Punch Profile Design: Sinker EDM or Profile Grinding?

A small change in punch geometry can sometimes lead to a significantly different manufacturing process.

Recently, we received a stamping die punch drawing with a stepped transition in an approximately 11 mm section.

During our technical review before production, we noticed that the original stepped geometry would require precision Sinker EDM to manufacture the transition.

Instead of producing the part exactly as originally designed, we discussed a small geometry modification with the customer.

The stepped transition was changed to a semicircular transition.

This small design change allowed us to finish the profile using Profilschleifen.

The Original Punch Design

The original drawing used a stepped transition in the 11 mm section.

The geometry was manufacturable, but producing this particular transition would require a precision EDM operation.

For this type of feature, Sinker EDM can be an appropriate manufacturing process. However, it would introduce an additional process requirement for this component.

For a precision stamping punch, the choice of process can affect:

• Profile control
• Machining time
• Process complexity
• Manufacturing cost
• Final geometry

This is why we review the geometry before production rather than looking only at the nominal dimensions.

A Small Geometry Change

Our technical team suggested replacing the stepped transition with a semicircular radius.

The customer reviewed the proposed change and agreed to modify the design before production.

With the revised geometry, the transition could be finished by Profilschleifen.

For this particular punch, this gave us a more direct and controllable way to produce the required profile and transition.

It also allowed us to avoid an additional Sinker EDM operation, helping reduce machining time and manufacturing cost.

The key point is not that Profile Grinding is always better than Sinker EDM.

Different EDM and grinding processes have different strengths and applications.

The important consideration is whether the part geometry is suitable for the selected manufacturing process.

Why Geometry Matters in Precision Tooling

A drawing may contain many dimensions, radii, steps and transitions.

Some of these features may look relatively minor, but they can have a significant influence on how the component is manufactured.

For example, changing a stepped transition to a suitable radius may open up a different manufacturing route.

In this case:

Original geometry
Stepped transition
↓
Precision Sinker EDM

Revised geometry
Semicircular transition
↓
Profilschleifen

The finished component still needs to meet the functional requirements of the tooling.

But the manufacturing route can become different simply because of a relatively small geometry change.

Profile Grinding for Precision Punches

Profilschleifen is particularly useful for precision stamping tooling components where controlled profiles, transitions, radii and dimensional accuracy are required.

Depending on the material, geometry and tolerance requirements, profile grinding can be used for components such as:

• Stamping die punches
• Carbide punches
• Die inserts
• Cutting components
• Forming components
• Precision stamping die components

For complex punch geometries, the ability to control the profile is an important part of the manufacturing process.

The goal is not simply to achieve a dimension.

It is to reproduce the required geometry accurately and consistently.

Design for Manufacturability in Stamping Tooling

This case also highlights a simple principle of Design for Manufacturability (DFM).

DFM does not always mean making a major change to a component.

Sometimes, a small modification to one feature can make the part easier to manufacture while maintaining its intended function.

A radius, transition or corner may look like a small detail on a drawing, but it can influence:

• Which machine process can be used
• How many operations are required
• How the profile can be controlled
• Machining time
• Overall manufacturing cost

This is why communication between the tooling designer and manufacturing team can be valuable before production begins.

The Geometry Influences the Process

This project was a good reminder of something we see frequently in precision tooling:

The drawing defines the geometry, but the geometry influences the manufacturing process.

The best manufacturing route is not always determined after machining starts.

Sometimes, it begins with a small discussion during drawing review.

In this case, one small change to the punch profile allowed us to use Profilschleifen for the transition instead of adding a Sinker EDM operation.

The customer accepted the proposed change, and the revised design was used for production.

Small geometry change. Different manufacturing route.

Need Precision Profile Grinding for Stamping Tooling?

We manufacture precision stamping tooling components through Profile Grinding, Wire EDM and other supporting processes, depending on the geometry and technical requirements.

Our focus includes precision punches, die inserts and other critical tooling components for stamping applications.

If you have a punch or die component with a complex profile, tight tolerances or difficult transitions, we can review the drawing and determine a suitable manufacturing route.

Hepha Precision Technology
Precision Profile Grinding & Wire EDM for Stamping Tooling