic zones.<\/li>\n\n\n\n<li>Apply consistent draft angles to avoid tight or mismatched shut-offs.<\/li>\n\n\n\n<li>Keep wall transitions near parting lines gradual to avoid local pressure buildup.<\/li>\n\n\n\n<li>Validate parting line placement early with a DFM review.<\/li>\n\n\n\n<li>Confirm that injection pressure and clamp force won\u2019t exceed mold tolerances\u2014simulate if needed.<\/li>\n<\/ul>\n\n\n<h2 class=\"wp-block-heading\" id=\"h-3-improper-parting-line-placement\"><strong>#3 Improper Parting Line Placement<\/strong><\/h2>\n\n\n<p>A parting line is where two mold halves (core and cavity) meet. Incorrect parting line placement can create visible seams or flash, especially if it crosses functional or cosmetic features. It can lead to poor fit, extra finishing, or aesthetic defects.<\/p>\n\n\n\n<p><strong>Root Causes<\/strong>: Incomplete DFM analysis, mismatched mold alignment, overlooked geometry transitions.<\/p>\n\n\n\n<p><strong>Design Fixes:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Plan parting lines early\u2014before locking aesthetic or functional geometry.<\/li>\n\n\n\n<li>Avoid placing parting lines over logos, snap-fits, sealing surfaces, or alignment features.<\/li>\n\n\n\n<li>Align parting lines with sharp edges, ribs, or recesses to naturally hide them.<\/li>\n\n\n\n<li>Use symmetrical parting lines where possible to balance ejection forces.<\/li>\n\n\n\n<li>Validate placement in DFM review and confirm mold opening direction.<\/li>\n<\/ul>\n\n\n    <section class=\"article-author-block\">\r\n        <div class=\"article-content-wrapper\">\r\n            <div class=\"author-block\">\r\n                            <\/div>\r\n                <div class=\"quote-block\" style=\"border-color: #0E6AED;\">\r\n                    <p><b>Pro Tip:<\/b><span style=\"font-weight: 400;\"> If the design requires multiple sliders or inserts, simplify wherever possible\u2014parting line complexity drives up mold costs.<\/span><\/p>\n                <\/div>\r\n        <\/div>\r\n    <\/section>\r\n\n\n<h2 class=\"wp-block-heading\" id=\"h-4-bubbles-and-voids\"><strong>#4 Bubbles and Voids<\/strong><\/h2>\n\n\n<p>These appear as visible bubbles or hidden voids and reduce strength, cause dimensional errors, or leave surface blemishes. They&#8217;re often due to trapped air or uneven cooling. It can weaken structural integrity, compromise dimensional accuracy, and affect final appearance.<\/p>\n\n\n\n<p><strong>Root Causes<\/strong>: Moisture in resin, poor venting, sudden thickness changes, inconsistent wall design, high-shrinkage materials.<\/p>\n\n\n\n<p><strong>Design Fixes:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Maintain consistent wall thickness\u2014limit variation to \u00b110%.<\/li>\n\n\n\n<li>Avoid abrupt thick-to-thin transitions; taper gradually to ensure uniform flow and cooling.<\/li>\n\n\n\n<li>Add ribs to replace solid masses and promote even packing.<\/li>\n\n\n\n<li>Use venting features in deep or enclosed areas.<\/li>\n\n\n\n<li>Choose materials with low shrinkage for thick geometries (e.g., use ABS over HDPE).<\/li>\n\n\n\n<li>Simulate filling and cooling behavior to detect and eliminate air-trap zones.<\/li>\n<\/ul>\n\n\n    <section class=\"article-author-block\">\r\n        <div class=\"article-content-wrapper\">\r\n            <div class=\"author-block\">\r\n                            <\/div>\r\n                <div class=\"quote-block\" style=\"border-color: #0E6AED;\">\r\n                    <p><strong>Pro Tip:<\/strong> Voids often form in areas thicker than 4 mm\u2014core them out to prevent shrinkage and internal defects.<\/p>\n                <\/div>\r\n        <\/div>\r\n    <\/section>\r\n\n\n<h2 class=\"wp-block-heading\" id=\"h-5-gate-vestige\"><strong>#5<\/strong> <strong>Gate Vestige<\/strong><\/h2>\n\n\n<p>Gate vestige is a visible mark or protrusion where the plastic was injected. While minor, it can affect aesthetics or function in tight-fitting assemblies.<\/p>\n\n\n\n<p><strong>Root Causes<\/strong>: Oversized gates, poor gate placement, manual trimming, exposed gate on cosmetic surfaces.<\/p>\n\n\n\n<p><strong>Design Fixes:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Place gates on non-cosmetic or hidden surfaces\u2014inner walls, underside flanges, or recessed areas.<\/li>\n\n\n\n<li>Use tunnel or submarine gates for automatic vestige removal.<\/li>\n\n\n\n<li>Plan trimming method and location during the DFM stage.<\/li>\n\n\n\n<li>Integrate flat or ribbed features near gates to visually mask vestige.<\/li>\n\n\n\n<li>Specify surface finish or gloss level around the gate to reduce visibility.<\/li>\n<\/ul>\n\n\n    <section class=\"article-author-block\">\r\n        <div class=\"article-content-wrapper\">\r\n            <div class=\"author-block\">\r\n                            <\/div>\r\n                <div class=\"quote-block\" style=\"border-color: #0E6AED;\">\r\n                    <p><strong>Pro Tip:<\/strong> Edge gates are easy to implement, but switch to tunnel gates for cleaner break-off and minimal cosmetic impact.<\/p>\n                <\/div>\r\n        <\/div>\r\n    <\/section>\r\n\n\n<h2 class=\"wp-block-heading\" id=\"injection-molding-defects-caused-by-process\">Injection Molding Defects Caused By Process<\/h2>\n\n\n<p>Process-related defects commonly result from improper control or incorrect settings within the molding cycle. Variables such as injection pressure, injection speed, mold\/resin temperatures, cooling rates, and material conditions significantly influence these defects. Unlike mold design issues, process-related problems often can be mitigated through adjustments in machine settings\u2014without extensive mold modifications.