Plastic Welding

Plastic Fabrication

Finding the right plastic welding equipment can be a real challenge. When looking to find plastic welding equipment to fit your need it is crucial that you know its application. Although there is a fitting solution for all plastic welding requests, some welding tools are not suitable for certain kinds of plastic materials. Simply put: If you know the material, the working area, the kind of assembly, your choice of plastic welder will be much easier.

Today’s markets are flooded with an infinite number of plastic materials and blends. In such an environment trying to recognize the plastic’s family is not easy, but it is very important that you do. All plastics are different to each other in behaviour and in chemical structure. The type of plastic welding rod used will make the difference between a strong weld and poor weld quality.

Commonly available plastic materials can be recognized by four simple identification tests. Most testing labs offer plastic identification as a service or you can try the following tests yourself.

Scratching Test

This test though is not very accurate it helps to give you an insight in to what plastic you might be working with. Some plastics like ABS or PVC are harder and some are softer like PE and PP.

To check whether it is a hard or a soft type of plastic, scratch on its surface with your fingernail. If you see a scratch mark then it is not a hard plastic like ABS, PVC. So what you are looking at is something like PE, PP, PTFE or another similar softer material.

Sound Test

Because of the dissimilar weights and surface hardness of different types of plastics, each type, sound different when a piece of it is dropped on the floor. However, it is hard to determine an exact identification this way.

Take a solid piece of the material and drop it on the floor from a height of about 5-10 inches (or 10–25 cm). You will hear specific tones. A trained ear can detect slight differences in a plastic's tone. This method is often used to determine the plastics family.

Floating Test

Different plastic materials have a different weight that can be higher or lower than the weight of water.

Take a sample piece of the plastic and drop it in to a glass of water with room temperature. Observe its behaviour. Except for PE and PP all other plastics will sink.

Burning Test

This method is the most accurate test you can do by yourself. Different plastic material reacts differently when burning. For this test you should have prior knowledge as to how different types of plastics behave and smell while burning. If possible, keep samples of plastic materials that you already know to compare with the unknown plastic.

Go to an open place with fresh air, scrape off a sample of the plastic you want to test and burn it. Observe the reaction, flame or no flame, colour of flame, carbon above the flame, etc. Then after killing the flame smell the smoke for familiar odours. PE produces a Blue/Yellow flame, smokes, and smells like paraffin (candle). PP produces a Blue/Yellow flame, drips, and smells diesel like. Avoid the use of matches to light the fire to prevent the smell of sulphur getting in the way.

The combined results of these four tests should help you identify the plastic material you are working with. After getting to know your plastic you can start the plastic welding process.