Titanium Casting Defects

Joe90,
I guess I'll shoot mine anyway. I'm almost certain that there are more in there. There are probly some in every handle, they are just not exposed or are too small to see with the naked eye. I looked closer and found some more on the top of the handles above the pivot pins.
I've heard that Ti is difficult to machine. Maybe its just cheaper to cast than to machine the handles from billets.
 
The alloy that's used for the handles is 6AL-4V, if that means anything to anyone. I've got some minor imperfections on the serface, but they only look like they're about a half- to a quarter-millimeter deep. I've also got sopme scuffs on the blade, but since this is my EDC, I'm not worried about it.
 
It is much cheaper to cast Ti now than to machine it. The trade off is the imperfections and the fact that every BM-42 will be different. You can actually use your imperfections as a sort of fingerprint since no 2 will be the same. All the handles on the Tachyon will be CNC'd (not cast) and there should be NO imperfections for those who may think all Ti is the same :D
 
Hmmmmm
Now after reading this post I looked at my bm42A and noticed the same thing as blade_420 except that it is on the opposite handle and the opposite side. The "holes" do look the same as 420's does. May be mine was also made by the same mold. Maybe someone should email the people of benchmade and ask them about these "defects".
 
Hello Blackjack_21 ...

6AL-4V is an alpha/beta titanium alloy which can be heat treated to give good properties of strength. It is used in aircraft manufacture as well as golf clubs. A more technical evaluation can be found at:

http://www.efunda.com/materials/all...ge_Title= Metal Alloys Keyword Search Results

Chinese Man ...

I have addressed this with Benchmade - "info@benchmade.com" - but have yet to hear back from them. I checked their own forum, but did not come across any reference to this particular issue. Perhaps a number of other peoples 'enquiries' directed at BM would help matter's along a little. ;)

I'll let the group know when I hear anything.
 
Originally posted by Mike Turber
It is much cheaper to cast Ti now than to machine it. The trade off is the imperfections and the fact that every BM-42 will be different. You can actually use your imperfections as a sort of fingerprint since no 2 will be the same. All the handles on the Tachyon will be CNC'd (not cast) and there should be NO imperfections for those who may think all Ti is the same :D
Click to expand...

No offence Mike, but this sounds more like good marketing than anything else ... Sort of like "we've deliberately put defects into the product so as give everyone the oportunity of receiving a totally unique and personalised item".

To quote Benchmade (taken from their own web site):

"Benchmade Knife Company, Inc. warrants to the original owner that the knife will be free from defects in materials and workmanship."
 
Here's a quick update for those who are interested:

I've just received a mail back from Travis Noteboom (Marketing Coordinator) at Benchmade, who states:

"I've forwarded your questions and concerns to Angie here at Benchmade. She is involved not only in the warranty aspect of the knives but is active in the engineering of our knives. She should get back to you either today or tomorrow at the latest."

I'll keep everyone posted when I receive something back from Angie.
 
Hi all,

Here's the scoop:

The BM42, BM43 and BM47 Handles are cast from a titanium alloy - 6AL-4V. This has been confirmed. The casting of the handles follows the investment casting process. Here's a simplistic summary:

1. Produce a high quality injection mold in the shape of the final cast.
2. The injection mold is used to produce wax versions of the handles.
3. The wax handles are dipped successively into a ceramic slurry and allowed to dry.
4. When the ceramic exteriior is thick enough the wax is removed.
5. The wax is removed using high pressure steam and then a furnace firing procedure.
6. Moltem alloy is poured into the empty ceramic "shell".
7. The exterior ceramic shell is removed and the titanium machined as required.

Here's a couple of links for those who wish to know more:
http://itri.loyola.edu/rp/10_01.htm
http://www.postprecisioncastings.com/process.html
There are many others, but I felt that these gave a nice overview - good diagrams also.

So, what did Benchmade say? ...

"I would like to thank you for contacting us and asking what's up. This allows us the opportunity to better serve the customer and improve our products. We here at Benchmade take great pride in our work and designs and want to make it right. Our products are constantly evolving and improving. We would like to think of it as a Butterfly growing into a beautiful piece of work. With out your help this would be a much longer process. The 42 handles are 6AL-4V Titanium and the method of casting is called Investment casting ( also called "Lost Wax"). The molten titanium is poured into the mold (created from wax) within a vacuum chamber. This is what causes gas bubbles and this is what you are seeing.
We have been working closely with the process and with the input from customers such as yourself we hope to develop new processes that address these issue. So keep your eyes open for the future models to see what we have in store. I hope this was helpful to you and that it has answered some of your questions. Please feel free to contact us at any time if you have any other concerns or ideas for us to take a look at."

