PMI Foam Core Perforation&Grooving:Balancing Resin Flow and Core Integrity

time：

2026-09-24 21:12

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PMI foam cores are often machined with perforations and grooves to control resin flow and air evacuation.But every opening removes core material.The challenge:improve resin flow without compromising core integrity.

Key Considerations

1.Purpose

Perforations and grooves can facilitate resin flow,support air evacuation,connect flow paths,or provide assembly clearance.They must be designed around the actual manufacturing process—not added simply to maximize resin movement.

2.Perforation Effects

Effectiveness depends on hole diameter,spacing,pattern,core thickness,resin viscosity,and process configuration.No universal pattern works for every application.

3.More Flow Is Not Always Better

Excessive perforation removes core material,reduces local continuity,and increases resin consumption,weight,and machining time.The goal is controlled flow—not maximum flow.

4.Grooving vs.Perforation

Feature	Best For
Perforation	Through-core resin or air movement
Grooving	Directional flow routes
Combination	Complex geometries

5.Design Factors

Hole size,spacing,groove width/depth,pattern,core thickness,location relative to inserts and joints,and CNC capability must be considered together.

6.Process Match

Infusion:Match flow pattern to infusion direction and resin viscosity.

RTM/HP-RTM:Design around injection points and pressure distribution.

Prepreg:Perforations should have a specific purpose,not copied from infusion designs.

7.Protect Critical Areas

Avoid removing core material near inserts,fasteners,joints,and load-introduction zones.Design sequence:

Load requirements→Core geometry→Flow requirements→Feature design→CNC machining

8.CNC Customization

CNC machining enables customized perforation patterns,groove networks,variable depths,and localized flow channels—placing features only where needed.

9.Design Checklist

Question	Check
Why needed?	Resin flow,air evacuation,assembly?
Where needed?	Entire core or localized?
How much flow?	Process requirements
How much removal?	Remaining core integrity
Critical zones nearby?	Inserts,joints,load areas
Manufacturable?	CNC capability and tolerances
Verified?	Flow and structural requirements