Coining

Coining forms sharp, high-detail features by squeezing sheet metal in a closed die, producing precise embossing with high tonnage and minimal springback.

Overview

Coining (coin stamping) is a high-pressure stamping process that plastically compresses metal in a closed die to create crisp details—logos, text, knurls, serrations, and fine radii—without cutting through the material. The metal flows locally under extreme load, which minimizes springback and holds tight feature definition compared with conventional forming.

Choose coining when you need repeatable, high-resolution surface features or localized thickness redistribution on flat or mildly formed parts, typically at medium to high volumes where dedicated tooling cost is justified. It works best on ductile metals and relatively small feature areas.

Tradeoffs: coining requires high press tonnage and robust tooling, driving higher die cost and longer lead times. Large coined areas can thin material, create die wear, and amplify sensitivity to material hardness and thickness variation. Parts may need downstream deburr/cleaning if coining is combined with piercing or trimming operations.

Common Materials

  • Stainless Steel 304
  • Stainless Steel 316
  • Aluminum 1100
  • Brass C260
  • Copper C110
  • Low Carbon Steel 1010

Tolerances

±0.002"

Applications

  • Coined electrical contact dimples
  • Embossed part marking and traceability text
  • Serrations on lock washers and retention features
  • Coined knurl/grip patterns on stampings
  • Riveting/fastener staking seats
  • Raised sealing beads on thin-gauge covers

When to Choose Coining

Coining fits parts that need sharp, repeatable surface detail or localized material flow on sheet metal, especially for cosmetic or functional texture. It’s most cost-effective when volumes justify dedicated dies and you can control material thickness and temper. Expect best results on relatively small coined regions rather than large-area forming.

vs Progressive Die Stamping

Choose coining when the key requirement is sharp detail or controlled local plastic flow that standard progressive forming stations can’t hold consistently. Coining can be integrated into a progressive die, but it often needs dedicated tonnage, tighter shut-height control, and tool steels suited to high contact stress.

vs Transfer Die Stamping

Choose coining when you need high-definition features on parts that are otherwise manageable without multi-stage transfers. Transfer dies excel at handling larger or more 3D parts; coining is the right add-on when a specific face needs crisp embossing, serrations, or a sealing bead with minimal springback.

vs Deep Drawing

Choose coining when the part is primarily flat or lightly formed and the value is in surface detail or localized thickness/features. Deep drawing is aimed at creating cups and shells; coining won’t efficiently generate deep walls but can add sharp features to drawn parts where needed.

vs Blanking & Piercing

Choose coining when you need formed features (raised, recessed, or textured) rather than just cut edges and holes. Blanking/piercing defines perimeter and apertures; coining adds functional geometry like contact dimples, serrations, and legible markings that survive plating and handling.

vs Transfer Die Stamping

Choose coining over transfer-only forming when the print calls out crisp edges, fine text, or controlled feature height that depends on high compressive deformation. Transfer forming alone tends to round features and can show more springback on tight details.

Design Considerations

  • Keep coined areas as small as function allows to reduce tonnage, thinning risk, and die wear
  • Specify material temper/hardness and thickness tightly; coining sensitivity to variation drives feature-height scatter
  • Call out critical coined feature height/depth and allowable thinning; avoid over-constraining cosmetic areas
  • Provide generous transitions into coined regions to limit cracking, especially on harder tempers and stainless
  • Place coined details away from edges/holes when possible to prevent distortion and breakout during coining
  • Include a datum scheme for inspecting coined features; define whether measurements are after plating/coating if applicable