Welding Plastics 2

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					                                            GETTING STARTED WELDING

There are several things you should know before you begin welding with the ‘HOT-JET’®. This welder is not limited to welding
polyethylene, however the following discussion is. This process is true welding, where all materials beg in to liquefy and flow
together to become as one. SUMMIT-USA uses Low Density Polyethylene (LDPE) for its molded products.

The tip and barrel become very HOT in use. Be careful where you touch the welder and be careful
where you set it down.    In order to prolong tool life, turn heat off and allow fan to run three minutes
or more before switching power OFF. This prevents ambient overheating of the air-cooled heating
element, an expensive item.

The welder operates on 120vac and uses only 4 amps at full power. There are three controls on the tool.
    1. The center switch turns the welder ON and OFF.
    2. The RED knob is the heat control with settings from 1 to 9, 9 being hottest.
    3. The BLACK knob controls air volume with settings from 1 to 4, 4 being greatest.
             Experiment with the settings, but we suggest a heat setting of 6 and a fan setting of 3.

The self-feed welding tip is designed to accept either 7mm or 3/16” triangular welding rod. It is not necessary to use this tip
at all times. In some instances it may be more efficient to weld free-hand by heating the two surfaces and the rod
simultaneously and feeding the filler rod in by hand. This method can be particularly useful when filling a large or deep ga p.
In some cases it may be possible to replace missing plastic by spanning the hole with a lattice of welding rod and then
heating the entire mass, causing it to flow to form a surface. It is also possible to cut out a damaged area using a holesaw .
Use the same holesaw to obtain a patch piece from a hidden area and weld this patch into the damaged spot.

When using the welding tip you must keep the inside of the rod feeder clean or the rod will jam. When you complete a
welding pass, simply cut the rod at the end of the weld and then pull the rod through the welding tip to remove it. Do not
attempt to pull the rod out the back of the welding tip, as this will surely foul the rod feeder channel. If the rod feeder c hannel
should become fouled, it can be cleaned with a propane torch.

Keep a diagonal cutter handy in order to cut the rod at the end of the weld. This will eliminate the problem of trying to
disengage a partially melted rod without fouling the welding tip. After the rod has been cut, push it through the welding ti p to
remove it, rather than attempting to pull the melted end back through the tip. Turn off the heat and allow the welder to cool for
at least three minutes before switching off the power.


WELDING begins by heating all three components of the weld; the two parent materials and the filler rod. A poor weld will
crack or separate from the base material. Proper heat penetration is the key to a good weld. The filler rod will become more
transparent as it heats. Assist the rod with gentle feed pressure as you move the welder in a weld pass. Use pressure on the
tip’s follower shoe to force the melted rod into the joint. The resulting cratering will be trimmed away.

Keep a diagonal cutter handy in order to cut the rod at the end of the weld. This will eliminate the problem of trying to
disengage a partially melted rod without fouling the welding tip. Do not allow the remnant of a rod to remain in the tip. Whe n
you are through with the welder, turn off the heat, but leave the fan running for three minutes before switching off the power.

Now the weld can be trimmed. There are several trimming scrapers available. Choose the one that works the best for you.
The weld can be power sanded, hand sanded, scraped, or cut to finish. If there are scratches or ‘hairs’ , they can be removed
with hot air or flame.

We provide natural color welding rod, but if you must color-match you can cut your own rod on a bandsaw from matching

Cyclone joints should be welded when the joint is closed. Joints close when the plastic is warm, and open when the plastic
is cool.

Adams joints should be welded when the slide is warm,

Tube Slide joints can be welded at any time.

Aqua Deluxe joints can be welded at any time.
                                          BASIC RULES FOR WELDING PLASTICS

The majority of plastics used are thermoplastics, which, as a rule, are suitable for plastic repair without any difficulties.
Thermoplastics become plastic with the application of heat. By comparison, Fiberglass products are made with thermoset
plastics. The following rules should be observed.

    1. Identifying plastic; Check whether the plastic part to be welded has a plastic identification code. If the code is
    missing or unrecognizable, easily conducted tests can be helpful:

                Floating test in water. Take a small piece of plastic from the part to be repaired and test if this floats on
                 the water surface (PP-EPDM, HDPE, LDPE, PP) or sinks (PVC-U, PVC-P, ABS, PC).

                Flame test. Different plastics emit distinct odors when burned.

                Surface condition. The surface of plastics can be differentiated from horn-like (PVC-U, PVC-P) to waxy
                 (PP-EPDM, HDPE, LDPE).

                Adhesion test with welding rod. Heat up the welding rod and the plastic part by applying hot air. Apply a
                 weld bead several inches in length, using heat and pressure. Leave a tail of un-welded rod at the end of the
                 pass. Once cooled, use pliers to pull the un-welded tail. It should break off rather than pull loose.

    2. Four basic rules for plastics welding:

            Weld like with like material. Only materials that are the same can be welded. (Exception—LDPE can be
             welded with HDPE rod) A weld of PP with PVC or PE will fail.

            Correct temperature. The plastic must be heated until it is plasticized (doughy). Heat setting and air flow
             control this.

            Even Pressure. When welding with rods, the pressure is applied to the welding rod. When lap-welding sheet
             goods or tarps, the pressure is applied with a seam roller.

            Consistent welding speed. An even working speed should be maintained.

TEMPERATURE, PRESSURE, TIME. These are three critical variables to achieve a good weld.

    1.   Temperature setting will be different for different plastics. It is crucial to be able to adjust tool temperature and to
         maintain that temperature throughout the welding process. The Leister tool’s temperature is control led electronically.

    2.   Pressure is very important. Pressure is applied by pressing the filler rod into parent material. Adjust the pressure
         during the weld-pass to maintain consistent penetration.

    3.   Time is critical. If you move too fast or too slow, the quality of the weld will be compromised.

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