Have been through this mucho many times in the chemical industry. Customer always wants the highest purity they can get. It avoid potential for problems from that trace impurity.
Plan routinely points out that the purity requires extra processing and extra cost. Most customers don’t need the quality they demand and won’t notice if shipped lower quality product. Happens all the time.
Re: titanium. The main reason to use titanium is higher melting point. It is not especially light.
Titanium mp 3034 F, density 4.502 g/ml
Aluminum mp 1220 F, density 2.699 g/ml
Numbers from Wikipedia. Retains strength at higher temps.
Thay is no excuse for the supplier to lie to the customer. The supplier must tell the customer that the higher purity costs 10X more, then the customer can decide.
The industry does that all the time. Tech grades of product. And especially in certain industry like chemicals for semiconductor processing offer special highly purified grades.
Works fine in markets willing to pay the price and large enough to make the numbers work. But many other situations are out there.
There is no excuse for customer not to know if their product is sensitive to a materials specs. Most do not bother to check it out and merely order off the shelf. “This is what we usually buy.”
The essence of the discussion is that no one really knows if high purity is required or what affects purity might have on performance. Now those studies are just beginning.
And for an airplane that contains thousands of parts think about the implications. Impact could be huge.
Or, a sample part was received from a trusted supplier and tested. The tests showed the part worked as needed so that was made as the spec. No tests were done on a part with a lesser percentage of titanium so they don’t if such a part was adequate. This is still a failure to comply with the spec.
Mike
I think you are making up an issue that is not reality. Thousands of parts on aircraft have no safety function. Off the shelf is OK for those parts. If they fail, then they do not effect flight safety. Non-safety parts are like seats, overhead lights, toilets, etc.
The safety related parts are a different group. If they fail they that can cause an accident. Jet engines, wings, flaps, cockpit instruments & controls, etc. are safety related and must meet safety specifcations. If suppliers provide non-conforming parts they should be arrested go to JAIL if found guilty. The suppliers are legally responsible for meeting specs.
Remember the car airbag problems several years that caused injuries and deaths. The supplier of those faulty airbags was responsible and they paid huge sums of money for their failure to meet safety specifications.
Nuclear power plants purchase safety related parts and equipment from suppliers. When these items do not meet the safety specifications then they are violating federal nuclear regulations. They must report their failures to the NRC and the utility who purchased the parts. The nuclear plant may be required to shutdown and removed all defective components and parts. The supplier is responsible for all costs and may be criminally prosecuted.
The aerospace rockets have the same type of safety requirements for many of the parts and components of rockets. The suppliers are legally responsible for meeting specs.
Sorry have you been around the aircraft engine manufacturers?
This is not true. It is not just beginning.
I do not have your expertise in chemistry. But this is not brand new to this industry.
Take for example the arm rest on a passenger seat. They probably want it as light as possible and durable enough to do the job.
Its easy enough to select an existing metal specification with extensive details.
Do they actually know that hundreds of other aluminum alloys don’t work–are not suitable. I doubt it.
Over specification is common. And wasteful.
Not picking on any one person. I have seen this notion several times in this thread, a notion of “so what if what we provide doesn’t meet specs?” I submit that providing the material as specified in the PO is not an option. If I order 1095 steel, I want 1095 steel, not pot metal. If a vendor wants to provide something other than 1095, they can submit material samples for testing by my engineers to see if it performs satisfactorily. Simply substituting other material, without my knowledge, let along my approval, is NOT acceptable.
/rant
Steve
My pure guess is that is nothing more than a greed play.
Let’s say you’re a JC vendor of raw materials for some process. And you learn that your customer isn’t really checking the material you send over. So you send a batch of slightly lower quality material over and see if the customer notices. If they catch it right away, you can always play the “oops, we made a mistake” card and go back to the specified material.
But if they don’t notice, you start sending that lower quality material all of the time, while still charging for the higher quality. Tada! Improved profits.
Then a couple months later, you repeat the process. Catch you? “Oops” and go back to what you were sending. Catch you again? “Oops” again, with promises to dig deeply into your processes to “correct” things.
As long as you can get away with sending lower quality material, you are improving your profits. Meeting spec isn’t important. Profits are important.
–Peter
All hail Shiny-land, where fraud is “good business practice”. Years later, the customer says "wow, this stuff is corroding pretty fast for 20 stainless, and sends a sample to be analyzed. Metallurgical lab reports back, “somewhat nasty piece of 304 stainless”. But, by then, the CEO of the vendor, who perpetrated the fraud, has made his packet off the company and retired.
Remember Tim commenting on his ChiCom “stainless steel” grill, that rusted after only a couple years?
Steve
Nearly every buyer says exactly that. But reality is there are 10,000 shades of gray between 1095 steel and pot metal. We are not talking about complete fraud. We are talking about minor variations.
If the product is 10 notches off spec, only about 1% of customers are sophisticated enough to notice. If 100 notches of those 10,000 perhaps 10% will notice.
Plant guys routinely tell you that reprocessing off spec product is very costly. The off spec material has all your manufacturing costs in it. It is a very expensive raw material. They much prefer to sell it–sometimes at a discount. They can work it off by blending into good product. Dozens of strategies. This is real world manufacturing. Just don’t get caught at it.
In aviation they are much more likely to notice.
If it is for an armrest I guess not.
A typical product may have as many as 20 specifications. A few customers check a few to spot a mislabeled shipment. Few are equipped to check all of them.