Hole diameter design rules apply to photochemical etching of stainless steel parts | INNOETCH

For photochemical etching of stainless steel parts, hole diameter should generally not be specified smaller than the material thickness, with more stable results usually achieved when hole diameter is 1.1 to 1.5 times thickness or larger. This baseline applies to round through-holes in standard perforated components, but the practical limit changes with stainless steel grade, sheet temper, hole shape, pattern density, etch direction, edge expectations, and whether the controlling dimension is measured on the etched top, etched bottom, or a functional mid-wall position.

Why hole size cannot be judged separately from material thickness

Etching removes metal from exposed openings in a controlled way, so the starting sheet thickness directly affects how cleanly a hole can break through and how much wall taper or corner radius may remain. A hole that looks small on a CAD view may be easy to produce in thin stainless foil but difficult to hold consistently in a thicker sheet, because etchant action must penetrate the full section while still preserving adjacent bars, webs, and part edges.

When that ratio falls below approximately 1:1, the feature should be treated as a special review item rather than a standard manufacturable opening. In some thin-gauge applications, smaller openings may be possible, but feasibility should be confirmed before tolerances are finalized or tooling artwork is released.

How hole shape, spacing, and pattern density change the process window

Round holes are usually the most stable etched opening geometry because they distribute etchant flow more evenly than narrow slots, sharp-cornered squares, elongated holes, or dense decorative patterns. As geometry becomes more asymmetric, local etching can become less uniform, which shifts effective opening size and makes edge quality more sensitive to process control.

Hole diameter also interacts with the material between features. If hole-to-hole spacing or hole-to-edge distance is too narrow, the shared web can undercut more quickly, producing oversized openings, reduced straightness, or fragile sections that are difficult to handle and inspect. This is especially relevant for precision mesh, filter screens, speaker grilles, encoder discs, fluidic plates, and other perforated stainless steel components where open area, pitch, and web strength all affect function.

• Isolated holesusually have a wider process window than dense arrays because local etchant exchange is more predictable.
• Dense hole fieldsmay show size differences across the panel if etchant flow varies between edge and center regions.
• Narrow slotsshould be reviewed against both width and length, because long narrow openings can etch unevenly along their axis.
• Holes near part edgesrequire extra spacing review to avoid edge breakdown or weakened land areas.

Which drawing details determine whether a hole requirement is production-ready

The etched opening may have a slight radius or break at the surface, and in thicker material the wall is not always perfectly straight. Designers should therefore state which diameter controls function: the top opening, the bottom opening, a specified mid-wall size, or a go/no-go assembly condition.

When preparing files for quotation or prototype review, include the stainless steel grade, sheet thickness, hole diameter, tolerance expectations, hole pitch or spacing, hole-to-edge distance, surface requirements, burr or edge expectations, quantity range, and application conditions. If a reference sample exists, identify which dimensions are functional and which are visual or general reference. Flatness notes should also be added for thin perforated parts with high open area, because these parts can be more sensitive to handling and inspection method. For project review, drawings, material specifications, dimensions, tolerances, quantity and application requirements can be sent to nico@innoetch.com.

How to verify hole features before sample approval and production release

Before approving samples, confirm that the inspection method matches the part’s actual use. A hole measured optically from one side may give a different value than a pin gauge check or a functional assembly test, so the acceptance method should be defined early rather than resolved after parts are produced. This reduces iteration time and helps avoid situations where a drawing appears acceptable on paper but requires adjustment for stable etching.

A practical review sequence for stainless steel etched holes is。

1. Confirm material grade and finished sheet thickness.
2. Check that hole diameter is not below material thickness without special engineering review.
3. Verify hole-to-hole and hole-to-edge spacing against web strength and undercut risk.
4. Mark critical dimensions separately from non-critical dimensions.
5. Define the inspection method for hole size, edge quality, and opening consistency.

INNOETCH Technology (Dongguan) Co., Ltd. is a professional precision metal etching manufacturer located in Dongguan, Guangdong, China, established on March 3, 2003. The company supports prototype development, engineering design optimization, precision manufacturing, process control, quality management, and stable mass production under ISO 9001 quality management. On INNOETCH, design review focuses on burr-free edges, fine etched structures, smooth openings, tolerance control, and batch-to-batch uniformity for custom etched stainless steel and other thin metal components.

Frequently Asked Questions

Can photochemically etched stainless steel holes be smaller than material thickness?

Features below the 1:1 diameter-to-thickness ratio require project-specific review. They may be possible in some thin materials or limited patterns, but they are more sensitive to alloy, etch uniformity, spacing, and edge quality requirements.

Why do dense hole arrays need more design review than single holes?

Dense arrays change local etchant exchange across the sheet, which can shift hole size between regions of the panel. Spacing, pitch, open area, and web width must be checked together to avoid over-etching or weak sections.

Should hole tolerances be marked to the top, bottom, or middle of the etched opening?

The controlling dimension should follow the function of the hole. If the opening is used for alignment, fluid flow, screening, optical transmission, or assembly clearance, mark the specific diameter location or functional check method on the drawing.

What edge condition is normal for etched stainless steel holes?

Photochemical etching typically produces burr-free edges, but a slight etch radius or corner break may be present depending on thickness, exposure control, and etch time. Edge expectations should be stated clearly if they affect function or inspection. In actual projects, Innoetch can help review materials, drawings, samples and application conditions for a more suitable manufacturing and application approach. For project-specific review, customers can provide drawings, samples, material specifications, dimensions, tolerances, quantity, application conditions and delivery requirements to Innoetch.