{"id":52783,"date":"2026-04-24T20:00:00","date_gmt":"2026-04-24T12:00:00","guid":{"rendered":"https:\/\/zetarmold.com\/?p=52783"},"modified":"2026-04-24T12:32:31","modified_gmt":"2026-04-24T04:32:31","slug":"conception-de-contre-depouille-de-moule-dinjection","status":"publish","type":"post","link":"https:\/\/zetarmold.com\/fr\/conception-de-contre-depouille-de-moule-dinjection\/","title":{"rendered":"Deux moules \u00e0 injection m\u00e9tallique ouverts expos\u00e9s sur une table d'atelier avec diverses pi\u00e8ces autour d'eux."},"content":{"rendered":"<div class=\"callout-key\" style=\"background:#f0f7ff; border-left:4px solid #2563eb; padding:1em 1.2em; border-radius:6px; margin:1.5em 0;\">\n<strong>Principaux enseignements<\/strong><\/p>\n<ul>\n<li>Audit des contre-d\u00e9pouilles en quatre \u00e9tapes : premi\u00e8rement, d\u00e9finissez votre ligne de joint et la direction d'\u00e9jection. Deuxi\u00e8mement, ex\u00e9cutez l'analyse de d\u00e9pouille dans la direction d'ouverture du moule. Troisi\u00e8mement, pour chaque surface signal\u00e9e, demandez-vous : puis-je ajouter une d\u00e9pouille et \u00e9liminer la contre-d\u00e9pouille ? Puis-je utiliser un plan de joint ? Ai-je r\u00e9ellement besoin de cette fonctionnalit\u00e9 ? Quatri\u00e8mement, pour les fonctionnalit\u00e9s qui survivent aux trois questions, planifiez le type de m\u00e9canisme \u2014 coulisseau ou \u00e9jecteur lat\u00e9ral \u2014 et incluez le nombre de m\u00e9canismes dans votre estimation budg\u00e9taire de l'outillage.<\/li>\n<li>Three options to handle an undercut: side-action slider, internal lifter, or redesign to eliminate it. Redesign is almost always the cheapest \u2014 if the function can be preserved.<\/li>\n<li>Sliders are better for external undercuts (side holes, clips, ports). Lifters are better for internal undercuts (snap-fits, ribs on inner walls). Using the wrong mechanism adds unnecessary complexity.<\/li>\n<li>A shut-off (pass-through) can replace a slider for many snap-fit and tab features by placing a hole in the part floor directly below the feature \u2014 zero added tooling cost.<\/li>\n<li>The 5-degree rule: an undercut with less than 5 degrees of draft on the release angle is asking for galling, sticking, and premature wear on the mold mechanism.<\/li>\n<\/ul>\n<\/div>\n<p>You designed a clip. A snap-fit. A side port. Made total sense on the CAD model. Then you got the <a href=\"https:\/\/zetarmold.com\/fr\/dfm-injection-plastic-parts\/\">DFM<\/a><sup id=\"fnref1:1\"><a href=\"#fn:1\" class=\"footnote-ref\">1<\/a><\/sup> rapport\u00e9 et le fabricant d'outils l'a cercl\u00e9 en rouge : '<a href=\"https:\/\/zetarmold.com\/fr\/injection-molding-complete-guide\/\">undercut feature<\/a><sup id=\"fnref1:2\"><a href=\"#fn:2\" class=\"footnote-ref\">2<\/a><\/sup> \u2014 n\u00e9cessite un coulisseau. \u00bb Le devis a augment\u00e9 de $8,000 et le d\u00e9lai de fabrication a augment\u00e9 de trois semaines.<\/p>\n<p>Cette histoire se r\u00e9p\u00e8te plusieurs centaines de fois par jour dans le d\u00e9veloppement de produits. Le point frustrant est que la plupart des contre-d\u00e9pouilles ne sont pas n\u00e9cessaires \u2014 elles sont une habitude de mod\u00e9lisation qui n'a pas \u00e9t\u00e9 d\u00e9tect\u00e9e assez t\u00f4t. Ce guide explique ce que les contre-d\u00e9pouilles co\u00fbtent, pourquoi elles co\u00fbtent autant, comment traiter celles que vous ne pouvez pas \u00e9liminer, et comment d\u00e9terminer quel type de m\u00e9canisme votre conception n\u00e9cessite r\u00e9ellement.<\/p>\n<h2>What Is an Undercut and Why Does It Stop Your Part From Coming Out?<\/h2>\n<p>Un contre-d\u00e9pouille est toute caract\u00e9ristique moul\u00e9e qui bloque l'\u00e9jection en ligne droite \u2014 la pi\u00e8ce ne peut sortir du moule sans un m\u00e9canisme sp\u00e9cial. Lorsque le moule s'ouvre, le noyau se retire et la pi\u00e8ce est pouss\u00e9e hors du noyau par des broches d'\u00e9jection. Pour que cela fonctionne, chaque surface de la pi\u00e8ce doit \u00eatre visible depuis la direction Z \u2014 ce qui signifie qu'il n'y a aucune caract\u00e9ristique qui pi\u00e9gerait m\u00e9caniquement la pi\u00e8ce dans le moule.<\/p>\n<p>An undercut is any feature that blocks that straight-line ejection. The most common examples: a hole in the side of a part (perpendicular to the mold opening direction), a snap-fit arm that curves inward, a thread on a cylindrical feature, a recessed groove running around the perimeter of a part, or a hook that points back toward the parting line.<\/p>\n<p>The problem is mechanical, not cosmetic. If you try to pull the part straight out with an undercut present, you either tear the part, damage the mold, or both. The mold must have a mechanism that gets out of the way before the part is ejected. That mechanism is what costs money.