Plastic / Aluminum / Laminate

  Plastic Tubes

The typical plastic tube manufacturing process is composed of the following steps:

• Extrusion
• Heading
• Decorating
• Capping

The first phase of the manufacturing process is extrusion. A mixture of resin and color concentrate is placed into an extruder hopper. The extruder is temperature controlled as the resin is fed through to ensure proper melt of the resin.

The material is extruded through a set of sizing dies that are encapsulated within a right angle cross section attached to the extruder. At this point, the sleeve is water-cooled and ready for cutting. The sleeve is fed through a set of dies at which time it is sliced to a given length by a rotating knife. The balance of the manufacturing process can be accomplished in one of three ways.

The most common method in the U.S. is the "downs" process of compression, molding the head onto the tube. In this process, the sleeve is placed on a conveyor that takes it to the heading operation where the shoulder of the head is bound to the body of the tube while, at the same time, the thread is formed. The sleeve is then placed on a mandrel and transferred down to the slug pick-up station. The hot melt strip or slug is fused onto the end of the sleeve and then transferred onto the mold station. At this point, in one operation, the angle of the shoulder, the thread and the orifice are molded at the end of the sleeve. The head is then cooled, removed from the mold, and transferred into a pin conveyor.

Two other heading methods are used in the U.S. and are found extensively worldwide: injection molding of the head to the sleeve, and an additional compression molding method whereby a molten donut of resin material is dropped into the mold station instead of the hot melt strip or slug.

The beaded tube is then conveyed to the accumulator. The accumulator is designed to balance the heading and decorating operation. From here, the tube goes to the decorating operation where, with offset printing, it is decorated with up to six different colors. Inks for the press are premixed and placed in the fountains. At this point, the ink is transferred onto a plate by a series of rollers. The plate then comes in contact with a rubber blanket, picking up the ink and transferring it onto the circumference of the tube. The wet ink on the tube is cured by ultra-violet light or heat. A similar method is used to apply a protective coating to the tube.

After decorating, a conveyor transfers the tube to the capping station where the cap is applied and torqued to the customer's specifications. The tube is then transferred to a conveyor belt and packed into a tray. The trays are packed into cartons that are sealed and ready for shipment.

Aluminum Tubes

The metal, lead, tin or, more often, aluminum tube, has been around since 1841. As a testimony to its versatility and resilience, it is now packaged throughout the world with production in excess of a half billion pieces per year in the United States alone.

The manufacture of aluminum tubes starts with an aluminum slug or blank, as it is called. It is fed into a set of tools in the die which then extrude it. This extrusion press then roughly forms a completed tube form. Once this extrusion process takes place, the aluminum becomes work hardened.

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.

Laminate Tubes

Laminate tubes are manufactured by using the laminate feed stock that is simply a poly-foil-poly structure that has polyethylene on either side of a thin gauge of foil. Some laminate structures also incorporate paper. The most popular way of decorating the laminate feedstock material is by either letterpress or rotogravure printing. Rotogravure printing is used extensively to provide a high quality print buried within the laminate structure. Letterpress printing is used to decorate the surface of the laminate feedstock just prior to tubing that is ideal for added flexibility or smaller quantities.

The laminate tubes are formed by placing the rolls of laminate material onto the needles of the machine. The material is then taken in a flat state and fed through the forming rolls, which very gently turn the tube and form it into a cylinder of variable size depending on the customer's needs. Heat generated by high frequency fuses the sides of the material together to form a solid cylindrical tube. After the tube has been formed, it goes to the cutting station that slices it into various lengths.

After the tube has been formed into the desired cylindrical shape and length, the tube is transferred to the heading operation. As with plastic tubes, several heading methodologies are available. One particular method uses a preformed head. The tube is then placed onto a mandrel, the preformed head and shoulder are fed down vibrator shoots and fused to the top of the tube by means of heat generated by high frequency energy. Other methodologies apply the head to the sleeve in a similar manner to plastic tubes - either by injection or compression molding whereby heat fuses the head to the tube body.

After the complete tube has been formed, it goes to the capping station. The cap -- flat style, fez style or pedestal style -- is chosen based on the customer's needs. The cap is applied and torqued to the desired torquing requirements. The tube is then ejected onto a conveyor and taken to a packing operation where it is packed into a carton and is ready for the customer.