Forging vs stock removal strengh

[Natlek]

Forged Bar:
Directional alignment through the forging process has been deliberately oriented in a direction requiring maximum strength. This also yields ductility and resistance to impact and fatigue.

Machined Bar:
Unidirectional grain flow has been cut when changing contour, exposing grain ends. This renders the material more liable to fatigue and more sensitive to stress corrosion cracking.

Cast Bar: No grain flow or directional strength is achieved through the casting process.

 

[hugofeynman]

We tested m390, (3rd generation) and it showed no difference. I’ve now done samples in 4v/V4e, vanax, z-tuff, and I think one other to see if 1st and third generation steels are different in transverse toughness.

Let’s wait, then.

As Fredrik Haakonsen wrote in another forum:

“Rolled sheet or flat bar to near finished dimension, and length direction parallel to the rolling direction. When you have the blade in this orientation the inclusions have less effect as they are oriented in the rolling direction. If cut in transverse direction the toughness and strength can be significantly lower. There are small differences between conventional steels and PM/ESR steels in the longitudinal direction (rolling direction), but PM and ESR steels doesn’t lose as much toughness in the transverse direction. Still, PM and ESR steel isn’t as good in transverse direction as longitudinal direction and the difference can be significant.”

In my understanding, Warren, only if a steel has an perfectly homogeneous structure with no inclusions at all (doesn’t exist yet), it would be equal to make a knife cutting the blank in any direction, but, as Fredrik points: “PM steels doesn’t have absence of flaws. They still have inclusions, they are just smaller and more evenly distributed. In some PM steels sulfur are added to increase machinability, giving larger inclusions. The PM process was developed to make higher alloyed steel that is hard to make with conventional process. Cleanliness is just improvement that has come later on.”.

Sincerely, I much preferred that there’s no difference in toughness between rolling direction of the steel, because I have some really big (and thick) knives that where made from large pieces cut from giant blocks (the “grain” direction it’s uncertain...), this “grain” orientation thing is relatively new to me, but makes sense, and if my knife Guru (Haakonsen) says it makes the difference, it must do!

 

[Natlek]

I agree with N Natlek that forging makes tougher tools, knives included, but here we are not talking about forging with a 3kgs hammer! We are talking about a several tons hammer that will “push” the steel to the final shape, with same gigantic pressure in all points. This will make a tougher tool IF the next stages are well made (stress relief, good heat treatment and minimal grinding) and the right forging temperature is achieved, like D DevinT pointed out. Unfortunately, in knife world, this stamping/closed die forging process it’s mostly used in the best “cheap” knives (Wildsteer May be an exception, but they are using just an “average” steel). RMJ Tactical is the only reputable company (that I know of) that is using this process to make their Shrike model (not anymore, I’m afraid). Having said that, my money is in a stock removal knife made by a reputable maker, in a steel he masters, where the blank is cut parallel to the rolling direction of the steel and all stages of making that knife are made by said maker.

H.Roselli knives are made almost like you describe..I say almost because they still make some grind on blade ...

 

[hugofeynman]

Forged Bar:
Directional alignment through the forging process has been deliberately oriented in a direction requiring maximum strength. This also yields ductility and resistance to impact and fatigue.

Machined Bar:
Unidirectional grain flow has been cut when changing contour, exposing grain ends. This renders the material more liable to fatigue and more sensitive to stress corrosion cracking.

Cast Bar: No grain flow or directional strength is achieved through the casting process.

Reason is on your side, but maybe if you politely explain your arguments, more people understand.

Most guys are comparing “a man with a hammer” forging to stock removal, not closed die forging vs cnc machining/stock removal.

 

[hugofeynman]

H.Roselli knives are made almost like you describe..I say almost because they still make some grind on blade ...

Wildsteer also makes some minor grinding, it’s almost inevitable, I’m afraid. But the ideal “grain” structure is there, from forging!

 

[Natlek]

Reason is on your side, but maybe if you politely explain your arguments, more people understand.

Most guys are comparing “a man with a hammer” forging to stock removal, not closed die forging vs cnc machining/stock removal.

Most time probably it is my bad English ...but in this case I think that I make clear statement..............

IF knife is forged to final dimension must be stronger then stock removal knife . How much I have no idea

 

[Willie71]

This is what I said about knife ...........So do you agree with that ?

About bad and good equipment we can discuss in another thread . I open one but was closed by moderator.....You can open new one

Stock removal knives are forged longitudinally already, so no difference. Not what you said at all.

 

[Willie71]

Let’s wait, then.

As Fredrik Haakonsen wrote in another forum:

“Rolled sheet or flat bar to near finished dimension, and length direction parallel to the rolling direction. When you have the blade in this orientation the inclusions have less effect as they are oriented in the rolling direction. If cut in transverse direction the toughness and strength can be significantly lower. There are small differences between conventional steels and PM/ESR steels in the longitudinal direction (rolling direction), but PM and ESR steels doesn’t lose as much toughness in the transverse direction. Still, PM and ESR steel isn’t as good in transverse direction as longitudinal direction and the difference can be significant.”

