AN fitting form milling
AN fitting form milling
Im currently doing a lot of short run castings(batch numbers 40-100) requiring an- fittings of various sizes. The ones Im dealing with are an-8, 10, 16, and 20. These are coming to me pre-made with an approx thread length of 10mm across all the an- sizes. Im not fully up to speed on the many types of an- adapters but these ones have all UNF threads on my casting entry side and the ends are just flat(no cone/taper). They contain an o-ring also that needs to seat against a tapered edge on the casting.
I have a cnc mill but it has not got a tool changer so as you can understand the tool changes are slowing things down even though I load ten castings into the jig at a time.
The castings at the fitting areas are just the size of the an- counter-bore at the face - as in it is like dealing with an 8mm walled tube end. There is no extra material outside the counter-bore as you would have if it was in the middle of a tank/flat surface.
Currently Im machining them in 4 steps.
The end face is milled flat with a 10mm solid carbide end mill, this totally provides the counter-bore/flat face in one move(circle).
Im then milling the inside with the same 10mm bit in two z passes, each approx 7mm deep. This provides the finish diameter for the carmex single point(s) thread mill.
I then change tools to the thread mill and machine the thread.
The thread mill then gets swapped out(again!) and an angled cutter fitted to provide the finished angled seat for the an- o-ring to seal against.
As you can clearly see, this is a lot of work.
Ive looked for an- form drills with not much luck. Im not sure if you are to spec these exactly the bore you need(possible chatter risk?), or say a third the bore size and treat them like an end mill and machine around in a circular fashion - cutting the finish bore, and counter bore in one pass.
Im also not sure if I should add the angle seat pass to this tool and cut that at the same time too. Im then wondering if I could also add a threading insert to the mix and do the entire lot in one go finishing at the bottom of the cut with a complete circle after tracking down from the thread cutting(spiral cut)
Obviously with an undersize form bit I could do all of the different sizes with one, but I wouldn't be able to add in the threading insert to the single tool as the threads are different depths in respect to the minor(internal diameter).
Im confident the thread mill could be done with the rest, as the tool could be made very short and stiff if I did go with one tool per fitting.
If I had to make a tool at this point I wouldn't mind, I could fix carbide inserts to it for long life.
So, what are peoples opinions and how the hell are these normally done?
Its worth keeping in mind that this is a ''No one will die if it fails'' sealing application - but obviously them not leaking is a plus
Sorry for the long winded post on something pretty 'simple' but the tool changing is driving me insane.