Knife forging is a hot topic amongst knife aficionados and collectors. I feel it’s safe to say that there isn’t a single aficionado or collector in the knife industry who hasn’t formed an opinion on “forged knives.” There’s a reason I’m putting that in quotes – and that’s because what people mean when they say “forged knives” and what the actual definition of a forged knife is almost always vary. But we’ll get into that. In fact we’ll get into everything I can think of related to forged knives. So let’s just jump into it.
Definition: What Is Knife Forging?
Knife forging is a step in the knife-making process whereby an ingot, cast, or poured mold of steel, that will eventually become a knife, is beaten into shape, either by hammers or by a machine’s rollers, to improve tensile and fatigue strength.
Is this different from what people usually mean when they talk about knife forging?
While all knives are technically forged (and yes, that means the Spyderco or other production EDC knife you’ve got in your pack is also technically has forged steel), when people refer to “forged knives” they mean knives where a blacksmith has physically beaten the blade into shape with a hammer as opposed to ground away excess materials using abrasives or a CNC machine in a production process. Smithing is basically what people often mean when they say “knife forging.” We’ll get into this more later.
So wait – all knives are forged?
Yes. All modern knives are forged.
When steel is made, it is forged from the ingot after it is cast.
When steel is poured into a mold, it will need to be formed into shape, after which the end result will be manipulated to create a sense of homogeneity which, as I’ve already explained, is what forging is (in layman terms). In the process of forging a knife, you redistribute material around to improve the properties. Without going through the specifics of this process, basically, if you take steel, cast it, and don’t forge it into shape using rollers or whatever process you’d like to use, then the tensile and fatigue strength will be impacted greatly. You’d end up with a pretty weak knife.
So knives that are not forged are really weak?
Yes. Which is why production knives like Spydercos, Kershaws, Cold Steels, etc. – basically everything you can buy on the market – all feature steel that was forged at the foundry. Again, we’ll get into more of this later, after you read over the process of knife making.
Side note; some smart alec will not doubt mention cast knives that promote a dendrite structure but those are a useless advertising gimmick, and are super super rare. I can think of only a couple off the top of my head.
The Process of Knife Making & Why Bother Forging
The interesting thing is, people don’t seem to realize that steels as we use them do not naturally occur in nature. For a steel to be considered good for working/tooling application, it has to be as pure of impurities as physically possible, and that’s not how steels come out of the ground. As a matter of fact, steel as we know it doesn’t come out of the ground at all- its manufactured from iron ore.
To get knife steel to this point before a knife is made out of it, companies will take specific elements and compounds, mined by corporations, then, using the ones they want, mix them altogether.
Sadly, due to certain compounds reacting in predictably negative ways due to being exposed to oxygen and other elements, we have to form the steel using one of only a handful of different processes.
These include:
- Vacuum induction melting,
- Vacuum arc remelting, and
- Electroslag remelting
This steel forming process designed simply to remove what you don’t want from the final product, so the totality of the steel is comprised of compounds that are beneficial to your end goal (of creating a good, strong steel with the right attributes for a knife). Some of the compounds you want to stay in your end goal product include: carbon, vanadium, & molybdenum.
Once there’s a pure-ish steel to work with, that is taken and formed into something usable – whether that’s an ingot, a sheet, or a bar – to make a knife out of.
Simple steels like 10XX series carbon steels are cast using a conventional method and then forged so that the grain (and by grain, I don’t mean a literal grain in terms of structure, but rather the directional properties, much like wood) ends up with superior properties for knife-making purposes.
How does forging do this? The process of forging rearranges the atoms in steel so that they’re quite literally different from how they were arranged before the forging process. It’s the very same atoms, but because of the way they were arranged before they were forged, versus how they’ve been rearranged during the process of forging and then stayed in this arrangement after, there’s no question that after the forging process has taken place, the slab of steel is much more superior for its intended purpose: to be turned into a high performing knife.
If you’ve ever batoned through wood (I have a point to this I swear), for instance, you know that a couple of things are 100% true of batoning:
- It’s way easier to do if you go with the grain of the wood,
- It’s terrible to baton through a piece of wood if there’s a knot in it.
