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Tom Gardner
Guest
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 Posted: Wed Aug 30, 2006 1:23 am Post subject: Carbide grade help |
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Here's a pic of part of a wire cutter. It cuts 3 pieces of .110" x .017"
oil tempered flat wire at a time. There are three 3/4" x 1/4" square
carbides. They are red in the model. The wire advances 3" out of the lower
carbide through a 1/8" square mouse hole. (Yes, we have square mice) The
arm then moves up and snips the wire driven by a cam follower in eccentric.
Each carbide has 8 cutting edges and I would be thrilled to get a week from
each edge or 200,000 cuts. That's about what I get on my other machine
using round carbides, so it's not unreasonable.
The problem I'm having is the top carbide is chipping after 200 cuts, the
arm carbide seems not to chip. It is C5 TiN coated. The arm is in tapered
roller bearings an is very ridged. The green block behind the carbides has
a fine thread adjustment screw and caps that clamp the carbides are not
shown but mount using the visible holes.
Since the mechanism is already built and mounted, I'd prefer not to build a
new design. Once I figure this out, the machine is done!
I have no idea what grades to try next and I wonder how much pressure to
apply to the carbides.
http://www.metalworking.com/DropBox/carbide_wire_cutter.jpg |
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Tom Gardner
Guest
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| Posted: Wed Aug 30, 2006 5:18 am Post subject: Re: Carbide grade help |
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I also seek advice about the amount of overlapp I would need after the cut.
Curently, it's about .025" |
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D Murphy
Guest
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| Posted: Wed Aug 30, 2006 5:19 am Post subject: Re: Carbide grade help |
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"Tom Gardner" <tom(nospam)@ohiobrush.com> wrote in
news:_m1Jg.12292$%j7.7024@newssvr29.news.prodigy.net:
| Quote: | Here's a pic of part of a wire cutter. It cuts 3 pieces of .110" x
.017" oil tempered flat wire at a time. There are three 3/4" x 1/4"
square carbides. They are red in the model. The wire advances 3" out
of the lower carbide through a 1/8" square mouse hole. (Yes, we have
square mice) The arm then moves up and snips the wire driven by a cam
follower in eccentric. Each carbide has 8 cutting edges and I would be
thrilled to get a week from each edge or 200,000 cuts. That's about
what I get on my other machine using round carbides, so it's not
unreasonable.
The problem I'm having is the top carbide is chipping after 200 cuts,
the arm carbide seems not to chip. It is C5 TiN coated. The arm is
in tapered roller bearings an is very ridged. The green block behind
the carbides has a fine thread adjustment screw and caps that clamp
the carbides are not shown but mount using the visible holes.
|
Tom,
Switching to C2 would give you a "tougher" grade which would be less likely
to chip. But I wonder if the problem is with the wires impacting the top
block too sharply more than anything else.
You could try putting the carbide on the moving pice on an angle, or
changing the ramp on the cam, so that the moving cutter moves slowly until
it starts to bite the wire then accelerates quickly after that point.
You could also see if you can get the carbide inserts made in a die grade
of carbide rather than a cutting grade, then have them coated to give a
decently hard cutting edge.
| Quote: |
Since the mechanism is already built and mounted, I'd prefer not to
build a new design. Once I figure this out, the machine is done!
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Hmm. Well you could try this MF30 grade from Mitsubishi or see if you can
get something similar from your current supplier.
<http://blank.mitsubishicarbide.com/mmc/en/product/material/index.htm>
I doubt pressure is the problem. I think what you need is impact strength.
If the failure were caused by pressure, the carbide would rupture after the
first cut. And it would be a catastrophic failure rather than a chipped
edge.
The comparitive number you are looking for is "Fracture toughness" as given
in the Mitsubishi link above.
But I would also think about simple ways that you can mod the machine to
reduce the impact on the carbide.
--
Dan
Scopulus est usquequaque nefas |
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Guest
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| Posted: Wed Aug 30, 2006 5:52 pm Post subject: Re: Carbide grade help |
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Find out the grade used in hammer drill tips -it should have the kind
of impact resistance you require.
Tom Gardner (nospam) wrote:
| Quote: | Here's a pic of part of a wire cutter. It cuts 3 pieces of .110" x .017"
oil tempered flat wire at a time. There are three 3/4" x 1/4" square
carbides. They are red in the model. The wire advances 3" out of the lower
carbide through a 1/8" square mouse hole. (Yes, we have square mice) The
arm then moves up and snips the wire driven by a cam follower in eccentric.
