TROUBLE SHOOTING IN CALENDARING PROCESS
Calender sheet surface from various faults and deficiency in properties:
1) Compound formulation: The use of wrong ingredients or wrong quantities.
2) Pre-Mixing: Inadequate compounding caused by insufficient mixing too low a mixing temperature.
3) Poor Gauge: Improper temperature, improper compound, improper flow
4) Discoloration: Due to regrind material, poor compound, quality of pigment.
5) Streaks: Poor compound, improper temperature contamination
6) Thickness variation; deflection in rolls misalignment
7) Film curling or side bending: Wrong roll design, non uniform roll temperature.
Advantaging of rolling Process:
1) Delivery/output of a calendar is high
2) Versatile in product design and pattern and permits lamination and embossing without additional equipment.
3) Increase in maximum width of film/sheet.
4) Better control of film/sheet thickness.
5) The property are more uniform a cross the width of the product.
6) Better optical property due to cooling chilled rolls.
7) PVC being heat sensitive material, it is suffer by calendaring process than extrusion process.
The sheet may be soft, stiff or filled. It can be of homo-polymer, co-polymer, filled or plasticizes compounds. The calendar product quality is dependants on compound formulation.
The application include sheets in hospitals, inter-blankets, rain coats, table cloths, bathroom screen drapers , water tank liners, wall covers, thermoform sheets, listed packaging sheets, packaging application, medical application, stationary application, file, folders, luggage bag application, counter tops, flooring, upholstery, automobile application etc. They may be heat sealed: Heat shrunk for blister packaging or used plain as wrapping materials, it serve as mush as, swimming pool liners, reservoir films and vapor barriers etc.