Thermoforming- Making a Hot Tub Using Heating Elements

Heaterbands manufacture inline flow vessels which heat water to comfortable levels. Call Heaterbands on 0121 772 003 for more information.

It’s a beautiful day outside; the birds are singing, not a cloud in the sky, and there’s a corner of the garden that just cries out “perfect spot for a hot tub!”  But before you buy your dreamy, relaxing bit of kit, give a thought to how these oversized bird baths are made – and what on earth have heating elements got to do with the whole process....?

A new hot tub will start life as a small heap of polyethylene plastic granules which will eventually be turned into a fully functional hot tub. The polyethylene granules are a chemically complex material that is both UV and chemically resistant.  A manufacturing process often chosen for the production of hot-tubs is thermoforming, in which the largest use of energy will be in the heating element section.

Thermoforming is a general term applied to processes that reheat a previously manufactured sheet of plastic and then forms it into its final shape. The process of thermoforming is relatively inexpensive compared to other plastic processes and is best suited for large products that do not require a great deal of precise details or sharp edges. The plastic sheeting can be as thick as 1/2" in sizes up to about 10' x 20', making it the ideal application for the manufacture of hot tubs.

In making a hot-tub, the thermoforming process starts with a sheet of plastic, reheated using heating elements, to a very pliable but less than molten state, placed over an ergonomically designed mould and then vacuumed or pressure blown into it. The moulds may be air or liquid cooled.  Once the mould is cooled below its reset temperature, the hot tub is released from the mould ready to be trimmed and further machined, such as holes cut and drilled.

So there you have it – heating elements and the manufacture of a hot-tub – now go and get your swimmers on!

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