<\/p>\n\n\n\n<p>Typical process-related defects include:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Flow Lines<\/strong><\/li>\n\n\n\n<li><strong>Burn Marks<\/strong><\/li>\n\n\n\n<li><strong>Warping<\/strong><\/li>\n\n\n\n<li><strong>Vacuum Voids<\/strong><\/li>\n\n\n\n<li><strong>Sink Marks<\/strong><\/li>\n\n\n\n<li><strong>Weld Lines (Knit Lines)<\/strong><\/li>\n\n\n\n<li><strong>Jetting<\/strong><\/li>\n\n\n\n<li><strong>Discoloration<\/strong><\/li>\n\n\n\n<li><strong>Surface Delamination<\/strong><\/li>\n\n\n\n<li><strong>Splay Marks (Silver Streaking)<\/strong><\/li>\n<\/ul>\n\n\n\n<p>By clearly differentiating mold design-related defects from process-related defects, engineers can effectively pinpoint root causes, streamline troubleshooting, and consistently achieve optimal <a href=\"https:\/\/xometry.pro\/en\/articles\/injection-moulding-overview\/\">injection molding<\/a> quality.<\/p>\n\n\n<h2 class=\"wp-block-heading\" id=\"h-6-flow-lines\"><strong>#6<\/strong> <strong>Flow Lines<\/strong><\/h2>\n\n\n<p>Flow lines appear as streaks or wavy patterns on the surface of molded parts. These visual defects often show up near gates, corners, or holes where the molten plastic changes direction or slows down. While processing conditions are often the primary cause, design flaws can make flow lines worse or more likely to occur.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><div class=\"wp-block-image__wrap\"><img decoding=\"async\" width=\"628\" height=\"480\" src=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/flow-lines-1.png\" alt=\"example of flow lines in injection molding \" class=\"wp-image-119553\" srcset=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/flow-lines-1.png 628w, https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/flow-lines-1-300x229.png 300w\" sizes=\"(max-width: 628px) 100vw, 628px\" \/><a class=\"wp-block-image__fancy-box-button\" href=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/flow-lines-1.png\" data-fancybox=\"gallery-107796\" data-caption=\"Example of flow lines, Source\" aria-label=\"Open full image\"><img src=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/flow-lines-1.png\" class=\"wp-block-image__fancy-box-button-thumbnail wp-post-image\" alt=\"\" loading=\"lazy\" decoding=\"async\"><svg class=\"wp-block-image__fancy-box-button-icon\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"18\" height=\"18\" viewBox=\"0 0 18 18\" fill=\"none\" aria-hidden=\"true\">\r\n               <path d=\"M0 2V6H2V2H6V0H2C0.895 0 0 0.895 0 2ZM2 12H0V16C0 17.105 0.895 18 2 18H6V16H2V12ZM16 16H12V18H16C17.105 18 18 17.105 18 16V12H16V16ZM16 0H12V2H16V6H18V2C18 0.895 17.105 0 16 0Z\" fill=\"#092C47\"\/>\r\n             <\/svg><\/a><\/div><figcaption class=\"wp-element-caption\"><em>Example of flow lines, <a href=\"https:\/\/www.intouch-quality.com\/blog\/injection-molding-defects-and-how-to-prevent\">Source<\/a><\/em><\/figcaption><\/figure>\n\n\n\n<p><strong>Design Fixes:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Keep wall thickness uniform to support stable flow and reduce velocity fluctuations.<\/li>\n\n\n\n<li>Use gradual transitions between thick and thin sections to avoid directional turbulence.<\/li>\n\n\n\n<li>Avoid abrupt geometry changes; round off corners with fillets at least equal to wall thickness.<\/li>\n\n\n\n<li>Position gates strategically in thicker sections to maintain temperature and flow consistency.<\/li>\n\n\n\n<li>Avoid thin sections far from the gate\u2014they cool faster and are prone to visible flow fronts.<\/li>\n<\/ul>\n\n\n\n<p><strong>Things To Keep in Mind During Manufacturing:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Improper venting may trap air and disrupt smooth filling.<\/li>\n\n\n\n<li>Inadequate mold temperature or low injection speed causes premature cooling.<\/li>\n\n\n\n<li>Poor gate placement or size leads to inconsistent material flow.<\/li>\n<\/ul>\n\n\n    <section class=\"article-author-block\">\r\n        <div class=\"article-content-wrapper\">\r\n            <div class=\"author-block\">\r\n                            <\/div>\r\n                <div class=\"quote-block\" style=\"border-color: #0E6AED;\">\r\n                    <p><strong>Pro\u00a0Tip<\/strong>: In high-appearance parts, slightly adjusting the surface texture or applying matte finishes can help visually mask minor flow lines without compromising structural integrity.<\/p>\n                <\/div>\r\n        <\/div>\r\n    <\/section>\r\n\n\n<h2 class=\"wp-block-heading\" id=\"h-7-burn-marks\"><strong>#7<\/strong> <strong>Burn Marks<\/strong><\/h2>\n\n\n<p>Burn marks are process-related injection molding defects that appear as yellowish, brown, rusty, or black discoloration on the surface of molded parts\u2014often near the end of the flow path or around air traps. While primarily considered aesthetic flaws, in more severe cases, they may indicate localized overheating that leads to polymer degradation and even structural weakness in the affected areas.<\/p>\n\n\n\n<p><strong>Design Fixes:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Trapped air due to poor venting<\/strong>: Improve venting channels or add air escape vents to allow gases to exit the mold cavity safely before resin arrival.<br><\/li>\n\n\n\n<li><strong>Excessive injection speed or pressure<\/strong>: Reduce injection speed and pressure slightly to prevent rapid compression of air pockets that leads to overheating and ignition.<br><\/li>\n\n\n\n<li><strong>Excessive melt or mold temperature<\/strong>: Lower the melt temperature or optimize cycle time to avoid <strong>polymer<\/strong> degradation near air traps.<br><\/li>\n\n\n\n<li><strong>Contaminants or degraded material in the mold<\/strong>: Clean mold surfaces and avoid using degraded resin to prevent burnt residues that mimic burn marks.