WELDING OPERATIONS:
There are three basic types of plastics welding with hot-air:
Tack Welding, Hand Welding and High-Speed Welding.
TACK WELDING
Tack welding is a shallow fusion of the mating surfaces of
the material. It possesses little tensile strength. It holds the
pieces together until the regular bead is welded. Tack weld-
ing eliminates the need for clamps, jigs and additional
manpower.
For practice welding, prepare the material as follows:
1. Take two pieces of 1/8” thick PVC sheets, each about 2”
wide by 6” long. Bevel one of the long edges of each piece
to about 30º for a total included angle of 60º. Do not
bevel to a feathered edge.
2. Remove all dust and chips. Do not use a solvent. This will
soften the material and result in a poor weld.
3. Clamp one of the beveled pieces flat on a work bench with
the bevel pointed upward. Place the other pieces so that
the beveled edges face each other. Install the tacker tip.
Hold the welder upright at an angle of about 80º perpen-
dicular to the surface of the material.
4. Hold the loose PVC piece firmly against the clamped piece.
Touch the point of the tacker tip quickly but firmly along
the mating surfaces, making short (½” to ¾”) tacks at inter-
vals of about 1 ½ to 2” along the joint.
5. Then draw the point of the tacker tip along the entire
joint, fusing the edges together. This operation must be
performed quickly. Hesitation at any point can result in
charred spots that must be removed before further
welding. The two pieces are now fused together with
sufficient strength for handling.
HAND WELDING
Hand welding can provide very high tensile strength, if
properly accomplished. It is recommended for welding
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