Blow molding is an innovated manufacturing process to create products for industrial or everyday purposes. Blow molding is a process that is similar to the concept of glass blowing. There are several advantages for blow molding including versatility, consistent rigid structure and durability properties. Most plastics are resistance to chemicals, abrasion and other forms of abuse. Blow molding utilizes a plastic device called a parison which is expanded through the use of a metal rod or compressed air into a desired shape of the manufacturer. Blow molding is ideal for mass producing products such as water bottles or plastic containers. There are different styles of blow molding such as injection stretch blow molding and reheat & blow molding. Based on the desired product a manufacturer will choose which method accordingly. Blow molding companies invoke quality control programs to ensure the plastic walls are uniformly thick.
The use of plastic molding has revolutionized the world and products that typically use materials such as glass or metal are replaced with plastic. The usability of blown molded plastic is unmatched and nearly any industry benefits from plastic solutions. One of the biggest advantages of blow molding is the shear output from plastic manufacturers. Small or large businesses can order plastic products and receive their orders in a short amount of time. These products are commonly produced from polycarbonate, polypropylene, polystyrene, polyamide, polyethylene, Barex, butadience styrene, and acetal. The strength of the plastic is due to the fact that the polymers of plastic form durable webbing structures which is why a small amount of plastic can be stretched out without compromising integrity.
Blowmolding products include CD cases, tanks and any
consumer item that is hollow and three dimensional in shape. Blow molded
products can be used to hold automotive oil, cosmetics, pesticides and
herbicides. Blow molded plastics are all thermoplastic resins, and include high
and low density polycarbonate, polypropylene, polyvinyl chloride, Barex,
butadiene styrene, polystyrene, polyamide, polysulfone and acetal. There are 3
main types of plastic blow molding-injection blow molding, extrusion blow
molding and stretch blow molding. These processes are 2 steps and vary mostly
during the preform stages. Blow molded products take their shape depending on
the shape of their mold cavity. They come in standard sizes and shapes, while
some custom blow molding products are specifically made for unusual and unique
The blow molding process begins with melting down the plastic and forming it into a parison, or preform by injection molding. The parison is a tube-like piece of plastic with a hole in one end in which compressed air can pass through. A metal ram pushes the softened and malleable preform, expanding it to the desirable height of the product. Using a blow pin, air pressure is introduced through the inside of the parison, forcing it to balloon out and assume the shape of the mold cavity. The end product is cooled by conduction, cold water running through the mold cavity, or the evaporation of volatile fluids in the container. The purpose of blow molding services is to form a uniform finished product that is smooth, airtight and does not need to be joined together in any way. The whole process takes a few seconds, and blow molding machines can produce up to 20 thousand containers in an hour. Blow molding services use three basic methods for producing blow molded plastic: extrusion, injection and stretch blow molding.
Extrusion blow molding is the simplest type that allows for a wide variety of container shapes, sizes and neck openings, along with handleware of many kinds. It is based on the glass blowing process, and uses 2 mirror molds to create the containers, which causes a thin seam down the middle. Injection blow molding is a hybrid of the injection molding and blow molding services and is suitable for smaller containers but not for handleware of any kind. This process injection molds the plastic preform right before it is blown into a mold. There are two different types of stretch blow molding-injection stretch blow molding (ISBM) and reheat and blow (RHB) molding, both of which are typically used to manufacture P.E.T bottles for juice, water, etc. In the ISBM process, a preform is injection molded and then transferred to another station on the machine, where it is blown. Because ISBM is so costly, it requires long runs for products such as peanut butter jars, water bottles and liquor bottles. In RHB, a preform is purchased from a vendor that has already put it through an injection molding process. It is then reheated in a relatively simple machine in order to prepare it for blowing. RHB is advantageous because the purchaser does not have to invest in expensive injection molding machinery but still has access to a large catalog of existing preforms.
Distinct advantages exist for choosing the blow molding process over other plastic manufacturing processes. It is the most well-suited method for forming hollow plastic parts. It has much lower mold costs than injection molding. Blow molding has a faster cycle time than that of rotational molding. In many cases, one blow molded plastic piece can take the place of many individual parts. However, the scattering of mold thickness is a potential problem, and quality control is important to make sure none of the blow molded products have holes, leaks or unevenly thin walls. Strong, precisely even walls are better created by rotational molding or plastic extruding, but for the thousands of applications which require high volume production over precision, plastic blow molding is an ideal choice.
Blow Molded Plastics Terms
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