Foundry stuff. Today, cos it was raining and cool (20 C)(eat your heart out you kiwis ) did a run of pistons, but split the pour with a run of our aluminium kart brake discs. At Ø200 mm, they weigh around 400 gm compared to the 1 kg of a conventional CI ventilated disc, both being 2 mm thick. We use the same high (18%) silicone alloy that we use for the pistons.
To cast these, we spin the die, pouring down the centre and feeding from the inside. If not spun, the die cavity would not fill.
However, in the spinning, the centrifugal pressure of the aluminium would try to force open the die. This is resisted by bobweights that provide a clamping force to prevent the top half of the die from lifting and hence leaking.
Irrespective, the whole thing is spun within a stainless barrel with a drop down lid; if the lid isn’t down the rotation is interlocked out. Safety stuff really. The type of the actual barrel can be easily recognised, but as we probably helped emptying it, we felt it would be ok to use it.
There are ejection pins in both the top and bottom die halves. To grip the top of the die, a neat “desmodromic?” mechanism was devised to actuate grippers for the top die to initiate initial movement.
After the casting, there is a trimming op, then a solution heat treatment and then a 3 stage machining sequence.
Sorry the pics are on the piss, but it just does that.
Not even made in China.
"Success is the ability to go from one failure to another with no loss of enthusiasm.”
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