Overview

reel to reel etching for encoders produces the slotted code wheels and linear scales that sit at the heart of rotary and linear encoders, on a continuous metal reel instead of as individual sheets. Thin 301 or 304 stainless foil from 0.05 mm to 0.30 mm is laminated, exposed and etched from both sides, so the radial slot width, slot count and duty cycle come straight from the artwork. Because the process is chemical, slot walls stay vertical and the disc leaves the line flat and burr-free, which is what keeps the optical edge clean and the pulse train symmetric. Reel-to-reel handling means one coil can carry thousands of identical code wheels for automated pick-and-place.

For a buyer, reel to reel etching for encoders is defined by radial slot width and registration. The slot width fixes the mark-to-space ratio, while the registration between the inner and outer slot rings decides phase accuracy and direction sensing, so both must be called out with a datum and a tolerance rather than a typical value. A qualified reel line holds ±0.01 mm on slot width and ±0.02 mm on concentricity, and logs line speed and tension so a full coil stays on pitch. Prototype reels use the same film and line as production, so a code wheel that passes an encoder signal test transfers to volume without re-qualifying the pattern.

Parameter Window

• Available Materials: precision-rolled 301/304/316L stainless, 17-7PH, copper and nickel-iron alloy foils
• Material Thickness Range: 0.05-0.30 mm foil on 150-300 mm reels; spliceable coils for long runs
• Tolerance: ±0.01 mm on radial slot width, ±0.02 mm on concentricity, ±0.05 mm on slot pitch
• Minimum Feature: 0.05 mm slot width at 0.10 mm pitch on 0.05 mm foil; web down to 0.05 mm
• Surface Options: passivated, blackened, anti-reflective coating, adhesive backing, hub bonding, slit-to-width
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Encoder Pattern Review — Import the slot count, radial width, duty cycle and index mark, and define the datum for both slot rings.
2. Foil & Reel Selection — Choose 301 for spring flatness or 316L for harsh sites, and set reel width and core size.
3. Web Cleaning & Lamination — Degrease the moving web and laminate resist on both faces under closed-loop tension.
4. Exposure — Expose the slot pattern through registered films as the reel indexes, keeping concentricity to the hub.
5. Development — Develop on the fly and inspect slot opening for residual resist before the etch chamber.
6. Etching — Spray from both sides with dwell tied to line speed so radial slot width and wall verticality hold.
7. Stripping & Finishing — Strip, passivate or blacken for contrast, then bond hubs or apply backing while still on reel.
8. Inspection & Rewind — Scan slot width, pitch and concentricity by camera, log speed and tension, then rewind to length.

Core Advantages

1. Controlled radial slot width: Slot width holds ±0.01 mm, so the mark-to-space ratio and pulse symmetry stay on spec.
2. Tight registration: Inner and outer slot rings register to ±0.02 mm, which protects phase accuracy and direction sensing.
3. Clean optical edge: Vertical, burr-free slot walls give a sharp light-dark transition with low jitter.
4. Reel-to-reel throughput: A continuous coil yields thousands of code wheels for automated assembly with little handling.
5. Stable pitch: Line speed and tension are logged, so slot pitch does not drift from the first metre to the last.
6. Prototype-to-volume parity: Trial and production reels share one film and one line, so the signal test carries over unchanged.

Typical Applications

• Rotary encoders: Optical code wheels for motor feedback, robotics and servo drives.
• Linear encoders: Etched scales for CNC axes, coordinate measuring machines and stages.
• Motor commutation: Index and commutation discs for brushless DC and stepper motors.
• Automation sensors: Slot patterns for photoelectric switches and proximity sensing.
• Metrology and test: Calibration discs and reference gratings for instrument alignment.
• Consumer and office: Printer, scanner and encoder wheels supplied in reel form for high-volume assembly.

Design Notes & Process Considerations

1. Slot width and datum: For reel to reel etching for encoders, state radial slot width, duty cycle and the datum for concentricity; a typical slot value is not enough.
2. Registration budget: Allow ±0.02 mm between inner and outer rings, or phase error grows at high line counts.
3. Side-etch bias: Slots are drawn undersize by 10-20% of foil thickness per side to land on the finished width.
4. Flatness for reading: Call out flatness per 100 mm; a wavy disc changes the air gap to the sensor head.
5. Surface contrast: Specify blackening or anti-reflective coating so the optical receiver sees a clean edge.
6. Reel logistics: Define reel width, core, splice marking and maximum metres per coil for the assembly feeder.