Microhole burrs can interfere with an opening that otherwise meets its diameter requirement. An edge that appears minor on a larger part can become significant when the entire passage measures only a fraction of a millimeter.
For a custom component, the goal is a clearly defined acceptable edge. This guide explains the requirements for doing so. Also, start with our microholes spotlight for an overview of the complete feature.
Separate Burrs from Other Edge Conditions
A burr is unwanted material projecting from an edge. Loose debris is a separate cleanliness issue. A machining process can also leave surface changes or attached material that require a different description. Grouping every condition under a general note can make acceptance difficult to interpret.
At the same time, a deliberately specified chamfer or edge radius is part of the design. It should not be confused with damage or accidental rounding. State which conditions are permitted and where they apply.
Why Entrance and Exit Edges Both Matter
A through-hole has at least two edges to review. Their function may differ. One might contact an adjacent surface while the other faces a fluid stream or a delicate assembly component. Define the critical side rather than assuming the same treatment is appropriate everywhere.
For a hypothetical 40-micron opening, a 4-micron projection into the passage occupies 10% of the nominal diameter in that direction. This simple comparison does not predict performance, but it illustrates why the absolute size of an edge defect needs context.
If an edge changes the usable entrance or exit diameter, review it alongside the microhole taper requirements. The inspection location should be clear enough to distinguish the edge treatment from the bore.
Make the Edge Requirement Measurable
A note such as burr-free may communicate intent without explaining acceptance. When edge condition is critical, discuss what will be inspected and how. Useful details include:
- The entrance, exit, or both sides covered by the requirement.
- Any maximum permitted projection or edge break.
- Restrictions on loose particles and attached debris.
- The required condition after finishing and cleaning.
- The agreed inspection method and acceptance examples, where useful.
Do not add extremely tight edge limits automatically. Tie the requirement to fit, flow, handling, or another function so the manufacturing review can focus on what the part needs.
Finishing Can Change the Opening
A finishing operation intended to improve an edge may also change its dimensions or shape. Review the finished hole, including any post-processing, against the drawing. A satisfactory as-machined opening does not by itself establish the final condition after subsequent operations.
The appropriate sequence depends on the material and geometry. Micromachining services are a starting point for discussing the component as a whole.
Verify Edge Quality Across a Pattern
For microhole arrays, specify how edge defects or blocked openings will be assessed across the pattern. A single attractive microscope image should not stand in for an agreed inspection plan.
Our microhole inspection guide explains how to connect visual checks, dimensions, and functional requirements.
Discuss Your Microhole Edge Requirements
Send your drawing, material, quantities, and a description of how the hole functions. Include edge limits and cleanliness requirements with the RFQ so we can coordinate a review of manufacturing and finishing options.
- Upload your CAD file or drawing
- Review custom dimensions and material options
- Receive engineering support for your application