{"id":2244,"date":"2026-07-04T04:29:17","date_gmt":"2026-07-03T20:29:17","guid":{"rendered":"https:\/\/metalstampingparts.ltd\/?page_id=2244"},"modified":"2026-07-04T04:29:17","modified_gmt":"2026-07-03T20:29:17","slug":"hemmed-edge-stamped-parts-dfm-guide","status":"publish","type":"page","link":"https:\/\/metalstampingparts.ltd\/hemmed-edge-stamped-parts-dfm-guide\/","title":{"rendered":"Hemmed Edge Stamped Parts DFM Guide"},"content":{"rendered":"

Short answer:<\/strong> A hemmed edge can make a stamped part safer to handle, stiffer, cleaner in appearance, and less sensitive to exposed burrs. The RFQ should define hem type, material thickness, inside radius, visible face, coating or paint route, edge gap, cracking limits, final dimensions, and whether the hem is functional, cosmetic, or both.<\/p>\n

Hemmed edges appear on covers, guards, panels, appliance parts, brackets, hand-contact edges, and enclosure features. A hem can hide a cut edge and add stiffness, but it can also trap coating, crack at corners, change final size, and require extra forming stations.<\/p>\n

Use this page with the edge break specification guide<\/a>, burr control guide<\/a>, sheet metal enclosure DFM guide<\/a>, and DFM review before tooling guide<\/a>.<\/p>\n

Hem design choices before quoting<\/h2>\n\n\n\n\n\n\n\n\n
Choice<\/th>\nWhy it matters<\/th>\nRFQ detail<\/th>\n<\/tr>\n<\/thead>\n
Open hem<\/td>\nEasier to form and less likely to trap coating, but may leave a visible gap.<\/td>\nGap limit, edge direction, and visible side.<\/td>\n<\/tr>\n
Closed hem<\/td>\nCleaner appearance and safer edge, but higher cracking and thickness buildup risk.<\/td>\nMaterial ductility, radius, and crack acceptance.<\/td>\n<\/tr>\n
Teardrop hem<\/td>\nCan reduce cracking on thicker or harder material.<\/td>\nAllowed shape, final envelope, and tooling route.<\/td>\n<\/tr>\n
Corner treatment<\/td>\nCorners can split, overlap, or create sharp pockets.<\/td>\nRelief, notch, radius, and cosmetic standard.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Pick the hem for the function<\/h2>\n

A hand-contact edge may need a closed or nearly closed hem so the user never touches a sharp sheared edge. A stiffening flange may only need an open hem or return. A cosmetic cover may care more about outside appearance, rack marks, and coating buildup than maximum strength.<\/p>\n

Do not add a hem only because the edge looks nicer in CAD. It changes blank size, forming sequence, press tonnage, springback, and inspection. If the part also has holes, slots, louvers, or tabs near the hem, review spacing with the punched holes and slots guide<\/a> and process sequence checklist<\/a>.<\/p>\n

Watch material and finish limits<\/h2>\n

Ductile low-carbon steel may hem more easily than hard stainless, HSLA steel, or some aluminum tempers. Tight folds can crack at the outside surface or leave a raised witness line. Grain direction, burr side, coating thickness, and corner relief all matter.<\/p>\n

If the part is powder coated, painted, plated, or pre-coated, define whether the hem is formed before or after finishing. A closed hem can trap liquid, cleaning residue, or powder. A post-coated hem may chip during forming. Connect the decision to the powder coating masking guide<\/a> and pre-coated steel guide<\/a>.<\/p>\n

RFQ details to include<\/h2>\n