<br><\/li>\n\n\n\n<li><strong>Improper runner or gate design<\/strong>: Redesign runners and gates to ensure smooth resin flow and reduce the chance of air entrapment in dead zones.<br><\/li>\n<\/ul>\n\n\n\n<p><strong>Things To Keep in Mind During Manufacturing:<\/strong><\/p>\n\n\n\n<p>If burn marks consistently appear in the same area of a part, consider relocating the gate or modifying the flow path to avoid trapping air in that region\u2014this simple design adjustment can significantly reduce thermal buildup and eliminate burn-related discoloration.<\/p>\n\n\n<h2 class=\"wp-block-heading\" id=\"h-8-sink-marks\"><strong>#8<\/strong> <strong>Sink Marks<\/strong><\/h2>\n\n\n<p>Sink marks are small depressions or dimples that form on the surface of a part, typically in thicker areas or near ribs and bosses. These defects occur when the outer surface of the part cools and solidifies faster than the interior, which continues to shrink and pulls the surface inward.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><div class=\"wp-block-image__wrap\"><img decoding=\"async\" width=\"1024\" height=\"404\" src=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/sink-marks-1024x404.png\" alt=\"Thickness distribution at the boss connection part and potential sink marks. \" class=\"wp-image-119565\" srcset=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/sink-marks-1024x404.png 1024w, https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/sink-marks-300x118.png 300w, https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/sink-marks-768x303.png 768w, https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/sink-marks.png 1038w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><a class=\"wp-block-image__fancy-box-button\" href=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/sink-marks.png\" data-fancybox=\"gallery-107796\" data-caption=\"Thickness distribution at the boss connection part and potential sink marks. Source: ResearchGate\" aria-label=\"Open full image\"><img src=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/sink-marks.png\" class=\"wp-block-image__fancy-box-button-thumbnail wp-post-image\" alt=\"\" loading=\"lazy\" decoding=\"async\"><svg class=\"wp-block-image__fancy-box-button-icon\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"18\" height=\"18\" viewBox=\"0 0 18 18\" fill=\"none\" aria-hidden=\"true\">\r\n               <path d=\"M0 2V6H2V2H6V0H2C0.895 0 0 0.895 0 2ZM2 12H0V16C0 17.105 0.895 18 2 18H6V16H2V12ZM16 16H12V18H16C17.105 18 18 17.105 18 16V12H16V16ZM16 0H12V2H16V6H18V2C18 0.895 17.105 0 16 0Z\" fill=\"#092C47\"\/>\r\n             <\/svg><\/a><\/div><figcaption class=\"wp-element-caption\"><em>Thickness distribution at the boss connection part and potential sink marks. Source: <a href=\"https:\/\/www.researchgate.net\/figure\/Thickness-distribution-at-the-boss-connection-part-and-potential-sink-marks_fig1_323311019\">ResearchGate<\/a><\/em><\/figcaption><\/figure>\n\n\n\n<p><strong>Design Fixes:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Minimize wall thickness in thick areas to promote even cooling.<br><\/li>\n\n\n\n<li>Apply proper design rules for ribs and bosses: rib thickness should be no more than 50\u201370% of the adjoining wall.<br><\/li>\n\n\n\n<li>Avoid stacking thick features (e.g., bosses on top of ribs) unless absolutely necessary.<br><\/li>\n\n\n\n<li>Use coring techniques to remove excess material in thick sections without compromising strength.<br><\/li>\n\n\n\n<li>Collaborate with your manufacturer to optimize gate placement and ensure sufficient packing pressure in key regions.<\/li>\n\n\n\n<li>Choose materials like ABS, polycarbonate (PC), PMMA (acrylic)<br><\/li>\n<\/ul>\n\n\n\n<p><strong>Things To Keep in Mind During Manufacturing:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Inadequate cooling time or uneven mold temperature can lead to internal shrinkage.<br><\/li>\n\n\n\n<li>Excessive material thickness in local areas traps heat, causing delayed solidification.<br><\/li>\n\n\n\n<li>Low injection pressure or packing pressure reduces the ability to compensate for shrinkage.<\/li>\n\n\n\n<li>Semi-crystalline plastics (like PA, POM, PP) tend to shrink more and are more prone to sink marks.<\/li>\n<\/ul>\n\n\n<h2 class=\"wp-block-heading\" id=\"h-9-surface-delamination\"><strong>#9<\/strong> <strong>Surface Delamination<\/strong><\/h2>\n\n\n<p>Surface delamination appears as peeling or flaky surfaces caused by contamination or incompatible materials that prevent proper adhesion between plastic layers.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><div class=\"wp-block-image__wrap\"><img decoding=\"async\" width=\"634\" height=\"530\" src=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/delamination.png\" alt=\"Delamination of an injection molded part\" class=\"wp-image-119577\" srcset=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/delamination.png 634w, https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/delamination-300x251.png 300w\" sizes=\"(max-width: 634px) 100vw, 634px\" \/><a class=\"wp-block-image__fancy-box-button\" href=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/delamination.png\" data-fancybox=\"gallery-107796\" data-caption=\"Delamination of an injection molded part, Source\" aria-label=\"Open full image\"><img src=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/delamination.png\" class=\"wp-block-image__fancy-box-button-thumbnail wp-post-image\" alt=\"\" loading=\"lazy\" decoding=\"async\"><svg class=\"wp-block-image__fancy-box-button-icon\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"18\" height=\"18\" viewBox=\"0 0 18 18\" fill=\"none\" aria-hidden=\"true\">\r\n               <path d=\"M0 2V6H2V2H6V0H2C0.895 0 0 0.895 0 2ZM2 12H0V16C0 17.105 0.895 18 2 18H6V16H2V12ZM16 16H12V18H16C17.105 18 18 17.105 18 16V12H16V16ZM16 0H12V2H16V6H18V2C18 0.895 17.105 0 16 0Z\" fill=\"#092C47\"\/>\r\n             <\/svg><\/a><\/div><figcaption class=\"wp-element-caption\"><em>Delamination of an injection molded part, <a href=\"https:\/\/www.intouch-quality.com\/blog\/injection-molding-defects-and-how-to-prevent\">Source<\/a><\/em><\/figcaption><\/figure>\n\n\n\n<p><strong>Design Fixes:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Avoid combining incompatible resins or overmolding dissimilar materials.