Casting in metal vs. plastics (was: Re: [DSII] Genre)

>Nyrath the nearly wise <nyrath@clark.net> wrote:
>>Michael Llaneza wrote:
>>> IMHO the best thing GW ever did
>>> was the plastic Epic-scale infantry. Plastic is expensive to set up
a
>>> production run for, but dirt cheap over a long production run.
>>
>> I was always curious about that.
>> An uninformed layman would think that metal miniatures
>> would be more expensive to produce than plastic ones.
>>
>> I guess plastic is less forgiving a medium to work with.
>    It's actually based on the set up costs. Lead or pewter metal
moulding
>requires less work to start up than plastic moulding.
>    Plastic moulding requires a steel mould to made and this takes a
lot of
>work and time to make, so making the set up costs very high. On the
other
>hand, the mould lasts for a very long time, so that the per item cost
over a
>long run will be low.
>    Metal moulding only requires a mould that is easy to make, so
making the
>start up costs low. In most cases of figure moulding, the mould is
destroyed
>to remove the moulded items. Each batch of metal miniatures requires a
new
>mould which is easily made from a master miniature. Hobby books show
how to
>mould miniatures using the sand casting method. I sure Jon Tuffley can
>explain more about metal casting, if he wants to.

OK, you asked for it!!	<grin>
We spin-cast in black rubber moulds (vulcanised nitrile rubber, same
sort
of stuff (and strength) as a car tyre. You CAN use RTV silicones
instead,
but these tend to be kept either for initial prototyping or else used by
hobby casters who don't have a vulcanising press - RTV moulds are more
expensive and don't last anywhere near as long as vulcanised ones. The
casting machinery (caster, melting pot and vulcaniser) will cost you
something in the region of £6000 or so for "professional" kit, less for
more basic ones. The blank mould discs (from which you press the moulds)
are a few pounds a pair, and their life is anything from a couple of
hundred spins upwards, depending on how hard you run them - if they're
not
left to cool down between spins they'll burn out faster.
In contrast, a single mould for an injection plastic sprue is in the
order
of tens of thousands of pounds, and the machinery to do it even more.
Metal
casting can, in theory, be done by almost anyone with a little bit of
money
and a garden shed; injection plastics require a major factory set-up.
It's worth doing a metal miniature if you think you're going to sell a
hundred of them or so; for plastics, you need to KNOW you'll sell many
thousand sets of a given item before you can even THINK about doing it.
That's why even GW restrict their plastics releases to the things they
know
will shift in bucketloads to the snotlings, and still do their more
"specialised" stuff in metal.

Jon (GZG)

Jon (GZG)

>    Miniatures being usually low volume items, metal moulding is the
way to
>go for most companies. If you're making and selling a lot of miniatures
like
>GW, plastic moulding is the key to making a lot of money.
>    Hope that helps!
>
>Andrew Martin
>Who has debugged software
>controlling plastic moulding machinery,
>in the era before PLCs.
>Shared email: Al.Bri@xtra.co.nz ICQ: 26227169
>Blind See-Saw, DSII, DSII FAQ, GZG-L email FAQ, FUDGE, UY, MSH & WBG:
>    http://members.xoom.com/AndrewMartin/