In my understanding, Warren, only if a steel has an perfectly homogeneous structure with no inclusions at all (doesn’t exist yet), it would be equal to make a knife cutting the blank in any direction, but, as Fredrik points: “PM steels doesn’t have absence of flaws. They still have inclusions, they are just smaller and more evenly distributed. In some PM steels sulfur are added to increase machinability, giving larger inclusions. The PM process was developed to make higher alloyed steel that is hard to make with conventional process. Cleanliness is just improvement that has come later on.”.

Sincerely, I much preferred that there’s no difference in toughness between rolling direction of the steel, because I have some really big (and thick) knives that where made from large pieces cut from giant blocks (the “grain” direction it’s uncertain...), this “grain” orientation thing is relatively new to me, but makes sense, and if my knife Guru (Haakonsen) says it makes the difference, it must do!

I’m reserving judgement until test results are in too. I’ve always accepted that the steel would be stronger longitudinally, but complex shapes like ring and pinions or turbines might have been the driving force behind the development of third generation pm technology. In our original test, I didn’t supply any 20cv cut transversely to compare. Longitudinally 20cv and m390 were the same. I might have an inch or two of the 20cv left from the initial testing to try a transverse sample.

 

[Willie71]

Reason is on your side, but maybe if you politely explain your arguments, more people understand.

Most guys are comparing “a man with a hammer” forging to stock removal, not closed die forging vs cnc machining/stock removal.

I agree with you in theory here, but this is well beyond any of our capabilities on this forum, excepting the commercial damascus makers. In real world use, I see blades break at the tang, usually from stress risers, or at the tip from overheating. Would forging minimize breaking at the tang? Maybe, but if you forged the tang to a 90deg angle, it would still likely fail. However, a radiused transition whether filed, ground, or forged has been shown to be plenty strong.

 

[hugofeynman]

I agree with you in theory here, but this is well beyond any of our capabilities on this forum, excepting the commercial damascus makers. In real world use, I see blades break at the tang, usually from stress risers, or at the tip from overheating. Would forging minimize breaking at the tang? Maybe, but if you forged the tang to a 90deg angle, it would still likely fail. However, a radiused transition whether filed, ground, or forged has been shown to be plenty strong.

I confess I’m mostly theoretical, Warren, in the knife world. I’m a knife collector with a big fascination for toughness (Noss has the fault with his tests), but unfortunately I don’t use knives that much (now I’m moving to a bigger house, with lots of terrain to use knives and axes).

From my readings and from conversations with Metallurgists and people much more knowledgeable than me on these matters, I’ve come to understand that drop forging (closed die forging) makes the tougher knives (open die forging, like Gränsfors Bruks axes are made, is probably the second best process to make a tough tool), because it makes better segregation lines (if the forging temperature is not too high).

This process, as you can watch here (minute 0:30):

and here (minute 03:00):

, if the forging temperature is the ideal, will make the toughest possible tool with no weaknesses (unless someone messes with geometry grinding it improperly, obviously). These tools have no weak points, if heat treated well, of course.

 

[Lieblad]

Would forging minimize breaking at the tang? Maybe, but if you forged the tang to a 90deg angle, it would still likely fail. However, a radiused transition whether filed, ground, or forged has been shown to be plenty strong.

Fwiw, I forge tang transitions fairly sharp. At least as sharp as tight radius portion of my anvil edge, whats about .04" Never a breaking problem, and would never file it sharper.

 

[Larrin]

I do see a lot of people cutting rough shapes prior to forging, particularly for tips. I wonder sometimes how much forging the "grain" to shape actually occurs with a typically forged knife.

 

[kuraki]

Thanks Is that your last argument that you are right?

No, because I neglected the fact that someone as ignorant on so many topics as you would need a better description just to understand how inept they are.

kuraki said on internet and that is gospel ?How many link you want to show you that you are wrong ?
https://www.researchgate.net/profil...s-in-Threading-of-Steel-Cold-Forged-Parts.pdf
https://www.yamawa.com/en/support/catalog/pdf/handbook-03_roll.pdf


Yes , almost nobody...............BUT

What’s better about form taps? Well, they have several advantages over cut taps that will make you want to use them more often. For one, they don’t make any chips. A form tap does just that, it “forms” the threads in the hole with pressure, as opposed to “cutting” threads.

That brings us to the next advantage; the threads are much stronger because they are “formed” into place. If you need strong threads in your parts, form taps are the way to go.

