Welding two metal pieces together is a pretty normal thing, right? But have you ever wondered if we can weld plastic together as well? Interesting and shocking to hear, isn’t it?
Well, besides the fact that plastics can be welded together, it doesn’t mean that we can weld all types of plastics. Only a specific type of plastic that is capable of standing the heat of welding can be welded together.
When welding two metals together, we have to follow a certain procedure and use specific equipment for that. It is a little different in the case of welding plastic because it requires a lot of attention and care.
Now if you are thinking about how to weld plastic, we are here to let you know.
Welding plastic together?
The first question that comes to our mind is: “Can we weld plastics?”
We have already given you an answer to that. The second question is: “How to weld plastics together?”
As we have already mentioned, only some specific nature of plastics can be joined using welding. Plastic welding is usually done on thermoplastic surfaces with the use of heat.
How do weld plastics together?
The two plastic pieces are heated together to create a bond formation in them. This leads to the joining of two plastic parts. The process involves the application of heat and pressure on the surfaces and after that, cooling them off.
In addition, the heat you are supplying to the surfaces varies from plastic to plastic. Also, there are other factors involved as well which we need to take care of.
You have to determine how much extent the plastic can be welded. Moreover, you have to choose a specific type of welding technique as well.
This type of plastic formation is done globally because all of us are aware of plastic demand in the world. For example, we use plastic as cutlery, storage cans, construction pipes, internet cables, and medical equipment as well.
Steps to follow during welding plastic
It is very difficult to blend two plastic pieces during plastic formation. In addition, if you are new to wedding plastic, then you need tons of practice. Here we are giving you the simplest steps to follow during welding plastic:
- Clean and ready the working space
- Plastic Joining
- Weld completion
Cleaning and preparing working space
This is the first thing you need to do before welding the plastics. Because there is a chance that the dirt and contaminants on plastic surfaces will cause hindrance during welding.
Setting up your working space in a ventilated area
As you are aware that welding creates a lot of heat, so make sure to set your equipment in a properly ventilated area. Also, to ensure your safety, wear heat-resistant gloves and goggles and also cover your whole body to be safe from the heat.
Removing contaminants from the plastic surface
Now, the second step is to clean the plastic surface thoroughly using water and soap. This way, all the dirt will be removed and you will face no problem during welding.
In case you see any stains on the surface, make sure to remove them using any liquid solvent to smoothen the plastic surface.
Labeling the plastic pieces
While choosing the plastics to weld, you will see letters written on each of them. These letters are used to distinguish between different types of metals.
For instance, if you are going to weld two polyethylene plastic pieces together, then you need to choose the pipes that have PE written on them.
Using a welding rod test kit on plastic rods
If you are still confused about the plastic rods you have, so besides checking the lettering, there is another way to find the type of plastic. You can use a welding rod test kit for this purpose.
To conduct the test, take the rod you want to test. Heat it and try to join its one end with the plastic you think is very similar to it. Now try to pull the rod off from plastic. If both of them are sticking together, it shows that both the plastics are of the same material.
Otherwise, if they don’t stick and get separated easily, then both of them are different from each other.
Using sandpaper to remove paint from the plastic surface
In case you see any paint on the surface of plastic, then you can use sandpaper or sand wheel to remove it. Using sandpaper requires a lot of physical effort so to avoid that you can use a sand wheel for efficient working.
Clamping the two plastic pieces together
After cleaning, all you have to do is to put the two metal pieces together. Arrange them in a way you want them to be joined and then fix the surfaces using C-clamps to firmly attach the joining surfaces.
The second stage of welding plastic is to join them using heat.
Preheating the welding torch
For this purpose, you need to preheat the welding torch for at least 2-3 minutes. As you are aware the intensity of heat to melt plastic is different for different types of plastics.
For this, we have to be very careful while heating the plastic because extra heat will melt the plastic ruining the surface and plastic itself.
Use a tack-welding technique to join the ends
By using a tack-welding heat gun, you can heat the plastic surfaces to join their ends if they are loose by any chance. Provide some heat to the edges. Wait for the pieces to melt and then fix them for joining. It will prevent the pieces from moving during welding.
Trimming the ends of welding rods
To get a smooth and effective result after welding, it is advised to trim the edges of welding rods diagonally using pliers. If you don’t have pliers in your hand, you can use a trimming knife as an alternative to pliers.
During welding, there is a chance of bubble formation when plastic melts. Cutting the ends of welding rods helps to prevent this problem as well.
