"Nutz" wrote in message
...
Sure its not metal but it's not politics or global warming!

I was wondering why rotomolded plastic water tanks are so expensive.

The raw materials are generally regarded as cheap, the manufacturing
process seems on the surface to be simple. I guess transport /
distribution of a bulky product could be costly. Anyone got some ideas?

Also there are economies of scale involved. Not physical size but volume.

There are probably an uncountable number of guys here who could take make
you a machine nut by taking a piece of steel, drilling a hole in it, taping
it, and then cutting the outside so you could grip it with a wrench. It
would probably take me an hour to make one nut that way in my shop. I
charge $80 for my time (I do not make that much by a long shot). There are
a few more guys in this group who could take iron ore. melt it, add some
other stuff, and then produce your one nut in their shop.

Or, they could buy some production equipment for a few hundred thousand
dollars and make your one nut.

In any case the material is cheap. In the first case the labor is
expensive. IN the second the equipment is expensive, and for one nut the
setup, electric, fuel, and labor are expensive along with the several
hundred thousand for the production tooling in the factory. However, if
they make one nut or a million the tooling cost doesn't change. In fact the
tooling cost probably doesn't start to change much from tool replacement and
repair until they have made a few hundred thousand of them.

So in the first case it costs $81 for one nut.

In the second it costs $500,000 to make one nut.

Now add in overhead, additional fuel, insurance, repairs, etc.

The first shop could make a 1,000,000 nuts for $81,000,000 dollars, and they
are still $81 each.

The factory could make 1,000,000 nuts for $750,000. Their nuts cost 75¢
each to produce.

Fortunately the demand for nuts is in the trillions in the world, and
factories all over the world are geared up to produce billions of them.
This production volume drives the production cost down. The consumer demand
keeps the volumes high enough to keep the factories operating at their most
efficient level, and competition between factories keeps the profit margins
charged reasonable.

I would bet real money the demand for nuts is in the trillions. What is the
demand for roto-molded tanks?

They might be able to make them for a few dollars each if they could gear
upto produce them continuously in the hundreds of millions.

Heck, have you ever seen a blow mold operate? Milk jugs go in as a slug of
plastic and come out as a plastic jug and go right into the bottling part of
a milk plant. They cost pennies a-piece. But they make hundreds of
millions of them. That plant to make them cost a million dollars to setup.