<\/p>\n<figure style=\"text-align:center;margin:2em 0;\">\n<img loading=\"lazy\" decoding=\"async\" width=\"800\" height=\"457\" src=\"https:\/\/zetarmold.com\/wp-content\/uploads\/2026\/04\/injection-mold-design-800x457-1.jpg\" alt=\"Injection mold design components\" class=\"wp-image-53248 size-full\" style=\"max-width:100%;height:auto;\" srcset=\"https:\/\/zetarmold.com\/wp-content\/uploads\/2026\/04\/injection-mold-design-800x457-1.jpg 800w, https:\/\/zetarmold.com\/wp-content\/uploads\/2026\/04\/injection-mold-design-800x457-1-300x171.jpg 300w, https:\/\/zetarmold.com\/wp-content\/uploads\/2026\/04\/injection-mold-design-800x457-1-768x439.jpg 768w, https:\/\/zetarmold.com\/wp-content\/uploads\/2026\/04\/injection-mold-design-800x457-1-18x10.jpg 18w, https:\/\/zetarmold.com\/wp-content\/uploads\/2026\/04\/injection-mold-design-800x457-1-600x343.jpg 600w\" sizes=\"(max-width: 800px) 100vw, 800px\" \/><figcaption style=\"font-size:0.78em; color:#888; font-style:italic; margin-top:4px; text-align:center;\">Conception de moules d'injection<\/figcaption><\/figure>\n<h2>Why Do Undercuts Make Injection Molds So Much More Expensive?<\/h2>\n<p>Voici ce que vous payez r\u00e9ellement lorsque un fabricant d'outils vous propose un m\u00e9canisme de contre-d\u00e9pouille. Comprendre cette d\u00e9composition vous aide \u00e0 \u00e9valuer si le co\u00fbt du m\u00e9canisme est justifi\u00e9 ou si la reconception m\u00e9rite le temps d'ing\u00e9nierie.<\/p>\n<p>A single external <a href=\"https:\/\/zetarmold.com\/fr\/conception-de-moules-dinjection\/\">side-action slider<\/a><sup id=\"fnref1:3\"><a href=\"#fn:3\" class=\"footnote-ref\">3<\/a><\/sup> involves: cam pin design and machining ($800\u2013$2,000), the slider body itself machined from tool steel ($1,500\u2013$4,000), guide rails and wear plates ($400\u2013$800), cooling circuit extension to the slider ($300\u2013$600 if needed), and integration testing during T1 trials (1\u20132 additional trial rounds, $1,000\u2013$2,500). Total for one slider: $4,000\u2013$10,000 at a typical Chinese mold shop, $8,000\u2013$20,000 at a North American shop.<\/p>\n<p>An internal <a href=\"https:\/\/zetarmold.com\/fr\/conception-de-moules-dinjection\/\">lifter<\/a><sup id=\"fnref1:4\"><a href=\"#fn:4\" class=\"footnote-ref\">4<\/a><\/sup> est g\u00e9n\u00e9ralement moins cher : $1 500\u2013$4 000 par poussoir dans un atelier chinois. Mais les poussoirs sont plus difficiles \u00e0 refroidir \u2014 ils sont enfonc\u00e9s profond\u00e9ment dans le noyau o\u00f9 les canaux de refroidissement ne peuvent pas facilement atteindre \u2014 et ils sont plus sujets au grippage sous de fortes forces d'\u00e9jection. En production \u00e0 haut cycle (500 000+ coups), les poussoirs n\u00e9cessitent un remplacement plus fr\u00e9quent que les coulisseaux.<\/p>\n<p>L'impact sur le temps de cycle est un autre co\u00fbt qui ne appara\u00eet pas dans le devis de l'outillage. Les coulisseaux et les leviers ralentissent la s\u00e9quence d'ouverture du moule et d'\u00e9jection. Un moule avec deux coulisseaux fonctionne g\u00e9n\u00e9ralement 3 \u00e0 8 secondes plus lentement par cycle que le moule \u00e9quivalent sans eux. \u00c0 100,000 cycles annuels, cela repr\u00e9sente 83 \u00e0 222 heures-machine par ann\u00e9e \u2014 un co\u00fbt r\u00e9el continu au-del\u00e0 du premium d'outillage.<\/p>\n<div class=\"claim claim-true\" style=\"background-color: #eff7ef; border-color: #eff7ef; color: #5a8a5a;\">\n<p><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" viewbox=\"0 0 24 24\" width=\"20\" height=\"20\" fill=\"currentColor\"><path d=\"M9 16.17L4.83 12l-1.42 1.41L9 19 21 7l-1.41-1.41z\"><\/path><\/svg><b>\u00ab Chaque coulisseau \u00e0 action lat\u00e9rale ajoute $4,000\u2013$10,000 au co\u00fbt d'outillage chez un atelier de moules typique. \u00bb<\/b><span class=\"claim-true-or-false\">Vrai<\/span><\/p>\n<p class=\"claim-explanation\">The cost comes from cam pin design, slider body machining from hardened tool steel, guide rail installation, and the additional T1 trial shots needed to verify slider timing and travel. Complex sliders with hydraulic actuation can cost $15,000+ each.<\/p>\n<\/div>\n<div class=\"claim claim-false\" style=\"background-color: #f7e8e8; border-color: #f7e8e8; color: #8a4a4a;\">\n<p><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" viewbox=\"0 0 24 24\" width=\"20\" height=\"20\" fill=\"currentColor\"><path d=\"M19 6.41L17.59 5 12 10.59 6.41 5 5 6.41 10.59 12 5 17.59 6.41 19 12 13.41 17.59 19 19 17.59 13.41 12z\"><\/path><\/svg><b>\u00ab Les leviers sont toujours moins chers et plus simples que les coulisseaux \u00e0 action lat\u00e9rale pour traiter les contre-d\u00e9pouilles. \u00bb<\/b><span class=\"claim-true-or-false\">Faux<\/span><\/p>\n<p class=\"claim-explanation\">Lifters are cheaper upfront for simple internal undercuts, but in high-volume production they often cost more over the life of the tool. Lifters run hotter (difficult to cool), are prone to galling under the combined ejection and lateral forces, and require more frequent replacement. For external undercuts, a slider is almost always the right choice mechanically.