Lynn E. Hanover

I retired from my work in my beloved US Government as a technician in the acquisition area of The Defense Supply Center Columbus (Ohio). DOD, DLA, DSCC, SDP. One of the many schools Uncle Sugar sent me to was Specs and Standards school At Fort Lee Virginia. It turns out that most of those specs that so many people put so much faith in, are just acquisition tools written by morons like me. In fact the primary source for specs is the manufacturer that is making the piece we are already buying.



You don't get to see specs for cutting edge technologies because it is a blueprint for how a piece is made, or has enough intel to give most of a process or procdure away. So, the idea that It does not exist because you cannot find it on some list, is just foolish. You will not find much new stuff in your IHS library.



Government inspecters do use in-house specs to do in-process inspections inside a manufactueres facility, but may not posess the spec or remove it from the inspection area. The government may not even know what specs are used by any manufacturer for any particular part.



In most acquisitions the government is using the manufacturers in-house spec, which will be marked "Limited rights" and it is a violation of federal law to divulge specific data from that spec or drawing. The spec may also be elevated to NOFORN, which means no foreign access to this drawing or spec.



Where the "Rights" to data are purchased by the government, you will see, for example, Boeing drawings, in wide distribution. In those cases, as you would guess, the design is frozen to the last drawing date owned by the government. Where the government inspector has specific drawings to inspect to, they will inspect to the first level only unless there are contract clauses that call out exceptions to lower level specs.



The best acquistion situation is that where the buy is for a part number. Period. No in house inspection is called out in the contract, and inspection at destination for count and condition is all that the government is allowed to do. You will discover that NASA buys an enourmous amount of its stuff with no specs at all, just count and condition. In a large number of acquisitions, we had only the top drawing for use in identifying the piece. One or two outside dimentions and a color.



Our worst fear was a young engineer piling on specs as fast as he or she could look them up. You just shut off your source of supply by doing that. You may be aware that the government under pressure from our beloved congress and 60 minutes, has turned over to the SAE thousands of military specs and standards.



Without comment or consultation, the SAE set about (standardizing) hundreds of these items by removing this or that and inserting the "similar" SAE subspecs. This to make more money for themselves, because the spec in no longer free, but must be purchased from SAE.



So, for example in the area of stainless AN fittings, the type of stainless is changed and none of the manufacturers have ever made the parts from that material, and are not interested in starting to do it that way. Presto, you are out of stock on that item. We would have to call up the extinct version of the spec, and then write in the material exception to the new spec on each and every contract, covered by that spec.



We are just getting over the "just in time" contracting that the congress thought would work so well. The car companies have quit doing that in most cases. It requires more complete end items to be deployed to end up with the same number end items available. So, instead of a fitting on the shelf in Germany, you need an extra M1A1 Abrams tank.



What would have been cheaper? The fitting or the tank?



During WWII there were hundreds of quick built "Liberty" ships assembled all around the country for use in shipping war fighting supplies to Europe. Many were lost with all souls to submarines and surface ships.

This included those going inside the arctic circle taking aircraft the our friends the Russians. It was then thought that the Germans must have subs operating in those waters. This was not the case.



One day a Liberty ship made it into port with a foot wide split in the main deck from stem to stern.

The 60 below zero temps had made the steel alloy so weak that nearly any stress would fail it in a grand manor.



So there were no subs at all. The ships lost had split open below the water line, and sunk so fast that not even one SOS had gone out. A bucket of aluminum added to each batch of melted scrap iron cured the problem. So there is the begining of the idea for cryo treating of metals to gain this or that characteristic.



The Titanic disaster was another example of poor (nonexsistant) metalurgy.



I reacently toured a propeller manufacturing facility, where I did not notice any paper work attched to any "In-process" blades. The fellow leading the tour said they had their own quality system. I was expecting M-I-45208, or the similar Metric (French bullshit) spec everyone loves to advertise so much. So I doubled back and inspected each batch cart as it went through the plant. There was only one piece of paper for each cart. A few numbers, no names, machine numbers, blade serial numbers, no way to connect any blade to a manufacture date. A recent AD covering some of their products included some serial numbered hubs, some part numbers for that same hub, and a notation that some retailers may have applied part number of their own to those hubs. In othere words anyone with one of that style prop has to remove it and inspect the hub, to see if it is mismachined. They think they made 40 (or so) bad hubs, but they have no idea where they ended up.



