The next step is to trim the tube to the specified length on both the top and bottom ends. At this point, the tube is threaded which enables us to screw on the cap. During extrusion, aluminum becomes work hardened so during the next step, it is passed through a process which makes the metal malleable. This is done at about 460 degrees centigrade.
The next step, which is used primarily in the pharmaceutical industry, is the spray application of an internal lining. This acts as barrier protection for metal sensitive products between the exposed aluminum and the pharmaceutical, or other product, to be packaged.
If the tube is not internally coated, it will bypass the internal lining step and go to the next step which is the coater rolling of a base coat onto the tube. This coat prepares the tube for the application of offset printing. The base coat is then cured and brought back to a printing machine which puts on the customer’s specified colors and copy. You can see all these tubes detailed for the different customers who require different types of decoration.
Tubes for some products require a fold sealant that acts as a barrier to prevent product seepage from the fold end of the tube. The final step in the production of aluminum tubes is the capping operation. And, again, customers generally dictate the types of styles and caps that they like. Primarily, four different materials — polypropylene, and high, medium, and low density polyethylene — are used as cap material.
The tubes are then checked, packed in boxes, inspected and loaded either into cartons or on skids for final shipment to the customer.