<\/p>\n<\/div>\n<h2>Can You Redesign the Part to Eliminate the Undercut?<\/h2>\n<p>Redesigning the part is the cheapest way to handle an undercut \u2014 in our DFM reviews, roughly 30% of undercuts are eliminated at zero cost.<\/p>\n<p>The most common elimination strategies are: re-orienting the part in the mold (sometimes rotating 90 degrees eliminates the undercut entirely), adding a through-hole below a snap-fit feature (the shut-off technique), splitting the part at the undercut feature so each half molds cleanly, or converting an undercut snap to a cantilevered snap that deflects during assembly rather than requiring a mold mechanism.<\/p>\n<p>Nous recommandons la technique de fermeture comme premi\u00e8re option \u00e0 \u00e9valuer car elle est la plus souvent n\u00e9glig\u00e9e. Si vous avez un bras d'assemblage \u00e0 encliquetage qui s'\u00e9tend vers l'int\u00e9rieur depuis une paroi, placer une fen\u00eatre ou un trou directement sous ce bras permet au m\u00e9tal du moule de 'se toucher' (fermer) par l'ouverture \u2014 la caract\u00e9ristique se forme sans aucun m\u00e9canisme coulissant. La pi\u00e8ce a un petit trou que la plupart des conceptions peuvent accommoder. Impact sur le co\u00fbt : z\u00e9ro. Impact sur le d\u00e9lai : z\u00e9ro. Cela devrait toujours \u00eatre la premi\u00e8re option \u00e9valu\u00e9e.<\/p>\n<figure style=\"text-align:center;margin:2em 0;\">\n<img fetchpriority=\"high\" decoding=\"async\" width=\"800\" height=\"457\" src=\"https:\/\/zetarmold.com\/wp-content\/uploads\/2026\/03\/injection-mold-steel-cavity-selection.jpg\" alt=\"Guide de Conception des Contre-d\u00e9pouilles pour Moule \u00e0 Injection | ZetarMold\" class=\"wp-image-52608 size-full\" style=\"max-width:100%;height:auto;\" srcset=\"https:\/\/zetarmold.com\/wp-content\/uploads\/2026\/03\/injection-mold-steel-cavity-selection.jpg 800w, https:\/\/zetarmold.com\/wp-content\/uploads\/2026\/03\/injection-mold-steel-cavity-selection-300x171.jpg 300w, https:\/\/zetarmold.com\/wp-content\/uploads\/2026\/03\/injection-mold-steel-cavity-selection-768x439.jpg 768w, https:\/\/zetarmold.com\/wp-content\/uploads\/2026\/03\/injection-mold-steel-cavity-selection-18x10.jpg 18w, https:\/\/zetarmold.com\/wp-content\/uploads\/2026\/03\/injection-mold-steel-cavity-selection-600x343.jpg 600w\" sizes=\"(max-width: 800px) 100vw, 800px\" \/><figcaption style=\"font-size:0.78em; color:#888; font-style:italic; margin-top:4px; text-align:center;\">Mold cavity steel selection<\/figcaption><\/figure>\n<h2>When Should You Use a Side-Action Slider?<\/h2>\n<p>A <a href=\"https:\/\/zetarmold.com\/fr\/injection-mold-complete-guide\/\">side-action slider<\/a> is the standard mechanism for external undercuts \u2014 side holes, clips, threads, and ports. The slider forms the undercut feature during the shot, then retracts as the mold opens \u2014 before the part is ejected.<\/p>\n<p>Les coulisseaux \u00e0 goupille coulissante sont actionn\u00e9s par des broches inclin\u00e9es fix\u00e9es \u00e0 la partie fixe du moule. Lorsque le moule s'ouvre, la broche inclin\u00e9e force le coulisseau \u00e0 se r\u00e9tracter perpendiculairement \u00e0 la direction d'ouverture. L'angle de la came varie g\u00e9n\u00e9ralement de 15 \u00e0 25 degr\u00e9s. En dessous de 15 degr\u00e9s, la force de la came est insuffisante. Au-dessus de 25 degr\u00e9s, la force lat\u00e9rale pendant l'ouverture cr\u00e9e des charges lat\u00e9rales dangereuses sur la plaque du moule. Les coulisseaux hydrauliques contournent cette contrainte et sont utilis\u00e9s lorsque la course requise d\u00e9passe ce que la g\u00e9om\u00e9trie de la came permet, ou lorsque le moule est trop compact pour accueillir une longueur standard de broche de came.<\/p>\n<p>R\u00e8gles de conception pour les coulisseaux : d\u00e9pouille minimale de 5\u00b0 sur toutes les surfaces du coulisseau \u2014 nos moules fonctionnent entre 80,0\u00b0C et 120,0\u00b0C, et le frottement acier sur acier \u00e0 ces temp\u00e9ratures provoque une usure rapide, contact acier sur acier minimum de 2,0mm \u00e0 la ligne de jointure sur toutes les faces (c'est le 'blocage' qui emp\u00eache les bavures pendant l'injection), et la poche du coulisseau doit \u00eatre ventil\u00e9e pour \u00e9viter les pi\u00e8ges \u00e0 air. La profondeur du contre-d\u00e9pouille d\u00e9termine la course requise du coulisseau : pour chaque 1mm de profondeur de contre-d\u00e9pouille, il faut au moins 1,5mm de course du coulisseau, plus une marge de s\u00e9curit\u00e9 de 3mm pour le d\u00e9moulage de la pi\u00e8ce.