Any known quality system in use here? I think not.



NASCAR uses cryo on high stess parts like axles. Fools wasting their time and money?



There is more on heaven and earth than you or I will ever know.



But again I run on.



Lynn E. Hanover

Cheers!

Ok so explain to me the process of cryotreating. At what temperature do we subject the parts to? For how long? What is the rate of change in temperature? Are there any peices that get tested to ensure a change in mechanical properties has occured and met your requirements? How does the rate of cooling affect surface hardness or tensile strength? How does it affect fatigue life? I can't find any information from that in any text book, spec, standard anywhere. Metals has been around a lot longer than the ability to make liquid nitrogen and hydrogen. If you are telling me that no one has invetigated or tried to drop a peice of steel into liquid hydrogen or nitrogen I would be stunned.



Specs and standards exist because someone took the time to do the R&D on the process and material to ensure that when others want to acheive teh same results they can be duplicated. It is fine to say, hey I want that part heat treated or stress relieved, because I want a certain surface hardness or fatigue life. But when the guy who operates the oven goes, so how long do I stick it in there for? What to do you. say, "stick it in for an hour?", what temp sir? "I don'tknow, what temperature do you use to roast a turkey?" Do you want me to air cool it or quench it in oil? All those things influence the final strength of the peice. That is what the spec is for. The spec tells you that hey, for given temp, for given rate of heat, for duration, and for rate of cool you get 175 ksi. If you skip a process you only get 150 ksi. That too me is important.



Revised drawings calling out a different material compared to the original design has no bearing specs and standards in this argument. A drawing is not a specification. A specification is instructions on how to conduct a process. A drawing outlines and details a part that is to be created.



You use these specs not in purchasing but in the design. If you designed a part and you need a certain strength and margin and you called for specific heat treatments to the material for your part then it better be done. I don't know what happens in the USA govt or military now, but in my current industry of aerospace... **** like that doesn't happen.



A specification/standard is used by the design engineer so that he/she can correctly select the correct material for their design. If you were in cutting edge design work you may be able to invent some new way of heat treating a material to get you an extra 5% of whatever, calling out for weird processes and such that isn't common to industry. An ASME/AMS/NASA spec has been written for engineers to follow.



It is up for teh company's QC to ensure that the part was manufactured according to design. the spec is not Quality control! It is a tool for selecting material. Just like how you look up the strength of different metals.



If I called for 7075 aluminum for a part, and the machinist used 6061 or 2023, it's not the spec's fault. It is the QC and the machinist not paying attension.

Cheers!

If I called for 7075 aluminum for a part, and the machinist used 6061 or 2023, it's not the spec's fault. It is the QC and the machinist not paying attension. The AMS spec tells me 7075-T6 has a yeild strength of 73 ksi where as 7075-O grade has a yeild strength of only 15 ksi. If my design parts need to carry a load that subjects it to a yeild strength of 50 ksi, I'm giong to call out the use of 7075-T6 and call out the proper spec for 7075 and tell the manufacturer that I want them to solution treat and precipatation harden the peice after rough machining per AMS-H-6088 to the T6 temper. Then I would have him remachine it for the final dimension. If the piece is cylic loaded I would then figure out if it will fail during it's operational time to fatigue, but won't if I stress relief it. Then i will call out stress relief and dye inspect

Lynn E. Hanover

Cheesy

the liberty ships were one of the first completely welded ships as well i think, so they didnt have any inbuilt crack arresting features such as rivits and pannels, almost all steels have a brittle-ductile transition temperature which happens to be in the region of normal/cold environments. Im pretty sure you will find that austenite will transform to martensite below 0 degrees, the austenite-martensite is not a diffusion controled process like austenite-pearlite etc. The martensite start temperature is not always above zero either, have a look through some cooling curves (TTT diagrams)

Lynn E. Hanover

When I was young, you were not permitted to throw away any kind of metal. It had to be turned in for the war effort. The need to collect and melt ironlike scrap into plate stock at a high rate, no doubt resulted in some unrecorded recipes of iron/steel alloys. The effect of cold stress was often fatal. Welding was hit or miss, (My mom was a welder) I was thirty before I laid down a bead she liked. She worked nights sanding parachute packing paddles (like paint stiring sticks).



