Undercuts in CNC machined parts\u2014features such as T-slots, dovetails, O-ring grooves, or internal snap-fits\u2014cannot be reached by a standard end mill from a conventional direction. Poorly designed undercuts often lead to higher costs, longer lead times, and special tooling requirements. Following proven design-for-manufacturability (DFM) best practices helps engineers create functional parts that are easier and more economical to machine.<\/p>\n\n\n\n
1. Eliminate unnecessary undercuts whenever possible<\/strong> 2. Ensure clear tool access and adequate clearance<\/strong> 3. Keep undercuts shallow and use standard dimensions<\/strong> 4. Avoid tight tolerances on non-critical surfaces and consider material<\/strong> By applying these CNC undercut design best practices\u2014prioritizing accessibility, standard tooling, shallow features, and functional necessity\u2014engineers can significantly improve manufacturability, reduce cost, and accelerate production. Review undercut features with your CNC supplier before finalizing drawings to ensure a smooth path from design to finished part.<\/p>\n","protected":false},"excerpt":{"rendered":" Undercuts in CNC machined parts\u2014features such as T-slots, dovetails, O-ring grooves, or internal snap-fits\u2014cannot be reached by a standard end mill from a conventional direction. Poorly designed undercuts often lead to higher costs, longer lead times, and special tooling requirements. Following proven design-for-manufacturability (DFM) best practices helps engineers create functional parts that are easier and […]<\/p>\n","protected":false},"author":1,"featured_media":1394,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-1616","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/www.atc-mould.com\/index.php?rest_route=\/wp\/v2\/posts\/1616","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.atc-mould.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.atc-mould.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.atc-mould.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.atc-mould.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1616"}],"version-history":[{"count":1,"href":"https:\/\/www.atc-mould.com\/index.php?rest_route=\/wp\/v2\/posts\/1616\/revisions"}],"predecessor-version":[{"id":1617,"href":"https:\/\/www.atc-mould.com\/index.php?rest_route=\/wp\/v2\/posts\/1616\/revisions\/1617"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.atc-mould.com\/index.php?rest_route=\/wp\/v2\/media\/1394"}],"wp:attachment":[{"href":"https:\/\/www.atc-mould.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1616"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.atc-mould.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1616"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.atc-mould.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1616"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
The most effective strategy is to avoid undercuts entirely if they are not functionally required. Many undercuts can be replaced by redesigning the part: split it into two components that assemble with fasteners, convert an internal feature into an external profile, or use an open groove instead of a closed undercut. Removing non-essential undercuts typically reduces machining cost by 30\u201350% and simplifies inspection.<\/p>\n\n\n\n
A cutting tool must first enter through an existing opening (slot, hole, or edge) and then move laterally. Make the entry width larger than the tool shank diameter and add 0.5\u20131 mm clearance. For one-sided undercuts, keep the primary opening width at least four times the undercut depth so the tool has room to maneuver without collision.<\/p>\n\n\n\n
Limit undercut depth to roughly 2\u20133 times the cutter diameter (up to 3\u20134 times for standard T-slot cutters) to maintain tool rigidity and surface finish. Prefer common tool sizes: T-slot widths of 3\u201312.7 mm, dovetail angles of 45\u00b0 or 60\u00b0, and internal corner radii of at least 0.3\u20130.8 mm. Matching standard cutters eliminates the need for expensive custom tools.<\/p>\n\n\n\n
Apply strict tolerances only where function demands them. Soft materials machine more easily; hard alloys increase tool wear and may require slower feeds. When geometry remains challenging, evaluate 5-axis machining, part splitting, or secondary operations early in the design stage.<\/p>\n\n\n\n