<br><\/li>\n\n\n\n<li>Use single-material designs unless overmolding is proven compatible.<br><\/li>\n\n\n\n<li>Minimize the use of release agents that can interfere with bonding.<br><\/li>\n\n\n\n<li>Confirm material compatibility with your supplier before prototyping.<br><\/li>\n<\/ul>\n\n\n\n<p><strong>Things To Keep in Mind During Manufacturing:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Dry hygroscopic materials thoroughly.<br><\/li>\n\n\n\n<li>Purge machines between material changes.<br><\/li>\n\n\n\n<li>Keep hoppers, nozzles, and barrels clean to prevent contamination.<\/li>\n<\/ul>\n\n\n<h2 class=\"wp-block-heading\" id=\"h-10-weld-lines-knit-lines\"><strong>#10<\/strong> <strong>Weld Lines (Knit Lines)<\/strong><\/h2>\n\n\n<p>Weld lines (or knit lines) appear where two melt fronts meet but don\u2019t fully bond, leaving behind visible seams or structural weaknesses.<\/p>\n\n\n\n<p>This defect is especially common in parts with complex geometries, multiple gates, or features that interrupt the flow of plastic (e.g., holes, bosses, or ribs).<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><div class=\"wp-block-image__wrap\"><img decoding=\"async\" width=\"1024\" height=\"589\" src=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/weld-line-1024x589.png\" alt=\"An example of weld line from an injection molded part\" class=\"wp-image-119601\" srcset=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/weld-line-1024x589.png 1024w, https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/weld-line-300x173.png 300w, https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/weld-line-768x442.png 768w, https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/weld-line.png 1704w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><a class=\"wp-block-image__fancy-box-button\" href=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/weld-line.png\" data-fancybox=\"gallery-107796\" data-caption=\"An example of weld line from an injection molded part, Source: IPQCCO\" aria-label=\"Open full image\"><img src=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/weld-line.png\" class=\"wp-block-image__fancy-box-button-thumbnail wp-post-image\" alt=\"\" loading=\"lazy\" decoding=\"async\"><svg class=\"wp-block-image__fancy-box-button-icon\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"18\" height=\"18\" viewBox=\"0 0 18 18\" fill=\"none\" aria-hidden=\"true\">\r\n               <path d=\"M0 2V6H2V2H6V0H2C0.895 0 0 0.895 0 2ZM2 12H0V16C0 17.105 0.895 18 2 18H6V16H2V12ZM16 16H12V18H16C17.105 18 18 17.105 18 16V12H16V16ZM16 0H12V2H16V6H18V2C18 0.895 17.105 0 16 0Z\" fill=\"#092C47\"\/>\r\n             <\/svg><\/a><\/div><figcaption class=\"wp-element-caption\"><em>An example of weld line from an injection molded part, Source: <a href=\"https:\/\/www.ipqcco.com\/blog\/injection-molding-weld-line-defect-causes-inspection-precaution\">IPQCCO<\/a><\/em><\/figcaption><\/figure>\n\n\n\n<p><strong>Design Fixes:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Minimize the number of flow fronts by simplifying geometry and reducing obstructions.<br><\/li>\n\n\n\n<li>Place gates to direct flow so that convergence occurs away from high-stress zones.<br><\/li>\n\n\n\n<li>Use ribs or bosses near weld lines to improve mechanical strength.<br><\/li>\n\n\n\n<li>Avoid holes, inserts, or abrupt geometry changes that split flow unnecessarily.<br><\/li>\n<\/ul>\n\n\n\n<p><strong>Things To Keep in Mind During Manufacturing:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Increase mold and melt temperatures to improve flow front bonding.<br><\/li>\n\n\n\n<li>Adjust injection speed to delay solidification at convergence zones.<br><\/li>\n<\/ul>\n\n\n\n<p>Improve venting around potential weld line locations.<\/p>\n\n\n    <section class=\"article-author-block\">\r\n        <div class=\"article-content-wrapper\">\r\n            <div class=\"author-block\">\r\n                            <\/div>\r\n                <div class=\"quote-block\" style=\"border-color: #0E6AED;\">\r\n                    <p><strong>Pro Tip<\/strong>: In load-bearing or high-stress components, reposition gates or redesign the part to relocate weld lines away from mechanically critical zones.<\/p>\n                <\/div>\r\n        <\/div>\r\n    <\/section>\r\n\n\n<h2 class=\"wp-block-heading\" id=\"h-11-warping\"><strong>#11 Warping<\/strong><\/h2>\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<p>Warping refers to visible bending, twisting, or bowing of the molded part. It happens when different sections of the part cool and shrink unevenly, resulting in internal stresses that distort its shape.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><div class=\"wp-block-image__wrap\"><img decoding=\"async\" width=\"1024\" height=\"472\" src=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/warping-Shrinkage-variation-of-an-injection-molded-part-as-simulated-within-Autodesk-Moldflow.-autodesk-blog-1024x472.png\" alt=\"Shrinkage variation of an injection molded part\" class=\"wp-image-119613\" srcset=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/warping-Shrinkage-variation-of-an-injection-molded-part-as-simulated-within-Autodesk-Moldflow.