The basics of plastic welding

Since the commercialization of plastics began in the mid 20th century, plastics have grown to become integral parts of our everyday lives. From our cars to water containment and transport systems to the very utensils we eat with, plastics are incorporated, at least in some small way, into almost every product we use.

But sometimes the plastics we use need to be repaired or modified. Both professionals and DIY home-fixers can achieve these tasks by way of welding the plastic.

Plastic welding, otherwise referred to as hot gas welding or hot air welding, is the process of using a hot air gun, a welding rod and applied pressure to make fabrications on a plastic object.

The plastic surface, known as the substrate, and the welding rod are heated to their thermoplastic states, which is the optimal temperature the materials must be at to expand and allow for structural reorganization. The plastics are softened and can be pushed into a new position by the welder before cooling and hardening into place.

Acceptable thermoplastics are polypropylene, polyethylene, PVC, CPVC, FEP, PFA and PVFD. The materials of the welding rod and substrate must be identical.

Reaching temperature

Heating materials to their thermoplastic states involves achieving temperatures within a specified range. Generally, PVC and CPVC have very small ranges compared to polypropylene and polyethylene. Reaching a thermoplastic state with a heat gun such as the PH-1400 LCD, featured in the Master Proheat Plastic Welding Kit can be easy, as it allows you to see and control the gun's temperature and air flow via mechanical knobs read on a digital screen.

There are a variety of nozzles that can be used, each with their own benefits in certain situations. The most common plastic welding nozzles are tacking, round, high speed and a combination tacking and high speed.

The area intended to be welded should be clear of any dust or debris with a clean cloth. Do not use chemicals or solvents to clean the area, as it may cause an unwanted reaction during welding.

Getting the job done

Each pass with the heat gun and welding rod is known as a capping run. Scraping excess or frayed plastic from the welding site needs to occur before welding begins and after each successive capping run as well.

The job is finished when the welded capping runs sit just above the outside surface material. In some cases where aesthetics are a concern, such as in car bumper repair, it may be necessary to scrape away the topmost layers of weld to improve the weld's appearance.

The advantages of hot gas welding as opposed to other types of plastic fabrication are that the equipment is portable, durable and the process does not very long.

Plastic welding can be used to fabricate plastic auto bumpers, flooring, water and chemical tanks, plumbing fittings and many other items across the home or work site.

Contact the experts at Master Appliance today for the latest heat gun technology. With a multitude of options to choose from, there's a heat gun that's perfect for your application.

masterheat Written by: