Blow molding machines

Fig. 14.26 Diameter (SD, thickness (S7), and weight (Sw) swell of a parison extrudate from a commercial blow-molding machine equipped with CCD camera equipment and parison pinch-off mold based on the design of Shepak and Beyer (69). (a) A chain extended multibranched polyamide-6 resin (b) the former with 12% glass fiber of 10 pm diameter 60 1 L/D and (c) polyolefin modified polyamide-6 with some carbon black. [Reprinted by permission from A. H. Wagner and D. Kalyon, Parison Formation and Inflation Behavior pf Polyamide-6 During Extrusion Blow Molding, Polym. Eng. Sci., 36, 1897-1906 (1996).]...

Figure 8-4. Schematic of three-station blow-molding machine (McCrum, Buckley, and Bucknall 1997, courtesy of Oxford University Press). Station 1 injection molding of parison station 2 blow molding of bottle station 3 ejection of bottle.

It is estimated that in USA there are about 17,000 extruders, 70,000 injection molding machines, and 6,000 blow molding machines producing about one-third of the world s plastic products. For the 80,000 IMMs in USA the usual report shows that 30% are under five years old, at least 35% are five to ten years old, and the rest are more than ten years old. 

Use is made of screw tip valves, popularly called non-return valve, ball check valve, or sliding ring valve. They are used in reciprocating injection and injection blow molding machines (IMM and IBMM) to control the melt flow in one direction (Chapter 4). There is also the smearhead for IMM, IBMM, and extruder. Back flow will not occur... 

The term dispersion refers to how well the pigments are wetted out in the plastic matrix (see below), whereas distribution refers to the uniformity of color in the part. Finally, in referring to the parts fabrication process, the term molder is used below to represent any the following pieces of equipment injection molding machine, injection or extrusion blow molding machine, or rotational molding machine. 

This type of extrusion blow molding machine uses something called a shuttle machine to get all the parts in place. Alternatively, a rotary machine, illustrated in Figure 14-61, can be used. Rotary extrusion blow molders are used in high volume applications, as in the production of laundry detergent bottles. 

The third and most successful approach was accomplished on a wheel-type blow molding machine. Unlike the shuttle machine where only gravity acts on a downward extruded parison, a wheel machine draws or pulls the parison from the die. This allows extension in the extrusion direction and the opportunity to thin down the barrier layer and reorient the mica platelets. 

At the heart of the process is the blow-molding machine. This technology is not unique to aseptic (Mocessing. In the machine, molten plastic is extruded under high temperatures (around 200 C) and pressures (350 bar) as a hollow... 

More recent is the University of Twente mixing ring (or TMR). This device is made olf three parts smooth wall barrel extension, a torpedo with semi-spherical indentations (similar to these in CTM) and a perforated sleeve that goes between them. The sleeve provides shallow indentations. It slowly rotates between the torpedo and the barrel by the virtue of a drag flow. The flow in TMR is both dispersive and distributive. The advantage of TMR is its suitability to improve mixing in injection or blow molding machines [Housz, 1989]. 

Two process variants exist. In both, the first step is to provide sterility for the blowing operation, including the air used in forming the container. In the blow and hold process, the bottle is sealed in the mold to preserve its sterility, and can then be released into a non-sterile environment. In a subsequent filling operation, it is cut open under sterile conditions, filled, and sealed again. In the blow-fill-seal process, the bottle is blown, filled with product (often while still in the mold), and sealed, all within the sterile environment of the blow molding machine, either at a single station or at multiple stations. 

For the second test, a quantitative measurement is made of the amount of plateout material that builds-up on the blow-pin of a extrusion blow molding machine. The testing procedure consists of the following ... 

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