<\/p>\n<div class=\"claim claim-true\" style=\"background-color: #eff7ef; border-color: #eff7ef; color: #5a8a5a;\">\n<p><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" viewbox=\"0 0 24 24\" width=\"20\" height=\"20\" fill=\"currentColor\"><path d=\"M9 16.17L4.83 12l-1.42 1.41L9 19 21 7l-1.41-1.41z\"><\/path><\/svg><b>\u00ab Les coulisseaux actionn\u00e9s par des broches de came doivent rester dans une gamme d'angle de came de 15 \u00e0 25 degr\u00e9s pour une op\u00e9ration fiable. \u00bb<\/b><span class=\"claim-true-or-false\">Vrai<\/span><\/p>\n<p class=\"claim-explanation\">Below 15 degrees, the horizontal force component from the cam is too small to reliably retract the slider against friction and any residual part gripping. Above 25 degrees, the side load transmitted to the mold plate during opening becomes high enough to cause parting line damage and premature wear on the cam pin and slider pocket.<\/p>\n<\/div>\n<div class=\"claim claim-false\" style=\"background-color: #f7e8e8; border-color: #f7e8e8; color: #8a4a4a;\">\n<p><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" viewbox=\"0 0 24 24\" width=\"20\" height=\"20\" fill=\"currentColor\"><path d=\"M19 6.41L17.59 5 12 10.59 6.41 5 5 6.41 10.59 12 5 17.59 6.41 19 12 13.41 17.59 19 19 17.59 13.41 12z\"><\/path><\/svg><b>\u00ab Vous pouvez concevoir un coulisseau pour lib\u00e9rer n'importe quel contre-d\u00e9pouille, quelle que soit sa profondeur ou sa g\u00e9om\u00e9trie. \u00bb<\/b><span class=\"claim-true-or-false\">Faux<\/span><\/p>\n<p class=\"claim-explanation\">Les coulisseaux ont des limites g\u00e9om\u00e9triques. Les contre-d\u00e9pouilles tr\u00e8s profonds (&gt;25mm de course) n\u00e9cessitent des corps de coulisseaux volumineux qui concurrencent les canaux de refroidissement et les broches d'\u00e9jection pour l'espace. Les contre-d\u00e9pouilles avec g\u00e9om\u00e9trie complexe \u2014 surfaces courbes, angles rentrants \u2014 peuvent n\u00e9cessiter un m\u00e9canisme de coulisseau \u00e0 deux \u00e9tages ou rotatif, ce qui ajoute $8,000\u2013$20,000 et une complexit\u00e9 significative. Parfois la r\u00e9ponse honn\u00eate est que la g\u00e9om\u00e9trie doit changer.<\/p>\n<\/div>\n<h2>When Are Internal Lifters the Right Choice?<\/h2>\n<p>Lifters are angled ejector pins that release internal undercuts \u2014 snap-fits, ribs, and grooves that sliders cannot reach. Classic lifter applications: snap-fit hooks on the inside of a housing, rib features that have negative draft, internal groove features, and boss retention rings that face inward.<\/p>\n<p>Un levier est essentiellement une broche d'\u00e9jection inclin\u00e9e. Lorsque la plaque d'\u00e9jection avance pour pousser la pi\u00e8ce hors du noyau, l'angle du levier cause son mouvement lat\u00e9ral simultan\u00e9 \u2014 lib\u00e9rant le contre-d\u00e9pouille interne. L'angle typique du levier est de 5 \u00e0 15 degr\u00e9s de la verticale. Moins de 5 degr\u00e9s produit un mouvement lat\u00e9ral insuffisant pour la lib\u00e9ration de la pi\u00e8ce. Plus de 15 degr\u00e9s cr\u00e9e une usure excessive sur la glissi\u00e8re du levier et la cavit\u00e9 dans le noyau.<\/p>\n<p>Lifter sizing matters. In our shop, our engineers have replaced undersized lifters on three separate production molds across our 45 machines \u2014 a lifter that is undersized for the ejection force will gall and seize, leaving aluminum or steel deposits in the pocket and eventually jamming the ejection system. Size the lifter cross-section to handle at least 2\u00d7 the expected ejection force, and specify H13 steel for the lifter body in any production mold running above 100,000 cycles.<\/p>\n<figure style=\"text-align:center;margin:2em 0;\">\n<img loading=\"lazy\" decoding=\"async\" width=\"800\" height=\"457\" src=\"https:\/\/zetarmold.com\/wp-content\/uploads\/2025\/12\/molding-slide-diagram.webp\" alt=\"Injection molding side-action slider mechanism\" class=\"wp-image-51676 size-full\" style=\"max-width:100%;height:auto;\" srcset=\"https:\/\/zetarmold.com\/wp-content\/uploads\/2025\/12\/molding-slide-diagram.webp 800w, https:\/\/zetarmold.com\/wp-content\/uploads\/2025\/12\/molding-slide-diagram-300x171.webp 300w, https:\/\/zetarmold.com\/wp-content\/uploads\/2025\/12\/molding-slide-diagram-768x439.webp 768w, https:\/\/zetarmold.com\/wp-content\/uploads\/2025\/12\/molding-slide-diagram-18x10.webp 18w, https:\/\/zetarmold.com\/wp-content\/uploads\/2025\/12\/molding-slide-diagram-600x343.webp 600w\" sizes=\"(max-width: 800px) 100vw, 800px\" \/><figcaption style=\"font-size:0.78em; color:#888; font-style:italic; margin-top:4px; text-align:center;\">Side-action slider design<\/figcaption><\/figure>\n<h2>How Do You Audit Your Design for Undercuts Before Tooling?<\/h2>\n<p>A draft analysis is the fastest way to find undercuts \u2014 every surface with negative draft in the mold-opening direction is flagged automatically. In any modern CAD system, a draft analysis tool will highlight surfaces that have negative draft in the mold opening direction. Run it before you finalize your design. At ZetarMold, we see this on every new project \u2014 every red surface is either an undercut or a surface without draft \u2014 both problems that will cost you money.