BALFORD.Metalworking engineering answers

Special stamping techniques

Can a stamped or drawn part have a sharp internal corner instead of a radius?

Reviewed by: Shawn, BalfordReviewed 14 October 20266 cited sources

Answer

Use Practical Internal Corner Radii An end mill leaves a radius in any internal vertical corner. A truly sharp corner means another process—like Wire EDM—or a design change. Bumping up the radius lets us run a larger, stiffer cutter, which typically shortens cycle time and gives you more consistent surface finish. Don't spec the corner radius exactly equal to the cutter radius.

ProcessSpecial stamping techniques
Material / topicsharp internal cornersmall internal radiusextruded corner
Related pagesExtrusion With Sharp Corners In Deep Drawn Stamping

Sources

  1. CNC Milling Design Guide | Balford
    3. Use Practical Internal Corner Radii An end mill leaves a radius in any internal vertical corner. A truly sharp corner means another process—like Wire EDM—or a design change. Bumping up the radius lets us run a larger, stiffer cutter, which typically shortens cycle time and gives you more consiste...
  2. Wire EDM Services China | Precision Wire Cutting
    Do I need a start hole? For internal profiles, yes — the wire must pass through the material, so a start hole is required. For external contours the wire can start from outside the blank. We confirm the start-hole position and diameter during DFM review. What corner radius can wire EDM hold? Wire ED...
  3. CNC Milling Services China | Custom Milled Parts
    What is the practical limit on internal corner radii? A standard rotating cutter leaves a radius equal to its own. Deep pockets and small corners may need smaller tools (and therefore more passes) or a secondary process such as wire EDM for truly sharp corners. We review corner radius against functi...
  4. How To Calculate Blank Size For A Deep Drawn Cup?
    Why does the formula give a larger blank than the real part needs? Because it assumes a sharp bottom corner and a wall that keeps the full sheet thickness. A radiused bottom corner removes material from the calculation, and real drawing thins the wall slightly, so a cup with a generous radius typica...
  5. Wire EDM Services China | Precision Wire Cutting
    Cut after heat treatment without annealing the material. Narrow slots & intricate profiles Features milling cannot reach with a practical tool. Through features Precise through profiles with controlled corner radius. Low-force parts Thin or delicate sections that would distort under cutting force. W...
  6. CNC Machining Parts Manufacturer in China | Balford
    How does Balford handle NDA and drawing confidentiality? We sign NDAs before detailed file exchange, store customer files on controlled internal systems and restrict access to the project team. Your revision control and confidentiality requirements can be written into the agreement before any drawin...

What an engineer still needs from you

  • material and material condition (grade, temper)
  • material thickness, plus the key diameter, height and wall thickness
  • tolerances, burr direction and the visual acceptance standard
  • annual volume - it decides whether tooling is single-hit, progressive or transfer
  • surface finish, and any secondary machining, annealing or plating

Need a DFM feasibility assessment for your project?

Send the engineering drawing (STEP or PDF) with the material grade, thickness and annual volume. Balford engineers then check it against the process window - draw ratio, wall thickness, tolerances, blank and tooling route - and come back with what is feasible and what is not. An answer on this page cannot replace that review.

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This page is an engineering answer, not a quotation and not a dimensional acceptance. It is generated from Balford's published material and held to the verified company fact sheet.