Please enable JavaScript.

Coggle requires JavaScript to display documents.

Week 4: Packaging Closures & Integrity, Gaskets: rubber or plastisols…

- - - - Inexpensive
      - single-use
    - - Pry-off Finish: with large solid ring of glass to enable corrugation of crown to be crimped
      - Twist-off: has 4 non-continuous thread where the crown can crimp into the threads to form seal.
  - - - Provides hermetic sealing, tampering evident & retain gases/ vacuum.
      - Re-closable.
    - - Range from 18 – 38mm. Made from coated, decorated aluminium sheet and lining material (e.g. plastics or plastisols )
        
        Plastic tamper evident closure (HDPE or PP) is typically 28mm. For carbonated drinks, PET bottle has 4 vertical slots to allow venting of CO2 during opening. Breaks in the thread of cap align with the slots to allow gradual release of pressure
        
        ROTE metal cap (no threads) are dropped onto container finish. Roll-on capping machine rolls cap’s sidewalls into container & forms a thread in the closure that duplicates container’s thread
  - - - Enable faster closure than continuous threaded metal closure since seal can be accomplished in lesser rotation (<90o)
        
        Lug & container’s thread interlock to create a camming action. Hermetic seal is formed when the softer liner & closure touch
      - With or without vacuum safety button (raised, circular area in centre of panel) version available. Safety button acts as visual indicator to consumer and automatic online detection for low/no vacuum containers
      - Suitable to retain vacuum. Can open without using tool. Good re-sealablity
    - - 30 to 110mm size with smooth or fluted side walls. ECCS with 3,4 or 6 lugs & flowed-in plastisol liner or gaskets
  - - - 1st stage – Cover’s curl edge interlock with can body flange by tucking flange underneath body hook. Cover and can body make up 3 layers
      - 2nd stage – Seam is tighten by rolling and compressing these thickness. Lining compound at curl edge of cover will form a seal within the double seam to fill any imperfections
- - - - multi-laminate liner inside a closure is exposed to high frequency electromagnetic field. The current produces localized heat in foil sufficent to melt the sealant layer without contacting the coil & package
    - - Suitable for laminated material e.g. foil with LDPE/LLDPE
      - Most common heat sealers used in industry. Can be continuous application e.g. band sealer