<\/p>\n<p>The four-step undercut audit: first, define your parting line and draw direction. Second, run draft analysis in the mold opening direction. Third, for every flagged surface, ask: can I add draft and eliminate the undercut? Can I use a shut-off? Do I actually need this feature? Fourth, for the features that survive all three questions, plan the mechanism type \u2014 slider or lifter \u2014 and include the mechanism count in your tooling budget estimate.<\/p>\n<p>\u00c0 ZetarMold, nous effectuons une revue DFM sur chaque nouvelle pi\u00e8ce avant de proposer l'outillage. En 20 ans d'application de ce processus, la nouvelle pi\u00e8ce typique d'un ing\u00e9nieur qui n'a jamais fait d'injection-moulage a 3 \u00e0 5 contre-d\u00e9pouilles involontaires. Apr\u00e8s DFM, 70 \u00e0 80% de ceux-ci sont \u00e9limin\u00e9s ou convertis en fermetures sans co\u00fbt d'outillage. Les 20 \u00e0 30% restants n\u00e9cessitent des m\u00e9canismes \u2014 mais au moins vous savez exactement ce que vous payez avant que l'acier soit usin\u00e9.<\/p>\n<table style=\"width:100%;border-collapse:collapse;margin:1.5em 0;\">\n<caption style=\"font-weight:bold;margin-bottom:0.5em;\">Undercut Solution Decision Matrix<\/caption>\n<thead>\n<tr>\n<th style=\"border:1px solid #ddd;padding:8px;background:#f5f5f5;\">Undercut Type<\/th>\n<th style=\"border:1px solid #ddd;padding:8px;background:#f5f5f5;\">Localisation<\/th>\n<th style=\"border:1px solid #ddd;padding:8px;background:#f5f5f5;\">Best Solution<\/th>\n<th style=\"border:1px solid #ddd;padding:8px;background:#f5f5f5;\">Approximate Cost Add<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"border:1px solid #ddd;padding:8px;\">Side hole \/ port<\/td>\n<td style=\"border:1px solid #ddd;padding:8px;\">External wall<\/td>\n<td style=\"border:1px solid #ddd;padding:8px;\">Side-action slider<\/td>\n<td style=\"border:1px solid #ddd;padding:8px;\">$4,000\u2013$10,000<\/td>\n<\/tr>\n<tr>\n<td style=\"border:1px solid #ddd;padding:8px;\">External snap-fit \/ clip<\/td>\n<td style=\"border:1px solid #ddd;padding:8px;\">Outer wall<\/td>\n<td style=\"border:1px solid #ddd;padding:8px;\">Slider or shut-off<\/td>\n<td style=\"border:1px solid #ddd;padding:8px;\">$0 (shut-off) or $4K\u2013$8K (slider)<\/td>\n<\/tr>\n<tr>\n<td style=\"border:1px solid #ddd;padding:8px;\">Internal snap-fit<\/td>\n<td style=\"border:1px solid #ddd;padding:8px;\">Inner wall<\/td>\n<td style=\"border:1px solid #ddd;padding:8px;\">Lifter or shut-off<\/td>\n<td style=\"border:1px solid #ddd;padding:8px;\">$0 (shut-off) or $1.5K\u2013$4K (lifter)<\/td>\n<\/tr>\n<tr>\n<td style=\"border:1px solid #ddd;padding:8px;\">External thread<\/td>\n<td style=\"border:1px solid #ddd;padding:8px;\">Outer cylinder<\/td>\n<td style=\"border:1px solid #ddd;padding:8px;\">Rotating unscrewing mechanism<\/td>\n<td style=\"border:1px solid #ddd;padding:8px;\">$8,000\u2013$20,000<\/td>\n<\/tr>\n<tr>\n<td style=\"border:1px solid #ddd;padding:8px;\">Internal thread<\/td>\n<td style=\"border:1px solid #ddd;padding:8px;\">Inner cylinder<\/td>\n<td style=\"border:1px solid #ddd;padding:8px;\">Collapsible core or unscrewing<\/td>\n<td style=\"border:1px solid #ddd;padding:8px;\">$10,000\u2013$25,000<\/td>\n<\/tr>\n<tr>\n<td style=\"border:1px solid #ddd;padding:8px;\">Circumferential groove<\/td>\n<td style=\"border:1px solid #ddd;padding:8px;\">Around perimeter<\/td>\n<td style=\"border:1px solid #ddd;padding:8px;\">Slider or parting line relocation<\/td>\n<td style=\"border:1px solid #ddd;padding:8px;\">$4,000\u2013$12,000<\/td>\n<\/tr>\n<tr>\n<td style=\"border:1px solid #ddd;padding:8px;\">Undercut eliminated<\/td>\n<td style=\"border:1px solid #ddd;padding:8px;\">Any<\/td>\n<td style=\"border:1px solid #ddd;padding:8px;\">Redesign \/ shut-off \/ draft modification<\/td>\n<td style=\"border:1px solid #ddd;padding:8px;\">$0<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Threads deserve a special note. External threads on a cylindrical part are routinely handled by placing the parting line along the thread centerline \u2014 the thread forms across both halves of the mold and the part releases cleanly. Internal threads almost always require either an unscrewing mechanism (expensive, slow) or a hand-loaded insert that gets removed after the shot (labor-intensive). If an internal thread is necessary, consider whether a self-tapping screw boss or a heat-set insert can replace the molded thread. Post-molded inserts are available in brass or stainless steel in standard metric sizes from M2 to M12, and they install reliably in any thermoplastic with a simple heat-press tool.