How inflatable pool toys are made

A pool float is flat vinyl panels fused at the seams by a high-frequency electric field, with no glue or stitching.

stations: 7
things upstream: 22
raw sources: 9
steps from the ground: 6

The short version

Most pool toys are thin PVC vinyl. Two flat sheets are cut to size, a flat strip valve is welded inside one of them, and the pair goes under a welding die shaped like the toy. A high-frequency electric field heats the plastic from within until the layers melt together along the seam. Excess is trimmed, and the toy gets inflated for a test.

Roll out the vinyl sheet

Polyvinyl chloride, often called vinyl, is the most common material for pool floats and air mattresses, because it is cheap, durable and water-resistant. It is made into thin flexible sheet.

Goes in
PVC
Cut the panels

Flat sheets are cut to the size the toy requires. They usually run about 0.18 to 0.35 millimeters thick, and their edges become the future seams.
Weld in the valve

One patent builds a one-way valve from two heat-weldable strips joined into a flat tube. It is welded to the inner face of one sheet before the toy closes up, and a non-weldable coating inside stops the weld from sealing its opening.

Goes in
PVC
Stack under the die

One sheet is laid over the other under a high-frequency welding machine, whose die follows the outline of the finished toy.
Weld the seams

The die comes down and clamps the sheets between a pair of electrodes. A high-frequency field excites the molecules in the plastic, which heats from inside and fuses under pressure. The clamp holds until the joint hardens.
Trim the flange

Excess vinyl outside the seam is cut away, either by a cutting die built into the welding machine or after the shell comes out.
Inflate and test

The airtight toy is inflated and checked, since the material must not let air leak through the seams.

End of the lineInflatable pool toy

Worth repeating

Radio-frequency welding only works on plastics whose molecules carry an electrical dipole, such as PVC.
For heavy-duty inflatables, panels of coated nylon or polyester are stitched and then sealed with glue or seam tape, because stitching leaves thousands of tiny holes.
The welded flange that sticks out around a pool float is a cheap and fairly weak seam, and it wears by catching on things.