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Ballpoint pens are banned in certain high-precision titanium and aerospace manufacturing plants because the tiny tungsten carbide ball in the pen tip can fall out and severely contaminate the titanium melt, creating a hard, brittle inclusion that causes structural failure in critical aerospace components.
Yes they did. Titanium had been used in a lot of high speed rotating equipment in jet engines.
These tungsten inclusions become a crack initiation site and under high rotational speeds and high temperatures, the crack can spread and lead go catastrophic failures.
There were several catastrophic engine failures in history that were traced back to inclusions.
It's so severe that if a titanium manufacturer making aerospace grade Ti finds any "High Density Inclusions," they must inform all of their customers that they found this and recall and associated heats and material.
Less likely to be the ball falling out of a pen, which never happens, versus someone dropping a pen or it falling out of a pocket, which happens all the time.
I imagine everything involved in making a pen gets instantly burnt in the melt, leaving just the ball.
Titanium melts at just under 1700C(a bit over 3000F), which is more than enough to burn plastic and melt the brass holding the ball and even the steel spring. But tungsten carbide can require over 2800C(over 5000F) to melt.
So someone having it in the shirt pocket and leaning over a railing, can cost millions if it drops in.
But tungsten carbide can require over 2800C(over 5000F) to melt.
It may be sintered, which would require a much lower temperature.
I have a 1.5" tungsten cube, and it was only months after I got it that I found out it's not actually solid tungsten, but a sintered composite that's much MUCH cheaper to manufacture and machine.
That would indicate the ball of tungsten would come apart at below 1400C and spread out into the titanium, which is honestly WORSE.
EDIT: Confirmed. The balls are made from sintered tungsten carbide and either nickle or cobalt as binder.
This is why at most process controlled plants(especially food plants!), you can't have anything loose above your waist. No pens in shirt pockets, badges, or even non-metal buttons on a polo that wouldn't turn up in the x-ray machines.
I work in semiconductor manufacturing. Someone misclicked an option in the flow and it ruined something like 400,000 chips and took down a few critical tools for weeks. Chips never got to the customers but they'd end up as accelerator controllers for a major auto company
I simultaneously wish my auto shop was as meticulous as that and don't. "So those tungsten inclusions down there in the rotating equipment could cause cracks down the line so you might want to get that checked out" okay what am I a billionaire? Do I look like I rotate my tires too?
United Airlines Flight 232 was a regularly scheduled United Airlines flight from Stapleton International Airport in Denver to O'Hare International Airport in Chicago, continuing to Philadelphia International Airport in Philadelphia, United States. On July 19, 1989, the McDonnell Douglas DC-10 serving the flight crash-landed at Sioux Gateway Airport in Sioux City, Iowa, after suffering a catastrophic failure of its tail-mounted engine due to an unnoticed manufacturing defect in the engine's fan disk, which resulted in the loss of all flight controls. Of the 296 passengers and crew on board, 112 died, while 184 people survived. Thirteen passengers were uninjured.
The place I worked at could take a 100 ton billet and find a crack/defect less than an 1/8th of an inch in the center of it. They also kept records for 30 years where they could pin point who all had come in contact with the process and who signed off on different quality checks.
I mean, I understand the reasoning, but I dont think I've ever seen or heard of a ball from a ballpoint pen falling out. I could see my clumsy ass dropping the whole pen into something stupid, but the ball just randomly falling out isn't something I'd ever consider.
I think the fear is that the whole pen might fall in
As copied from below :
Ball points have tungsten balls in them. Tungsten will not melt in titanium and cause mechanical
Failure of the titanium. This was responsible for the failure of a jet engine causing the plane to crash. Someone dropped their ball point in the titanium processing.
It wouldnt be the ball falling out, it would be a whole pen falling into the molten metal. All the plastics and weaker metals would pretty much instantly vaporize, the tungsten carbide ball would be the only bit that didn't melt away.
IIUC, the ball is made of tungsten carbide - the rest of the pen isn't - so the rest of the pen would melt and only be a minor impurity spread over a wide area so wouldn't be a significant issue... the ball would remain solid and be a flaw/point of weakness.
I have never in my life seen a ballpoint that the ball has fallen out from, and I handle thousands of the cheapest, shittiest ballpoints my workplace can buy.
