Transformation of metal from slug into tube by the impact extrusion process does not involve any assembly of parts in the fabrication of collapsible tubes. Assembly as such takes place only after the tube is processed, i.e. fitting a closure to the nozzle of the tube. These are, however, instances where the threaded nozzle portion is a plastics molding made separately and fixed to the shoulder of the tube by mechanical swaging or rolling operation, or where the nozzle portion is injection molded into a specially designed tube shoulder. In such instances there is another assembly stage to closure fitting and packing into cartons.
Type of Closures
Closures for collapsible tube are generally made of plastic materials today, and both thermosetting and thermoplastic types are available with a variety of external shapes and internal threads for screwing tightly on to shapes of nozzle or canula, elongated caps are made to cover both canula and threaded portion, and seal the canula at its top. Membraseal type tube are usually pierce open with a spike cap of polyethylene or hard plastic. These are also a few novel on the market which offer a captive feature, but these are not used in large quantities.
IS: 3101-1979 specifies tests for:
a. Collapsibility or degree of annealing
c. Lacquer curing
d. Lacquer porosity
e. Lacquer product compatibility
f. External decoration
g. Metal particles tests for these tubes
The detail of testing procedures is however, covered in IS: 7183-1973 "Methods of Tests for Aluminum Collapsible Tubes."