{"id":7854,"date":"2026-06-05T17:53:58","date_gmt":"2026-06-05T09:53:58","guid":{"rendered":"https:\/\/rilong-mold.com\/?p=7854"},"modified":"2026-06-05T17:54:00","modified_gmt":"2026-06-05T09:54:00","slug":"common-injection-molding-defects-and-solutions","status":"publish","type":"post","link":"https:\/\/rilong-mold.com\/es\/common-injection-molding-defects-and-solutions\/","title":{"rendered":"Common Injection Molding Defects and Solutions"},"content":{"rendered":"

Injection molding defects typically arise from four factors: material, process, mold, and machine<\/strong>. This guide covers 28 common defects, prioritized for quick on-site troubleshooting.<\/p>\n\n\n\n

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Part 1: Surface\/Appearance Defects<\/h2>\n\n\n\n
Defect<\/th>Description<\/th>Key Solutions<\/th><\/tr><\/thead>
1. Sink Marks<\/strong><\/td>Local surface depression<\/td>Increase pack\/hold pressure & time; enlarge gate; optimize rib thickness (\u22640.6\u00d7 wall)<\/td><\/tr>
2. Charred Streaks<\/strong><\/td>Silver\/brown streaks<\/td>Reduce injection speed<\/strong>; avoid sharp corners; check material drying<\/td><\/tr>
3. Moisture Streaks<\/strong><\/td>Wavy silver streaks<\/td>Pre-dry material thoroughly<\/strong>; increase mold temp; lower melt temp<\/td><\/tr>
4. Air Streaks<\/strong><\/td>Grooves, dots or lines on surface<\/td>Add\/deepen vents; adjust injection speed; change gate location<\/td><\/tr>
5. Colored Streaks<\/strong><\/td>Inconsistent color<\/td>Increase back pressure; lower melt temp; use mixing screw<\/td><\/tr>
6. Glass Fiber Streaks<\/strong><\/td>Rough surface, exposed fibers<\/td>Raise mold\/melt temp; inject faster; use shorter glass fibers<\/td><\/tr>
7. Gloss Differences<\/strong><\/td>Matte or shiny spots<\/td>Increase and balance mold temp; raise pack pressure; optimize transfer point<\/td><\/tr>
8. Jetting<\/strong><\/td>Snake-like pattern near gate<\/td>Reduce injection speed<\/strong>; enlarge gate; raise melt\/mold temp<\/td><\/tr>
9. Record Grooves<\/strong><\/td>Wavy ripples on surface<\/td>Increase injection speed\/pressure; raise melt\/mold temp<\/td><\/tr>
10. Dull Spots Near Gate<\/strong><\/td>Shadow near gate<\/td>Reduce speed near gate; enlarge gate; add radius transition<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
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Part 2: Internal\/Filling Defects<\/h2>\n\n\n\n
Defect<\/th>Description<\/th>Key Solutions<\/th><\/tr><\/thead>
11. Blistering<\/strong><\/td>Round\/oval internal voids<\/td>Vacuum: lower speed, increase pack pressure; Gas: dry material, increase back pressure<\/td><\/tr>
12. Voids<\/strong><\/td>Irregular cavities in thick sections<\/td>Locate gate at thickest wall; avoid sudden wall thickness changes<\/td><\/tr>
13. Short Shot<\/strong><\/td>Incomplete filling<\/td>Increase injection pressure\/speed\/temp; enlarge gate; improve venting<\/td><\/tr>
14. Weld Line<\/strong><\/td>Visible line where flows meet<\/td>Raise melt\/mold temp\/speed; add venting; use overflow tab<\/td><\/tr>
15. Cold Slugs<\/strong><\/td>Hardened material lumps<\/td>Check nozzle temp; add cold well; adjust decompression<\/td><\/tr>
16. Dark Spots<\/strong><\/td>Black spots on light parts<\/td>Clean screw\/barrel; check material for contaminants; lower melt temp<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
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Part 3: Deformation\/Mechanical Defects<\/h2>\n\n\n\n
Defect<\/th>Description<\/th>Key Solutions<\/th><\/tr><\/thead>
17. Warpage<\/strong><\/td>Overall part distortion<\/td>Balance cooling; optimize gate location; adjust packing; balance ejection<\/td><\/tr>
18. Deformation During Demoulding<\/strong><\/td>Bending\/collapse on ejection<\/td>Increase cooling time; lower pack pressure; add ejector area; check undercuts<\/td><\/tr>
19. Visible Ejector Marks<\/strong><\/td>White marks at ejector pins<\/td>Increase ejector count\/area; add draft angle; lower pack pressure<\/td><\/tr>
20. Ejection Grooves<\/strong><\/td>Scratch lines on side walls<\/td>Increase cooling time; increase draft angle; polish in ejection direction<\/td><\/tr>
21. Stress Whitening\/Cracks<\/strong><\/td>White marks or cracks<\/td>Lower pack pressure; optimize ejection; add radii to part design<\/td><\/tr>
22. Broken Film Hinge<\/strong><\/td>Hinge fracture<\/td>Move gate away from hinge; raise mold temp; increase hinge thickness moderately<\/td><\/tr>
23. Flaking of Surface Layer<\/strong><\/td>Layer separation<\/td>Check material purity\/compability; optimize plastication; reduce injection speed<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
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Part 4: Other\/Process Defects<\/h2>\n\n\n\n
Defect<\/th>Description<\/th>Key Solutions<\/th><\/tr><\/thead>
24. Diesel Effect (Burner)<\/strong><\/td>Local burning (yellow\/black)<\/td>Reduce injection speed<\/strong>; add venting; change flow pattern<\/td><\/tr>
25. Flash<\/strong><\/td>Excess plastic at parting line<\/td>Increase clamp force; reduce injection\/pack pressure; repair mold<\/td><\/tr>
26. Filamentation<\/strong><\/td>Stringy plastic near gate<\/td>Lower nozzle temp; increase cooling time; check hot runner<\/td><\/tr>
27. Plate Out<\/strong><\/td>Deposits on mold\/vent surfaces<\/td>Lower melt temp; shorten cycle time; check additive compatibility<\/td><\/tr>
28. Electroplated Part Defects<\/strong><\/td>Blisters\/cracks after plating<\/td>Reduce molded-in stress; dry material thoroughly; avoid sharp corners; use high-gloss mold finish<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
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Quick Troubleshooting Checklist<\/h2>\n\n\n\n
    \n
  1. Material<\/strong>\u00a0\u2013 Is it properly dried? Free of contaminants?<\/li>\n\n\n\n
  2. Mold<\/strong>\u00a0\u2013 Are vents sufficient? Is gate design appropriate?<\/li>\n\n\n\n
  3. Proceso<\/strong>\u00a0\u2013 Adjust in this order: temperature \u2192 speed \u2192 pressure.\u00a0Change only one parameter at a time.<\/strong><\/li>\n\n\n\n
  4. Machine<\/strong>\u00a0\u2013 Is screw non-return valve worn? Is barrel temperature stable?<\/li>\n<\/ol>\n\n\n\n

