Bottle-shaped containers are molded by 3 processes: EBM (extrusion blow molding), IBM (injection blow molding) and ISBM (injection stretch blow molding). EBM is the oldest and least sophisticated of these processes. The following is a list of benefits and problems associated with ISBM and IBM produced bottles. Many users mix up Injection Stretch Blow Molding (ISBM) and Injection Blow Molding (IBM) in particular. The difference between these two is the word “stretch”, which refers almost exclusively to PET which is stretched to give added strength.
- IBM (Injection Blow Mold)
Injection blow molding is used specifically to create hollow plastic packaging components such as bottles or other containers of smaller volumes. The material to be used is melted such that it is malleable and will accept manipulation. Then it is gathered into a parison (a blob of hot material with a hollow top and interior) and set into the mold in order to be blown out to cover the interior walls. The machines used by Copar quickly and efficiently produce individual components, as the heating and cooling times of plastic are short. Almost as soon as the material has been molded, it can be withdrawn and finished.
Advantages of IBM processing:
▪ The preform can be injection molded in a profiled shape that corresponds to the requirements of the blow mold form.
▪ The neck form is molded in its entirety at the injection stage, resulting in a quality and precision that is superior to a blow-molded neck.
▪ There is no pinch-off scrap to be removed and recycled and no bottom seam.
Disadvantages of IBM processing:
▪ The process is difficult to use with high melt viscosity materials
▪ Integral handles, and multi wall constructions are all impractical.
Procedure of IBM:
- Molten material is injected around a pin
- The pin with the hot material surrounding it is removed from the injector
- The pin and material are set into a mold
- The mold is closed around the pin and the hot material
- Pressurized air is blown through the pin to push the material out into the interior of the mold
- The mold is opened and the molded component and pin removed
- A finishing bolt travels along the pin to remove it from the component
- The finished piece of packaging can move on to be cleaned up and decorated
- ISBM (Injection Stretching Blow Mold)
The basis of a lot of packaging container manufacturing is ISBM, which stands for injection stretch blow molding. The process begins with a plastic preform that is heated and pushed into a mold by a pin which then ejects pressurized air out of several openings. The material then fills the mold, shaping the container. The majority of ISBM lines use a three-step process that involves injection, molding, and removal phases. Our machines have an added conditioning step after the initial injection. This phase optimizes the temperature of the preforms allowing optimal material usage and the capacity to create shapes more complex than circular, like ovoidal, square, or polygonal.
Advantages of ISBM processing:
▪ Precision formed neck has smooth inside surface and requires no trimming.
▪ Maintains critical neck-finish dimensions for reliable sealing.
▪ Precise bottle weight.
▪ Better distribution of plastic and more overall uniformity.
▪ Smooth glossy surfaces inside and out.
▪ Molecular orientation of polymer chains can significantly improve bottle impact strength, transparency, stiffness, and gas-barrier properties for resins such as PET and PP.
Disadvantages of ISBM processing:
- High capital cost.
- Floor space required is high
Procedure of ISBM:
- Plastic is pushed into a pre-form mold
- A pre-form is created, which can be stored or shipped
- The pre-form is released
- In the conditioning station the pre-form is heated
- An injection pin pushes the soft pre-form into the mold
- Air is ejected from the pin to expand the material
- The material takes the shape of the mold and is completed
- Large ISBM containers have become practical for biotech applications since quality considerations are often more critical than cost. Pharmaceutical manufacturers bring ISBM advantages to biotech in sizes up to 20 liters.