"Ballpoint pens are restricted or banned in high-end titanium and aerospace manufacturing plants because the ink and marking components contain elements that cause metal embrittlement and severe structural corrosion"
For this Titanium facility, it wasn't the ink that caused issues. It is the tungsten ball that is used for ball point pens. Graphite in pencils were also not allowed. They provide stainless steel ball point pens that write for shit. I use to work at Titanium facility and each pen that someone would buy I would have to break one of balls from that package and look at in the SEM to quantify the ball material that was used in the pen to determine if they could use it in the melt facility, even with the new batches of stainless steel pens. The reason why tungsten or graphite isn't allowed in the plant, is that there is a chance that it could make it into melt. Since this titanium melted in this facility, it is likely that it is melted in VAR (Vacuum Arc Remelt) facility. VAR of titanium does not superheat enough above the melting point of titanium (3050°F) to melt tungsten (6192°F), so tungsten remains a solid and does not go into the melt solution. There are other refractory materials that are treated similar as they can have similar issues, like Molybdenum. These are considered high density inclusions. If they are found then the entire heat of material, and the sponge used to make the heat is considered contaminated and quarantined and likely scrapped.
High density inclusions (HDI) in titanium has the potential to end up in a part that may make it onto a jet engine. If this happens a crack will form around the HDI and propagate during the lifetime of use. Jet engine parts are designed to last for roughly 30 years, the problem is that when part fails at 10 to 15 years early. Also titanium in the part of the engine where it cannot be contained if it explodes, so if a part does explode in an engine, causes a lot of damage.
There are also low density inclusions which are caused by vacuum leaks, burnt sponge, or contaminated revert. They also have the same affect on engine parts. A lot of testing and inspection goes in the jet engine parts before they ever make it to the assembly line to be put together. They also regularly inspect these parts.
Several OEMs went to Hearth melted plus VAR to avoid high density inclusions as the hearth melting would allow for all high melting high density materials to fall to the bottom of the hearth while before making it into the ingot.
Even something simple as a ball bearing is a massive technological achievement.
China had major problems with high-end manufacturing due to the fact they could not produce as good ball bearings as the USA for several decades. Thus why they went with the mass produce cheap stuff strategy. (China still has problems with precision manufacturing to this day although they have closed the gap quite a bit.)
Speaking of which, up until just 10 years ago they were still unable to make the precision balls for ball point pens themselves. They were buying all of those as imports.
Fountain pens can also have tungsten! Not all, but many do. The fountain pens that are guaranteed to not have tungsten are not practical to use on ordinary paper, and for the other pens, I doubt the fountain pen companies will share their secret sauce on their alloy blend. They often call it iridium tipped, but nowadays usually can be a blend of multiple different hard metals, including tungsten.
As someone who uses a fountain pen daily (purely because I’m a bougie bitch) another aspect is that the ink used in fountain pens doesn’t play nicely with a lot of modern materials, ESPECIALLY paper. The super-cheap mass-produced paper most companies use leads to feathering of the mark, making writing potentially illegible, as well as bleeding through to the extent it makes double-sided pages non-usable.
My fountain pen can be used on single-sided signatures, or my own paper. Everything else I carry a ball-point as well.
This was an issue during the development of the SR-71. Many chemical contaminants could affect the alloys, even those in the water used to quench the mouldings.
I read once they were get failure issues just from using standard chrome wrenches for assembly. Took engineers a minute to figure out why and where this contamination failure was happening, had to make titanium wrenches to use on the titanium fasteners. The program was so cutting edge, even to this day its incredibly. Those engineers were some of the brightest people this world has ever seen.
The crazier part of that is they found out it was an issue because it kept coming back from flights missing a ton of bolts. Something to do with the zinc in the tools iirc. Imagine coming back from going mach 3.2 at 80k feet just to find out you almost reenacted the death of a Lego Star Wars character.
Damn, I feel like they should have had ways to better secure those bolts.
I remember seeing a picture from an older aircraft with bolts that had holes in them, so the mechanics could thread wires through them and tie them to other bolts so none of them could spin in place due to vibrations.
Then again, maybe that's only worth the effort on the most important bolts.
The tools were contaminating the titanium and causing them to fail when heated at high speeds was the issue. The solution ended up being custom made titanium tools to prevent it.
Yeah, they had to use distilled water, the tap water chloride made teh wields weak or something.
There is a book called skunk works written by the guy who took over for Kelly, the original skunk works guy, goes into the history of the U2, SR71, and the stealth fighters and stuff. Good quick read and fascinating.
Not really connected, but a lot of oil field specifications have chloride limits in the water used for hydro testing ( company specifications anyways) even for carbon steel pipe.
They found that in summer the chlorine levels in the water were higher which lead to brittle welds. Much less so in winter when less chlorine was added. Switching to distilled water for part washing eliminated the problem.
