Overview

Etched stainless steel grating uses photochemical machining to cut precise line, slot and bar patterns into thin stainless foil without a stamping die or mechanical force. The grating artwork is imaged onto photoresist, developed, and the exposed metal is dissolved in a ferric-chloride spray, so line width, pitch and duty cycle are set by the artwork and etch time rather than by tool pressure. Typical substrates are 304 / 316L and low-expansion Invar 36 between 0.02 mm and 0.3 mm. Because removal is chemical, the grating leaves the line flat, burr-free and stress-free, with straight slot walls and no rolled edges or heat tint — essential when the part is read by an optical encoder, spectrometer or metrology camera.

For buyers of encoder scales, spectrometer slits, alignment reticles and stray-light baffles, the process solves three recurring problems. Punching or laser cutting thin foil leaves dross, burrs and heat-affected edges that scatter light and blur slot boundaries; optical parts demand line width, pitch and cumulative accuracy at the 0.03 mm scale; and any residual stress warps the foil and shifts the optical path. Chemical machining forms every slot on a sheet at the same rate, holding line width and pitch consistent from the first sample through volume production, and an anti-reflective blackening or electropolished finish keeps stray reflections low.

Parameter Window

• Available Materials: 304 / 316L stainless, 430 stainless; also Invar 36 / 316LVM for low-expansion builds
• Material Thickness Range: 0.02–0.3 mm foil
• Tolerance: ±0.005 mm line width, ±0.01 mm pitch, cumulative pitch error specified per 100 mm
• Minimum Feature: 0.03 mm line/slot, 0.03 mm bar, duty cycle up to 50%
• Surface Options: electropolishing, nitric/citric passivation, black oxide / PVD anti-reflective coating, precision dicing, optical-grade clean
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Artwork & Pitch Verification — Convert the line/slot pattern to vector art, verify pitch, duty cycle and cumulative error budget.
2. Material Certification & Prep — Verify grade, thickness and flatness, then shear to exposure size under clean handling.
3. Cleaning & Lamination — Degrease and laminate dry-film resist on both faces to keep fine bars fully supported.
4. Double-Sided Exposure — Image front and back with registered photo-tools so slots stay vertical through the foil thickness.
5. Development — Wash out unexposed resist to open the slot areas and inspect for residue bridging narrow bars.
6. Controlled Etching — Spray ferric chloride tuned to time, temperature and conveyor speed for straight walls and uniform line width.
7. Stripping & Blackening — Remove resist, neutralize, then blacken, passivate or electropolish to cut stray reflections.
8. Optical Inspection & Clean Packing — Measure line width, pitch and defects on a vision system, then pack flat in clean trays.

Core Advantages

1. Straight burr-free walls: Chemical removal leaves clean vertical slot edges with no dross, so optical contrast stays sharp and scattering stays low.
2. Ultra-fine uniform pitch: 0.03 mm lines and bars form together across a sheet with tight width spread and consistent duty cycle.
3. Stress-free flatness: With no shear or heat input, thin foil stays planar, keeping the optical path and reading head in focus.
4. No die cost: Each new grating pattern is a new film, keeping prototype scales and custom pitches economical.
5. Cumulative pitch accuracy: Panel-level registration holds line placement over long scales, limiting accumulated error.
6. Low-reflection finish: Etched stainless steel grating accepts black oxide, PVD or electropolishing, suppressing stray light in readout systems.

Typical Applications

• Optical encoder scales: Linear and rotary grating scales that set position feedback resolution.
• Spectrometer & monochromator slits: Precision entrance and exit slits with clean, straight edges for defined bandpass.
• Moiré & metrology reticles: Alignment and measurement grids for machine vision and flatness inspection.
• Light baffles & stray-light grids: Fine bar arrays that block off-axis light in optical instruments.
• EMI & optical shielding grids: Conductive meshes that shield while passing a controlled light or air fraction.
• Precision aperture & code arrays: Encoded slot and aperture patterns for sensors and indexing devices.

Design Notes & Process Considerations

1. Aspect ratio: Keep slot width at or above material thickness; very narrow, deep slots distort from undercut and thin the bar.
2. Pitch and cumulative error: State nominal pitch, tolerance and allowable accumulated error per 100 mm, not just line count.
3. Duty cycle callout: Define line-to-bar ratio and open fraction, since contrast and stiffness move together.
4. Flatness and mounting: Specify flatness per 100 mm and the mounting method, as clamping can bow a thin scale and shift readings.
5. Anti-reflection treatment: Call out blackening, PVD or electropolish and the target reflectance for the detector wavelength.
6. Optical cleanliness: With etched stainless steel grating, define particle limits, handling and clean packing, since a single speck can read as a false line.