Now imagine you could rearrange atoms that form the grain of the wood to make that wood ideal to baton through. You could restructure the atoms in that wood all in one direction, and to be very consistent, so that the new grain makes the wood essentially perfect to baton through. That’s sort of like what you’re doing in the forging process. You’re rearranging the atoms of the steel that make up the grain in the steel so that when the steel is then made into a knife, the knife is ideal for its intended purpose (to be high performing, strong, resilient, etc.).
I could go into ridiculous detail on the science of the matter, but frankly I won’t do it justice compared to veterans like Kevin Cashen who have written on the topic quite extensively. Please visit here if you are curious about the science, but be aware that Kevin really doesn’t hold back.
So, we’ve established that all steels found in our knives are forged. Even PM (powder metallurgy steel) is technically forged by taking teensy ingots and mushing them together into one big ingot. This is a ridiculous over-simplification, but without getting too in depth from a scientific standpoint, this is the best I can do.
Just remember that the idea is the end product. Whether the steel is cast conventionally, spray formed, or PM, the general goal is having complete homogeneity in the mix of elements that will form the knife steel, and making the end result of the arrangement of the atoms ideal for their intended purpose of eventually becoming a strong, high-performing knife.
The end result always varies slightly due to the inherent differences, though PM steel will always be superior to conventionally cast steel simply due to having more granular control over the end product. Precision will always rule supreme given all other factors being equal.
When someone who understands metallurgy (and as an aficionado, I like to think I know more than most, but am a mere pupil compared to Cliff Stamp & Kevin Cashen) talks about forging, they are really just talking about a step in the process of manufacturing steel for knife-making purposes.
Smithing: Or Bladesmith “Forging”
When a bladesmith talks about forging, however, what they are doing is spinning the mechanical process of forging (the true definition) into some kind of emotional argument that makes their knives look more desirable than production knives.
Honestly, I get the appeal of smithed knives. Who doesn’t want a one-of-a-kind knife that was beaten into shape by the sheer strength of one artisan and his hammer. But when you’re talking about performance, facts are facts: this process of beating the knife physically with a hammer really has no impact on the tensile and fatigue strength of a knife. Smithing does not result in higher performance knives.
In fact, the steel that knife bladesmiths buy is already forged, in the true sense of the word. All bladesmiths do is beat the already forged steel they have into shape with frequent trips to the forge.
If you want a knife based on craftsmanship and uniqueness, then by all means go with a “forged”/smithed blade by a proper bladesmith, but from a performance point of view, it’s superfluous to requirement and will limit your steel options greatly.
“Forged Knives” (i.e. Bladesmithed knives) VS Production Knives
This following response is going to piss off a lot of people (though I’m sure I’ve done that already), but frankly, the major difference between “forged”/smithed knives and production knives is that the production blade (assuming it’s from a reputable manufacturer) will have tighter tolerances, predictable reactions when dealing with lateral force, and superior properties as a result of a machine deciding when the blade is done as opposed to one man eyeballing it and mulling over the fact that the knife is probably finished.
This is a simple reality and the knife industry is swamped with people who try to sell magic processes regurgitated into some bizzare pseudo-science, but we need to be objective when looking at the issue at hand.
How “Forged”/Smithed Knives Are Made
- Take the steel ingot (that was already forged in the true sense of the word when they received it!)
- Heat it
- Beat it
- Repeat until desired shape is achieved
- Grind a rough edge
- Heat treat
- Grind, clean up, and affix the trim (handle, hilt etc.)
- Sell for a substantial markup because you beat on it for hours on end and that takes work
How Production/Stock Removal Knives Are Made
- Take sheet of steel (stock) which is again, already “forged”.
- Cut, stamp, or laser the shape of the blade out (depending on the steel- some steels don’t like being stamped out).
- Grind the bevels out using high powered grinders (wheels or belts)
- Heat treat
- Grind, clean up, and affix the trim (handle, hilt etc.)
- Sell for whatever price the market is willing to bare; dependent on the branding, designer, and where it’s made.
As you can see, the difference in the two processes of creating knives isn’t substantial.
Smithing knives, or “forging” as a bladesmith would advertise, only adds unpredictable elements into the mix, with no real benefits to knife making.
