Hole-drilling EDM
- Small diameter deep holes in hardened steel
- Start points buried inside the block
- Minimal lateral force compared with some mechanical drills
Glossary
Hole-Drilling EDM for Molds: Start Holes, Vents & Deep Holes
Hole-drilling EDM uses a tubular electrode to drill small deep holes in hardened mold steel.
Definition
What Is Hole-Drilling EDM?
Hole-drilling EDM (small hole or fast hole EDM) uses a hollow tubular electrode to drill small deep holes in conductive steel.
Dielectric fluid flushes through the tube while sparks erode the hole axis.
Mold shops use it for wire EDM start holes, vent paths, cooling line access, and broken tap relief without a pre existing open edge.
See theEDMglossary hub for how hole drilling fits with sinker and wire EDM.
Toolmaking
Small hole EDM for deep start holes
Tubular electrode drilling in hardened mold plates.
- Wire EDM paths often start from an EDM drilled hole.
- Vent and cooling holes may use the same process.
- Broken tap relief avoids scrapping plates.
Applications
Hole-drilling EDM on injection molds
Confirm hole purpose on the tooling print before quoting lead time.
Wire EDM start holes when the wire path begins inside solid steel
Vent or air paths in hardened plates when conventional drill cannot reach
Cooling channel access or cross holes on thick mold plates
Broken tap or drill removal in assembled mold stacks
Versus other methods
When hole drilling EDM wins
Diameter and depth limits depend on machine and electrode stock.
Conventional drill or milling
- Open access holes in soft steel before heat treat
- Large diameters with standard tooling
- Through holes where a drill can enter from an open face
Process
Planning notes for RFQ
Link vent and wire EDM pages when holes tie to those systems.
State whether holes are for wire start, venting, cooling, or repair
Hardened steel location affects whether EDM drilling is required
After the start hole, wire EDM may finish the through slot or pocket
Go deeper
Related tooling links
Each link covers a different follow on step from the drilled hole.
EDM overview
Three EDM processes in one hub.
EDM overviewWire EDM
Cuts the profile after a start hole.
Wire EDMSinker EDM
Blind features without through access.
Sinker EDMVent
Vent paths and last fill on plastic parts.
VentVenting guide
Part design for air escape.
Venting guideVisual reference
Photos from molding and tooling programs
Images are selected from the NetProto Forge media library for this topic.
Small hole EDM drilling wire start hole in mold steel
Small hole EDM drilling wire start hole in mold steel
Close up of EDM drilled hole in hardened tool steel
Close up of EDM drilled hole in hardened tool steel
Tubular EDM electrode at mold plate surface
Tubular EDM electrode at mold plate surface
FAQ
Frequently Asked Questions About Hole-Drilling EDM
What is hole-drilling EDM used for in molds?
Wire start holes, deep vent paths, cooling access, and broken tap relief in conductive steel.
How is it different from sinker EDM?
Hole drilling follows one axis with a tube electrode. Sinker EDM copies a three dimensional electrode shape.
Does hole-drilling EDM work on aluminum molds?
EDM requires conductive workpieces. Most production injection molds use steel plates where this process applies.
Will a start hole show on my plastic part?
Wire start holes land in steel, not on the part surface, when the process is planned correctly.
Can hole drilling replace vent design?
It can create a steel path. Vent sizing and placement still follow mold vent rules on the part geometry.
How does this relate to wire EDM?
Many wire paths begin with a small hole drilled by EDM so the wire can thread inside the block.
Next step
Confirm hole and vent scope
Upload CAD with vent, cooling, and insert notes so hole drilling EDM is scoped with the rest of the tool.