-autodesk-blog-1024x472.png 1024w, https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/warping-Shrinkage-variation-of-an-injection-molded-part-as-simulated-within-Autodesk-Moldflow.-autodesk-blog-300x138.png 300w, https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/warping-Shrinkage-variation-of-an-injection-molded-part-as-simulated-within-Autodesk-Moldflow.-autodesk-blog-768x354.png 768w, https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/warping-Shrinkage-variation-of-an-injection-molded-part-as-simulated-within-Autodesk-Moldflow.-autodesk-blog.png 1322w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><a class=\"wp-block-image__fancy-box-button\" href=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/warping-Shrinkage-variation-of-an-injection-molded-part-as-simulated-within-Autodesk-Moldflow.-autodesk-blog.png\" data-fancybox=\"gallery-107796\" data-caption=\"Shrinkage variation of an injection molded part, Source: Autodesk Blog\" aria-label=\"Open full image\"><img src=\"https:\/\/xometry.pro\/wp-content\/uploads\/2025\/04\/warping-Shrinkage-variation-of-an-injection-molded-part-as-simulated-within-Autodesk-Moldflow.-autodesk-blog.png\" class=\"wp-block-image__fancy-box-button-thumbnail wp-post-image\" alt=\"\" loading=\"lazy\" decoding=\"async\"><svg class=\"wp-block-image__fancy-box-button-icon\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"18\" height=\"18\" viewBox=\"0 0 18 18\" fill=\"none\" aria-hidden=\"true\">\r\n               <path d=\"M0 2V6H2V2H6V0H2C0.895 0 0 0.895 0 2ZM2 12H0V16C0 17.105 0.895 18 2 18H6V16H2V12ZM16 16H12V18H16C17.105 18 18 17.105 18 16V12H16V16ZM16 0H12V2H16V6H18V2C18 0.895 17.105 0 16 0Z\" fill=\"#092C47\"\/>\r\n             <\/svg><\/a><\/div><figcaption class=\"wp-element-caption\">Shrinkage variation of an injection molded part, Source: <a href=\"https:\/\/blogs.autodesk.com\/simulation\/2020\/06\/03\/injection-molding-the-causes-of-warpage\/\">Autodesk Blog<\/a><\/figcaption><\/figure>\n\n\n\n<p><strong>Design Fixes:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Use uniform wall thickness throughout your design to ensure consistent cooling.<br><\/li>\n\n\n\n<li>Avoid large, flat surfaces without ribs or curvature\u2014they&#8217;re more prone to deformation.<br><\/li>\n\n\n\n<li>Add structural supports such as ribs to reduce warpage while keeping the part lightweight.<br><\/li>\n\n\n\n<li>Choose low-shrinkage materials like filled resins for better dimensional stability.<br><\/li>\n\n\n\n<li>Reduce sharp transitions between thick and thin walls to avoid differential cooling rates.<br><\/li>\n<\/ul>\n\n\n\n<p><strong>Things To Keep in Mind During Manufacturing:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Balance cooling channels across the mold.<br><\/li>\n\n\n\n<li>Use temperature-controlled mold circuits to reduce cooling rate differences.<br><\/li>\n\n\n\n<li>Lower mold temperatures and increase packing pressure where applicable.<br><\/li>\n<\/ul>\n<\/div>\n<\/div>\n\n\n<h2 class=\"wp-block-heading\" id=\"h-12-jetting\"><strong>#12<\/strong> <strong>Jetting<\/strong><\/h2>\n\n\n<p>Jetting creates snake-like surface defects caused by high-speed melt streams entering the cavity and cooling before they fuse with surrounding material.<\/p>\n\n\n\n<p>This defect not only affects the aesthetics of the molded part but can also create localized areas of weakness due to incomplete bonding between the layers of material.<\/p>\n\n\n\n<p><strong>Design Fixes:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Use overlap or fan gates to reduce flow velocity at entry.<br><\/li>\n\n\n\n<li>Choose smoother transitions between wall sections and avoid sharp corners.<br><\/li>\n\n\n\n<li>Use gradual fillets at inlets and reduce wall thickness jumps.<br><\/li>\n\n\n\n<li>Lower initial fill rates during the prototype phase to assess flow behavior.<br><\/li>\n<\/ul>\n\n\n\n<p><strong>Things To Keep in Mind During Manufacturing:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Decrease injection speed at the start of the cycle.<br><\/li>\n\n\n\n<li>Increase mold temperature to allow better fusion.<br><\/li>\n\n\n\n<li>Optimize gate dimensions to reduce direct impingement.<\/li>\n<\/ul>\n\n\n<h2 class=\"wp-block-heading\" id=\"h-13-vacuum-voids\"><strong>#13<\/strong> <strong>Vacuum Voids<\/strong><\/h2>\n\n\n<p>Vacuum voids are internal air pockets within the part. While not always visible, they can weaken structural integrity.<\/p>\n\n\n\n<p><strong>Design Fixes:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Avoid thick, solid cross-sections. Use hollowed-out shapes where possible.<br><\/li>\n\n\n\n<li>Add coring features or internal channels to reduce bulk material.<br><\/li>\n\n\n\n<li>Plan for venting where air entrapment is likely.<br><\/li>\n\n\n\n<li>If internal voids are critical, request micro-CT or sample-cut inspection.<br><\/li>\n<\/ul>\n\n\n\n<p><strong>Things To Keep in Mind During Manufacturing:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Improve mold venting and use gas-assist injection if needed.<br><\/li>\n\n\n\n<li>Adjust packing pressure and holding time to eliminate trapped air.<br><\/li>\n\n\n\n<li>Use slower injection speeds to allow air escape.<\/li>\n<\/ul>\n\n\n<h2 class=\"wp-block-heading\" id=\"h-14-discoloration\"><strong>#14<\/strong> <strong>Discoloration<\/strong><\/h2>\n\n\n<p>Discoloration is any unwanted color variation on the molded part, often due to resin degradation, contamination, or inconsistent coloring agents.<\/p>\n\n\n\n<p><strong>Design Fixes:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Use stable, well-tested colorants with high thermal resistance.