How We Got Here: The “Forged”/Smithed Knife Superiority Myth
The core issue at hand is that bladesmiths who forge their knives have a vested interest in saying that there is a performance bonus to their knives. Even companies who make kitchen knives babble on endlessly about how their German cold forged knives are better than x because of y. It’s all nonsense designed to justify a higher markup due to increased labour, and in the case of those kitchen knives (looking at you Henckels), it’s not even a person “forging” the knife, it’s a machine that mushes the blade into shape in a dozen or so strikes. Hardly the romantic image we have from their glossy brochures, aye?
No, “forged”/smithed knives are not stronger, sharper, or in any shape or form better than knives made using the stock removal method.
As a matter of fact, custom knives in general are not stronger, sharper, or in any shape or form better than knives made using the stock removal method. Custom knives are simply rarer, and consequently command a higher price. And there is nothing wrong with that.
What’s interesting about this whole situation is that we as a society have evolved to respect high quality and precision manufacturing, but when it comes to our hobbies, we do tend to take the emotional route. A blade has no soul, a bloke hammering on it for hours on end will not impart magical properties to a knife, and yet for some reason, so many of us fall for it. I understand the sentiment that there is something very comforting about owning something that was built uniquely, especially in these times of mass manufactured goods from China. But hiding behind thoroughly debunked arguments of superior performance is silly and misses the point entirely.
This is not a situation that is unique to the knife world. I think it impacts all fringe hobbies. A mechanical watch hand assembled in Switzerland will have inferior timekeeping performance to a cheap quartz Timex. That is a fact, but because we can observe this fact by measuring it, the watch industry instead talks about craftsmanship and unique design rather than performance.
When it comes to knives, if I hand you a knife that is forged and say it’s better, you kind of have to take my word for it. You can’t measure the objective performance in the same way you can with accurate timekeeping, and this is how we get into these tricky myths perpetuated by knife-makers that have a vested (financial) interest in keeping the myth going.
To Conclude
In 2005, CNC machines began to be utilized by all manner of budding knife makers, and people on the forums freaked out. The definition of custom became blurred to the point that arguments broke out, friendships were burned, and new words were created to explain differences in knife creation (midtech, for instance).
It’s utterly silly in my opinion. If you want a knife with nostalgic, old world appeal and charm, or hand made craftsmanship, buy a custom knife that has been hammered into shape.
Don’t pretend it’s for “performance” reasons. That would be patently untrue, and all it does as add more myths to an industry already rife with them.
I hope you found this informative. Thank you to Phillip for asking this question about forging on our knife myths article. It made me realise I needed a full article on the topic, and not just a section in a larger piece on knife myths.
Please do check out Kevin Cashen’s article for way more in-depth discussion on the topic, as it’s quite exhaustive and will answer all the technical questions you have far better than I ever could.
I am not a metallurgist so it would be futile for me to argue about the superiority of a hand forged blade vs a factory mass produced blade, but as far as overall handling and performance I would argue that a highly skilled bladesmith can build certain characteristics into the knife that would be unrealistic for a production mass produced knife to achieve.
A Coldsteel , CRKT,Busse … Bowie isn’t even in the same league as compared to a Bagwell, Knight, Tomberlin, …MS when it comes to handling and performance.
Another point I would address is not only do artisan bladesmiths have a vested interest in selling a superior hand forged product they also have a vested interest in upholding their reputation. Unlike Spyderco, Buck, Coldsteel … they can’t just box up their model #xxxmeto and send it out the door.
So there is some quality control involved beyond some unknown employee overseeing the production of the knife.
When I just want a me to knife that I won’t lose any sleep over should it be lost or damaged then I will, do and have purchased production knives. But when I want a knife with superior handling characteristics and is a pure pleasure to use I will always choose a knife forged by a skilled craftsman.
Interesting perspective John, I would actually argue the opposite. Its expensive for production companies to adjust a design due to the tooling cost etc. so they have a financial incentive to get right on first try. Likewise with ergonomics, buying a custom knife “off the shelf” the bladesmith has a limited amount of experience with different size hands as opposed to large scale manufacturers that do group tests & prototypes long before releasing something to market. I will say that in my eyes the biggest advantage custom knives have are differential heat treats (lower HRC on the spine, higher on the edge) which is something I really appreciate.
Talking about fit and finish/quality. Check out Chris Reeve Knives, Zero Tolerance, Rockstead etc.. I don’t think any custom maker can come close. That said they are pretty damn pricey so I suspect bang for buck a midrange custom will be something special. Honestly these days tolerances are getting so good and knives are such high performance I just buy what I like and don’t over think it too much (beyond country of origin).
