which are individual parts of preform molds

Of the three main methods, this is the least common, despite high production capability. The next option is known as injection blow molding. Some of the various parts and containers that can be made using extrusion blow molding include hollow polyethylene products, milk bottles, automotive ducts, watering cans, and industrial drums. If the jar or container requires a wide neck, it may be necessary to perform the additional process of spin trimming. It only works for hollow parts, and the finished packages tend to be of low strength.

On the other hand, there are some key disadvantages. It’s possible to create a wide variety of complex parts using this method, even with handles being incorporated into the design. The advantages of extrusion blow molding start with the fact it is a fast production method, with relatively low tooling costs. Finally, the mold opens and the workpiece is ejected. At this point, the plastic is cooled with water flowing through lines machined into the mold for this purpose. Next, it is enclosed in a metal mold, such as aluminum or stainless steel air is then forced into the parison, causing the plastic within to take on the shape of the mold. The first of the techniques, extrusion blow molding, involves the container material being melted and extruded into a hollow tube. In 1999, more than ten billion such bottles were sold. In 1977, there was not a single soft drink sold in a plastic container. Once the process was optimized it took hold rapidly. Over the next decade, blow molding struggled to take hold at an industrial level, as there was not enough variety in the early machines and the production rates were too slow.Īs retailers, especially in the food and beverage industry, sought a packaging alternative to glass, plastic became a very attractive option. It is then ready for the next stage of the production process.īlow molding dates to the late 1930’s, when Enoch Ferngren and William Kopitke took the basic principles of glass blowing and applied them to the first blow molding machine. After the plastic has cooled, the mold opens and ejects the container or other part. This pressure causes the plastic to expand against the mold, forcing it to take on the mold’s shape. The parison or preform gets enclosed in the two halves of the blow mold cavity, at which point it will be filled with air. A preform is a plastic tube, much like a test tube in apprearance, that is heated to an elastic temperature and internally pressurized. A parison is defined as an extruded tube of molten plastic that allows compressed air to enter, expanding and cooling it. It starts by melting plastic resin and shaping it into a parison or preform. One of the most prevalent uses of this technique is to create plastic containers, although many other hollow shapes are also possible.Īll these methods have certain steps in common.

What is blow molding?īlow molding is a common manufacturing process that involves the production of hollow plastic parts. The three commonly used methods of blow molding are extrusion blow molding, injection blow molding and injection stretch blow molding. The most likely method is a technique known as blow molding, and there are several processes by which it is accomplished.Įven if a company is not directly responsible for producing containers, but instead purchases them from a distributor, it is helpful to understand the various techniques for creating them as it will determine what’s possible in terms of packaging design, production workflow and economy of manufacturing. Any manufacturer that produces plastic bottles, or any other hollow plastic container, is familiar with their common production methods.

Which are individual parts of preform molds