RE: [CAD_CAM_EDM_DRO] cast iron

Terry, Allan -

Wow! I'm going to have a hard time finding patience to wait so long! The
effect of gradual thermal cycling of the weather seems to make sense, as far
as relieving stresses, but can't this be accelerated in an oven? My machine
castings will be similar in size/shape to the Rong Fu cast-column mill-drill
(RF-45?). On something that size, any guesses as to what order of magnitude
we're talking about for warpage? Is the warpage caused by stresses during
use, or do things just creep over time regardless?

Thanks,

Carlos (wanting to be finished this year) Guillermo
VERVE Engineering & Design


Terry wrote -

> Firstly the object must be rough machined to remove the surface skin and
> expose any blow holes. The skin is very abrasive because there
> will be some
> of the mould material mixed in. The first cut should get under
> this layer in
> one go and I tend to use old TCT tooling for this purpose. The skin should
> only be removed in places where it is necessary for the finished article.
>
> The ageing process relies on the constant slight heating and
> cooling of the
> weather. Which is why it is called weathering. It is possible to speed the
> process up by placing the casting under glass such as in a south facing
> green house without heating. A cold frame will do just as well.
> After three
> months the casting can be finished machined. If the object is not required
> for some time I often do another rough machine and put the casting back
> outside until it is needed. Then finish machine and grind.
>
> Terry
>