Forging vs stock removal strengh

[Jesenius]

I think somebody has.

We have done testing on our local Czech & Slovak knife forum, twice. First one (imho) was not optimal due to dimensional differences between tested blades. Second one I didn't read, yet.

If You like You can read it on following links using translator:

Test #1:
http://www.knife.cz/Knifecz/tabid/36/ctl/Details/mid/1122/ItemID/334/Default.aspx

following discussion:
http://www.knife.cz/Default.aspx?tabid=53&g=posts&t=13779

Test #2:
http://www.knife.cz/Knifecz/tabid/36/ctl/Details/mid/1122/ItemID/373/Default.aspx

following discussion:
http://www.knife.cz/Default.aspx?tabid=53&g=posts&t=23442

 

[kuraki]

Here is an interesting tidbit. When we order some marine shafting for repairs, at times the agencies require it to be forged. If its not stronger, why?

As a supplier to defense and other large OEMs like Deere, I was surprised when I first realized how often design considerations were made "because I heard/thought/assumed something was better" regardless of information to the contrary.

"My pappy said so I believe it like gospel" isn't limited to internet forums.

 

[skillgannon]

In a knife steel discussion we are using plate/barstock. I don't know that many come in a as cast condition. All of that rolling is mechanical pretty similar to forging. Correct me if I'm wrong here. This sounds like a 3 sided argument with only 2 sides being argued. We have forging vs cast that I think everyone is more or less on the same page and then we have forging vs rolled. Rolled being basically a forged product but has some directional attributes that could affect it. Since most Smith's are not working with anything in the cast condition we are asking if taking a rolled billet and hitting it improves it in a significant way.

This is where edge packing can be brought up.

 

[kuraki]

What about MIM blades? I think the argument could be a tetrahedron if we wanted

 

[DevinT]

Yeah, I’m not sure if forging the tip, the bevels, and the narrow tang will make a tougher knife. As rolled bar stock is forged down from several tons down to one pound per foot. One more inch in each direction may not be enough.

I see a lot more makers hurting the blade by incorrect forging (forging too hot) than any benefit from the shaping.

This argument is as old as Bill Moran and Bob Loveless.

Forging knives did lead to forging pattern welded damascus and the deeper study of metallurgy, which saved custom knives back in the late ‘80s.

The bigger the story, the more hype, the more expensive the knife becomes. I’ve heard lots of wild stories over the years.

Hoss

 

[Ken H>]

I see a lot more makers hurting the blade by incorrect forging (forging too hot) than any benefit from the shaping.

Hoss has the right answer there, I suspect many more blades are damaged by forging than by stock removal. It takes a LOTS of care to properly forge a blade.

As to the prop shaft being spec'd to be forged - most likely it was to spec the shaft not to be cast. Just as in an engine, forged pistons and forged crank where always the "go to", but that was to avoid cast crank and pistons.

 

[Jonathans]

All our rolled steel starts out as continuously cast ingots. The rolling process is a forging process of sorts. Large dimensionql material such as ships shafts, are not rolled, they are formed by computer controlled forging hammers. However, the material I referred to above is required to have further forging applied. I have a hunch that Kuraki hit the nail on the head.

 

[Jessetheknifeguy]

Cool thanks for the replies. Just something I was wondering while I'm supposed to be doing homework

 

[Natlek]

IF knife is forged to final dimension must be stronger then stock removal knife . How much I have no idea
Forming taps make stronger thread then cutting taps because they push metal/grain on side . . .
If this is important in industry I can t see why not in knife too , at least theoretical

During the head-forming process, it’s important that the grain flow lines of the metal form in the proper direction , grain lines that sharply move toward the radius of the head-to-shank junction fail to have a good grain flow. This may leave the fastener susceptible to the head breaking off during installation.

 

[Willie71]

I knife is forged to final dimension must be stronger then stock removal knife . How much I have no idea
Forming taps make stronger thread then cutting taps because they push metal/grain on side . . .
If this is important in industry I can t see why not in knife too , at least theoretical

You are describing a very different ‘grain” than we typically talk about with knives. I’m sure you will dismiss what I’m saying, since I waste my time with bad equipment. I’ve never seen a knife shaped like your diagrams above. FYI, I used the same example over 5 years ago when I was first learning about metallurgy (engine crank though, not bolt threads.) I accepted I was wrong, and moved on.

 

[kuraki]

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.

 

[hugofeynman]

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.

 

[Willie71]

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.

We tend to make knives along the grain direction when we follow the rolling direction. We are testing third generation pm steels to see if the claims of improved transverse toughness are real.

An example where this does not happen is with various Damascus patterns, most notable mosaics, which look very spectacular, but are often made with endgrain.

 

[Willie71]

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.

Bicycle spokes are rolled, not cut. Very specific application though. 2mm diameter.

 

[hugofeynman]

We tend to make knives along the grain direction when we follow the rolling direction. We are testing third generation pm steels to see if the claims of improved transverse toughness are real.

An example where this does not happen is with various Damascus patterns, most notable mosaics, which look very spectacular, but are often made with endgrain.

Warren, in pm steels, there’s also some differences between blank cut parallel to the rolling direction of the steel and cut transverse. Smaller differences as if the steel is ingot, but there is, Fredrik Haakonsen assured me.

 

[Willie71]

Warren, in pm steels, there’s also some differences between blank cut parallel to the rolling direction of the steel and cut transverse. Smaller differences as if the steel is ingot, but there is, Fredrik Haakonsen assured me.

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.

 

[Natlek]

As a supplier to defense and other large OEMs like Deere, I was surprised when I first realized how often design considerations were made "because I heard/thought/assumed something was better" regardless of information to the contrary.

"My pappy said so I believe it like gospel" isn't limited to internet forums.

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

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.

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.

 

[Natlek]

You are describing a very different ‘grain” than we typically talk about with knives. I’m sure you will dismiss what I’m saying, since I waste my time with bad equipment. I’ve never seen a knife shaped like your diagrams above. FYI, I used the same example over 5 years ago when I was first learning about metallurgy (engine crank though, not bolt threads.) I accepted I was wrong, and moved on.

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

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

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

 

[kuraki]

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

As many ways as you like. No one cares what you think about anything because you're a fucking moron.

 

[Natlek]

Thanks Is that your last argument that you are right?