<\/p>\n<figure style=\"text-align:center;margin:2em 0;\">\n<img loading=\"lazy\" decoding=\"async\" width=\"800\" height=\"457\" src=\"https:\/\/zetarmold.com\/wp-content\/uploads\/2025\/12\/3d-injection-mold-design.webp\" alt=\"3D injection mold design with mechanism detail\" class=\"wp-image-51778 size-full\" style=\"max-width:100%;height:auto;\" srcset=\"https:\/\/zetarmold.com\/wp-content\/uploads\/2025\/12\/3d-injection-mold-design.webp 800w, https:\/\/zetarmold.com\/wp-content\/uploads\/2025\/12\/3d-injection-mold-design-300x171.webp 300w, https:\/\/zetarmold.com\/wp-content\/uploads\/2025\/12\/3d-injection-mold-design-768x439.webp 768w, https:\/\/zetarmold.com\/wp-content\/uploads\/2025\/12\/3d-injection-mold-design-18x10.webp 18w, https:\/\/zetarmold.com\/wp-content\/uploads\/2025\/12\/3d-injection-mold-design-600x343.webp 600w\" sizes=\"(max-width: 800px) 100vw, 800px\" \/><figcaption style=\"font-size:0.78em; color:#888; font-style:italic; margin-top:4px; text-align:center;\">3D mold design<\/figcaption><\/figure>\n<h2>How Can Parting Line Strategy Eliminate Undercuts for Free?<\/h2>\n<p>La relocalisation de la ligne de joint est la seule solution de contre-d\u00e9pouille qui co\u00fbte $0 \u2014 elle convertit un contre-d\u00e9pouille en une surface avec d\u00e9pouille. D\u00e9placer ou remodeler la ligne de joint peut convertir un contre-d\u00e9pouille en une surface avec d\u00e9pouille standard \u2014 sans co\u00fbt d'outillage suppl\u00e9mentaire. C'est l'approche que les guides des concurrents couvrent presque jamais en d\u00e9tail, et c'est l\u00e0 que l'exp\u00e9rience compte le plus.<\/p>\n<p>The basic principle: if a surface creates an undercut at a flat parting line, try stepping, angling, or contouring the parting line to follow that surface. A side hole that would require a slider at a flat parting line might be fully released at a stepped parting line that bisects the hole. The limitation is that complex parting lines take longer to machine and must be matched precisely between core and cavity \u2014 adding $1,000\u2013$4,000 in machining time, but usually much less than a full slider mechanism.<\/p>\n<p>Trois strat\u00e9gies de ligne de joint qui \u00e9liminent les contre-d\u00e9pouilles communs : la ligne de joint \u00e9tag\u00e9e (pour les bossages, nervures et protub\u00e9rances pr\u00e8s de la zone de joint), la ligne de joint inclin\u00e9e (pour les caract\u00e9ristiques sur surfaces coniques ou inclin\u00e9es), et la ligne de joint profil\u00e9e qui suit la g\u00e9om\u00e9trie naturelle de la pi\u00e8ce. Nous mod\u00e9lisons toutes ces trois options dans notre revue DFM et pr\u00e9sentons la diff\u00e9rence de co\u00fbt afin que le client puisse d\u00e9cider si le changement de conception est justifi\u00e9.<\/p>\n<h2>Frequently Asked Questions About Injection Mold Undercut Design?<\/h2>\n<h3>Combien co\u00fbte l'ajout d'un seul coulisseau au co\u00fbt de l'outillage de moulage par injection ?<\/h3>\n<p>A single cam-pin-driven side-action slider adds $4,000 to $10,000 to tooling cost at a typical Chinese mold shop, and $8,000 to $20,000 at North American or European shops. The cost covers cam pin design and machining, slider body from hardened H13 tool steel, guide rail installation, wear plates, and the additional T1 and T2 trial shots needed to verify slider timing, travel distance, and parting line sealing at the shut-off faces. Hydraulic or two-stage sliders cost proportionally more due to actuation hardware.<\/p>\n<h3>Quelle est la diff\u00e9rence entre un slider et un lifter dans le moulage par injection ?<\/h3>\n<p>A slider handles external undercuts on the outer surfaces of a part, moving perpendicular to the mold opening direction via a cam pin or hydraulic cylinder mounted on the mold plates. A lifter handles internal undercuts on the inner surfaces of a part, moving at an angle during the ejection stroke \u2014 its travel is integrated into the ejector plate motion. Sliders sit in the parting line area; lifters are embedded inside the core. For external side holes and clips, use a slider. For internal snap-fits and inner wall features, use a lifter or consider a shut-off.<\/p>\n<h3>Puis-je \u00e9liminer un sous-d\u00e9pouille en utilisant un mat\u00e9riau flexible ?<\/h3>\n<p>Parfois oui. Pour les assemblages \u00e0 encliquetage peu profonds et les petits crochets, les r\u00e9sines plus douces comme le TPE, le TPU ou le polypropyl\u00e8ne \u00e0 faible durom\u00e8tre peuvent se d\u00e9former suffisamment lors de l'\u00e9jection pour franchir un petit contre-d\u00e9pouille sans m\u00e9canisme \u2014 une technique appel\u00e9e \u00e9jection forc\u00e9e. La directive de conception est que la profondeur du contre-d\u00e9pouille ne doit pas d\u00e9passer 2 \u00e0 5 % du diam\u00e8tre local de la pi\u00e8ce pour que cela fonctionne de mani\u00e8re fiable sans marques de stress visibles ou fissures. Les mat\u00e9riaux rigides comme l'ABS, le PC ou le nylon charg\u00e9 de verre ne peuvent \u00eatre \u00e9ject\u00e9s forc\u00e9ment des contre-d\u00e9pouilles sans dommage.