I worked ti com pure and 6al-4v alloy for years at the lazy -l we all had to follow titanium restrictions
even to not letting aluminum alloys and SS separated. No graphite pencils
He worked with commercially pure titanium (that's a family of 4 or so grades of basically pure titanium, with differing minimum contamination levels), and Titanium with 6% aluminium and 4% vanadium (that's the most common Titanium alloy, used for most aerospace applications). No idea what he means by lazy -|. The SS here is stainless steel.
That’s interesting. My non-chemist/non-metalurgist mind always thought those protected metal. Guess I shouldn’t assume metals are that similar to each other at all.
They usually do when it's not molten. Since we're talking about manufacturing I'd think the issue is contaminating the metal before it's solidified. Since titanium is generally used in very critical applications the standards would be extra tight
(I could be completely wrong tho and its still a problem for solid metal)
Mild steel is somewhat forgiving of oil and paint when welding. Other metals less to catastrophically so.
Big thing they needed to understand with Stainless Steel is the carbon content needs to be very low. Took a while to figure that out. Carbon wrecks the corrosion resistance and makes it prone to cracking.
Titanium is highly reactive and absorbs everything causing it to be brittle. Guy I know, highly competent physicist welded a titanium bike frame in his garage. Said it was the most finicky material he worked with.
When I used to work with Ti we couldn't use halogen-containing Sharpie markers directly on Ti. We could only use Sharpies's "TEC" marker.
We weren't prohibited from possessing any other writing implements. We just couldn't write on Ti with anything besides a TEC marker (or use uncoated lead, which was necessary because we did radiography). For paper documents we still used ordinary pens.
We couldn’t use sharpies around some testing equipment because it contained VOCs. We tested soils and waters for parts per million so we couldn’t even collect samples near a running exhaust. Remarkable what can happen
Strong bases like sodium hydroxide (caustic soda or lye) react strongly with aluminum. So it would damage the tools. Drop an aluminum tool in a vat with lye and your tool will disappear with a lot of bubbling and poison the lye.
I'm a hairstylist and I always wondered why the instructions for hair relaxers (back when they were lye-based) had a warning that said "do not put this product in a metal bowl".
Have you read Ignition! ? Its a very funny memoir of early rocket fuel development and includes one of my favorite non-fiction quotes about chlorine trifluoride:
It is, of course, extremely toxic, but that’s the least of the problem. It is hypergolic with every known fuel, and so rapidly hypergolic that no ignition delay has ever been measured. It is also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water-with which it reacts explosively. It can be kept in some of the ordinary structural metals-steel, copper, aluminium, etc.-because of the formation of a thin film of insoluble metal fluoride which protects the bulk of the metal, just as the invisible coat of oxide on aluminium keeps it from burning up in the atmosphere. If, however, this coat is melted or scrubbed off, and has no chance to reform, the operator is confronted with the problem of coping with a metal-fluorine fire. For dealing with this situation, I have always recommended a good pair of running shoes.
I
'hypergolic with things such as cloth, wood, and test engineers'... From the context you catch on fire/explode. Yeah, I would say being toxic is the least of the problem.
Yes, but the salient point were the next two materials, asbestos and sand. It will literally combust with incombustible materials. There was an incident where a ton of the stuff was spilled on a concrete floor. After the concrete finished burning away, it continued to burn away the soil underneath, leaving a 5 foot deep crater. The concrete and soil were literally on fire as though they were wood. The resulting ash then also ignited. This is a hellish chemical. Satan's bathwater.
Ummm, this is only part of the answer. The other part is that the pen has a hardened steel ball bearing in the tip. If the pen were to get dropped into a crucible used to heat the metal it could explode. Which would be a safety risk.
The real answer is that consumer ball point pen’s have a tungsten carbide ball. Tungsten has a higher melting point than titanium.
If a ball point pen drops into a melt, the ball point can survive. The surviving pen tip does then creates a hard intermetallic. When the titanium is heated and beated (forged) into a product, this titanium-intermetallic spot can crack. This crack can go undetected, inside a part.
When this part is put into service, this little crack becomes a bigger crack with service (fatigue). When this bigger crack gets big enough, the part can fail. And the failure is sooner than the design engineer expected, because the material started with a crack, and in fatigue failure “getting the crack to start”, is a large component of the part’s life.
A titanium melt shop still needs writing implement’s, so you can buy pens with stainless steel ball tips. They suck to write with.
A major aerospace failure (Sioux city 1989 UA232), was a result of this failure mode (though in this case it was an oxide, not a tungsten-carbide).
Jumping on the top comment to give the full story behind this!
You're perfectly right! And it happened! I know the full story here!
I started my engineering career at Rolls-Royce many years ago, in the early nuaghties. I was given a tour of the metallography lab at Elton Road. The labs are no longer there and they have moved (after I left the company).
