Jump to content

Recommended Posts

A local tech school offered to over-haul my press which had issues with the die holders. And they also made a system to punch axe/hammer eyes... including a hot punch and stripper to knock the steel off as the die rises. It's going to be pretty nice once I get it worked out. But after the first test the punch (actually more of a chisel) started showing deformity. I believe they just used mild steel. So how much does steel type really factor in when you are dealing with something like this... high heat and pressure? I have some 1" square 5160... would this be a significant improvement? Is there any real reason to heat treat?

Link to post
Share on other sites

I have found that punching with a press is much more a matter of press speed than punch material.

If you allow your punch to become red/ orange then nothing will save it . this happens pretty quick .

I use H13 but found that even that will end up overheating .

Basically you need to be into and out of the hot steel before the punch reaches the temp where its temper is lost , with H13 thats about 650C .

punch volume makes a lot of difference .As does the temp of the steel you are punching . you will sometimes get better results on red steel rather than orange , especially with mild.

I can get away with overheating punched by hand but not on a press.

 

my punching press moves at 2" a second . I downgraded the power from 18 tonne to 12 tonne and upped the speed correspondingly . massive improvement.

2 stage pumps are not so good for punches unless you are punching on the high flow stage.

Edited by owen bush
Link to post
Share on other sites

Great stuff Owen. Just what I needed. Just curious... how big (in cross-section) is your punch? And is it actually a 'punch' in that it removes a plug of steel? The one I'm experimenting with is almost full size for.... say a hammer eye. I was surprised that I could actually get that to work (for the most part).. but it does deform the stock more than I like... around the perimeter of the eye.. if that makes sense.

 

I have found that punching with a press is much more a matter of press speed than punch material.
If you allow your punch to become red/ orange then nothing will save it . this happens pretty quick .
I use H13 but found that even that will end up overheating .
Basically you need to be into and out of the hot steel before the punch reaches the temp where its temper is lost , with H13 thats about 650C .
punch volume makes a lot of difference .As does the temp of the steel you are punching . you will sometimes get better results on red steel rather than orange , especially with mild.
I can get away with overheating punched by hand but not on a press.

my punching press moves at 2" a second . I downgraded the power from 18 tonne to 12 tonne and upped the speed correspondingly . massive improvement.
2 stage pumps are not so good for punches unless you are punching on the high flow stage.

Link to post
Share on other sites

I run a standard punch that is tapered oval flat end to form the standard hour glass eye shape . the punch goes through one side , turn , punch out plug ( normally 4 to 6mm or so) . then force punch further through side one until it protrudes out of the other side of the eye. I use a spacer bolster block. turn over and do same from other side.

I used to use 2 punches . but have settled on one .I have a selection of them for axes.

Link to post
Share on other sites

I run a standard punch that is tapered oval flat end to form the standard hour glass eye shape . the punch goes through one side , turn , punch out plug ( normally 4 to 6mm or so) . then force punch further through side one until it protrudes out of the other side of the eye. I use a spacer bolster block. turn over and do same from other side.

I used to use 2 punches . but have settled on one .I have a selection of them for axes.

Wow.. only 4-6 mm eh? That must be why mine is really deforming the area that I'm punching. Mine is quite a bit larger.

Link to post
Share on other sites

sorry the plug that is punched out is 4-6 mm thick .

ill take piccie and measure the die. are you using lube?

Link to post
Share on other sites

punch small end is roughly 20mm by10mm oval.

 

16662918755_ec66d55082_c.jpg

 

I used to use the punch on the left and then 2nd with the punch on the right for hammer eyes . now I just use the punch 2nd from the left on its own . It was ground flat ended but has stabilised its shape to rounded nose having been over heated a few times.

I have a quicker ram that I will set up with slimmer punches but at the moment any slimmer punches would be destroyed by over heating.

I looked into tungsten and high tungsten/steel alloys and they are expensive and more to the point not within my realm of understanding.

I use a graphite grease lube.

Edited by owen bush
Link to post
Share on other sites

sorry the plug that is punched out is 4-6 mm thick .

ill take piccie and measure the die. are you using lube?

Yeah... I use Anti-Seize. Not sure if they sell it in the UK but it's a graphite based lubricant. I mixed fine charcoal powder into it and I paint it on between heats. Okay well your punches are not all that different than mine. Not sure why mine is doing what it is doing then. The best way I can describe it is that the sides of the eye are getting pulled down into the hole.. which distorts things. For example... the area with the punched hole is no longer flush and square.. it's rounded and concave and 'sucked in' looking. I will take a picture next time. :) It worked out okay on an axe I did yesterday because I had to forge the ears on a mandrel anyway. But if I wanted to do a hammer.... it would have been pretty strange looking.

 

Thanks a lot for those pictures and info. I'm in the process of re-making this punch from H13 so I will see how things go with that.

Link to post
Share on other sites
  • 9 months later...

coming back to this post, did you sort it out? could it be that your steel is too hot. I have found that the steel needs to only be as hot as is needed for the punch to penetrate it. the hole ends up better in shape and the punch does not heat up as much.

Link to post
Share on other sites
  • 3 weeks later...

coming back to this post, did you sort it out? could it be that your steel is too hot. I have found that the steel needs to only be as hot as is needed for the punch to penetrate it. the hole ends up better in shape and the punch does not heat up as much.

Jeez Owen.. I never saw this. NO.. I've still been having issues with the deformity.. but I've managed to learn to solve it in forging afterwards.. But I will have to try it at a lower heat.... Thank you!!!

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...