Bobbin Build The package geometry

Bare Bobbin Diameter mm

Full Bobbin Diameter mm

Traverse Lift mm

Package Density kg/m3

Frame & Doffing What fills it and what it costs to change

Roving Linear Density ktex

Front Roller Delivery m/min

Doff Time min

Spindles on the Frame

Shift Length h

Doff Interval

— min

Running time to fill one set of bobbins

Package, Loss & Output

Roving per Bobbin: — kg
Roving Length per Bobbin: — m
Production Lost to Doffing: — %
Doffs per Shift: —
Roving per Doff: — kg
Effective Frame Production: — kg/h
Package Volume: — dm3
Build Ratio: — x

The package is treated as a plain annular cylinder. A real roving bobbin is built with tapered ends so that it can be doffed and handled without the coils collapsing, and that taper removes a few per cent of the nominal volume - so measured capacity runs below the geometric figure. Package density must be measured rather than assumed; it moves with twist, winding tension and build settings. The doff time entered should be the full frame-stopped time including creeling and restart, not the time to strip the bobbins - restart to full speed is a real part of it. Effective production assumes doffing is the only stoppage; ends down, cleaning and lot changes are additional and are not included here.

Roving Bobbin Build, Doff Interval & Changeover Loss — free, with the formula and a worked example, at Textile School.