Estimate roll outside diameter from core OD, film length and thickness. This screens equipment and carton fit; winding tension, trapped air and dimensional variation still require a measured wound sample.
Use one unit system
Estimated roll OD = √(core OD² + 4 × length × thickness ÷ π)
For millimetre output, use core OD and thickness in millimetres and convert length to millimetres. Use core outside diameter, not the bore.
Worked example
For a 40 mm core OD, 300 m length and 10 micron film:
- 300 m = 300,000 mm; 10 micron = 0.010 mm.
- 40² + (4 × 300,000 × 0.010 ÷ π) ≈ 5,420 mm².
- √5,420 ≈ 73.6 mm estimated OD.
This is geometry, not a measured YIYUAN roll value.
Approve clearance physically
| Check | Record |
|---|---|
| Equipment | Maximum OD, loading path, guard/door/sensor clearance |
| Roll | Measured OD at several positions, weight and overhang |
| Carton | Protective spacing, orientation, count and closed dimensions |
The core-fit article covers dynamic use. YIYUAN’s listed lengths and thicknesses are inputs only; final OD depends on the exact build.