Each carbide has 8 cutting edges and I would be thrilled to get a week from
each edge or 200,000 cuts. That's about what I get on my other machine
using round carbides, so it's not unreasonable.
The problem I'm having is the top carbide is chipping after 200 cuts, the
arm carbide seems not to chip. It is C5 TiN coated. The arm is in tapered
roller bearings an is very ridged. The green block behind the carbides has
a fine thread adjustment screw and caps that clamp the carbides are not
shown but mount using the visible holes.
Since the mechanism is already built and mounted, I'd prefer not to build a
new design. Once I figure this out, the machine is done!
I have no idea what grades to try next and I wonder how much pressure to
apply to the carbides.
http://www.metalworking.com/DropBox/carbide_wire_cutter.jpg |
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Guest
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| Posted: Wed Aug 30, 2006 7:05 pm Post subject: Re: Carbide grade help |
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"Tom Gardner" <tom(nospam)@ohiobrush.com> wrote:
| Quote: | Here's a pic of part of a wire cutter. It cuts 3 pieces of .110" x .017"
oil tempered flat wire at a time. There are three 3/4" x 1/4" square
carbides. They are red in the model. The wire advances 3" out of the lower
carbide through a 1/8" square mouse hole. (Yes, we have square mice) The
arm then moves up and snips the wire driven by a cam follower in eccentric.
Each carbide has 8 cutting edges and I would be thrilled to get a week from
each edge or 200,000 cuts. That's about what I get on my other machine
using round carbides, so it's not unreasonable.
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Are you absolutely sure that your shear edges are not overlapping
during the cut?
Wes S |
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Tom Gardner
Guest
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| Posted: Wed Aug 30, 2006 7:56 pm Post subject: Re: Carbide grade help |
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<clutch@lycos.com> wrote in message news:ed45qh128jt@enews2.newsguy.com...
| Quote: | "Tom Gardner" <tom(nospam)@ohiobrush.com> wrote:
Here's a pic of part of a wire cutter. It cuts 3 pieces of .110" x .017"
oil tempered flat wire at a time. There are three 3/4" x 1/4" square
carbides. They are red in the model. The wire advances 3" out of the
lower
carbide through a 1/8" square mouse hole. (Yes, we have square mice) The
arm then moves up and snips the wire driven by a cam follower in
eccentric.
Each carbide has 8 cutting edges and I would be thrilled to get a week
from
each edge or 200,000 cuts. That's about what I get on my other machine
using round carbides, so it's not unreasonable.
Are you absolutely sure that your shear edges are not overlapping
during the cut?
Wes S
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I'm not sure what you mean, please explain. |
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Guest
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| Posted: Thu Aug 31, 2006 1:08 am Post subject: Re: Carbide grade help |
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"Tom Gardner" <tom(nospam)@ohiobrush.com> wrote:
| Quote: | Are you absolutely sure that your shear edges are not overlapping
during the cut?
Wes S
I'm not sure what you mean, please explain.
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Edges contacting edges. |
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Guest
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| Posted: Thu Aug 31, 2006 1:16 am Post subject: Re: Carbide grade help |
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"Tom Gardner" <tom(nospam)@ohiobrush.com> wrote:
| Quote: | I'm not sure what you mean, please explain.
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Never mind my overlap comments. You would know it just from listening
to it run.
Wes S |
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Fred R
Guest
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| Posted: Thu Aug 31, 2006 2:43 am Post subject: Re: Carbide grade help |
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Tom,
You might try shimming up your "mouse hole" so the incoming stock has no
room to take an angle or 'flap' right after the cut.
Tom Gardner wrote:
| Quote: | Here's a pic of part of a wire cutter. It cuts 3 pieces of .110" x .017"
oil tempered flat wire at a time. There are three 3/4" x 1/4" square
carbides. They are red in the model. The wire advances 3" out of the lower
carbide through a 1/8" square mouse hole. (Yes, we have square mice) The
arm then moves up and snips the wire driven by a cam follower in eccentric.
Each carbide has 8 cutting edges and I would be thrilled to get a week from
each edge or 200,000 cuts. That's about what I get on my other machine
using round carbides, so it's not unreasonable.
The problem I'm having is the top carbide is chipping after 200 cuts, the
arm carbide seems not to chip. It is C5 TiN coated. The arm is in tapered
roller bearings an is very ridged. The green block behind the carbides has
a fine thread adjustment screw and caps that clamp the carbides are not
shown but mount using the visible holes.
Since the mechanism is already built and mounted, I'd prefer not to build a
new design. Once I figure this out, the machine is done!
