Polyethylene Welding

Posted July 8th, 2013 in Uncategorized by howtoweldplastic

Polyethylene is the most widely used plastic worldwide. Within the world of plastics polyethylene belongs to the family of thermoplastics. This means when polyethylene is heated it is pliable and formable. After cooling it takes back solid form. This feature makes it a very useful plastic. This is also the reason polyethylene or PE is commonly used for all sorts of plastic manufacturing including plastic welding.

The advantage of polyethylene

There are many reasons  why PE is the most common plastic. A few are:

Thermoplastic  properties

Not all plastic product can be cast. Either the number of products is to small or the construction requires welded connections. Because PE a thermoplastic it can be welded perfectly.


PE is strong and tough.  For many products this is a crucial property.  high density PE (HDPE) is stronger than low density PE (LDPE).

Chemical resistance

One of the key features and benefits of polyethylene is that it is resistant to all kinds of chemicals; acids, bases and solvents.

Low electrical conductivity

PE is a good electrical isulator.

Relatively low stiffness

Polyethylene is more flexible than PVC and other plastics.

Before you start welding – Surface Preparation

Posted January 19th, 2013 in Uncategorized by howtoweldplastic

Before you start welding plastic it is essential to prepare the surface you are going to weld for optimal results. This time consuming job is necessary for quality welding. Surface preperation needs to be done to reduce surface oxidation, grease, dust or damage which reduce the effectiveness and quality of the welding process. First you will want to start with washing the piece of plastic to reduce chance of dirt making its way to the hotzone be sure NOT to use industrial detergents these can introduce film coatings that may also effect the welding results, to further prepare a surface for welding you need to get a scraper and remove a layer from the material, be sure to keep your working zone free of dust and prepare only the spot you are working on.

What tools will do as a scraper?

Paints and soils will easily be removed with a sanding disc, a grinding disc will do perfectly but be sure to watch out you don’t end up damaging your project at the wrong part. You could also use: Paint scrappers, a sharp blade or wire brushes, these tools are also great for assisting when the other tools don’t work out well. Now that you have prepared the surface you are about to weld, you are ready to go to the next step: welding!

Identifying Types of Plastic – Burn it!

Posted December 19th, 2012 in Uncategorized by howtoweldplastic

Different types of plastic have veryspecific burning properties. These properties can be used to identify different kinds of plastic. Before setting fire to plastic look to see if you can find a molded in identification logo. If you can’t find any, you can use the following technique to find out what plastic you are dealing with.


When burning Polyethylene the flame color will be yellow. The flame drips after a few seconds and the flame will sparkle a little. Also the fumes smell like burning candle wax.


When burning Polypropylene the flame color is yellow. The flame drips and does not sparkle. Burning Polypropylene smells like burned diesel.

Burning PP and HDPE

                           Note the Polypropylene(left) burns more stable.


When burning PVC the flame will extinguish by itself. The flame color is yellow with black smoke. The smell is particularly sharp. This sharp smell is produced by chlorine gas.

Beware: Burning plastics can be dangerous, molten plastic can cause severe skin burns. Inhaling the plastic fumes can cause health risks. Howtoweldplastic.com can not be held  responsible for your actions.




Identifying Types of Plastic – Does it Float?

Posted December 18th, 2012 in Uncategorized by howtoweldplastic

Some types of plastic seem nearly identical, luckily there are some easy ways to tell the difference.

Before you start welding plastic you should know exactly what material your about to weld. Different types of plastic require different types of thermoplastic welding rod, different heat settings and different welding techniques. In this article you will find how to identify the type of plastic you are dealing with.

First of all you need to determine if the plastic is a thermoplastic polymer or a thermoset polymer. Basically a thermoplast melts when heated and a thermoset doesn’t. So to determine this just hold something hot like a soldering iron(500 degrees F) to the plastic and see if it melts. If it does, great! This means you can weld it. If it doesn’t it means the plastic is a thermoset polymer and unfortunately you can not weld it.

Next thing to do is to see if it floats in water. This will determine if the density is greater or less than 1 kg per liter or 1 g/ml. If  the plastic floats the density is less than 1 g/ml. This means the plastic is either polypropylene (PP) or high-density polyethylene (HDPE). Which both have a density below 1 g/ml.  The density of PP is about 0.9 g/cm3. HMPE has a density of around 0.95 g/cm3.

Anything that doesn’t float in water is something else than PP or HMPE.