Klarinet Archive - Posting 000539.txt from 2005/06

From: ormo2ndtoby@-----.net (Ormondtoby Montoya)
Subj: Re: [kl] metal clarinets
Date: Sun, 26 Jun 2005 20:02:37 -0400

Keith wrote:

> Cost - the mould is more expensive but the
> subsequent operations cheaper.

I wonder whether this is true?

Molding machines are rated in terms of "tons of clamping force", which
means that a certain amount of clamping force is required to hold the
two halves of the mold together while the molten plastic is pumped into
the mold. If the mold halves separate, then plastic oozes out of the
old instead of filling the mold cavity completely. Presumably a mold
that is twice as long requires a much higher clamping force (twice as
much?).

I've seen injection molding machines in action. They can be huge - as
large or larger than an automobile --- in order to supply sufficient
clamping force over the entire platen which holds the mold.

There's also the matter of cooling, which must be engineered in order
that each part cools and shrinks evenly. Slow cooling means longer
cycle times, which translates directly into hourly production costs
because it controls how long an expensive machine must 'do nothing'
while the mold either cools or is removed from the machine and a
different mold inserted for the next part.

I don't know anything about extrusion, but I presume that a longer
extrusion with variable diameter faces similar 'extra production costs'.

Machining one less tenon + socket and applying one less cork may be a
relatively minor saving compared to the operating cost of a larger &
slower machine.

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