304 Stainless Ball Bearings

rwm

rwm

Robert
H-M Lifetime Diamond Member
Joined
Mar 25, 2013
Messages
4,614
I purchased s few of these bearing balls:

s-l1600.jpg

They are available on Ebay and come from China. They are billed as 304 Stainless.
I have tried to work them without success. The material is very hard and cannot be drilled even with carbide. They are a least moderately magnetic. I am doubting the alloy is as represented. Can 304 Stainless be hardened to this degree by some process? Are these really just chrome plated standard bearing balls? How can I test this before I complain? If they are somehow hardened could I anneal them to make them workable?
Other thoughts? Chime in you materials experts!
R

s-l1600.jpg

s-l1600.jpg

s-l1600.jpg

s-l1600.jpg

s-l1600.jpg
 
They would be useless as ball bearings if they were soft
 
300 series stainless steel is work harden and can get up in the high 50's on the Rockwell C scale. The only thing you could try is heating them up to around 1850- 2050 deg F. and attempt to cool rapidly. And I would almost guarantee a round ball of metallic material cooled rapidly may explode on you.

Edit: slightly indicates it's not a true grade of 304. Coming from China, their material grades do not follow ours. They follow the DIN specifications. I'll see if I can find what they use. And their grade is probably slightly magnetic.

Edit: Chinese equivalent is 5 CrNi 18 10, which is the same as the Germany DIN number.

http://mdmetric.com/pdf/ssgradetable.pdf
 
Last edited by a moderator:
I appreciate all the quick responses. This is more than slightly magnetic. In fact after testing, it is just as magnetic as a regular steel bearing ball.
I have had good results annealing work hardened stainless previously but I have never worked with balls. So...I heated it up to about 2000 deg and dropped it in a bucket of water to anneal it...twice.
No effect. Can barely drill into it with carbide.
Based on the magnetism and my inability to anneal these I am not sure what I really have.

R
 
Last edited:
I buy mine from McMaster Carr. They have a good selection.
I've seen others that are very expensive, especially metric sizes, like 1.2, 2.5, etc...
What size did you buy?
 
EmilioG said:
I buy mine from McMaster Carr. They have a good selection.
I've seen others that are very expensive, especially metric sizes, like 1.2, 2.5, etc...
What size did you buy?
Click to expand...
These are large. 30mm. My intent was to drill and tap them and use them for handles, not as bearings.
R
 
You could just buy some aluminum or stainless ball handles to begin with. McMaster Carr has them.
 
derf said:
You could just buy some aluminum or stainless ball handles to begin with. McMaster Carr has them.
Click to expand...
Duh...Because I didn't know they sold them!

6045k37p1l.png

Wow relatively cheap too. Stainless are $12. I decided to make a radius turner and make some in aluminum. I may go and order one in stainless next time I place an order.
Thanks for the heads up!
R



I like the idea of a boring head mounted in a boring bar holder. Not sure how smooth that would run.

R

6045k37p1l.png

6045k37p1l.png

6045k37p1l.png

6045k37p1l.png

6045k37p1l.png
 
Last edited by a moderator:
You must log in or register to reply here.
Back
Top