Tooling for 604 stainless

hagar · Jun 14, 2011

I recently had the need to produce some muzzle brakes from 604 stainless . I am using carbide tooling but even with flood cooling it is still hard on the carbide . I have not had much experience with stainless before . Any suggestions would be appreciated .

Thanks, hagar

FredC · Jun 14, 2011

Never heard of 604. Carbide by itself does not mean much. We have machined Allen screws by the hundreds and C5 which used to be considered good for such, would last only a few parts. Kennametal recomended a KC5010 and we could do a whole run with one insert! It has also worked on max hard 416 (about 45RC). Just recently someone posted else where that the KC5010 grade did not work for him. These grades appear to be material specific.
Another thing is material. In a screw machine shop I worked at, the customers supplied material and some batches of Japanese 304 back then could not be run 1/2 of the rated speed and still burned up tools so fast we would use a time card to keep up with sharpening. The same part with Carpenter project 70 would run for days at 110% of the rated SFM with out sharpening any of the tools. Too bad Carpenter does not supply small batches of material anymore.

tdmidget · Jun 14, 2011

604 is the same as 17-4 PH.

wesg · Jun 14, 2011

That would be 630.

Didn't find any reference to 604 with a quick search.

tdmidget · Jun 14, 2011

I can't find it now but it showed 15-17 Ni ,3-5Cr, and 3 Cu. Can't be much different machining wise. What hardness is it? There is quite a range on most precipitation hardening alloys.

hagar · Jun 15, 2011

My mistake it is 304 . Meets ASTM A240-92B

tdmidget · Jun 15, 2011

splains a lot. Maybe you could talk them into 604. much easier. Most stainless firearm parts are 17-4 or 416.

bridgeport · Jun 16, 2011

Funny, I was gonna ask if your x04 was 304. My advice is that you advise your customer to change alloy.

trevj · Jun 16, 2011

They probably spec'd 304 because it was the cheapest available material.

Misery to work, compared to the more expensive stuff, so charge accordingly. Charge enough, and they will likely be pretty motivated to pay more for material, if it saves them in the long run.

Have fun!

Cheers
Trev

hagar · Jun 16, 2011

Thanks to all for the help . It was because of the cost . hagar

By the way, is the 304 good for anything ?

bridgeport · Jun 18, 2011

A lot of the stainless pipe used in industry is type 304. It welds well.

hagar · Jun 18, 2011

Thanks again to all for the help . My customer liked the material not only because of the cost but he is an electrical high tech person and tells me that 304 is used extensively in electronics . Could be because it welds well .

IronReb · Jun 19, 2011

304 is gummy and a bitch to machine compared to other materials but money can be made working with it.One thing for sure is,be very careful trying to talk customers into using a different material,if the part fails because you talked him into another material your gonna be in a world of crap.

Best thing is to talk to a tool rep who knows his carbide,not all carbide is created equal.I have some grades the work well in 4140 and suck in stainless.My tool rep helped me choose the proper grade.Another thing my tool rep showed me was it's not always best to slow down surface footage in SS,sometimes you wanna speed it up,he explained to me that be increasing my speed it heated up the stainless and got it out of it's wanting to weld the chip to tool tip habits.

Again,best thing you could probably do is talk to a good tool rep who knows what the hell he is doing.He can suggest the best grade and speeds and feeds for the material your cutting.

hagar · Jun 19, 2011

IronReb said:
304 is gummy and a bitch to machine compared to other materials but money can be made working with it.One thing for sure is,be very careful trying to talk customers into using a different material,if the part fails because you talked him into another material your gonna be in a world of crap.

Best thing is to talk to a tool rep who knows his carbide,not all carbide is created equal.I have some grades the work well in 4140 and suck in stainless.My tool rep helped me choose the proper grade.Another thing my tool rep showed me was it's not always best to slow down surface footage in SS,sometimes you wanna speed it up,he explained to me that be increasing my speed it heated up the stainless and got it out of it's wanting to weld the chip to tool tip habits.

Again,best thing you could probably do is talk to a good tool rep who knows what the hell he is doing.He can suggest the best grade and speeds and feeds for the material your cutting.

Will do . I have already speeded up the feed and speed about 15% which is what I could find in my information and it is working better . The main problem I am having is when two holes intersect each other I get a lot of chatter and the tool tries to hang .