<\/p>\n<h3>Comment savoir si ma pi\u00e8ce n\u00e9cessite un curseur ou un \u00e9l\u00e9vateur ?<\/h3>\n<p>Run a draft analysis in your CAD tool using the mold opening direction as the reference. If the flagged surface is on the outer wall of the part \u2014 visible from outside and accessible from the parting line area \u2014 you need a slider or a design change. If the flagged surface is on an inner wall or a recessed feature inside the part cavity, you need a lifter or a shut-off hole. When in doubt, submit your part files for a DFM review \u2014 standard at most mold shops and typically provided at no charge for new projects.<\/p>\n<h3>Quel est le moyen le moins co\u00fbteux de traiter un contre-d\u00e9pouille en moulage par injection ?<\/h3>\n<p>The cheapest solution is always to eliminate the undercut through design modification \u2014 zero tooling cost, zero cycle time impact. The second cheapest is a shut-off or pass-through: adding a window or hole directly below a snap-fit or tab feature, allowing the mold steel to form the feature without any moving mechanism. If neither option works, a standard cam-pin slider is the least expensive mechanism at $4,000 to $10,000. Complex rotating or multi-stage mechanisms for internal threads are the most expensive undercut solutions available.<\/p>\n<h3>Un d\u00e9gagement augmente-t-il toujours le temps de cycle du moule ?<\/h3>\n<p>Yes, but the magnitude depends on the mechanism type. A well-designed cam-pin slider adds 2 to 5 seconds to the mold open sequence as the slider retracts before ejection can begin. A hydraulic slider requiring an additional hydraulic actuation stroke can add 5 to 10 seconds per cycle. At 100,000 annual shots, even 5 extra seconds represents 139 additional machine-hours per year \u2014 a real ongoing production cost on top of the tooling premium. Lifters generally add less cycle time than sliders since their motion is integrated into the ejection stroke.<\/p>\n<hr style=\"margin:2em 0;border:none;border-top:1px solid #e0e0e0;\" \/>\n<ol class=\"footnotes\">\n<li id=\"fn:1\">\n<p><strong>Entreprises de Moulage par Injection en Inde : Pourquoi les Grands Acheteurs Choisissent ZetarMold -<\/strong> DFM (Design for Manufacturability) refers to a systematic review of part geometry before tooling to identify features that increase mold complexity, cost, or defect risk, and to propose design modifications that reduce these risks. <a href=\"#fnref1:1\" class=\"footnote-backref\">\u21a9<\/a><\/p>\n<\/li>\n<li id=\"fn:2\">\n<p><strong>undercut<\/strong>: An undercut is a feature in an injection molded part \u2014 such as a hook, thread, snap-fit, or side hole \u2014 that prevents the part from being ejected straight out of the mold along the primary draw direction. <a href=\"#fnref1:2\" class=\"footnote-backref\">\u21a9<\/a><\/p>\n<\/li>\n<li id=\"fn:3\">\n<p><strong>side-action slider:<\/strong> A side-action slider is a mechanical mold component that moves perpendicular to the mold opening direction during ejection to release undercut features, driven by an angled cam pin or hydraulic cylinder. <a href=\"#fnref1:3\" class=\"footnote-backref\">\u21a9<\/a><\/p>\n<\/li>\n<li id=\"fn:4\">\n<p><strong>lifter:<\/strong> A lifter is an angled ejector pin or blade inside an injection mold that moves at an angle during the ejection stroke to release internal undercuts or snap-fit features on the inner walls of a part. <a href=\"#fnref1:4\" class=\"footnote-backref\">\u21a9<\/a><\/p>\n<\/li>\n<\/ol>\n<p><script type=\"application\/ld+json\">{\n    \"@context\": \"https:\\\/\\\/schema.org\",\n    \"@type\": \"FAQPage\",\n    \"mainEntity\": [\n        {\n            \"@type\": \"Question\",\n            \"name\": \"How much does a single slider add to injection mold tooling cost?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"A single cam-pin-driven side-action slider adds $4,000 to $10,000 to tooling cost at a typical Chinese mold shop, and $8,000 to $20,000 at North American or European shops. The cost covers cam pin design and machining, slider body from hardened H13 tool steel, guide rail installation, wear plates, and the additional T1 and T2 trial shots needed to verify slider timing, travel distance, and parting line sealing at the shut-off faces. Hydraulic or two-stage sliders cost proportionally more due to \"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"What is the difference between a slider and a lifter in injection molding?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"A slider handles external undercuts on the outer surfaces of a part, moving perpendicular to the mold opening direction via a cam pin or hydraulic cylinder mounted on the mold plates. A lifter handles internal undercuts on the inner surfaces of a part, moving at an angle during the ejection stroke \\u2014 its travel is integrated into the ejector plate motion. Sliders sit in the parting line area; lifters are embedded inside the core. For external side holes and clips, use a slider. For internal snap-\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Can I eliminate an undercut by using a flexible material?