Solvent bonding
The most common method of gluing is to solvent bond. Solvent bonding can be
achieved using methods employed in fabricating other thermoplastics such as
acrylic. The two most common methods are needle-type applicator capillary
action and edge dipping. Both methods rely on smooth edge preparation,
pressure and curing.
Note: Use extreme caution when working with solvents. Adequate ventilation
is essential. Control exposure levels according to OHS guidelines. Obtain
Material Safety Data Sheets from the solvent manufacturer.
Procedure
1. Smaller items with flat surfaces can be bonded by placing the pieces
together and applying the solvent along the edges using a needle applicator
or hypodermic syringe. Make sure the solvent flows along the entire joint.
For bonding larger items, immerse the surfaces to be joined in the solvent
until the material is softened.
2. Clamp them in position and hold until the bond is set.
Helpful hints
Edges must be clean and free from dirt. Light sanding of factory
polished surfaces will aid in adhesion. Surfaces should be smooth and
properly aligned. Recommended solvents are WELD-On #3 If joint whitening
occurs, it may be caused by excessive moisture. Several techniques reduce
whitening. Fabricate in a climate-controlled area with low relative
humidity. The addition of 10% glacial acetic acid in the solvent reduces
whitening. Thickening the solvent with resin or sawdust promotes slower
curing and reduces whitening. Be sure to retain fixture pressure until the
joint is solid.
It should be noted that some plastics such as polypropylene and
polyethylene are designed to be resistant to chemicals. These plastics that
are not dissolved by chemicals cannot be glued and to join them they need to
be hot-air welded.
PVC will glue, but in most cases a stronger joint will be achieved by
hot-air welding.
Plastics that can be dissolved by a chemical are generally glue able.
Most engineering plastics cannot be glued with solvent adhesives, although a
contact adhesive or silicone may be acceptable for your application.
If in doubt talk to our staff about the right adhesive for your job. |
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