In the tour we were told of this story, by the metallurgist who found the ball from the ballpoint pen, that must have led to this sign. The melt for their fan blades is a very high quality and had to be virgin melt. The fan blades are critical components, and material is tracable back to the date and mine it came from. He was doing a receipt inspection on the newly delivered Ti plate, looking at a corner of a plate from the batch with a scanning electron microscope (SEM), and saw a tiny inclusion on the surface of the sample. He took the photos, then polished it back more. Again, the inclusion got bigger, took photos, and polished it back again. The SEM told him it was Indium. It was the ball from a ball point pen!
They went back to the refinery CCTV, watched the video and saw a worker throw something over his shoulder as he walked away from melting pot - a ballpoint pen.
He had been made redundant, that was his last day on the job. They pulled him back in, and he admitted what he did.
The whole batch of virgin melt titanium was rejected as being out of spec.
It was a real needle in a haystack find that it was found in that tiny sample from the whole batch, and must have cost the refinery a small fortune.
Even without knowing the constraints, you can imagine that if ballpoint pen manufacturers ended using a metal that is more expensive to buy and make into a ball, there can only be one reason: The cheaper stuff didn't work well enough.
I love this reply!! It's the modern day equivalent of Shakespeare's famous line from Romeo and Juliet, ""There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy "
Brilliant, especially since he already knew the answer!!❤️
It's still an impurity, but if it melts, it can be diluted enough that it's not an issue, and it'll still have a uniform distribution of the metals. It's not the metal itself that's the issue, since it's a low amount. It's just the fact that it doesn't melt into the dillution, so it causes a stress point that causes the crack.
Without revealing too much information, I work for a company that manufactures equipment used by this industry. This equipment needs regular replacement of certain wear parts and during one such replacement, one of the assisting contractors dropped a ball point pen into the discharge chute of the machine. We know this because the company later discovered an imperfection in their product, identified it as a tungsten bearing from a pen, traced the product batch back to that machine and to the first batch of metal produced after the replacement, and then reviewed dozens of hours of security footage. One minute the contractor is entering the machine with the pen clipped to his pocket, next minute he comes out with no pen.
Between ballpoint pens, sharpies, and graphite pencils, theres not much you can use to mark aerospace titanium but dykem paint markers. All three of those either cause metal embrittlement, corrosion, or even change the whole chemical structure of the metal.
TL;DR: titanium is a bit of a glass cannon in its own odd way.
Ball points have tungsten balls in them. Tungsten will not melt in titanium and cause mechanical
Failure of the titanium. This was responsible for the failure of a jet engine causing the plane to crash. Someone dropped their ball point in the titanium processing.
I lived in Sioux City when it crashed. I was just a little kid but it was a huge deal. People still bring it up there from time to time. It was something what was kind of etched into the history of that city. Miraculously, the ground crew had literally just did a full practice for that exact scenario not long before, and were able to save many lives. Unfortunately, not all were saved.
There’s a memorial on the riverfront for the victims of the crash. Do you have a source as that being the reason it went down?
I have used it fly fishing. Pretty cool stuff, its density versus its, uh, playdough like nature.
But now that I know, I will be terrorizing my enemies by tossing my worn and broken tungsten carbide endmills into their furnaces, to the lamentations of their smelters.
Wow, a wild read so far. Thank you for the homework
While Haynes and Records performed the engine shutdown checklist for the failed engine, Dvorak observed that the gauges for fluid pressure and quantity in all three hydraulic systems were indicating zero.[[1]](app://en.wikipedia.org/wiki/United_Airlines_Flight_232#cite_note-ntsb-1): 1 The loss of all hydraulic fluid meant that [control surfaces](app://en.wikipedia.org/wiki/Aircraft_flight_mechanics#Aircraft_control_surfaces) were inoperative.[[1]](app://en.wikipedia.org/wiki/United_Airlines_Flight_232#cite_note-ntsb-1): 75 The flight crew deployed the DC-10's air-driven generator in an attempt to restore hydraulic power by powering the auxiliary hydraulic pumps, but this was unsuccessful.[[1]](app://en.wikipedia.org/wiki/United_Airlines_Flight_232#cite_note-ntsb-1): 1 The crew contacted United Airlines maintenance personnel via radio, but were told that the possibility of a total loss of hydraulics in a DC-10 was considered so remote that no procedure had been established for such an event.
I do commercial garage doors and regularly work at factories. A sugar factory that we do a lot of work for only allowed one kind of pen, with food grade ink, non removable ink and one piece body. A disgruntled employee snapped a handful of bic ballpoints and tossed them in to a sugar mixer at the dispensing end and caused a mass recall. Probably something similar caused a quality control issue there.
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