The implication is, as far as I can determine by this first response, that the manufacturing process has not been able to remove all of the residual wax from the ceramic shell. Hot metal and wax don't go well together! On contact with the hot metal, the wax turns into a gas which is then trapped by the incoming metal. This causes the holes - commonly known as porosity.

This is a maufacturing problem. I have asked for further clarification on what they are doing about it and, as always, will let the forum know what the results of my enquiries have been.

I sincerely hope that they can come up with a solution, as I think the BM42, BM43 and BM47 are all terrific looking Balisongs. It would be a shame to see this problem continue into the future.

Just got this one (general reponse time from Benchmade is terrific):
"I received the facts from Vance who is out of the office today and I will need to wait until Monday when he returns to ask what causes the gases. I didn't mean to imply anything just using the information that was given me and I not being up on the process didn't have any specific questions to clarify the information given. Vance is much more aware of the process than I. As far as when the new stuff is coming out I don't have a date yet but I do know that it is being pursued aggressively to solve this situation."

I'll keep you all posted.
 
Well damn! I guess I should buy as many of these soon to be rare production models. Maybe later down the road we will all be saying "Heh!, you remember back when Benchmade first produced the 40 Line and they had all those imperfections? Those where knives with character, sure wish I still had one of those beauties.":D

But I'll still have to buy some updated ones, I think I'm in this for the long haul!;)
 
That's one way of looking at it sure. Mike Turber may agree with you on this one too.

It certainly is an interesting dilema though - to buy something with known defects for the possibility of it becoming worth something more as a "collector" item in later years, or saying "Hey, why are you guys shipping a $150.00 product with know defects in it" and buying something else. (Question is, is there anything else out there in the same value ball-park? ... and if not, does this still make poor manufacturing standards acceptable?)

What about the rest of the Balisong forum ... What's your views?
 
Nearly all metals have disolved gassed in them when they are in the liquid state before casting. Vacuum melting can eliminate this, but I imagine its expensive. The other way to eliminate the problem is to add elements to the alloy that tie up the gasses and make nonmetallic inclusions. Silicon and Al are added to steel to tie up oxygen that bubbles out as the steel cools in the mold. Maybe BM could switch to a slightly modified alloy w/ something in it to tie up the gasses.
 
Whoops, hit the post button too soon. I really shouldnt say nearly all metals. I dont know for sure, but if it happens to one it could happen to others.
As far as how I feel about it in the BM handles, I dont think its a big deal. It detracts from the aesthetics, but that's probably all. As long as we all dont have out BM handles fall apart in 5 years from fatigue cracks that started at the holes, I dont see any real problem.
 
Hi Dragon,

I'm not sure that BM will have gone to the trouble of fatigue testing their titanium handles before putting them into production, though I'll be sure to ask them this.

If they haven't, then I guess we're all in it for the long run - only time and constant usage will give us the answer.
 
Well, it looks as if Benchmade are giving me the brush-off. I was 'promised' me a response on Monday (08/27/2001) to the current situation regarding my enquiries. Having not received one, I posted a reminder to Angie, and was prompted sent a very terse reply. :(

Obviously a very tense subject area at the moment.:confused:

Vacuum degassing is apparently taking the steel production by storm at the moment, allowing engineers to control the amount of Carbon and other base elements in the molten steel to fine tolerance levels. See http://www.memagazine.org/backissues/april98/features/vacuum/vacuum.html. Unfortunately, this does not give any details about Titanium, so I've accessed another company that may be able to shed some light. Again, I'll keep everyone posted.

Dragon, currently the cost of setting up degassing in Steel mills is very expensive (see above link). However, due to the need for higher quality steel, this process is worthwhile. In some instancse, it is the only way to lower the content of Carbon to a sufficient level that will allow cold steel manipulation to produce consistent quality results. Classic example apparently is in the manufacture of pressed steel plates for the automotive industry.
 
From the quick research I did, it seems the fatigue values for the alloy benchmade uses are about half the tensile strength. I seem to have this habit of rambling all around what I meant to say. I dont think that the stress put on a balisong is high enough to cause problems. Then again, I've seen the failures of some Bear balis in pictures here on the forum. We'll just have to do flipping endurance tests. Can anyone flip for 23 hours at about 250 times per minute?:D
 
Hi all ... looks like I spoke a little early the other day - I received a reply from Benchmade this afternoon. Here it is:

"Sorry it's taken me so long to reply to your questions, I've been extremely busy as of late.