There is only one variable that may be improved through forging. Damascus steel gets folded and stretched. Rinse and repeat. That would improve the homogeneity, if the steel lacked homogeneity to begin with.
The best steels (which is most modern steels these days) uses powder metallurgy technology, which effectively guarantees homogeneity. I agree that in the early years, damascus steel had its place.
So you’re saying that because the steel had already been “forged” when a blade Smith gets it that further forging does nothing? That is crazy. Yes it had already been forged. BUT. Further forging into the shape of the actual tool in this case being a blade is one of the most critical steps in that it mashes the edges so that the grain can flow in the shape of the tool as opposed to cutting through the grain. The final product is much superior than a knife that was “forged” in the factory & has been cut using a cnc or any stock removal method which cuts the grain as opposed to molding it to the final desired shape.
Hi Dan, feel free to contact a metallurgist for clarifications- your understanding of steel and what leads to performance is deeply flawed and I would encourage you to think about where your info comes from and if the source has a vested interest in pushing an agenda.
Fact is, modern CPM steels outcut every single traditional carbon based steel that would be used by an old school bladesmith. Both in terms of strength (3V etc.) and edge retention (S90V etc.) and those are all made using cnc or stock-removal techniques.
Thank you most informative, as I am looking to forge my own knives.
Fascinating! I just purchased 2 TUO Aus-10, 8.5″ Damascus Kiritsukes made in China; the steel is imported from Japan and finished in China. One is hammered and the other is not. I assume hammering in this type of knife is purely ornamental with the exception of perhaps helping food slide off of the blade more easily? The unhammered one is supposed to have a Rockwell Hardness of 62 +-2 and the hammered one, 62+. Do you think that minimal hammering could increase the hardness by that much?
From what I’ve read AUS-10 is somewhat comparable to VG-10 steel; is this correct?
These were Amazon Black Friday Deals at $55 each. When I get them I’m going to compare them to my Shun Kaji Damascus blades and my Fuji blades. The Fuji is a line produced just for Williams Sonoma and is very pricey; the Damascus “lines” are very pronounced and they appear to be “dripping” off the blade.
This is from the TUO description; “ADVANCED CRAFTMANSHIP MAKES THE GREATEST KNIFE BLADE?TUO Cutlery Ring-R Series Super Sharp Blade is expertly crafted from 67 Layers AUS-10 Japanese High Carbon Stainless Steel with Rose Damascus Pattern which has a good rust resistance and corrosion resistance. The AUSTENITE in steel can be completely transformed into MARTENSITE because the chemical composition can be controlled in the ? or ?-? phase by High-tech Vacuum Heating Treatment.”
The “Damascus Steel” does not appear to be sandwiching a harder steel between it.
I would love to hear your comments on the “China” angle. Most of my Chowhound friends are suspicious of any knives except for cleavers that are made in China.
Would love to hear your thoughts,
Joyce
Much like with everything, it depends on the factory in question. Hammering will not increase hardness- the final heat treat and tempering determine that. A reputable brand that manufacturers in China is likely to be fine, the reality is, knives are not complicated to make. The issue is that many “no name” brands cut corners, and tend to do so in China. Hence the reputation being questionable.
1. Hammering does increase the hardening, by rearranging the atomic packing. It is known as “work-hardening”. However hardened steel is brittle. Heat treatment part is done to relieve some of that hardening.
2. One benefit of folding the steel on itself is creating discontinuities within the grain structure. That mitigates the crack propagation.
3. High carbon steel is not without its merits. True, it doesn’t hold the edge as long as other steels, but it is easier to maintain and resharpen. Fewer passes over the honing rod are required.
Hi Dinesh,
1. All knives are forged as bar stock steel has already gone through this process so its a moot point.
2. Patently false, if you are referring to Damascus style folded steel, it actually creates weakness. The highest performance steels are all powder metallurgy based.
3. High carbon steel is a very broad term, almost all modern knife steels are high carbon by contemporary standards or use alternatives like vanadium or nitrogen. High Carbon steel will hold a knife longer than a low carbon steel all things being equal and regarding honing, honing hones the edge (as the name implies)- it does not sharpen it. Honing was common when steels were relatively soft and the edge would become deformed (not worn) and thus honing would straighten it (bringing it back dead center) and thus maintain cutting performance.
