Cleartran ZnS is a denser, tougher grade of zinc sulfide that requires more disciplined cutting control than standard CVD ZnS. Cut it with standard parameters and you get acceptable dimensions but elevated subsurface damage — which shows up later as scatter in the finished window. Cleartran ZnS window manufacturing done correctly delivers cut surfaces with Ra 0.6–1.2 μm and TTV within 8–15 μm on Φ50 mm blanks, ready for polishing with minimal additional stock removal.
We process Cleartran ZnS windows using endless diamond wire saws. This page covers the machine setup and the cutting results we deliver on Cleartran window blanks.
Why Diamond Wire Saw for Cleartran ZnS
Cleartran is brittle and chips at the blank edge when cutting forces are applied unevenly. Diamond wire saws are the preferred cutting method for Cleartran ZnS window manufacturing because the wire distributes cutting contact across many abrasive points simultaneously, keeping lateral force at any single point low.
The alternative — ID saw blade cutting — applies localized force at the cut entry and exit edges, which produces more edge chipping and deeper subsurface damage on Cleartran. For high-value Cleartran blanks where yield per boule matters, wire saws recover more usable windows per cut sequence.
| Parameter | Diamond Wire Saw | ID Saw |
|---|---|---|
| Kerf width | 0.25–0.45 mm | 0.3–0.6 mm |
| Edge chipping risk | Low | Moderate to high |
| Surface Ra after cutting | 0.6–1.2 μm | 0.8–2.0 μm |
| TTV (Φ50 mm) | 8–15 μm | 10–25 μm |
See the ZnS optics cutting machine guide for a detailed wire saw vs ID saw comparison across the ZnS material family.
Our Approach to Cleartran ZnS Window Cutting
We use the same endless diamond wire saw platform that we use for standard ZnS, ZnSe, and germanium optics processing. What changes for Cleartran is the process discipline around wire selection, feed control, and blank mounting — not the equipment itself.
Wire selection. We use electroplated diamond wire for Cleartran cutting. Wire diameter is matched to blank size — thinner wire for smaller blanks where kerf efficiency matters most, larger diameter wire for bigger blanks where dimensional stability across the full cut is the priority. The specific wire diameter for a given job is determined during first-article validation.
Entry and exit zone control. The wire entry and exit edges are where Cleartran chipping risk is highest. We use a programmable feed profile that runs slower during the entry and exit portions of each cut, and at full production speed through the main body of the cut. This prevents lateral force spikes at the moments when the wire is engaging or exiting the blank edge.
Blank mounting. Every Cleartran blank is bonded to a glass or carbon backing block before cutting. The backing prevents the wire from cutting into open air at cut completion, which eliminates one of the most consistent sources of exit-zone chipping.
Coolant. White mineral oil, with flow rate targeted at the wire entry point to keep the kerf clear of ZnS swarf throughout the cut. Debris that stays in the kerf scores the cut surface and produces streaks that require additional polishing to clear.
First-article validation. For every new Cleartran job, we cut and measure a first-article blank before committing to production parameters. Parameter windows shift with blank diameter, Cleartran boule origin, and wire wear state — the validated parameter set for one job may not transfer directly to the next.
Cutting Results We Deliver on Cleartran ZnS Windows
The output metrics from our standard Cleartran cutting setup:
| Output Metric | Achieved Value |
|---|---|
| Surface Ra | 0.6–1.2 μm |
| TTV (Φ50 mm blank) | 8–15 μm |
| Kerf width | 0.25–0.45 mm (depends on wire diameter) |
| Edge chipping | Controlled with backing support and entry/exit feed reduction |
Values assume the first-article validation step is completed. Blank size, geometry, and Cleartran grade all influence achievable results — for blanks or requirements outside our standard range, please share your drawing and target specs for a job-specific feasibility review.
Cleartran vs Standard ZnS: What Changes at the Cutting Step
| Cutting Factor | Standard CVD ZnS | Cleartran ZnS |
|---|---|---|
| Feed rate | Baseline | Reduced — Cleartran is harder |
| Wire tension control | Standard | Tighter — drift affects TTV more |
| Coolant flow | Standard | Higher — swarf management critical |
| Entry/exit feed control | Recommended | Mandatory |
| Backing support | Recommended | Mandatory |
| First-article validation | Standard | Required before each production batch |
The practical difference: Cleartran requires more process discipline at each step, not different equipment. The same wire saw platform handles both — the setup time and parameter verification are what change.
For related ZnS cutting guidance, see multispectral zinc sulfide processing and the ZnS optics cutting machine overview. For our full range of IR optical materials, see the infrared optics manufacturing equipment Pillar page.
FAQ
What machine do you use for Cleartran ZnS window cutting?
Endless diamond wire saw machines — the same platform we use for standard ZnS, ZnSe, and germanium optics processing. The machine does not change; the wire parameters and feed profile change to match Cleartran’s higher hardness and damage sensitivity.
What surface quality can you achieve on Cleartran ZnS windows?
Ra 0.6–1.2 μm and TTV 8–15 μm on Φ50 mm blanks with diamond wire cutting. These are the baseline values from our standard Cleartran cutting setup — actual results depend on blank size, wire diameter, and first-article validation findings.
What is the minimum order quantity for Cleartran ZnS window cutting?
We work with both single-piece trial cuts and production runs. Contact us with your blank dimensions and quantity to discuss lead time and setup requirements.
Can you cut Cleartran ZnS to custom shapes?
Yes. Our wire saw machines support straight cuts for window blanks, as well as contour cutting for non-rectangular window shapes. Send us your drawing for feasibility review.
How does Cleartran ZnS cutting differ from ZnSe cutting?
ZnSe is softer than Cleartran ZnS and generally runs at higher feed rates. The entry/exit zone feed reduction and bonded backing approach are similar for both materials. See the zinc selenide optics polishing page for ZnSe process details.
