Blow Molding

About Blow Molding and Blow Molding Services Including: Blow Molded Cases, Blow Molded Containers, Blow Molded Plastics, Blow Molders, Blow Moulding, Blowmolding, Custom Blow Molding, Extrusion Blow Molding, Injection Blow Molding, Plastic Blow Molding, Plastic Bottles & Stretch Blow Molding.

Blow moulding is a popular plastic molding process that produces hollow, thin-walled containers and offers high-cost efficiency, long run capacity and application versatility. Blow molders manufacture many different products, including toys, blow molded cases, sports equipment, garbage cans, planters, and most commonly, blow molded containers like plastic bottles that hold many beverages including water, milk, juices, carbonated soda, liquor, beer and other foods like peanut butter and cooking oil. They also hold automotive oil, cosmetics, pesticides and herbicides. Other blowmolding products include CD cases, tanks, and any consumer item that is hollow and three dimensional in shape. 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 processes.

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 Types

• Blow molded cases are formed by blow molding processes.
  
• Blow molded plastics are plastic parts formed by blow molding.
  
• Blow molders create hollow plastic parts.
  
• Extrusion blow molding is the process in which a hot parison or preform is placed into a two-part mold. In the mold, the parison or preform is inflated with compressed air, which presses it against the walls, and then is cooled and removed by separating the mold halves.
  
• Injection blow molding blends the two methods of blow molding and injection molding and is typically used in the manufacturing of soda bottles. A preform, which is similar to the parison, is either injection plastic molded and then transferred to a blow molding machine, or the injection and blow molders are combined.
  
• Injection stretch blow molding (ISBM) is a two-stage, stretch blow molding process in which a preform is injection molded and then transferred to another station where it is blown and ejected from the machine.
  
• Plastic blow molding is a process that uses inflated thermoplastics in molds.
  
• Plastic bottles are hollow containers made of plastic.
  
• Reheat and blow (RHB) is a stretch blow molding process in which a preform is injection molded by a vendor and then purchased and reheated by another company.