Thanks for dropping by mate!
Read this with enthusiasm and wonder how you didn’t have your legs broken by the Forged in Fire Cult. I have been “playing at making knives for years” and the only advantage of all that work and burn marks is I created some One Off Art Blades, but never anything really good enough for my wife to use in the kitchen. My father, a welder and hunter all his life, always told me to be aware of anyone in the woods with a chrome plated 24 inch Jim Bowie Hunting Knife and a automatic rifle. Same goes for the average knife buyer looking for a Radio Controlled Samurai Flying Sword. No, knife forging and knife milling are just hobbies unless you own General Steel Knives, Inc. It is fun though! REF: Those Forged in Fire contestants really scare me. What do the Judges libate on before the show starts????
Guess I dodged a bullet (or a blade!) ;) Never seen that show but it looks damn interesting! Thanks for bringing my attention to it mate!
I’m a collector considering hand making my own knives. Usually, as an experienced wood worker and semi- experienced metal worker, I would say “hand made is always better”.
In this particular case however, we are talking about a raw material and not a finished product. Because of the complexity of modern metallurgical processes. I feel that hand forging can’t possibly match the performance of factory forged steel designed by scientists and created by machinery that is calibrated, efficient and much more consistent than eyeballing in the barn.
Exactly my feelings on the matter Russell. Thanks for dropping by!
Not a metallurgical engineer, but a chemical engineer. For any practical purpose like building something, there is no such thing as pure iron. That means even in the CPM case no two samples can be exactly the same. Furthermore, there is no such thing as perfect mixing of the alloy components (even if they all could be.pure), but I am willing to bet that CPM produces a way more homogeneous blade than heating, hammering, folding, and hammering some more.
Fortunately, we don’t need pure to skin an elk
i think we got the idea that a forged blade, one that has been beaten to shape. is that at a time it was superior. since there wasnt an understanding of how to create pure steel, steel that was forged by a blacksmith was more pure, and stronger than say steel that was smelted and poured into a sand mold. today its a myth but it used to be fact.
Yes indeed, and whilst we as a society have evolved from thinking the Earth is flat- some myths do linger around for a shocking amount of time.
So is there any big advantage with a damascus blade apart from how it looks?
it really depends on the steel used, some damascus is faked by lazor etching. other damascus is made by two or more high quality steels, forge welded, twisted, and drawn out. then made into a blade. so no real advantage over a knife made with the same steel.
Exactly what Matthew said, its about aesthetics- not performance.
Thanks for the great article. I’m still a little unclear. So when Carter says, “by packing and condensing the grain, we preserve a lot of it’s inherent strength. If we were to simply grind away steel from the original piece of stock, the blade would only be as strong as the grain that remained in the blade”, is he incorrect? From the article it seems like the forging process, whether machine or by man, is what aligns the atoms and makes the steel stronger. Carter seems to be saying, by taking this piece of steel, that you point out in the article is technically already forged, if I take this forged steel I bought and then forge it more by hand, I can pack and compress the grain even more. This will further strengthen the steel. Please shed some more light on this for me using Carter’s example.
i think carter is refering to forging an ingot that has been smelted but not forged. you can only beat metal so much. a good way to think about it is bubble wrap. stack it up and you have a smelted ingot, the air pockets are impurities in the metal, as you beat on it with a human holding a hammer or a hydraulic press, the bubble pop and the material compresses. most modern knife companies heat a chunk of steel to forging temps, then stick it under a press that hammers the metal with a huge amount of force, creating the shape, aligning the grains, and beating out any impurities left. anyway hope this helps a bit.
Thanks for the response. I still trying to learn. Xavier’s article refers to an ignot as, “steel ingot (that was already forged in the true sense of the word when they received it”. My interpretation is that he is saying you can’t have an unforged ignot. So that would mean the ignot or billet that Carter is working with has already been forged. Help me out if I’m misunderstanding.
if you smelt your own steel (very rare, I don’t know of any bladesmith that does with performance in mind) then yes, it will need to be forged.
If you buy a bar stock, it will come forged by standard as per the manufacturing process.
