Four-station machine

The Martindale abrader is usually seen as a four station machine which uses cloth as the abradant, but coarser and faster acting materials can be substituted. The principal feature of this machine is that the test pieces are rubbed successively in different directions as the motion takes the form of a Lissajous figure. It is mostly used with coated fabrics62. 

The two molds needed for this process, an injection mold and a blow mold, may be located in the same molding machine or in different molding machines. In the first case, known as a one-stage process, there are multiple stations in the machine through which the material travels. For example, in a four-station machine the polymer would be injected into the preform, shuttled to a conditioning (profiled heating) station, shuttled to a blow station, and then shuttled to ejection. 

Figure 11 shows the blown bottle being ejected with the stripper moving out, and once the bottle is dropped into a container or on a conveyor belt, the stripper returns for the next cycle. Figure 13 shows a face bar which moimts to the rotating table (three-station machine requires three face bars and a four-station machine requires four face bars) to hold the core rods. 

FIGURE 26.7 The EndoLab knee simulator. This four-station machine is servo-hydraulically actuated for full force-control testing with soft tissue simulation. One of the test stations can be optionally used as a loaded soak control station. 

Generally, however, multiple station machines consist of a reciprocating screw horizontal machine with a round indexing table with four or more stations to which bottom mold halves are clamped. In this instance only one top mold half is used. Another design of rotary table machine employs four complete molds, one at each indexing station (see Fig. 4-11). 

There are both three- and four-station injection blow molding machines in the industry today. Wheaton Industries, which is one of the largest injection blow molders in the world, pioneered the four-station design, primarily for safety. However, with the movement to PET on the injection blow molding machines the fourth station has become a necessity to allow for the core rods to be conditioned through the use of an air chamber. The core rods are not temperature controlled, but are allowed to have their bodies or shanks, to cycle within a specified temperature window. 

Different configurations of turret machine are used to accommodate longer cooling or oven cycles. A four-arm, four-station layout is shown Fig. 15.18. The additional station is used to allow the cooling cycle to be extended— this is useful, for example, for thick parts or parts which are foamed. 

The injection molding technique using double layer technology is an alternative method. By this method the first preform is made of a thin layer of virgin PET. In the next step, melt from reground PET flakes is injected into the exterior of the preform layer made of virgin PET. Such technology requires two injection preform molds and subsequently a five station machine, compared with a standard machine which has four. 

The manufacturing cell occupies about 600 sq. ft. area and is comprised of two CNC machining centers (a mill and a lathe), a vision/inspection station and a Load/Unload station(Dock). These four stations and four assembly stations are connected by a conveyor system. The two closed loop conveyors are placed end to end in an L shape configuration. Figure 1 shows a schematic of the entire facility. The main conveyor loop connects the four... 

In addition to the accumulator head, a number of other machine advances have taken place in the past 20 years. These are in-mold prefinish, automated flash trimming, leak detection, and conveying to filling station. Also, dual accumulators allow up to four parisons to be extruded simultaneously and molded on the clamping unit. 

The compressor station consists of two sections of compressor machines, air tanks, a group of compressed air coolers, piping for air and for lubricating oil. The first section of compressor machines includes the first four stages of compression. After each stage, the air is cooled down from 125-130 to 40°C. Moisture is also removed during each intermediate period between successive stages of compression. The second compressor section includes one opposite piston compressor machine. 

Figure 15.18 Four-arm turret machine showing oven (1), cooler A (2), cooler B (3) and servicing (4) stations.

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