Both blow molding and injection molding are high-volume manufacturing processes that can mold plastic into various sizes and shapes. However, blow molding is used for hollow items with thin walls, while injection molding is employed for intricate solid components. Injection molding uses high pressure to squeeze plastic into a mold. On the other hand, blow molding uses pressurized air to stretch a hollow plastic tube into a mold. In general, blow molding is less expensive than injection molding. This is because blow-molded products require less expensive tooling. After all, they are less sophisticated. Moreover, heavy-duty hydraulic rams are needed for injection molding to inject the plastic raw material and prevent the mold from leaking plastic during the injection phase.
This guide will compare Injection molding and blow molding in terms of production rate, material manufacturing process, and other important things to know.
Injection molding is a manufacturing process that uses precise molds and tools to produce solid plastic components. The component containing the final product's design is called a mold. It is created from metals like steel and aluminum using a very accurate and precise CNC machining process.
The injection process begins when the mold is designed and made. The injection molding material is first melted at a very high temperature, although it depends on the plastic polymer. Moreover, the operator applies great pressure when injecting the molten plastic into the mold. After injection, the plastic polymer is cooled to make it harder before being ejected. The component can also go through a surface polishing procedure.
These are some of the benefits of injection molding:
● High precision
● Great color options, efficiency, and material flexibility
● Cost effect and suitable for high-volume production
● creation of multi-cavity molds with incredibly fine details
The mass production of solid items with excellent details and high precision is possible with injection molding. Combs, phone cases, and container tops are a few examples. It is also suitable for the fabrication of medical and automotive parts.
Blow molding is a method of plastic molding that is similar to glassblowing. The first step is to heat the raw plastic material to a specific temperature. However, it depends on the type of plastic. The heated plastic material is then extruded, or formed into a hollow tube, or parison, using an extrusion machine.
The operator places the subject in a mold that has been prepared and blows air into the mold at a pressure of around 80 psi. As a result, the parison enlarges and assumes its shape in the mold. After cooling, the plastic solidifies and takes the form of the hollow portions specified by the mold. Delegation then takes place.
These are the three main types of blow molding :
● Extrusion Blow Molding
There are two types: intermittent and continuous. On the one hand, the continuous variation entails feeding the parsley to the mold and severing it with a blade once it has cooled. On the other hand, intermittent variation expels the molded portion before inserting a new parison. The intermittent type is, therefore, less expensive and quicker.
● Injection Stretch Blow Molding
To create a plastic object combines blow molding and injection molding techniques to create a plastic component. Making a solid pre-form via injection molding is the first step in the procedure. The pre-form is then heated and has air blown into it by a machine.
● Injection Blow Molding
The parison must be injected into the mold cavity using a blow or core rod to do this. The outcome is that the pair will resemble a test tube. After the part is placed within the mold, the air is forced onto it to help it assume its shape.
These are some of the benefits of blow molding:
● Great component design flexibility
● It reduced the need for a two-part mold component
● Low initial machine investment
● Low cost of production compared to injection molding
Blow molding is a great way to save money and make things that work well. So, it is essential to create hollow parts with thin walls all the same size. Small businesses in industries like automotive, consumer products, medical parts, pharmaceuticals, etc., use it to make hollow parts like bottles, water tanks, etc.
The distinctions between blow molding and injection molding are listed below, along with tips on how to use them for your project.
The mold design is another essential difference between injection molding and blow molding. Injection molds should be exact so that the molten plastic flows the right way when they are used. So, it employs the CNC machining process. Because the mold is so precise, injection molding can be used to make plastic parts with complicated shapes. Also, the molds are made of solid and long-lasting materials that can be used repeatedly without losing quality.
On the other hand, blow molding molds can be made in different ways. Unlike injection molding, you don't have to worry about how to design the mold. Problems like air leaks, thinner walls, streaks, and flashes happen more during molding.
In injection molding, the plastic is sealed in the injection chamber and injected into a mold already made. So, the plastic is in both the injection chamber and the mold during the whole injection process.
On the other hand, blow molding makes a hollow tube or parison by heating the plastic and blowing air through it with an extrusion machine. After that, the parison is put in the mold, and the air is blown until the final product is made.
The most significant difference between blow molding and injection molding is that blow molding is used to make hollow parts, and injection molding is used to make solid parts.
Injection molding is the best way to make hard plastic parts like bottle caps, hair combs, and computer housings. On the other hand, blow molding is suitable for making hollow goods that are flexible or strong. Bottles, coolers, fuel tanks, and arena seats are all examples.
Blow molding costs less than injection molding because it takes less time and money to set up. A blow molding machine is also less expensive than an injection molding machine.
Both methods can be used on a wide range of products. But picking a material relies on how complicated it is and what properties you want it to have. So, you need help from a professional. Most of the time, soft and bendable plastics like Acrylonitrile Butadiene Styrene (ABS), High-Density Polyethylene (HDPE), Low-Density Polyethylene (LDPE), and Polypropylene are used for blow molding. (PP). On the other hand, injection molding works well with polymers and resins made of hard plastics like polycarbonate. Still, many materials for blow molding can also be used for injection molding. Some materials that are often used for blow molding and injection molding are:
● Acrylic
It is a type of plastic that looks like glass and can't be worn down, scratched, stained or damaged by UV light. It is often used in the food and drink industry.
● Acetal
Acetal is a strong plastic that can withstand heat, pressure, and wear. It is often used in mechanical and automotive uses because of this.
● Polyetheretherketone (PEEK)
It is thermoplastic and resistant to chemicals, radiation, and high temperatures. So, it is essential for making parts used in many medical, automobile, and industrial settings.
● Poly Vinyl Chloride (PVC)
PVC is strong, doesn't change shape, and doesn't burn, dissolve in liquids, or wear away quickly. So, it is a common material for injection molding in the business world.
● Polyesters
They have a high tensile strength and can be used to make trampolines, boats, and other things.
● Urethane
This low-cost material for injection molding can make exact parts. So, it can be used to produce goods with complicated designs.
Before choosing between blow molding and injection molding, you should know what makes each one different. Your ability to spend and what you want to make should be the main things that help you decide.
The best way to make hollow parts like bottles, water tanks, and so on is to use blow molding. But injection molding is the proper method if your project needs a solid part with a complicated shape.
Are you looking for an injection molding service that can quickly and cheaply produce high-quality plastic parts? Then you have what you are looking for. Ares Prototyping is a company that manufactures several parts quickly and offers services like injection molding. We make high-quality injection molds and plastic parts with our strong injection molding skills.
Our factories contain modern equipment and a professional team that can help you design molds, choose materials, and find cost-effective solutions. Also, outsourcing to us is easier because our instant quoting platform ensures that quotes are correct and design analysis is done quickly. So, you can share your design file and get a free DFM analysis and real-time quote within 12 hours.