Titanium 6-AL-4V spur gears hobbing
Titanium 6-AL-4V spur gears hobbing
(OP)
Does any one have any good or bad experience thoughts and knowledge of precision spur gears (AGMA Q10C) made of Titanium such as 6AL-4V or any 334-38 RC titanium alloy?
Any information will be appreciated.
Any information will be appreciated.





RE: Titanium 6-AL-4V spur gears hobbing
I haven't keep up with the coatings for Ti alloys so there maybe a better one available. The only one I recall being used was Tiodize, which one no recall.
We eventually we with a high strength steel gear designed to the 9's. The thing was so light I was kinda scared of it during testing. A TiN coating was eventually used on the gear
Have you checked the NASA site?
RE: Titanium 6-AL-4V spur gears hobbing
RE: Titanium 6-AL-4V spur gears hobbing
Thank you for your posts.
Fellow and hobbing are the same from my point of view and my question is basically referring to both methods and any other gear machining process.
My problem is not just the machining issues but basically how two spur gears made of high strength titanium will work together in mesh under quite heavy loads and high speeds.
RE: Titanium 6-AL-4V spur gears hobbing
RE: Titanium 6-AL-4V spur gears hobbing
The gears are fine pitch gears DP 72, 64, 48 ,32 PIC SDP BERG and others make gears from AL 2024-T4 with no problems. We did custom aluminum gears too with no problem.
We are now facing some "managers" who believe that switching from small 38RC stainless steels fine pitch gears to titanium "will save some weight".
We are sure this is a bad idea but we will be glad to find "outside help" to help those mangers climb down the tree.
1. This will make the gears much more expensive
2. The time to get them manufactured will be much longer
3. We expect galling etc.
It takes 100 smart guys to pull a stone some fool throw into a deep well
The problem currently that we have to confront some "managers" who believe they can lower some weight of a small 38RC steel gears by changing them to titanium gears.
RE: Titanium 6-AL-4V spur gears hobbing
I forgot to erase it.
RE: Titanium 6-AL-4V spur gears hobbing
RE: Titanium 6-AL-4V spur gears hobbing
The gears have to be made from a material that does not corrode such as stainless steel. Nitriding may be an option and was considered but as far as we know grinding of fine pitch gears is a problem or not possible. The tooth of the fine pitch gear is too small for case hardening because there will be no base metal left just only the brittle case (the sum of thickness of the case on both sides can be more than the tooth width).
RE: Titanium 6-AL-4V spur gears hobbing
RE: Titanium 6-AL-4V spur gears hobbing
RE: Titanium 6-AL-4V spur gears hobbing
RE: Titanium 6-AL-4V spur gears hobbing
http://www.uschromeofca.com
RE: Titanium 6-AL-4V spur gears hobbing
Hard chrome is usually quite thick compared to the size and dimensions of these gear teeth. According to QQ-C-320 CHROMIUM PLATING (ELECTRODEPOSITED) class 2 which is hard chromium plating should be at least 0.002" thick.
Therefore, the accuracy will be less than Q10C after the chrome plating. Grinding of fine pitch gears is a problem or even impossible to my best knowledge.
The gears are not subjected to only wear, there are high Hertz line or point contact stresses where the involutes contact. The chrome plate if not really thick will tend to break. Chrome plating is commonly used on shafts and surfaces that are not subjected to point or line loads.
.
RE: Titanium 6-AL-4V spur gears hobbing
RE: Titanium 6-AL-4V spur gears hobbing
I am aware of this process (wire EDM). We did it many years ago for first and quick prototypes and NASA did some research on it too in order to use 60RC fully harden gears for space use. The got close to the accuracy I am fter but not exactly, and the price is accordingly.
However, the issue here is fine pitch gears made of titanium alloy. It seems that no one in this forum have any experience or knowledge about it.
RE: Titanium 6-AL-4V spur gears hobbing
that is why I asked for the thicknesses.
I assume cost is not a factor and that weight
is their greatest concern. I also assume
that you will not be able to test several
prototypes. I would look at recess action
gearing to help reduce the chances of gaulling.
Will you be able to run-in these gears?
Plazma coating may be an option.
RE: Titanium 6-AL-4V spur gears hobbing
Although weight is crucial the cost is a major factor too.
As far as I know all recess gears are intended for one direction rotation. In our case the gear is used both as a speed increasing gear and as a reduction gear. The gears were designed and corrected for minimum specific sliding in both ways.
What to you mean by "run-in"? Is it as it was used with old cars for the first 500 miles run-in to let the parts match themselves by wearing out the imperfections of the involute profile? No, we do not have this option.
Our problem is even bigger because we may need to use the gears with dry lubrication (MoS2) and no grease or oil.
RE: Titanium 6-AL-4V spur gears hobbing
Is the MoS2 simply sprayed on with an alcohol
base? I was fairly certain that these would
be run dry. I also assume that lead or mercury
cannot be used to surface coat these.
RE: Titanium 6-AL-4V spur gears hobbing
RE: Titanium 6-AL-4V spur gears hobbing
with aluminum gears. The pinions were
steel. 10dp gears were the smallest
that we supplied.