<br><\/li>\n\n\n\n<li>Avoid designing parts that require frequent color transitions.<br><\/li>\n\n\n\n<li>Clearly specify RAL or Pantone codes and masterbatch ratios in documentation.<br><\/li>\n\n\n\n<li>Limit complex multi-material zones where color control is critical.<br><\/li>\n<\/ul>\n\n\n\n<p><strong>Things To Keep in Mind During Manufacturing:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Maintain proper barrel temperature profiles.<br><\/li>\n\n\n\n<li>Clean the screw and barrel between different color batches.<br><\/li>\n\n\n\n<li>Use proper dosing equipment for colorants or masterbatch.<\/li>\n<\/ul>\n\n\n<h2 class=\"wp-block-heading\" id=\"h-15-splay-marks-silver-streaking\"><strong>#15 Splay Marks (Silver Streaking)<\/strong><\/h2>\n\n\n<p>Splay marks are silvery streaks on the surface, typically near gates. They result from moisture, contamination, or excessive shear in the resin.<\/p>\n\n\n\n<p><strong>Design Recommendations:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Avoid abrupt transitions or sharp corners near gates.<br><\/li>\n\n\n\n<li>Add venting space around the gate area to allow moisture release.<br><\/li>\n\n\n\n<li>Choose materials with low moisture absorption or include drying protocols in sourcing.<br><\/li>\n<\/ul>\n\n\n\n<p><strong>Things To Keep in Mind During Manufacturing:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Pre-dry hygroscopic materials like PA, PC, and ABS.<br><\/li>\n\n\n\n<li>Reduce injection speed to minimize shear.<br><\/li>\n\n\n\n<li>Clean hopper and dryer filters regularly.<\/li>\n<\/ul>\n\n\n<h2 class=\"wp-block-heading\" id=\"h-16-contamination\"><strong>#<\/strong>16: <strong>Contamination<\/strong><\/h2>\n\n\n<p>Contamination occurs when foreign substances embedded in the molten material during processing. These defects often appear as dark spots, streaks, or unexpected inclusions on the part surface\u2014and in some cases, they affect the part&#8217;s strength or dimensional stability.&nbsp;<\/p>\n\n\n\n<p>Contaminants typically enter the process through poor material handling, improper <a href=\"https:\/\/xometry.pro\/en\/articles\/injection-molding-molds\/\">tooling and equipment<\/a> maintenance, or wear-related debris.&nbsp;<\/p>\n\n\n\n<p><strong>Design Fixes:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Avoid unnecessary material changes and color switches unless required.<br><\/li>\n\n\n\n<li>Limit deep ribs or narrow features where contaminants can become trapped or accumulate.<br><\/li>\n\n\n\n<li>Add draft angles to internal features for better flow and material flushing.<br><\/li>\n\n\n\n<li>Specify consistent resins across part families to reduce cleaning cycles and purge times.<br><\/li>\n\n\n\n<li>Use internal quality checks (e.g. material batch traceability) in designs requiring tight tolerances or visual precision.<br><\/li>\n<\/ul>\n\n\n    <aside class=\"article-content-aside\">\r\n        <a href=\"https:\/\/xometry.pro\/en\/articles\/injection-molding-molds\/\" class=\"aside-image sidebar__aside-image\"><img decoding=\"async\" src=\"https:\/\/xometry.pro\/wp-content\/uploads\/2024\/07\/complex-injection-mold-scaled.jpeg\" alt=\"Top view of a complex injection mold used in plastic manufacturing\"><\/a><a href=\"https:\/\/xometry.pro\/en\/articles\/injection-molding-molds\/\" class=\"aside-link\">Injection Molding Molds: Types, Lifespan and Design Tips<\/a>    <\/aside>\r\n    \n\n\n<p><strong>Things To Keep in Mind During Manufacturing:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Schedule regular machine maintenance to detect and fix tooling wear.<br><\/li>\n\n\n\n<li>Maintain a clean, oil-free production environment to reduce airborne contamination risk.<\/li>\n\n\n\n<li>Clean hoppers, barrels, and screw assemblies regularly to prevent buildup.<br><\/li>\n\n\n\n<li>Store resins in sealed, dry containers to prevent airborne dust and moisture exposure.<br><\/li>\n\n\n\n<li>Purge thoroughly between different resins or colorants to prevent cross-contamination.<br><\/li>\n<\/ul>\n\n\n<h2 class=\"wp-block-heading\" id=\"h-injection-molding-defects-by-severity-and-cost-impact\"><strong>Injection Molding Defects by Severity and Cost Impact<\/strong><\/h2>\n\n<div class=\"custom-table-block \" id=\"table-id-14\" >\r\n\t<div class=\"search-input-wrapper\">\r\n\t\t<svg width=\"16\" height=\"16\" viewBox=\"0 0 16 16\" fill=\"none\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\">\r\n\t\t\t<path d=\"M15.7812 13.833L12.6659 10.7177C12.5252 10.5771 12.3346 10.499 12.1347 10.499H11.6253C12.4877 9.39596 13.0002 8.00859 13.0002 6.49937C13.0002 2.90909 10.0911 0 6.50083 0C2.91056 0 0.00146484 2.90909 0.00146484 6.49937C0.00146484 10.0896 2.91056 12.9987 6.50083 12.9987C8.01006 12.9987 9.39742 12.4863 10.5004 11.6239V12.1332C10.5004 12.3332 10.5786 12.5238 10.7192 12.6644L13.8345 15.7797C14.1282 16.0734 14.6032 16.0734 14.8938 15.7797L15.778 14.8954C16.0718 14.6017 16.0718 14.1267 15.7812 13.833ZM6.50083 10.499C4.29167 10.499 2.50122 8.71165 2.50122 6.49937C2.50122 4.29021 4.28855 2.49976 6.50083 2.49976C8.70999 2.49976 10.5004 4.28708 10.5004 6.49937C10.5004 8.70852 8.71311 10.499 6.50083 10.499Z\" fill=\"#476175\"\/>\r\n\t\t<\/svg>\r\n\t\t<input type=\"search\" class=\"table-search-input\" id=\"table-search-14\" placeholder=\"Table search\">\r\n\t<\/div>\t\r\n\t<div class=\"table-wrapper\">\r\n\t\t<table style=\"border-collapse: collapse; width: 100%; height: 504px;\">\n<tbody>\n<tr style=\"height: 48px;\">\n<td style=\"width: 26.5464%; height: 48px;\"><b>Defect Type<\/b><\/td>\n<td style=\"width: 17.3969%; height: 48px;\"><b>Structural Impact<\/b><\/td>\n<td style=\"width: 16.2371%; height: 48px;\"><b>Cosmetic Impact<\/b><\/td>\n<td style=\"width: 