Many times we come across terms that we have never heard of, like extrusion blow moldings. Most people have no clear understanding even though they may know about Extrusion blow molding and hence we decided to offer information and try to clear your doubts through this blog post.
It’s not possible to give all the information through one blog post but we can give you a brief idea and understanding about the Extrusion blow molding. Let’s understand what is extrusion blow molding, what is extrusion molding process and what materials can be used for blow molding and few others. So lets start.
What is extrusion blow molding?
Extrusion blow molding (EBM) is one of the blow molding processes that helps in the production of plastic bottles, jars, and jugs. It is a process that is used to process different types of plastic like HDPE, PVC, PC, PP, and PETG. It is considered to be one of the best processes for turning plastic into different useful objects.
There are various advantages of EBM, it has lower mold cost and more capability of forming handles. EBM also has the multi-layer capability, EBM bottles can have up to 7 layers of materials to bond the other layers together. The advantages of EBM can differ from one manufacturer to another.
What is the extrusion molding process?
While talking about the extrusion molding process, you need to know that it is not a complicated one. The extrusion blow molding process starts with a parison. A parison is a tube-like piece of plastic with a hole in one end through which compressed air can pass.
Parison is held and sealed in a metal mold. This tube is then placed into a cooled metal mold, after which the air is blown into the tube to inflate it into the shape of a bottle, jar, container, or part. When the plastic has cooled down completely, the mold is opened and the part is taken out in perfect shape.
Now, the EBM process can either be continuous or intermittent. In the continuous one, the hollow tube is extruded continuously and the individual parts are cut off. And in the intermittent one, there are 2 further processes: in straight intermittent, the screw turns and stops and then pushes the melt out.
While, in the accumulator method, an accumulator collects the melted plastic and when the previous mold cools down and enough plastic has been gathered, a rod pushes the melted plastic to forms the parison.
What materials can be used for blow molding?
If you are working in a blow molding factory, you need to know the different materials that can be blow-molded:
1. HDPE- High-Density Polyethylene is the commonly used material in blow molding. Most of the containers and bottles are made up of this material. It is the material that is also used to make containers for shampoo and motor oil, coolers, fuel tanks, and industrial drums.
The reason that it is the most used material is that it is translucent and easily colored along with being considered as the safest plastic.
2. PP- Polypropylene is also a popular molding resin. It is the best material for elevated temperature applications because of its stiffness and lower density. It is also translucent and easily colored.
3. Polyester and Co-polyester- So, these are the materials that can be extrusion blown. Sometimes, they are used as a substitute to polycarbonate for making containers. Though polyester is not as tough and clear as other mentioned materials, It does not havebisphenol A which have a direct connection with severalhealth risks.
4. PET- Polyethylene Terephthalate is another plastic that can be used for blow molding. It is a polyester that is usually an injection blow molded into clear containers. PET is majorly used in the production of soft drinks and water bottles. EBM is less common with PET.
5. Urethane and Polyurethane- You are going to find Urethane more elastic than Polyurethane. It requires a special formula to turn into thermoplastic urethanes. It is the material that is generally used as one of the layers in a multi-layer blow molding product.
6. PC- Polycarbonate is one of the products that is used in the manufacturing of a wide range of products ranging from eyeglasses to bullet-proof glass. It is a strong and clear material that is frequently used to make 5-gallon water containers. It’s quite a strongmaterial mold well in basic shapes but it is quite a task to mold it in complex shapes.
All these are the materials that are highly used for blow molding and each of them is having its own benefits and drawbacks. And keeping their pros and cons in mind, each of them is used for the production of different products in China.
How do you melt plastic and mold?
For school science projects you can make plastic using materials found at home. Lets check the process:
To melt the plastic, you are going to take all the plastic objects you want to melt and remove the labels if there are any. Before the melting process, you are going to wash them properly and dry. And once they are dry, you are going to cut the plastic objects into small pieces.
Now, you are going to put these pieces of plastic into an oven-safe metal container and remember not to overfill it. After this take the toaster oven outside and heat it to 250 degrees Fahrenheit. It is good to melt the plastic outside to avoid harmful fumes.
Once the toaster oven is heated, place the metal container in it and leave it for 3-4 minutes. You are going to increase the heat in 25-degree intervals till the time plastic is melted completely. After the plastic is melted, pour it in a container for molding with a wooden stick.
Wait for the plastic to cool down completely and then take out the newly made plastic object carefully.
Does melted plastic release toxins?
Yes, the melted plastic releases toxins but the amount released indeed depends on plastic to plastic as different types of plastics are having different properties. You just need to be careful and take all the precautions while melting the plastic.
These are some of the necessary questions that are answered to give you knowledge about melting the plastic and molding it into a new object. You are going to find various suppliers, who are selling the plastic products that are made with the EBM process.