First let me clear up an apparent misunderstanding. It sounds to me like you're familiar with the investment casting process and your correct in stating that there shouldn't be any wax left when the metal is poured. The porosity in question is not caused by wax left in the mold.

The porosity mainly occurs from the pour itself. This is done in a vacuum chamber but the molten titanium is still poured into the mold which allows for "pockets" to form as the liquid metal fills the mold. These pockets occur in all investment cast parts (although much depends on part shape and complexity). The common solutions for such internal porosity is a centrifugal pour, where the actual mold is being "spun" during the pour, and a processes called HIPPING. This process heats up the casting to a determined temperature then applies a certain amount of pressure thus forcing all of the "solids" together and the "porosity" to the exterior of the part. This process works great but leaves all of the external porosity on the surfaces which then needs to be worked out. Both of these processes
are costly.

All Pacific Cutlery/Benchmade production bali-songs produced in the last 20 or so years were manufactured using investment casting. We have never had a structural failure returned from a customer (that I'm aware of). Although the titanium is a relatively new material for our bali-songs (we've been manufacturing these for about 20 months now) we have not had any structural failures due to porosity.

In regard to what testing we do, first we rely on our vendor for their
expertise. The same processes and standards are employed on our bali-song handles as are used for most of the investment cast titanium golf clubs, framing hammers and firearm parts that currently manufactured. For example, Ruger Firearms uses the same investment casting processes. Check out this site... http://www.rugerinvcast.com/.

In addition to vendor QA we also do our own destructive and functional
testing (I get the joy of personally working all new bali's as long and as hard as possible with the sole intent of destruction). Each knife gets put through a side load stress test during the adjustment step. This is to ensure integrity if a "prying" type of stress is put on the knife. We also will use a 2 ton arbor press to put the same type of stress on the handles that occur when you squeeze the handles together. This puts far more pressure on the handles/pivots than will ever be put on by hand.

Basically, it's a cosmetic problem and not structural.

So, what are we doing about this now and what are we going to do to
eliminate this problem in the future? We have a great vendor whom we're working closely with to eliminate this problem as well as an intensive focus in our own facility. For the future, we currently have some exiting things in the works (that is why I've been so busy!) that will totally blow your socks off. All I can say is please be patient with us. I promise you, you won't be disappointed.

At Benchmade we constantly want to innovate and evolve. The 42 was the first titanium investment casting in our industry, stainless steel
investment casting was old news. Titanium's a whole other beast. We're learning and growing and we appreciate customers like you who hold us accountable and drive us to perfection! Without customers like you we'd be any old knife company. Please continue to be the kind of customer that holds us to a higher standard.

I hope I've helped. Please feel free to e-mail me at any time: vance@benchmade.com"

There's still some other things that I think I'll email Vance about, but it seems to me that BM are very willing to accept and respond to concerns from their consumers. I like that. :)
 
That is the main reason why I do not want to buy a bali online, they will send you anything. I go to a store near me that has several in stock, and I pick and choose. Of course the flawless One I'll buy.
 
That's the pleasure of living somewhere where you can get to do that easily. Unfortunately here in SA, the only shop that I know of that stocks a good range of products (and the only one that I know of that stocks good balisongs) is approx 800 miles away. That's a 12+ hour drive. :( ... and though the shop will post the stuff down, I'm only in a position to "trust" the shop, and as we all probably know, not everyone has the same critical eye as oneself - unfortunately.

To tell the truth I was even contemplating a custom made one like Ralphs Gemini, but again, the US is a long way away, in the case of disappointment. (No offense intended to Ralph's workmanship by the way - I use his name purely as an example)
 
Well it look like the end of the road for this particular thread.

I've hit as many people as I can surrounding the issue of titanium investment casting (using HIP, etc). The overall opinion from the people I have had contact with is that the actual process produces excellent results when done correctly. There should be no defects.:D

I posted another number of questions to BM, but there has been no response since. It's been about a week now.:rolleyes:

So, what's the conclusion?

It appears to me that BM are aware of the problem and that they are, by all accounts, trying to resolve it. Until they have, I would suggest that if you're concerned about the visual appearance of your BM balisong, you do like Bladeswinger suggested. Check it out personally, before buying - if you can. :)

I guess while BM try to resolve this issue, there will still be some manufacturing problems with the casting of their Ti handles which will continue into the production line.

To be honest, I'm not sure that BM'll post me, or the forum for that matter, when they do finally correct the problem or move to a different process. "Bleeding edge", if you'll excuse the pun, manufacturing can have its fair share of problems.

Enjoy your balisongs. Joe. ;)
 
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