16.2371%; height: 48px;\"><b>Production Risk<\/b><\/td>\n<td style=\"width: 23.5825%; height: 48px;\"><b>Typical Cost Increase<\/b><\/td>\n<\/tr>\n<tr style=\"height: 24px;\">\n<td style=\"width: 26.5464%; height: 24px;\"><strong>Short Shots<\/strong><\/td>\n<td style=\"width: 17.3969%; height: 24px;\"><span style=\"font-weight: 400;\">High<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">Medium<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">High<\/span><\/td>\n<td style=\"width: 23.5825%; height: 24px;\"><span style=\"font-weight: 400;\">\u2191\u2191 (part rejected)<\/span><\/td>\n<\/tr>\n<tr style=\"height: 24px;\">\n<td style=\"width: 26.5464%; height: 24px;\"><strong>Flash<\/strong><\/td>\n<td style=\"width: 17.3969%; height: 24px;\"><span style=\"font-weight: 400;\">Low<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">Medium<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">Low<\/span><\/td>\n<td style=\"width: 23.5825%; height: 24px;\"><span style=\"font-weight: 400;\">\u2192 (trimming required)<\/span><\/td>\n<\/tr>\n<tr style=\"height: 48px;\">\n<td style=\"width: 26.5464%; height: 48px;\"><strong>Improper Parting Line Placement<\/strong><\/td>\n<td style=\"width: 17.3969%; height: 48px;\"><span style=\"font-weight: 400;\">Medium<\/span><\/td>\n<td style=\"width: 16.2371%; height: 48px;\"><span style=\"font-weight: 400;\">Medium<\/span><\/td>\n<td style=\"width: 16.2371%; height: 48px;\"><span style=\"font-weight: 400;\">Medium<\/span><\/td>\n<td style=\"width: 23.5825%; height: 48px;\"><span style=\"font-weight: 400;\">\u2191 (mold rework)<\/span><\/td>\n<\/tr>\n<tr style=\"height: 48px;\">\n<td style=\"width: 26.5464%; height: 48px;\"><strong>Bubbles &amp; Voids<\/strong><\/td>\n<td style=\"width: 17.3969%; height: 48px;\"><span style=\"font-weight: 400;\">Medium<\/span><\/td>\n<td style=\"width: 16.2371%; height: 48px;\"><span style=\"font-weight: 400;\">Medium<\/span><\/td>\n<td style=\"width: 16.2371%; height: 48px;\"><span style=\"font-weight: 400;\">Medium<\/span><\/td>\n<td style=\"width: 23.5825%; height: 48px;\"><span style=\"font-weight: 400;\">\u2191 (mold\/process changes)<\/span><\/td>\n<\/tr>\n<tr style=\"height: 48px;\">\n<td style=\"width: 26.5464%; height: 48px;\"><strong>Gate Vestige<\/strong><\/td>\n<td style=\"width: 17.3969%; height: 48px;\"><span style=\"font-weight: 400;\">Low<\/span><\/td>\n<td style=\"width: 16.2371%; height: 48px;\"><span style=\"font-weight: 400;\">Medium<\/span><\/td>\n<td style=\"width: 16.2371%; height: 48px;\"><span style=\"font-weight: 400;\">Low<\/span><\/td>\n<td style=\"width: 23.5825%; height: 48px;\"><span style=\"font-weight: 400;\">\u2192 (finishing\/gate changes)<\/span><\/td>\n<\/tr>\n<tr style=\"height: 24px;\">\n<td style=\"width: 26.5464%; height: 24px;\"><strong>Flow Lines<\/strong><\/td>\n<td style=\"width: 17.3969%; height: 24px;\"><span style=\"font-weight: 400;\">Low<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">High<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">Low<\/span><\/td>\n<td style=\"width: 23.5825%; height: 24px;\"><span style=\"font-weight: 400;\">\u2192 (process adjustments)<\/span><\/td>\n<\/tr>\n<tr style=\"height: 24px;\">\n<td style=\"width: 26.5464%; height: 24px;\"><strong>Burn Marks<\/strong><\/td>\n<td style=\"width: 17.3969%; height: 24px;\"><span style=\"font-weight: 400;\">Medium<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">High<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">Medium<\/span><\/td>\n<td style=\"width: 23.5825%; height: 24px;\"><span style=\"font-weight: 400;\">\u2191 (process tuning)<\/span><\/td>\n<\/tr>\n<tr style=\"height: 24px;\">\n<td style=\"width: 26.5464%; height: 24px;\"><strong>Sink Marks<\/strong><\/td>\n<td style=\"width: 17.3969%; height: 24px;\"><span style=\"font-weight: 400;\">Medium<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">High<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">Medium<\/span><\/td>\n<td style=\"width: 23.5825%; height: 24px;\"><span style=\"font-weight: 400;\">\u2191 (tool redesign)<\/span><\/td>\n<\/tr>\n<tr style=\"height: 24px;\">\n<td style=\"width: 26.5464%; height: 24px;\"><strong>Delamination<\/strong><\/td>\n<td style=\"width: 17.3969%; height: 24px;\"><span style=\"font-weight: 400;\">High<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">Medium<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">High<\/span><\/td>\n<td style=\"width: 23.5825%; height: 24px;\"><span style=\"font-weight: 400;\">\u2191\u2191<\/span><\/td>\n<\/tr>\n<tr style=\"height: 24px;\">\n<td style=\"width: 26.5464%; height: 24px;\"><strong>Weld Lines<\/strong><\/td>\n<td style=\"width: 17.3969%; height: 24px;\"><span style=\"font-weight: 400;\">Medium<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">Medium<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">Medium<\/span><\/td>\n<td style=\"width: 23.5825%; height: 24px;\"><span style=\"font-weight: 400;\">\u2192<\/span><\/td>\n<\/tr>\n<tr style=\"height: 24px;\">\n<td style=\"width: 26.5464%; height: 24px;\"><strong>Warping<\/strong><\/td>\n<td style=\"width: 17.3969%; height: 24px;\"><span style=\"font-weight: 400;\">High<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">High<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">High<\/span><\/td>\n<td style=\"width: 23.5825%; height: 24px;\"><span style=\"font-weight: 400;\">\u2191\u2191 (rework or scrap)<\/span><\/td>\n<\/tr>\n<tr style=\"height: 24px;\">\n<td style=\"width: 26.5464%; height: 24px;\"><strong>Jetting<\/strong><\/td>\n<td style=\"width: 17.3969%; height: 24px;\"><span style=\"font-weight: 400;\">Medium<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">High<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">Medium<\/span><\/td>\n<td