The real alloys went to aircraft and submarines and everything else was made of crap. What does nichrome from a pile of toasters and a pile of car springs make when melted into plate stock? In some cases a German 88 would hit a vehicle, and it would fly apart as though a toy of some kind. It was a damn grim time.

Supposed armor plating shattering like glass when hit, in the cold. A real moral builder.



Sorry all of you young guys missed it.





Lynn E. Hanover

RONIN FC

I feel like im right back at work.



Just to reinforce what Lyn is saying (as if he needs it) The prints follow a project from start to finish of that particular component. But to limit the chance of disclosing secret and propriatary info, a component, or unit, is built in several steps in different departments to keep a person or group of people from knowing or recording the exact specifics.



Cheers, Dont be surprised if you dont have all the detailed specifics reguarding processes used to fab or assemble everything. Its an elaborate system to keep knowledge in control.

Cheers!

Lynn, I believe we see the specification/spec idea that is being discussed for cryotreating/heat treating in this thread differently.



You are speaking of individual parts, such as Mil spec circular connector or mil spec wiring, or nuts and bolts. (Military specified parts), basically specifying that the part is the same if it has the same part number



I'm speaking of standards and specification for the production of parts, whether they be one off parts or parts that a GM engineer dreamed of for a suspension. A body of engineers, researchers, and academics researched the steps to follow to obtain a desired performance in the material. In this case we are speaking of heat treatments and cryo treatments. A recognized body be it SAE, AMSE, etc... has been able to repeat the researched process and has issued a way (standard) that others must follow in order to acheive the same result.



I'm not convinced that cryotreatments actually do anything. If you do say that I do not have access to all the documents and standards that the americans have classified or developed internally, then I would too assume Joe blow who runs cryo3000 or frozen rotors.com or whatever cryo treatment place doesn't either. I do not believe he/she has NATO security clearance and NASA clearence either. Then I must ask you how is he figuring out the steps necessary to subject parts to increase their performance? And how is he making claims as to how the parts have increased in performance? Did he drop the cryo treated part off his roof and say, the dent was smaller on the cryo peice than the one that was untreated?



How come I can't go down to the local metal supply shop to buy 4130-cryotreated grade, but I can buy 4130-heat treated grade? Liquid Nitrogen is not difficult to make? It would be super easy for the foundry to subject some of their peices to a liquid nitrogen dunk before shipping it out.



Unless I know exactly exactly what final

yeild stength

tensile strength

Rockwell hardness

change in dimension

Elongation at Break

Modulus of Elasticity

Bulk Modulus

Shear Modulus



I remain skeptical on claims of cryotreatments.

heretic

Yet, for years, people have preferred to use "seasoned" blocks, aka weathered, aka used, because pretty much all internal stresses will have normalized at that point.



Iron does weird things. It will move around long after you think you're done. Ford Y-blocks, fir instance, do some really odd things on the deck surfaces. Did Ford machine them with those weird rifts and valleys? No, the iron "settled" through use, and due to the idiosyncracies of the block casting, they all manage to settle into the same general shape.



BMW famously exploited this by using euphemized junkyard engine blocks for their F1 efforts. They held up better than new ones.

Cheers!

That process is called cold working. Plastic deformations cause the lattice to slip and forming a co-planar lattice which is stronger than a perfect lattice. Shot peening a peice of steel is a form of cold working. You can only cold work small objects. It is almost impossible to cold work something the size of an engine block with all it's intricate parts and pockets.