{"id":7838,"date":"2026-05-26T10:48:46","date_gmt":"2026-05-26T02:48:46","guid":{"rendered":"https:\/\/rilong-mold.com\/?p=7838"},"modified":"2026-07-27T10:11:42","modified_gmt":"2026-07-27T02:11:42","slug":"undercut-ejection-always-causing-scratches-this-s136-6-segment-collapsing-core-solves-it","status":"publish","type":"post","link":"https:\/\/rilong-mold.com\/ar\/undercut-ejection-always-causing-scratches-this-s136-6-segment-collapsing-core-solves-it\/","title":{"rendered":"Undercut Ejection Always Causing Scratches? This S136 6\u2011Segment Collapsing Core Solves It"},"content":{"rendered":"<p class=\"rilong-seo-summary wp-block-paragraph\"><strong>Undercut ejection mold:<\/strong> This article explains the key design, material, process, quality, and production considerations that engineers and sourcing teams should evaluate.<\/p>\n\n\n\n<h3 id=\"1-the-problem-the-long-standing-challenge-of-undercut-ejection-1\" class=\"wp-block-heading\">1. The Problem: The Long\u2011Standing Challenge of Undercut Ejection<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">In parts with undercut features, conventional forced ejection often leads to a series of issues:&nbsp;<strong>surface scratches, sticking, stress whitening, and even direct scrap<\/strong>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The root cause is simple: the part is \u201cpulled\u201d out before it has fully released from the mold.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Is there a way to actively create clearance for the part before ejection?<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The answer is a&nbsp;<strong>collapsing core<\/strong>.<\/p>\n\n\n\n<h3 id=\"2-the-solution-a-6-segment-collapsing-core-structure-1\" class=\"wp-block-heading\">2. The Solution: A 6\u2011Segment Collapsing Core Structure<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">In this mold, we adopted a&nbsp;<strong>6\u2011segment collapsing core (3 large + 3 small segments)<\/strong>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">How it works is straightforward:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>During molding<\/strong>: the segments expand outward to form the full undercut shape<\/li>\n\n\n\n<li><strong>Before ejection<\/strong>: the segments collapse inward, creating clearance for the part<\/li>\n\n\n\n<li><strong>During ejection<\/strong>: the part is released naturally, without forced extraction<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">The video below shows the smooth \u201cexpand &amp; collapse\u201d motion of this collapsing core. Even in a relatively tight mold space, this structure operates reliably:<\/p>\n\n\n\n<figure class=\"wp-block-video\"><video autoplay controls muted src=\"https:\/\/rilong-mold.com\/wp-content\/uploads\/2026\/05\/1234.mp4\" playsinline><\/video><\/figure>\n\n\n\n<h3 id=\"3-material-why-s136-1\" class=\"wp-block-heading\">3. Material: Why S136?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A collapsing core must not only move smoothly but also withstand long\u2011term production.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For this mold core, we chose&nbsp;<strong>S136 imported stainless steel<\/strong>&nbsp;for three key reasons:<\/p>\n\n\n\n<ol start=\"1\" class=\"wp-block-list\">\n<li><strong>Excellent mirror polish<\/strong>&nbsp;\u2013 the surface in contact with the part is smooth, reducing scratch risk<\/li>\n\n\n\n<li><strong>Strong corrosion resistance<\/strong>&nbsp;\u2013 resists rust during long production runs, suitable for high\u2011cleanliness applications<\/li>\n\n\n\n<li><strong>Long service life<\/strong>&nbsp;\u2013 high hardness and wear resistance, ideal for high\u2011volume production<\/li>\n<\/ol>\n\n\n\n<h3 id=\"4-results-proven-in-mass-production-1\" class=\"wp-block-heading\">4. Results: Proven in Mass Production<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">This mold has been validated through 300,000 shots<strong> cycles<\/strong>&nbsp; production:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Collapsing core operates smoothly with no sticking<\/li>\n\n\n\n<li>No scratches, no sticking on the part surface<\/li>\n<\/ul>\n\n\n\n<h3 id=\"5-typical-applications-1\" class=\"wp-block-heading\">5. Typical Applications<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">This collapsing core structure is particularly suitable for:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Parts with deep or complex undercuts<\/li>\n\n\n\n<li>High surface quality requirements (e.g., cosmetic parts, transparent parts)<\/li>\n\n\n\n<li>High\u2011volume production demanding long mold life and consistent stability<\/li>\n<\/ul>\n\n\n\n<h3 id=\"6-struggling-with-undercut-ejection-1\" class=\"wp-block-heading\">6. Struggling with Undercut Ejection?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">If you are facing undercut ejection problems, let\u2019s talk. We can explore together whether a collapsing core solution can help improve your yield rate.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ud83d\udce9 Contact us: sales1@rilong-mold.com<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n<p class=\"rilong-related-capability wp-block-paragraph\"><strong>Related capability:<\/strong> Explore Rilong\u2019s <a href=\"\/ar\/mold-designing-tooling\/\">mold design and tooling capabilities<\/a>, or send your drawing and production requirements for a technical review.<\/p>","protected":false},"excerpt":{"rendered":"<p>Undercut ejection mold: This article explains the key design, material, process, quality, and production considerations that engineers and sourcing teams should evaluate. 1. The Problem: The Long\u2011Standing Challenge of Undercut Ejection In parts with undercut features, conventional forced ejection often leads to a series of issues:&nbsp;surface scratches, sticking, stress whitening, and even direct scrap. The [&hellip;]<\/p>\n","protected":false},"author":7,"featured_media":7839,"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-7838","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized"],"blocksy_meta":[],"_links":{"self":[{"href":"https:\/\/rilong-mold.com\/ar\/wp-json\/wp\/v2\/posts\/7838","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/rilong-mold.com\/ar\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/rilong-mold.com\/ar\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/rilong-mold.com\/ar\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"https:\/\/rilong-mold.com\/ar\/wp-json\/wp\/v2\/comments?post=7838"}],"version-history":[{"count":6,"href":"https:\/\/rilong-mold.com\/ar\/wp-json\/wp\/v2\/posts\/7838\/revisions"}],"predecessor-version":[{"id":8046,"href":"https:\/\/rilong-mold.com\/ar\/wp-json\/wp\/v2\/posts\/7838\/revisions\/8046"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/rilong-mold.com\/ar\/wp-json\/wp\/v2\/media\/7839"}],"wp:attachment":[{"href":"https:\/\/rilong-mold.com\/ar\/wp-json\/wp\/v2\/media?parent=7838"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rilong-mold.com\/ar\/wp-json\/wp\/v2\/categories?post=7838"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rilong-mold.com\/ar\/wp-json\/wp\/v2\/tags?post=7838"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}