June 9, 2016
The Team at Keystone Threaded Products shows us that “Precision” doesn’t necessarily mean “Tiny” as they thread the ends of some 20 foot long, 10 inch stainless steel bars for a Metalworking press. The thread is a 10-1/4″ : 4 UNJ RH applied to each end of the 3 and a half ton bar.
20 feet long, two ends to thread, 3 and a half tons of precision.
At Keystone, they roll the thread form onto the material which makes for a stronger thread. Alignment and following the process is critical to assure a good thread.
Thread rolls create the thread form on the work piece.
Multiple passes are needed to build the thread up to the proper dimensions.
Half a million pounds of pressure are imparted on the rolls to plastically move the steel of the bar into the thread form. Read the gage.
Obviously it takes knowledge, skills, and experience to apply half million pounds to produce precision work.
Rich says that he’s rolled larger bars, but skills and experience and a great team to work with create the can do spirit that makes precision manufacturing a great career.
Here’s another look at a finished bar. Precision does not necessarily mean tiny!
Just another point of view so you can see the size of the work.
Thanks to Betsy Minnick and the Team at PMPA member Keystone Threaded Products for showing us that “Precision” is not a synonym for “Tiny.”
August 10, 2010
Because the steel grain structure is cold forged, rather than cut, rolled threads are up to 30% stronger…
Sketch iluustrating grain flow lines due to cold work of rolling.
While the strength of a thread is a function of section thickness, a thread rolled rather than cut thread is usually superior in mechanical properties, all other things being equal- here are 6 reasons why:
- The flow of the material by cold work during rolling reinforces the shape.
- The cold working strain increases mechanical properties, Surface Hardness,Tensile Strength, Yield Strength, and the Yield Strength / Tensile Strength ratio.
- The surface finish of the thread flanks is usually smoother due to the burnishing action of the rolls.Smoother finish means better fatigue life and fewer opportunities for stress risers.
- There is more material (section thickness). This results in material savings*, since the diameter of the blank will be between the major and minor diameter of the thread, rather than greater than the major diameter for a cut thread.
- The compressive stresses on the threads resulting from rolling improves the fatigue life.
- The root of the thread has a smoother radius, improving fatigue life.
Schematic view of the thread rolling process.
Pictures courtesy PMPA member Ray Industries
Click here for a video of the thread rolling process in action from PMPA member Rolled Threads Unlimited LLC.
*I got my first “learnin” on rolled threads at my customer Keystone Threaded Products back when my hair was not silver and B.K. (Before Kids): “Why do you always buy funny sizes Jim?” I asked. That was a great first lesson on how engineering can add savings:
Blank diameter will be between major and minor diameter = $ Saved.