Form taps are stronger and will last longer than cut taps. This will save you time and money in the long run, as you won’t have as many taps breaking in your parts.
1. It is a process without chip detachment since thread is formed and not cut. No chips interfere with the threading process and cause chip removal problems in blind holes. 2. Stronger threads are produced. The material flow follows the thread profile which results in greater thread strength, particularly for materials that are susceptible to strain hardening, such as steel and stainless steel. 3. It leads to a better thread calibration. As metal flows into the cavity let by tap and fulfils it, the possibility of producing oversized threads is low. 4. It uses stronger taps. The absence of chips eliminates the need for flutes, resulting in a stronger tool than cutting taps. 5. Tool life is strongly improved. Forming taps can last from 3 to 20 times more than cutting taps. 6. It is more efficient in production. Increased tool life, less tool breakage and faster speeds combine to reduce the cycle time and machine downtime.

Your entire premise against what I said is that roll form taps are common. What did I say? I'll remind you:

Nobody forms threads because it's stronger. *almost nobody. Outside of some very particular, specialized thin wall threading.

In general they form threads because it's cheaper.

Every reason you list that make form taps popular has to do with expense. The taps are stronger, because they have greater cross sectional density by not requiring the flutes necessary for chip evacuation and cutting clearance on cut taps. Not because they're forged. I know this is going to be a real bit of calculus for someone like you, but bear with me I'll break it down crayon style for you.

That's as simple as I can make it. If you still don't quite grasp it, maybe someone else can help you annoying twat.

 

[Natlek]

The taps are stronger, because they have greater cross sectional density by not requiring the flutes necessary for chip evacuation and cutting clearance on cut taps. Not because they're forged. I know this is going to be a real bit of calculus for someone like you, but bear with me I'll break it down crayon style for you.
That's as simple as I can make it. If you still don't quite grasp it, maybe someone else can help you annoying twat.

Well , seems that someone else is moron in this room not me and my bad English
What the hell forming taps have with this topic ???? I have no idea if they are made with forging process and it is not important in this topic .
I make that quote just for this .............THREADS are STRONGER !!!

A form tap does just that, it “forms” the threads in the hole with pressure, as opposed to “cutting” threads.

That brings us to the next advantage; the threads are much stronger because they are “formed” into place. If you need strong threads in your parts, form taps are the way to go.

 

[Natlek]

Did I need to post one milion link to show that forged parts are stronger then machined one ?
https://www.solmet.net/when-to-forge-or-machine
http://www.wodin.com/compare-forging-machining.html
https://www.sheldonbrown.com/dp-forging.html

 

[kuraki]

Holy fuck you're a stupid cunt. I'm not claiming the threads aren't stronger, only that it's not the reason anyone rolls threads.

As someone who spends $50,000 a year on taps I'm relatively qualified to make statements like that.

But no, let's just defer to the bumblefuck mechanic with an inferiority complex and a burning desire to prove to everyone his half ass bullshit is totally better than everyone else's.

 

[DevinT]

Did I need to post one milion link to show that forged parts are stronger then machined one ?
https://www.solmet.net/when-to-forge-or-machine
http://www.wodin.com/compare-forging-machining.html
https://www.sheldonbrown.com/dp-forging.html

Please show us all of your correctly forged to shape knives along with all of your high end forging equipment. Then show us all of your personal testing that shows us how big a difference it makes.

I thought you made knives by stock removal using recycled hss steel that came pre-hardened and you used cheap masonry bits to drill through hardened steel. I remember that they were finished all the way to a worn 40 grit belt finish.

Hoss

 

[Natlek]

Holy fuck you're a stupid cunt. I'm not claiming the threads aren't stronger, only that it's not the reason anyone rolls threads.

As someone who spends $50,000 a year on taps I'm relatively qualified to make statements like that.

But no, let's just defer to the bumblefuck mechanic with an inferiority complex and a burning desire to prove to everyone his half ass bullshit is totally better than everyone else's.

Then , there must be two moron in this room Topic is Forging vs stick removal strength . So I give one more example that show some data about that formed threads are stronger then cut one !! Taps and cost have nothing with that .
So do you agree that forged parts are stronger then machined one ? It is very simple question even for you !

 

[DevinT]

Then , there must be two moron in this room Topic is Forging vs stick removal strength . So I give one more example that show some data about that formed threads are stronger then cut one !! Taps and cost have nothing with that .
So do you agree that forged parts are stronger then machined one ? It is very simple question even for you !

“Stick removal”?

Hoss

 

[Natlek]

Please show us all of your correctly forged to shape knives along with all of your high end forging equipment. Then show us all of your personal testing that shows us how big a difference it makes.

I thought you made knives by stock removal using recycled hss steel that came pre-hardened and you used cheap masonry bits to drill through hardened steel. I remember that they were finished all the way to a worn 40 grit belt finish.

Hoss

You ask me to show you my correctly forged to shape knives and high end forging equipment ??? Come on ..... there was milion place where you can find reliable data about this subject . I read a lot about this subject long time ago /this is not first time thread like this to show on this forum/and fact is that forged part a stronger then machined one .If someone have proof that this is not try I would like to read about that .
And what does it matter here in this topic how I make some knives and how I drill holes is beyond me ....