Exotic Materials

[stuby]

Hello everybody. I am looking for some help with working with exotic materials. I am working on a 12"x.500 DIA molybdenum shaft. I need to drill a hole straight down the center through it all. I get about 2-3 inches into the material, and the shaft literally splits in half, and breaks my drill along with it. This has happened to me 3 times, and we tried to have it gun drilled and it also happened to them. Anybody have any experience with exotic materials that can shed some light on the situation for me? Send me a private message if you have worked with any other materials. Currently I am doing molybdenum, Tungststen, and sapphire. Thanks for any and all help.

[citizencnc]

Are you sure that you're not having a bad bar of mat'l to start with ? The reason I bring this up because I ran into this situation atlease 4 times in the past 3 years. These were waspalloy and 17-4. You can tell by looking at the finish between the splits pieces( use micro scope if possible) if they are dark then this could be the problem. Another way to verify is sending the mat'l out for X-ray.

[stuby]

Well, oddly enough that you say that. We were doing the some work with tungsten, and when we tried to thread it the crests simply fell off. We asked the customer about this, and he said that ALL tungsten stock, and ALL moly stock is sintered. They say you cannot get " Solid " stock for it. So I guess the answer is yes, the stock is bad. Any way around this at all? Did you find some miracle for your kryptonite metal?!? I suggested to the customer to make several smaller in length pieces, and thread them together with an OD thread on one side, and an ID thread on the other. Anyways, thanks for the reply, Im glad im not the only one dealing with this. Thanks.