In the steel industry and in the most general terms, anytime you see the word “stock” attached to another word; think, “stock used to make”. Barstock, Bushing Stock, Rifle Barrel Stock, Pump Shaft Stock, etc. would be stock that you can use to make those items. All details need to be clarified; is it pre-drilled, pre-hardened? What is the finish allowance? The term “stock” just means “may be used for”. Facetiously, a tree might be “Home Construction Stock”. i.e. not the finished product.
Keystock is generally a square or flat shaped lower to mid strength metal, either alloy or carbon steel, that is used to make keys. Those keys are inserted into shafts. A drive motor chuck will engage with the protruding key, and rotate the shaft. The idea is that this key is of less strength than the expensive shaft, so that if something interrupts the motion and causes failure, it will be the cheap little key that fails not the bin expensive shaft. Clear the obstruction, put a new key in, and you’re good to go, hopefully with an undamaged shaft.
The perfect piece of keystock would have less mechanical strength than the shaft, tuned to the actual application, but close enough that the shaft didn’t fail prematurely, contributing to expensive downtime. It would also be a cold drawn bar with good cross-sectional accuracy and a close oversize tolerance. The ideal oversize tolerance for many years was considered to be +.002″/-.000″. That tolerance would allow you to machine a standard keyway, in which the key would fit it in nice and snug. Undersized tolerance resulted in sloppy, loose keys. Too much oversize required un-welcomed machining.
My first experience with keystock was when I was about 10 years old. My uncle took me fishing in Canada. We were in a small aluminum boat with a little outboard motor. We were trolling at a very slow speed and he let me captain the “ship” for awhile. His only caution; stay away from the shallows and weeds; the only things I seemed to have a talent for. Every few minutes we snapped a key when the prop would strike something. We went through an entire little metal pill box of keys. That experience, and his humorous disapproval, stayed with me. The solutions were; chuck me out of the boat, or get somewhat stronger keys.
There is the conundrum. Too soft of a key and you have frequent expensive delays. Too hard of a key and you risk damaging an expensive shaft. (Goldilocks and the porridge issue).
Decades ago, Moltrup Steel, Pennsylvania, was considered the benchmark for keystock tolerance and cross-sectional accuracy. Having failed to secure the quality sufficient to satisfy their own needs, they embarked on producing the finest grade of keystock available. “Moltrup Quality” actually became a legitimate descriptor. I still see reference to Moltrup Keystock today, but am unfamiliar with the exact specifications, or how closely it follows the original “Moltrup Quality” of the past. Moltrup closed in 2002 and it has been my experience that the exacting tolerances disappeared with it. (Associated Steel always maintained a substantial inventory of Moltrup Quality material. It is a diminishing commodity but worth checking). When Moltrup closed, the potential market did not seem sufficient to justify the additional die work and drawing that would insure that high degree of accuracy. The tolerance on keystock gradually opened up to +/-.004″ to .007″ (that’s plus or minus). Even with sources that promote “Keystock”, or Moltrup Quality, pay close attention to the actual tolerance that you will most likely get.
The hardness (through multi-pass cold drawing/strain hardening), tolerance, and cross-sectional accuracy are all doable. Expensive, but doable. Requires a lot of fiddling in production for an item that does not represent any significant tonnage. Until something changes, keystock that is fine-tuned to allow maximum performance of the esoteric shaft application you are dealing with, will have to be made. Your choice, either make it, or chuck the kid out of the boat.
We have been actively pursuing adopting the metric system in the US roughly since the latter part of the 1700’s. Its been dubbed “Mandatory” in 1809. The success of those efforts has only been eclipsed by Y2K and the great reveal of the contents of Al Capone’s safe. In fact, for a quick chuckle, if you can still find a veteran businessman, mention you heard we are going to be exclusively adopting the Metric System in the USA next year.
At best we can say today that we have had success adopting the metric system in some of, but not all areas of measurement. Wikipedia does a nice job delineating areas where metric measurement has successfully been adopted in the US, (science, military, medicine). The only example of metric measurement that came to mind, however, was the 2 Liter bottles of soft drinks are now illegal in New York. At best we can say Americans are not keen on jumping quickly into metric measurement and saying goodbye to “foot-long” hot dogs and jokes about the inability of men to measure correctly.
A word of caution; while we are “actively” transitioning between metrics (written in decimal notation)
and “fractions”. Make sure both parties understand the exact point of accuracy that is being discussed. If you purchase a bar of 3-1/4″ Diameter, is your supplier visualizing the same 3-1/4″ Diameter bar (in fractional context?). Or are you really expecting a 3-1/4″ Diameter bar that is 3.250″ Diameter, accurate to the third decimal? What about 3-15/16″ Dia. (3.9375″ Dia. Are you expecting accuracy to the fourth decimal?). True, one topic is diameter size, while the subsequent text refers to accuracy or diameter tolerance. Normally, that would not be an issue. The two would be understood to be separate considerations. However, when you are ping-ponging two different measurement systems as interchangeable, there is a potential for surprise. Mishaps of this nature occur more often than should be the case.
For now, in the United States, think of any changeover of our measurement system sort of like METRXIT. It will likely still take a while. Over time, you will likely see dual notation on things like automobile speedometers, etc. But when it comes to steel bar sizes, fractional annotation may be here for a while. The “fractional” system, sometimes referred to as: The English System, or Imperial Units, has served us well. Change is inevitable. We know that. We’re workin’ on it.
Every once in a while, I have to engage in something that smacks of shameless sales dialog. This is one of those times. So, grit your teeth, send small children out of the room and just get through it.
If you are involved with heavy plate fabrication, and more specifically, if you occasionally handle hardened wear plate, you may want to give some thought to a product we carry that seems to be useful to fabrication and equipment repair facilities; Light Gage (1/8″) real 400bhn Q&T alloy wear plate. Forms well, readily weldable (not too rich of a chemistry to cause problems), and it provides weight reduction where installation and handling might be a problem; not to mention you can make wear resistant containers, hoppers, tanks, and that are lighter and therefore increase payload.
Perfect for emergency temporary patching of blow-outs on job-sites until heavier fabricated pieces can be delivered. An installer can get the pieces into hard to reach places where a repairman could handle the plate by hand. This is a nice alternative to 3/8″ and 1/2″ thick A36 liners. That’s a big reduction in weight! You may even find you benefit on the competitiveness of your bids. Depends on what the other guys are quoting.
We stock it in full sheets, 1/8″ x 60″ x 120″ long. We also cut pieces to order; simple rectangles and strips, but also configurations per sketch. Our sheet is cut on a Hi-Def Plasma, and our machine operator has been working with plate for 30 years. The cuts we get look almost like laser-quality with very little heat effected zone along the cut; even with alloy products.
NO SUCH THING AS WEAR RESISTANT STRUCTURALS? (Other than low-hardness A588). Think about tac-welding some clean-plasma-cut flat strips into the wear surfaces of channel and angle or beam.
CAUTIONARY NOTE; Working with hardened steel, anyone’s hardened steel, involves risks. Be sure to use appropriate safety gear (hot-mill gloves, hard had, safety glasses, etc.), Utilize persons experienced in handling hardened steels, to include certified welders, etc. Try to form against the grain, incorporate the largest bend radius the application will handle. And, COMMUNICATE, COMMUNICATE, COMMUNICATE. If there is something that you are not absolutely sure of; ask your vendor!
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