I like the bubble wrap analogy. I think in the case of White steel however, since it is so pure already, Carter says that you are condensing the grain structure and thereby strengthening the piece of metal. He has a picture in his book of the grain structure of two crane hooks. He shows a loser grain structure of one hook and says that was the final grain structure of a larger piece of metal that we did stock removal on to get to the final hook form. In the second picture he shows the same final dimensions of the hook, however this time the grain structure is more condensed because we packed and condensed the grain by forging it instead of just cutting off the excess.
I’m very new when it comes to blade smithing. Could you comment on Carters example and if he is wrong or not? And if he is wrong, could you explain why? Thanks again.
Howdy Phillip.
To put it bluntly, Carter has a vested interest in pushing forged knives. He is an excellent craftsman and bladesmith but a metallurgist he is not as proved in the many debates online where Cliff Stamp quite happily explained the science behind steel production-
For an example- https://www.youtube.com/watch?v=_9yUDhqbW2g
Sheet stock (including Hitachi white steel) is formed through a forging process, This process is rigorous and the end result is far more consistent (in terms of repeat-ability) than mashing the steel around with a hammer.
If Hitachi sold their “steel” as separate compounds for you to DIY at home, then forging would have a valid purpose- but since you buy it in stock form, its simply superfluous to requirement.
From a super technical stand point, reach out to Cashen or Cliff and they will drown you in data points that will make your eyes bleed (it certainly did mine).
http://www.cliffstamp.com/knives/forum/ is Cliff’s forum, he amongst many of the forumites really really know their stuff. Far more than me.
Hi. I had actually seen that video before. However, the subject matter is different that what we are talking about. Mr. Stamp says Carter’s chip test is meaningless but he doesn’t give a hypothesis as to why he thinks that.
I’m more interested in Carter’s assertion that a bar of forged metal that he buys from Hitachi can be forged further by hammering it and further condensing the grain structure. Is he wrong about that? Is it the case that whatever the grain structure is after the original company forged the metal, that is what the grain structure stays at forever? If one buys two bars of metal of the same size from Hitachi and makes two identical knives. One knife we just cookie cut the knife out. The other, we heat the metal up and forge it to the final knife shape keeping all the original metal. Do those two knifes have the same grain structure?
To me, it makes no sense but at this point I would differ to someone with an extreme understanding of metallurgy so as to not give you (by accident) a false understanding. Whats interesting is I have read a considerable amount on the matter and yet would find it hard to break down (linguistically) the nuances. I guess this is why we have experts ;) e-mail Cashen as previously mentioned, he knows this topic like the back of his hand (and has the technical expertise to express a satisfying answer for you).
edit: sorry for the late response- we have a threading limit on comments (nothing I can do about it) so I had to respond through the backend- feel free to e-mail me if you can’t reply here. Its a technical limitation that I can’t do much about.
I agree with you. I think it applies to a lot of material objects. Usually a process (like machines use) ensures quality and consistency. There are lots of great bladesmiths but they are still people. Things by people can vary in quality from day to day which is why we used to value a high quality item when someone made one. Now even the cheaper knives are actually high quality when compared to what you used to get.
All I can say is that I make knives because it’s cool and I like the process. I like knowing how it works and that it can be done with my own hands. That’s it! I like the “cool factor” :-) that and using reclaimed metals…. which usually ruins quality…. I think I just dug myself a hole.
Haha, I do love forged knives for precisely the reasons you listed- I would never argue from the perspective of a performance bias though.
Thanks for dropping by Ray!
Hello,
For the most part I agree with what you are saying, and that a knife “forged” by a blade smith isn’t a superior product just because it was beat by a hammer. However I do work in the steel industry and know for a fact that all forging is not equal and the grain structure of certain steels can indeed be changed by more or less forging, or sometimes simply a different method of forging. Since my company does not focus on knife steels (the steel we make is mostly structural and tool steels) I cannot say for sure which knife steels if any this apply’s to. It does not matter for all steels. In most the chemistry and heat treat make up the majority of the property’s.
Forging does definitely change the grain structure of steel, however in knife steel you can buy PM steel blades that will obliterate any traditionally forged steel in any metric all day, every day. CPM 3V for toughness & CPM S110V for edge retention being the obvious examples. For structural stuff, steel is manufactured in such enormous quantities that PM steel would rarely be the cost efficient choice, as far as I know CPM-3V for example, has never been used in building structures (correct me if I am wrong) due to the high machining and production cost.
Thanks for dropping by Roger, much appreciate your insights!