Microhole arrays place many small openings in a defined pattern. Potential applications include filter plates, suction fixtures, and components that distribute fluid across a surface. For these parts, the relationship between holes can be just as important as the size of each opening.
This article explores the pattern details to include when discussing custom microhole array components. Our microholes spotlight introduces the wider topic.
Define Hole Diameter and Pitch Separately
Pitch describes the spacing between hole centers. For a simple square pattern, the same center-to-center distance repeats in two perpendicular directions. Rectangular, staggered, and custom patterns need their own dimensions and orientation.
The remaining material between adjacent holes is often called the ligament. For equal circular holes on a straight row, its nominal width is pitch minus hole diameter. A hypothetical 50-micron hole on 100-micron pitch leaves 50 microns between openings before considering dimensional variation.
That example is a drawing calculation, not a production limit. The practical spacing needs review against thickness, material, tolerances, and handling requirements.
Calculate Nominal Open Area
Open area expresses how much of a specified region is occupied by openings. For an ideal repeating square array of circular holes, divide the area of one hole by the area of one pitch cell: open area fraction = πD²/(4P²), where D is diameter and P is pitch.
Using 50-micron holes and 100-micron pitch gives a nominal open area of approximately 19.6%. The calculation applies to the repeating pattern. The finished component’s overall open area may differ because of borders, mounting features, or regions with no holes.
Open area alone does not establish flow or suction performance. Passage length, hole shape, operating conditions, and the surrounding system also matter. If performance is critical, define a functional test in addition to the geometric pattern.
Locate the Whole Array on the Part
A pattern can have consistent spacing and still be misplaced relative to the component. Define the array’s origin, orientation, and relationship to the drawing datums. Include:
- Total hole count and the number of rows and columns where applicable.
- Pitch in each direction and any stagger or rotation.
- Position requirements relative to the relevant datums.
- Unperforated borders, mounting regions, and minimum edge distances.
- The permitted condition of partial holes at pattern boundaries, if any.
For a complex layout, a CAD file can communicate the pattern efficiently. The controlled drawing should still identify the tolerances and acceptance requirements.
Account for Edge Quality and Inspection
A pattern needs clean, usable openings as well as correct coordinates. Define how blocked holes, edge damage, and incomplete breakthrough will be evaluated. Our guide to microhole burrs and edge quality covers those details.
Agree whether every hole needs inspection or whether a sampling plan is appropriate for the project. Pattern checks should address location and missing or blocked openings as well as diameter. See the microhole inspection guide for planning questions.
Request a Quote for Custom Microhole Arrays
Send in the pattern file, drawing, material, thickness, and quantities. Identify the critical position, edge, and performance requirements. We can coordinate a manufacturing review using the complete pattern specification.
- Upload your CAD file or drawing
- Review custom dimensions and material options
- Receive engineering support for your application