    <\/p>\n\n\n\n

    <\/p>","protected":false},"excerpt":{"rendered":"

    Injection molding defects typically arise from four factors: material, process, mold, and machine. This guide covers 28 common defects, prioritized for quick on-site troubleshooting. Part 1: Surface\/Appearance Defects Defect Description Key Solutions 1. Sink Marks Local surface depression Increase pack\/hold pressure & time; enlarge gate; optimize rib thickness (\u22640.6\u00d7 wall) 2. Charred Streaks Silver\/brown streaks Reduce […]<\/p>\n","protected":false},"author":4,"featured_media":7855,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_gspb_post_css":"","kk_blocks_editor_width":"","_kiokenblocks_attr":"","_kiokenblocks_dimensions":"","footnotes":""},"categories":[1],"tags":[],"class_list":["post-7854","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized"],"blocksy_meta":[],"_links":{"self":[{"href":"https:\/\/rilong-mold.com\/es\/wp-json\/wp\/v2\/posts\/7854","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/rilong-mold.com\/es\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/rilong-mold.com\/es\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/rilong-mold.com\/es\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/rilong-mold.com\/es\/wp-json\/wp\/v2\/comments?post=7854"}],"version-history":[{"count":1,"href":"https:\/\/rilong-mold.com\/es\/wp-json\/wp\/v2\/posts\/7854\/revisions"}],"predecessor-version":[{"id":7857,"href":"https:\/\/rilong-mold.com\/es\/wp-json\/wp\/v2\/posts\/7854\/revisions\/7857"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/rilong-mold.com\/es\/wp-json\/wp\/v2\/media\/7855"}],"wp:attachment":[{"href":"https:\/\/rilong-mold.com\/es\/wp-json\/wp\/v2\/media?parent=7854"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rilong-mold.com\/es\/wp-json\/wp\/v2\/categories?post=7854"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rilong-mold.com\/es\/wp-json\/wp\/v2\/tags?post=7854"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}