The difference between blow molding and injection molding

Blow molding and injection molding are two common molding processes, but there are also many differences between the two. Today, Kunshan Juxinchang editor will give you a clear understanding of injection molding and blow molding processing.

There are several important differences between blow molding and injection molding, including molding processes, air utilization, and molded products.

1、 Molding process:

Roughly speaking, blow molding is injection+blowing, while injection molding is injection+pressing.

1. Blow molding processing

Also known as hollow blow molding, a tubular plastic preform obtained by extruding or injecting thermoplastic resin. Place it in a split mold while it is hot (or heated to a softened state), and immediately introduce compressed air into the mold blank after closing it, causing the plastic mold blank to inflate and adhere tightly to the inner wall of the mold. After cooling and demolding, various hollow products are obtained.

2. Injection molding processing

Thermoplastic injection molding is a method of melting plastic material and injecting it into a mold cavity. Once the melted plastic enters the mold, it is cooled and molded into a certain shape according to the mold cavity, and the resulting shape is often the finished product. No further processing is required before installation or use as a finished product, and many details such as protrusions, ribs, and threads can be molded in one step of injection molding. The injection molding machine has two basic components: an injection device for melting and feeding plastic into the mold, and a mold closing device.

2、 Air utilization:

Air is the enemy of injection molding. If there is air present during the manufacturing process, air pockets or bubbles may be generated, which can cause weaknesses in the product, leading to product defects and possible disposal.

But using the method of blowing air, air is very important. Blow molding processing revolves around air entering the mold to push out and expand the product. The amount of air that the mold can hold is limited before separating and leaving holes in the molten product. But without air, blow molding is impossible.

3、 Shaped products

Although there are slight differences between blow molding and injection molding types, there is a particular major difference between these two types of plastic manufacturing.

Generally speaking, blow molding is used to create a hollow space. For example, bottles are commonly used in the food and beverage industry, pharmaceutical industry, and countless other industries.

Injection processing is used to produce solid parts, such as plastic products. The blow molding process creates the shape of plastic products, while the result of injection molding is the product itself. Through injection molding, manufacturers only need to manufacture molds to ensure the success of their products. Any additional molds will be replicas of the original molds. However, for blow molding processing, manufacturers must pay special attention to production variables to ensure that each product has the same thickness.

The above are the differences between blow molding and injection molding. Do you understand? If you still don't understand, you can communicate and exchange ideas with Kunshan Juxinchang editor through QQ, WeChat, message or call the hotline