style=\"width: 23.5825%; height: 24px;\"><span style=\"font-weight: 400;\">\u2191<\/span><\/td>\n<\/tr>\n<tr style=\"height: 24px;\">\n<td style=\"width: 26.5464%; height: 24px;\"><strong>Vacuum Voids<\/strong><\/td>\n<td style=\"width: 17.3969%; height: 24px;\"><span style=\"font-weight: 400;\">High<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">Low<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">Medium<\/span><\/td>\n<td style=\"width: 23.5825%; height: 24px;\"><span style=\"font-weight: 400;\">\u2191 (tool redesign)<\/span><\/td>\n<\/tr>\n<tr style=\"height: 24px;\">\n<td style=\"width: 26.5464%; height: 24px;\"><strong>Discoloration<\/strong><\/td>\n<td style=\"width: 17.3969%; height: 24px;\"><span style=\"font-weight: 400;\">Low<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">High<\/span><\/td>\n<td style=\"width: 16.2371%; height: 24px;\"><span style=\"font-weight: 400;\">Low<\/span><\/td>\n<td style=\"width: 23.5825%; height: 24px;\"><span style=\"font-weight: 400;\">\u2192<\/span><\/td>\n<\/tr>\n<tr style=\"height: 48px;\">\n<td style=\"width: 26.5464%; height: 48px;\"><strong>Splay Marks<\/strong><\/td>\n<td style=\"width: 17.3969%; height: 48px;\"><span style=\"font-weight: 400;\">Low<\/span><\/td>\n<td style=\"width: 16.2371%; height: 48px;\"><span style=\"font-weight: 400;\">High<\/span><\/td>\n<td style=\"width: 16.2371%; height: 48px;\"><span style=\"font-weight: 400;\">Low<\/span><\/td>\n<td style=\"width: 23.5825%; height: 48px;\"><span style=\"font-weight: 400;\">\u2192 (drying\/parameter fixes)<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>&nbsp;<\/p>\n\t<\/div>\r\n<\/div>\r\n<style>\r\n\t.custom-table-block table{\r\n\t\theight: initial!important;\r\n\t}\r\n\t.search-input-wrapper{\r\n\t\tposition: relative;\r\n\t\tmargin-bottom: 24px;\r\n\t}\r\n\t.search-input-wrapper svg{\r\n\t\tposition: absolute;\r\n\t\ttop:50%;\r\n\t\tleft:12px;\r\n\t\ttransform: translateY(-50%);\r\n\t}\r\n\t.table-search-input{\r\n\t\tpadding: 0 0 0 40px;\r\n\t\tborder:1px solid #C1CAD1;\r\n\t\theight: 44px;\r\n\t\twidth: 201px;\r\n\t\tcolor:#092C47;\r\n\t\tfont-family: Open Sans;\r\n\t\tfont-size: 16px;\r\n\t\tfont-weight: 400;\r\n\t\tline-height: 24px;\r\n\t\tletter-spacing: 0em;\r\n\t\ttext-align: left;\r\n\t}\r\n\t.table-search-input::placeholder{\r\n\t\tcolor:#092C47;\r\n\t}\r\n\t\r\n\t.custom-table-block thead th{\r\n\t\ttext-align: left;\r\n\t\twhite-space:nowrap;\r\n\t}\r\n\t\r\n\t.custom-table-block thead{\r\n\t\tmargin-bottom: 14px;\r\n\t}\r\n\r\n\t.custom-table-block tbody tr:nth-child(odd){\r\n\t\tbackground-color: #F6F9FF;\r\n\t}\r\n\r\n\t.custom-table-block tbody, .custom-table-block thead, .custom-table-block tr, .custom-table-block td, .custom-table-block th{\r\n\t\theight: initial!important;\r\n\t}\r\n\t\r\n\t.custom-table-block tbody td{\r\n\t\tcolor:#092C47;\r\n\t\tfont-family: Open Sans;\r\n\t\tfont-size: 16px;\r\n\t\tfont-weight: 400;\r\n\t\tline-height: 24px;\r\n\t\tletter-spacing: 0em;\r\n\t\ttext-align: left;\r\n\t\tpadding: 7px;\r\n\t}\r\n\t\r\n\t.custom-table-block thead th{\r\n\t\tfont-family: Open Sans;\r\n\t\tfont-size: 16px;\r\n\t\tfont-weight: 700;\r\n\t\tline-height: 24px;\r\n\t\tletter-spacing: 0em;\r\n\t\ttext-align: left;\r\n\t\tcolor:#092C47;\r\n\t\tposition: relative;\r\n\t}\r\n\t.custom-table-block thead th:after{\r\n\t\tcontent:\"\";\r\n\t\tdisplay: inline-block;\r\n\t\tbackground-image: url(\"data:image\/svg+xml,%3Csvg width='12' height='8' viewBox='0 0 12 8' fill='none' xmlns='http:\/\/www.w3.org\/2000\/svg'%3E%3Cpath d='M10.585 0.585938L6 5.17094L1.415 0.585938L0 2.00094L6 8.00094L12 2.00094L10.585 0.585938Z' fill='%23476175'\/%3E%3C\/svg%3E%0A\");\r\n\t\tmargin-left: 8px;\r\n\t\tbackground-position: center center;\r\n\t\tbackground-size: 12px 7.5px;\r\n\t\tbackground-repeat: no-repeat;\r\n\t\twidth: 24px;\r\n\t\theight: 12px;\r\n\t}\r\n\t.custom-table-block{\r\n\t\tmargin: 20px 0;\t\r\n\t}\r\n\t.custom-table-block .table-wrapper{\r\n\t\twidth: 100%;\r\n\t\toverflow-x: auto;\r\n\t}\r\n\t@media(max-width: 768px){\r\n\t\t\/* .custom-table-block tbody td{\r\n\t\t\twhite-space: nowrap;\r\n\t\t} *\/\r\n\t\t.custom-table-block .table-wrapper{\r\n\t\t\tmax-width: calc(100vw - 16px);\r\n\t\t}\r\n\t}\r\n<\/style>\r\n\n\n\n<p>Avoiding injection molding defects isn\u2019t just about technical precision and design\u2014it\u2019s also about working with a partner who anticipates problems before they happen.<\/p>\n\n\n\n<p><strong>Have you encountered injection molding defects in your own projects?<\/strong><\/p>\n\n\n\n<p>Share your experience or insights with the Xometry Pro <a href=\"https:\/\/xometry.pro\/en\/community\/\">community<\/a>. Your story might help another engineer design better, faster, and smarter.<\/p>\n","protected":false},"author":50,"featured_media":107785,"comment_status":"open","ping_status":"closed","template":"","categories":[],"c-tag-articles":[],"global-tag":[14,82],"class_list":["post-107796","articles","type-articles","status-publish","has-post-thumbnail","hentry","global-tag-injection-molding","global-tag-design"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v26.7 (Yoast SEO v27.3) - https:\/\/yoast.com\/product\/yoast-seo-premium-wordpress\/ -->\n<title>16 Common Injection Molding Defects: Causes &amp; Solutions | Xometry Pro<\/title>\n<meta name=\"description\" content=\"Learn more about common injection molding defects such as short shots, flow lines, warping, etc. Discover their causes and how to prevent them.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/xometry.pro\/en\/articles\/injection-molding-defects\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"16 Common Injection Molding Defects: Causes &amp; 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