How To Heat-Weld Rubber?

Rubbers can be heat-welded depending on the type of rubbers- if they’re thermoplastic or thermosets. Manufacturing rubbers and plastics are essential, especially the sophisticated ones, as they are used in every part of human life. Heat welding rubbers isn’t a popularly known concept because it is assumed that due to the soft and brittle nature of rubbers, they cannot be welded but, can rubbers be heat-welded?

Rubbers can be heat-welded depending on the type of rubber. Rubbers can be said to be thermoplastic or thermosets. Due to the nature of thermosets, they cannot be heat welded as they’ll just burn and catch fire but thermoplastics can be heat welded and melted to join two thermoplastics together.

Heat welding is a vague concept, especially when it involves heat welding thermoplastics. In this article, I’ll explain the concept of heat welding, and how to heat weld rubber (thermoplastics).

What Is Heat-Welding?

Heat welding, also known as heat fusion or butt welding, is a type of welding process that joins two different thermoplastics using heat. The process heats both thermoplastics simultaneously and then presses them together after, then cooling them together to form a permanent bond. 

This is an efficient process used to rubbers (thermoplastics) together. It’s essential that these rubbers are thermoplastics or else they’ll just melt and burn off and the thermoplastics also have similar physical and chemical properties so that the bonding will be very effective. 

This process is popularly applied in plastic pressure pipe systems. It is used to join pipes and pipe fittings together, or to join two lengths of pipes to each other. 

There are three types of heat welding which are- butt welding, also known as butt fusion, socket fusion, sidewall fusion, and electrofusion. Butt welding is a type of hot plate welding that involves heating two plane surfaces of thermoplastic materials against a heated surface. After some time, the heating plate is removed and the two thermoplastics are pressed together and afterward allowed to cook under pressure to create the desired bond between both pieces.

Butt welding is distinguished from socket fusion using custom-shaped and custom-sized heating plates rather than the usual basic flat surface. The heads create more surface contact thereby decreasing the time needed to heat and fuse the pipe. Instead of joining just pipe to pipe, socket fusion joins pipes and fittings together.

Sidewall fusion differs from socket or butt fusion by performing the fusion into the side of the pipe wall in a transverse orientation to the main pipe, rather than in line with the pipe. Sidewall fusion is usually used with either butt or socket fusion methods as a complementary process.

Electrofusion, which is the last method of heat welding, is a method used for joining high-density polyethylene and other plastic pipes with special fittings that possess built-in resistive wire which is used to weld the joints together. 

Can You Heat-Weld Rubber?

Rubbers can be joined together by heat welding. Although the process is dependent on the type of rubbers which include- thermosets and thermoplastics. If thermosets are heat welded, they’ll not melt but just burn off but if thermoplastics are heat welded, they will melt and these molten thermoplastics can be joined together to create a bond between the thermoplastics being joined together.

Thermoplastics are tougher rubbers that can be melted in the presence of temperatures at their melting points. It’s required that the thermoplastics being heat welded, have similar physical properties as this is what aids the strength of the bond. An example of thermoplastics is polyethylene. 

It’s also required to understand the best heat welding method that works for the thermoplastics you’re looking to bond together as it’s essential in creating a durable final product. 

How To Heat-Weld Rubber?

The aim, which is to create perfectly blended rubbers (thermoplastics) together, can be a hard task especially if you’re new to it and if you don’t have your process outlined to not skip any steps. However, here are the processes to achieve your desired outcome:

Step 1: Clean And Set Up The Working Space

The very first step is to clean and set up your workplace correctly. The following are the steps to clean and set up your workspace:

  1. Set up your working space in a well-ventilated area: This very first step is important because it helps you protect yourself from the smoke from the welding process. Before you commence, put on all the required protective gears required.
  1. Remove debris from the thermoplastic by washing it with spam and lukewarm water: It is essential to remove all debris and impurities from the thermoplastic to eliminate any weak points that could be formed during the welding process.
  1. Label the thermoplastics you have chosen correctly: If you’ve noticed, the thermoplastics around you have a distinct letter. You can use these letters to label the thermoplastics.
  1. Use sandpaper to extract any paintings on the thermoplastic: You can achieve this by rubbing the sandpaper back and forth across the thermoplastic surface. This makes sure that the paintings don’t come in as impurities while welding.

Step 2: Welding The Thermoplastics

  1. Preheat the welding gun for about 2 – 4 minutes: Due to the different melting points of different thermoplastics, your welding temperature must be in line with the materials to be welded. The required temperature ranges from 2000℃ – 3000℃ or 3920℉ – 5720℉.
  1. Tack-weld the plastic ends to secure them together: By fitting a tack-welding nozzle on the welding gun, you can tack-weld the ends of any loose thermoplastics together.
  1. Use pliers to trim the edge of the welding rods: Snip the plier while holding the plier diagonally towards the welding rod. On the other hand, you can use a trimming knife instead of a pair of pliers to trim the endpoint of the rod.
  1. Insert a welding rod at the welding gun’s speed nozzle: Since the nozzle was designed to hold the rod while welding, it only makes sense that the welding rod is inserted in it. 
  1. Gradually move the speed gun over the thermoplastic: Ensure to always begin from the very top of the point you want to join both thermoplastics. 

Allow the plastic to cool after welding: It is required that the thermoplastic cools for at least 5 minutes before you continue working on it. An advantage of welded thermoplastics is that they cool in a very short time.

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