I think he's referring to quarter sliders rails.
People need to understand that DOM is "harder" on a Brinell scale. It is a cold drawn process and this gives excellent dimensional and finish parameters above HREW. DOM is a seamed material, most I've encountered over the years think it is seamless and therefore superior.
DOM has a much higher Carbon content in its metallurgy make-up making it harder to begin with. The harder a material the more brittle it becomes after welding or a machining process and simply by aging.
HREW is 1010 and DOM is 1020.
I used to get MTRs with all my steel and tube orders (just a habit from my oilfield/energy CWI and NDT Level II days) so I could look at the breakdown of the elements and percentages. No matter if the steel/tube was foreign or domestic they were all within .03% of each other on carbon and acceptable by all engineering codes and standards ON PAPER. But, IMO, that's a whole other ball of wax. ASTM, ANSI, ASME, API, etc... etc... allow mills and fabrication facilities to run on "blanket" inspection and metallurgical material data.
Take an air compressor tank. It has an ASME "U" or "UM" stamp for it (pressure vessel). It was built and accepted by previous construction and testing data. This means that a "blanket" approval for a "batch" of tanks can be run before another inspection has to be performed and materials tested. Compressor tanks usually run on a 2000-5000 piece blanket (some insurance AI's allow for years to pass instead of quantities regulated. Bigger mfg's piece numbers can easily double or triple without inspection) Therefore, a blanket MTR (material test report) for construction materials and a blanket inspection release = A product produced in a rapid environment, with limited or selective to NO quality control and constant changing blanket materials--- Watch your A$$.
Sorry, off soap box now...
J
It's not a soap box when it enlightens. This is all true. China and India know how to follow the manufacturing standards but without oversight, and demands by the customer, either explicit
or implied, the product is cheapened in easiest way.
I know a vendor who was building wheel spacers in house , here in the USA, with a specific
aluminum grade. He was wooed by a Chinese company to have them manufacture since they were already manufacturing similar wheel spacers of that same material ( sourced in China ).
He flew over to tour the plant. While walking past one of the cnc mills running a spacer body it slammed to a stop. The new machinery stops instantly when an issue is detected. A worker went to the machine , pulled the part and tossed it to a pile of discards. Being curios as to what happened,
he went over and picked up the discarded part and inspected it. The machine had stopped because
it hit a piece of chicken wire that was cast into the aluminum.
Technically their aluminum has the same ratings as does their DOM but like you say which piece gets tested vs which gets sold.
I know I used to build some shackle pins you're familiar with. I used only ETD150 from Lasalle,
140,00 PSI steel. When Karson hijacked them and sent it ti India the material went down the tubes.
I doubt it's 40,000 psi now, but they can build them for 1/3 the price.
and then off to the laser cutter.