Adjusting the welding rod in the welding gun’s nozzle
Before welding, you need to fix the welding rod in the nozzle of the welding gun. Make sure to put the clipped end in the first place because, during welding, you will have to use that side.
Joining plastic using a speed gun
You need to move the heating gun on the plastic joints to join them. Start from the top and then slowly melt the joints. The welding gun should make an angle of 45 degrees with the welding surfaces.
Use one hand to move the gun and with the other hand, try to fit the welding rod in the joint. This way, the chance of burning the plastic will be reduced. In case you experience or see any color changes in the joint during welding, then you can increase the speed of the torch a little.
The last step is to complete the welding process and then clean the welding surface for a smooth and clean appearance.
Cooling the plastic
Now you need to cool the plastic at room temperature for about 5 minutes before you start working on it again. One of the best things about welding plastic is that it can be cooled off very fast.
To make sure that the plastic has cooled off completely, you can move it close to your body. If you can feel the heat coming from the surface, it needs more time to be cooled. If not, then it is ready to be worked on.
Moreover, make sure that the welded surface is smooth and fixed before cooling. If not, then you can add more welding rods in the joints and wait for it to get cool.
Sanding after welding plastic
At first, we did sanding before welding to smoothen the surface for an effective weld. Now we are doing sanding to level the joint and plastic surface. Use sanding paper to make the surface neat. But be careful not to scratch the plastic surface.
Here the whole procedure of welding two plastic pieces together is completed.
5 methods to weld plastic together
Above we have learned about how to weld plastic together. Now we will see which techniques or methods we can apply when it comes to welding plastics:
- Hot air welding
- Laser welding
- Ultrasonic welding
- Vibration welding
- Radiofrequency welding
Hot air welding
In this process, plastics are welded together by the use of gas. Gas is heated in the welding gun by supplying electricity which produces heat to weld two plastic pieces together. This type of welding is also referred to as gas welding.
It is a very straightforward method for welding plastics. The two pieces which you need to be welded are placed together by contacting the joints.
Then a laser beam is passed through the joints which need to be connected. The laser beam combines both the pieces strongly giving an effective weld as a result.
In this method, high-frequency vibrations are used to produce heat. We use this process to join and reform thermoplastics. Here we convert the electrical energy into mechanical motion at a very high frequency.
This mechanical motion generates friction between the two plastic pieces. As a result, this friction gives rise to a bond between the joints of two pieces making them come in contact with each other. This way ultrasonic welding can be used to join plastics.
This process is a little similar to ultrasonic welding because it also used friction to produce heat between the joints to connect plastic pieces. The pieces which are to be joined are rubbed together along the joined.
Rubbing them creates friction and friction creates heat as this process is done at a high frequency. This heat is high enough to melt the joints and weld the plastic together.
This process uses high-frequency radio waves or electrical energy. These high-frequency waves then produce heat resulting in joining the plastic pieces. This method of welding plastic is preferred by welders as compared to other welding techniques.
Advantages of plastic welding
- First of all, no consumables are required because only the machine is enough to complete the task. You don’t have to work with glues, solvents, and other welding materials.
- Less surface preparation is needed because we only have to melt the joints to weld the plastic pieces.
- You can create aesthetically attractive bonds between plastics by welding them.
- Plastic welds are lighter in weight and they can be recycled easily.
- It is highly versatile because not only you can weld small plastic objects but also it can be done on large and commercial objects.
- Plastic welding is best suitable when it comes to mass production of an item. The equipment for this method can be easily arranged in assembly lines and items can be produced in large quantities.
Disadvantages of plastic welding
- While using the ultrasonic welding process, there is a limitation in that it can only be used to weld thin and small parts of plastics.
- The cost is expensive as compared to other welding processes in the market. Also, the cost of each method of welding plastic varies.
- While doing welding, there might be a requirement of making joint designs. But molding the joints to make different designs is difficult in plastic welding.
- Moreover, you need to be very careful while welding two plastic pieces. Because they need to be compatible with each other to give a strong and attractive weld in the result.
Before welding plastics, make sure that the plastic material is of high quality. Also, you need to have a good working machine and equipment so that there will be no problem during welding. Plus, to ensure your safety, you must follow the safety measures that we have discussed above.
Besides using a welding technique to weld plastics, there are other ways as well where you can join plastics without welding. So welding them is not always the solution. First, you need to analyze which method best suits your material. Then you can decide whether you want to weld plastic together or use any other method to do so.