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Sometimes yes. For shallow snap-fits and small hooks, softer resins like TPE, TPU, or low-durometer polypropylene can deform enough during ejection to clear a small undercut without a mechanism \\u2014 a technique called forced ejection. The design guideline is that the undercut depth must not exceed 2 to 5 percent of the part's local diameter for this to work reliably without leaving visible stress marks or cracking. Rigid materials like ABS, PC, or glass-filled nylon cannot be force-ejected from und\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"How do I know if my part needs a slider or a lifter?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Run a draft analysis in your CAD tool using the mold opening direction as the reference. If the flagged surface is on the outer wall of the part \\u2014 visible from outside and accessible from the parting line area \\u2014 you need a slider or a design change. If the flagged surface is on an inner wall or a recessed feature inside the part cavity, you need a lifter or a shut-off hole. When in doubt, submit your part files for a DFM review \\u2014 standard at most mold shops and typically provided at no charge fo\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"What is the cheapest way to handle an undercut in injection molding?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"The cheapest solution is always to eliminate the undercut through design modification \\u2014 zero tooling cost, zero cycle time impact. The second cheapest is a shut-off or pass-through: adding a window or hole directly below a snap-fit or tab feature, allowing the mold steel to form the feature without any moving mechanism. If neither option works, a standard cam-pin slider is the least expensive mechanism at $4,000 to $10,000. Complex rotating or multi-stage mechanisms for internal threads are the \"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Does an undercut always increase mold cycle time?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Yes, but the magnitude depends on the mechanism type. A well-designed cam-pin slider adds 2 to 5 seconds to the mold open sequence as the slider retracts before ejection can begin. A hydraulic slider requiring an additional hydraulic actuation stroke can add 5 to 10 seconds per cycle. At 100,000 annual shots, even 5 extra seconds represents 139 additional machine-hours per year \\u2014 a real ongoing production cost on top of the tooling premium. Lifters generally add less cycle time than sliders sinc\"\n            }\n        }\n    ]\n}<\/script><\/p>","protected":false},"excerpt":{"rendered":"<p>Points cl\u00e9s Chaque contre-d\u00e9pouille ajoute $2 000 \u00e0 $15 000 au co\u00fbt de l'outillage et 2 \u00e0 4 semaines au d\u00e9lai de livraison. Moins vous en avez, plus votre moule est construit rapidement et \u00e0 moindre co\u00fbt. Trois options pour g\u00e9rer une contre-d\u00e9pouille : glissi\u00e8re lat\u00e9rale, \u00e9jecteur interne ou reconception pour l'\u00e9liminer. La reconception est presque toujours la solution la moins co\u00fbteuse \u2014 si la fonction peut \u00eatre [\u2026]<\/p>","protected":false},"author":1,"featured_media":51776,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"","_seopress_titles_title":"Injection Mold Undercut Design Guide | ZetarMold","_seopress_titles_desc":"Injection mold undercut design adds $2,000\u2013$15,000 to tooling cost. Learn how sliders, lifters, and parting line strategies can reduce your costs and lead time.","_seopress_robots_index":"","_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[73],"tags":[150,48,100,89,90],"meta_box":{"post-to-quiz_to":[]},"_links":{"self":[{"href":"https:\/\/zetarmold.com\/fr\/wp-json\/wp\/v2\/posts\/52783"}],"collection":[{"href":"https:\/\/zetarmold.com\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/zetarmold.com\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/zetarmold.com\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/zetarmold.com\/fr\/wp-json\/wp\/v2\/comments?post=52783"}],"version-history":[{"count":0,"href":"https:\/\/zetarmold.com\/fr\/wp-json\/wp\/v2\/posts\/52783\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/zetarmold.com\/fr\/wp-json\/wp\/v2\/media\/51776"}],"wp:attachment":[{"href":"https:\/\/zetarmold.com\/fr\/wp-json\/wp\/v2\/media?parent=52783"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zetarmold.com\/fr\/wp-json\/wp\/v2\/categories?post=52783"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zetarmold.com\/fr\/wp-json\/wp\/v2\/tags?post=52783"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}