Blow moulding what is it

A patent from the time shows the process being used with celluloid polymer. These early methods were not suited for mass production. In the s, they developed commercial machines to manufacture blow-molded bottles and made mass production possible.

The materials available were too brittle and took too long to produce to effectively utilize the process to make large quantities. Blow molding exploded into industrial prevalence with the creation of low and high-density polyethylene. This revolutionized many industries including the soft drink bottling industry and the automotive industry.

Here are some commonly blow-molded products:. Blow molding is also widely used in the automotive industry and makes the design and mass production of auto parts simple and cost-effective. Here are some commonly blow-molded automotive parts:. To sum up, blow molding has a wide variety of uses and is a great way to produce a large number of parts inexpensively. There are a few different types of blow molding. Their differences lie mostly in how they form the parison, the size of the parison, and how the parison moves between the molds.

The main types of blow molding are:. After injection, the temperature of the plastic is lowered until sufficient viscosity is attained to hold its shape.

The second phase involves transferring the preform into another set of molds that contain the profile of the final product. The preforms are then blown to shape. After achieving the dimensions of the mold, the plastic is then cooled for ejection. The last phase is the ejection phase where the die is opened to release the product.

Some injection molding machines can have extra phases. The additional phases are used for additional heating or cooling cycles, preform conditioning, coating, and other secondary processes. Stretch Blow Molding: Stretch blow molding, also known as injection stretch blow molding, is basically a modification of the injection blow molding process.

This process also includes the three main phases with an additional step in the blow molding phase. In stretch blow molding, the preform is created by injecting the plastic melt into a die with a metal road at the center. The developed preform is then transferred to the product mold in preparation for the blow molding phase. Before inflating the preform, it is first stretched to a specific length by a stretch rod.

After stretching, the plastic melt is then inflated to the shape of the final product. After molding, the product is then cooled and ejected.

Stretch blow molding is not limited to plastic injection. Stretching can also be achieved in an extrusion blow molding machine. This is done by partially extruding the parison and stretching it with a pull rod. It is then enclosed by a die and is inflated to shape. The main objective of stretch blow molding is to create a product with a biaxially oriented plastic. Biaxial orientation is the process in which the plastic is stretched in two directions.

In the longitudinal direction, the plastic is stretched by the stretch rod while in the lateral direction, the plastic is stretched by inflation. A biaxially oriented plastic has many desirable qualities including high impact, tensile, and tear strength, improved barrier properties, and excellent transparency. With the increased mechanical properties, bottles and packaging materials can be made with thinner walls.

Note that not all plastics can be biaxially oriented. Injection molding requires a great deal of upfront engineering to develop detailed tooling or molds. Crafted from stainless steel or aluminum, molds are injected with liquid polymers at high temperatures under extreme pressure. The molds are then cooled to release complete plastic parts. Plastic injection molding is ideal for high-volume orders and mass production in projects requiring thousands or even millions of the same part.

Injection molds must have a high precision match between mold halves, so material flow is perfectly controlled. With injection molding, creating the mold is the key to building a perfect, precision part. When the production mold is finalized, and the machine is prepped, manufacturing begins. An initial run will be thoroughly examined for any part defects. If none are found, full production can begin. Depending on the part and the agreement with the molder, quality checks can take place on a regular basis.

They will check for strength, color correctness, and any common defects that can occur like flash or warping. Want to read the latest news from Monroe Engineering? Click Here. Skip to content. Get a Quote. What Is Blow Molding? More Popular Posts. Search for:. Privacy Policy We use cookies to improve your experience.