I have no idea what grades to try next and I wonder how much pressure to
apply to the carbides.
http://www.metalworking.com/DropBox/carbide_wire_cutter.jpg
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--
Fred R
"It doesn't really take all kinds; there just *are* all kinds".
Drop TROU to email. |
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Ken Sterling
Guest
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| Posted: Thu Aug 31, 2006 3:23 am Post subject: Re: Carbide grade help |
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| Quote: | Here's a pic of part of a wire cutter. It cuts 3 pieces of .110" x .017"
oil tempered flat wire at a time. There are three 3/4" x 1/4" square
carbides. They are red in the model. The wire advances 3" out of the lower
carbide through a 1/8" square mouse hole. (Yes, we have square mice) The
arm then moves up and snips the wire driven by a cam follower in eccentric.
Each carbide has 8 cutting edges and I would be thrilled to get a week from
each edge or 200,000 cuts. That's about what I get on my other machine
using round carbides, so it's not unreasonable.
The problem I'm having is the top carbide is chipping after 200 cuts, the
arm carbide seems not to chip. It is C5 TiN coated. The arm is in tapered
roller bearings an is very ridged. The green block behind the carbides has
a fine thread adjustment screw and caps that clamp the carbides are not
shown but mount using the visible holes.
Since the mechanism is already built and mounted, I'd prefer not to build a
new design. Once I figure this out, the machine is done!
I have no idea what grades to try next and I wonder how much pressure to
apply to the carbides.
http://www.metalworking.com/DropBox/carbide_wire_cutter.jpg
Tom, |
I am probably talking out my backside with this, but even tho you may
lose a couple of cutting edges, you could try to grind a relief on the
arm carbide of 6 or 7 degrees so it would act more like a cutting
wedge rather than a hard shear. The arm carbide is probably producing
a "sliding" motion, even though minute, and may be the reason it is
not chipping, and giving a little relief to the shear may stop the
shock the upper carbide is receiving. Worth a try, anyway.
HTH
Ken. |
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D Murphy
Guest
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| Posted: Fri Sep 01, 2006 2:18 am Post subject: Re: Carbide grade help |
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"Tom Gardner" <tom(nospam)@ohiobrush.com> wrote in news:IeCJg.4286$tU.3718
@newssvr21.news.prodigy.com:
| Quote: | Great link with lots of info, thanks! I'll post the answer when all my
samples are tried.
|
Please do post the solution. That's where the real learnin' is.
--
Dan
Scopulus est usquequaque nefas |
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Glenn
Guest
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| Posted: Fri Sep 01, 2006 2:18 am Post subject: Re: Carbide grade help |
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"Harold and Susan Vordos" <vordos@tds.net> wrote in message
news:4vuJg.414$5i7.268@newsreading01.news.tds.net...
| Quote: |
"Tom Gardner" <tom(nospam)@ohiobrush.com> wrote in message
news:_m1Jg.12292$%j7.7024@newssvr29.news.prodigy.net...
Here's a pic of part of a wire cutter. It cuts 3 pieces of .110" x
.017"
oil tempered flat wire at a time. There are three 3/4" x 1/4" square
carbides. They are red in the model. The wire advances 3" out of the
lower
carbide through a 1/8" square mouse hole. (Yes, we have square mice)
The
arm then moves up and snips the wire driven by a cam follower in
eccentric.
Each carbide has 8 cutting edges and I would be thrilled to get a week
from
each edge or 200,000 cuts. That's about what I get on my other machine
using round carbides, so it's not unreasonable.
The problem I'm having is the top carbide is chipping after 200 cuts, the
arm carbide seems not to chip. It is C5 TiN coated. The arm is in
tapered
roller bearings an is very ridged. The green block behind the carbides
has
a fine thread adjustment screw and caps that clamp the carbides are not
shown but mount using the visible holes.
Since the mechanism is already built and mounted, I'd prefer not to build
a
new design. Once I figure this out, the machine is done!
I have no idea what grades to try next and I wonder how much pressure to
apply to the carbides.
http://www.metalworking.com/DropBox/carbide_wire_cutter.jpg
I can't help but think that the wire isn't cutting clean, and pulling the
edge off the carbide on the return stroke. All it has to do is remove a
tiny amount from the edge and it will go down hill quickly. As you know,
carbide has very little tensile strength. Narrow down the clearance so
you achieve a dead clean cut, or improvise a way for the machine to pull
back the wire between cuts, so it can't make contact with the carbide
while
it's moving back to location. .
Harold
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Aha! .. Sorta like facing off in the lathe and going just a smidge past
center. The carbide goes away instantly when it hits the steel going the
other way and is being pulled?
Glenn |
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