Blow molding process has long been one of the main production methods of many industries in life. What is blow molding is something that every investor must clearly understand. Understanding how blow molding works and its pros and cons will help optimize the production quality of your upcoming project. The following article is the most detailed and reliable answer!
1. What is Blow Molding?
Blow molding is a popular manufacturing process used to produce hollow plastic products.
This process involves a series of steps to transform plastic material into various shapes and sizes. First, this process involves melting the plastic and forming a block or a piece of plastic in the form of a tube. Next, air is blown into the original plastic block. This step causes the plastic piece to swell into the shape of a pre-established mold.
2. The History of Blow Molding
Did you know that blow molding has been around for centuries? It shares its roots with the ancient art of glassblowing, where skilled artisans would heat glass until it melted and then use a tube to blow air into it, shaping the molten glass. This technique dates back to the 1800s.
By the 1930s, commercial blow molding machines were invented, paving the way for mass production. However, the materials available back then were brittle and took a long time to produce, making it challenging to create large quantities efficiently.
The widespread adoption of blow molding truly began with the creation of low and high-density polyethylene (LDPE and HDPE). Thanks to polyethylene (PE), we now have countless everyday products made by blow molding like soda bottles, car parts, and so much more!
3. How Does Blow Molding Work?
The blow molding process also includes steps that are not too complicated. The steps below can be repeated continuously for a long time, making blow molding always the ideal choice for mass production. Let’s find out the steps below:
3.1. Melting the plastic
To help the blow molding process be easier and smoother, it is necessary to melt the original raw plastic material. The materials commonly chosen for this process include thermoplastics such as polyethylene, polypropylene or PVC. This process helps to obtain soft, flexible and easy-to-mold plastic material.
3.2. Forming Parison
Parison in blow molding is understood as the plastic material after being melted and extruded into a hollow tube. They are Parison and will be the main component that will be inflated and shaped. During the injection blow molding process, the plastic will be injected into a pre-shaped mold to form Parison.
3.3. Positioning the Parison in the mold
In this step, the Parison is carefully placed inside the mold. The mold for blow molding is usually a mold that is made to represent the desired shape of the final product (such as a bottle, jar or container). In particular, this process requires the mold to be tightly closed around the Parison to ensure that they fit as tightly and accurately as possible.
3.4. Blowing air into the Parison
After accurate positioning, the next step in the blow molding process is to blow air into the Parison. The air is introduced to help inflate the plastic, causing it to expand and fill the inside of the mold. In addition, the air requires pressure to put pressure on the plastic, causing it to bulge tightly against the mold walls to form the desired shape.
3.5. Cooling and solidification
This process will help the blow molded product cool and harden inside the mold. When the plastic material has cooled, it will solidify into the shape of the final product. At this step, we can see the shape and structural integrity of the product.
3.6. Finishing the product
This is the final step in blow molding. The mold will be opened and the newly formed product will be pushed out. However, the product at this step still has excess plastic edges, also known as “flash”. The excess plastic will be cut off to ensure the aesthetics of the final product.
4. Types of Blow Molding
Blow molding is also divided into many different types. Depending on the production needs, manufacturers can choose the appropriate type of blow molding. Here is an overview of the types of blow molding:
- Extrusion blow molding (EBM): is often used to produce empty bottles, jars and containers.
- Injection blow molding (IBM): is ideal for small-sized items, such as medical containers or cosmetic bottles.
- Stretch blow molding (SBM): involves stretching the molding tube. This type of blow molding is suitable for producing PET bottles for beverages and other types of transparent containers.
- Co-extrusion blow molding: allows multiple layers of plastic to be extruded together. They are often used in the blow molding process of products such as fuel tanks or containers that need to be moisture-proof.
Read more: What are the different types of blow molding?
5. Advantages of Blow Molding
The reason why blow molding is always one of the ideal manufacturing options in mass production is because it possesses countless benefits. Here are some of the great benefits that the blow molding process brings:
5.1. Cost savings for large-volume production
Blow molding is known for its efficiency in optimizing costs during the production process. The blow molding method brings productivity to create a large number of hollow plastic items. Although it produces at a large capacity, the installation process is not too complicated and labor-intensive. After the mold and equipment are installed, the blow molding process will take place continuously without the need for secondary operations.
5.2. Use flexible materials
Choosing materials for blow molding is not too difficult. They work with a variety of thermoplastics, including polyethylene, polypropylene, and polyvinyl chloride (PVC). Thanks to the flexibility in choosing materials, manufacturers will have more options based on the specific properties they need. They can consider chemical resistance, durability or transparency, etc.
5.3. Ability to create complex shapes
This is one of the top criteria that makes blow molding always favored. They are an ideal method for manufacturing products with complex shapes. Not only basic designs, blow molding also produces applications with handles, curves and more complex details.
5.4. Lightweight and durable products
Blow molding has the criteria of producing light but durable products, with high impact and abrasion resistance. The weight criterion also helps a lot in the fuel saving process of the equipment that blow molding contributes to.
5.5. Reduced waste
Blow molding is a process of melting materials. Therefore, the excess plastic parts cut from the final product can also be reused. This not only saves material, but also helps to reduce material waste to the environment.
6. Disadvantages of Blow Molding
Despite the great benefits of blow molding, it does have some drawbacks. Consider the following to optimize the quality of your printed products:
6.1. High initial setup costs
Although blow molding is known for its cost-saving benefits for the production process, it does require initial setup costs. It requires investment in machinery, molds and some molding tools, so there will be a certain investment cost.
6.2. Surface defects
During the blow molding process, some small defects will sometimes occur on the surface of the product. The reason is that if the blank does not expand evenly in the mold, it will lead to uneven or imperfect surfaces. The solution to this problem is quite simple. Carefully check the quality of the plastic material, frame shaping and precise pressure to avoid causing uneven blank expansion.
7. Blow Molding Applications
7.1. Bottle and container manufacturing
Blow molding is considered an ideal choice in the plastic bottle and plastic container manufacturing industry. Some applications include plastic bottles for beverages, household cleaners and personal care products. These products often have excellent properties such as light weight, durability and beautiful and diverse designs.
7.2. Automotive technology
Blow molding contributes to the role of manufacturing large hollow parts in the structure of the machine. Some common applications are fuel tanks and air ducts for vehicles. The products are durable, strong and can withstand pressure and chemicals. In particular, blow molding gives the equipment a weight advantage. Light weight contributes to fuel economy during vehicle operation.
7.3. Containers and industrial containers
Blow molding is an excellent method for manufacturing general container applications. Most of these types of containers have excellent capacity to store liquids such as chemicals, oils and food products, etc. This method also helps to design containers with large sizes and large capacities.
7.4. Household items
This is also one of the popular applications in the production of household goods. Some applications include plastic containers, water bottles and detergent bottles. Thanks to the flexibility and good shaping ability of blow molding, these household products are often diverse and sophisticated in design.
7.5. Toys
Blow molding is the optimal production method for children’s toy applications. Many toys are hollow in shape such as balls, kitchenware sets, medical kits, fruit sets, etc. The toys that blow molding brings are often diverse in size and extremely eye-catching designs.
Read more: Top 10+ Innovative Plastic Products Made with Blow Molding
8. Conclusion
In conclusion, it can be seen that blow molding brings great convenience to the production process. They are considered ideal for the production of large quantities of hollow products. Besides, the benefits of blow molding for each application are very impressive and valuable. Understanding the process and advantages of blow molding will contribute to improving the production cost for your upcoming project. Our EuP Egypt is proud to bring the most useful and reliable information about plastic material knowledge. Contact us now!