Thanks, hagar

speerchucker30x3 · Jun 19, 2011

I make about a hundred of the fool things a year. Its kinda hard to say what you are trying to accomplish here as your description is rather vague, BUT! It sounds like your having trouble with the port hole drilling. When the drill breaks through to a previously drilled hole its only catching on one side of the bit until it begins cutting back into the main body of the break. This causes chatter, which chips and breaks the carbide drills. Drill an undersized through hole through the center of the break first that way when you drill the port holes the drill will meet the center hole and then start cutting on the center of the drill for the other side right away. Also ditch the carbide and go to stubby cobalt machine drills at 500 to 700 RPM depending on drill size and use a full flood of water coolant. This will work well with 304 but your chips will spiral up the drill and cause problems if your CNC drilling but you can step the drill down to break the chips. 416 is the obvious answer and your chips will egg roll, but its double the material cost.
Note: I gave up on 303 and 304 because of people whining about the difference in color between the breaks I was making and color of their barrels. Its also a pain in the ass to work with so it wasn't a big disappointment.

hagar · Jun 19, 2011

speerchucker30x3 said:
I make about a hundred of the fool things a year. Its kinda hard to say what you are trying to accomplish here as your description is rather vague, BUT! It sounds like your having trouble with the port hole drilling. When the drill breaks through to a previously drilled hole its only catching on one side of the bit until it begins cutting back into the main body of the break. This causes chatter, which chips and breaks the carbide drills. Drill an undersized through hole through the center of the break first that way when you drill the port holes the drill will meet the center hole and then start cutting on the center of the drill for the other side right away. Also ditch the carbide and go to stubby cobalt machine drills at 500 to 700 RPM depending on drill size and use a full flood of water coolant. This will work well with 304 but your chips will spiral up the drill and cause problems if your CNC drilling but you can step the drill down to break the chips. 416 is the obvious answer and your chips will egg roll, but its double the material cost.
Note: I gave up on 303 and 304 because of people whining about the difference in color between the breaks I was making and color of their barrels. Its also a pain in the ass to work with so it wasn't a big disappointment.

Thanks for the advice . That is exactly the problem I am having . I will try what you suggest . I have been bead blasting the brakes and that gives them a mat finish that almost matches the barrels perfectly . I am now using a mill/drill to drill the ports at about 750 RPM . So far I have not broken any tools but I do get a lot of chatter . The main ware on the carbide inserts is when I am profiling the brakes . I am going to look for a different insert for my work . I do not have CNC equipment . hagar

speerchucker30x3 · Jun 20, 2011

Cut the OD of your break before you drill the holes. Otherwise you will run into chatter as the tool crosses the holes. Cheap carbide tools will chip as they ride over the holes. If you must alter a diameter over holes use very sharp pointed HSS tools at low RPM "say 200 - 300" and low feed with lots of coolcut. 300 series stainless usually cuts quite well but your chips will not break into 6s an 9s well. Cheep crap!
I find that when turning undrilled 304 its best to keep your speeds down and your feeds up to get best tool life and a good finish. I also use a full flood of water on the tool as I cut. 300 series work hardens like there is no tomorrow so try to make the first cut the last cut. Be careful as cheep inserts can thermal shock and crack with water. I got some inserts from Kennametal here in Edmonton and they work well. The cheep Busy Bee and Tools for Cheep inserts last about 10 seconds. "slight exaggeration"
By the way the 300 series stainless is a much more silver/yellow color than the barrel steel. I got whined to death on that by whiny customers. Had to give a few their money back. I didn't like that much.

bridgeport · Jun 20, 2011

Type 303 is high sulfur 304 designed for free machining, yet retaining the other alloying elements of 304. Perhaps this would satisfy your customers requirements.

speerchucker30x3 · Jun 20, 2011

bridgeport said:
Type 303 is high sulfur 304 designed for free machining, yet retaining the other alloying elements of 304. Perhaps this would satisfy your customers requirements.

Very true bridgeport. I considered the same way back when I started making them. 303 is nice to work with. Just like 416 being the high sulfur, free machining version of 410 makes 416 so pleasant to play with. But Hagar notes cost is the reason for the 304. I gave up on the 303 because it cost more than 416. 303 would be nice to use if people could get over the cost and color because its a whole lot more resistant to the unpleasantness of life than 416 is. 416 will stain if its polluted by carbon steel and it does not fare well in coastal areas with salt air. Why won't steel makers listen to us and make what we want instead of all those multi billion dollar corporations. See if we send them Xmass cards this year. B******S !!!!!!!

hagar · Jun 20, 2011

I can't thank all of you enough for your input and advice . This is a fine example of why "Practical Machinist" is one of the most useful sites on the web . hagar

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