George:
<<<snip>>>
Gonaj@aol.com wrote:
>
> In a message dated 1/13/01 8:04:29 PM Central Standard Time, yd3@nvc.net
> writes:
>
> << Cut threads on fasteners are not as good as rolled threads. A thread
> "rolled" into the shank is similar to forging in that it changes the
> orientation of the material making it stronger. >>
>
> Blake;
>
> You need more information before you make such statements.
> The process of making rolled threads often creates some anomalies in the root
> and tip of the thread. These can seriously compromise the strength of the
> fastener.
>
> George
The following quote is from: Thread Rolling Inc., 34 Cedar
Street, East Hartford, CT 06108, URL http://www.threadrolling.com
"Thread rolling is the preferred method for producing strong,
smooth, precise, and uniform external thread forms. Thread
rolling is different from other types of threading processes like
cutting, grinding, and chasing.
"Thread rolling is a cold forging process. For the best quality
threads, it is performed on precision ground blanks. When less
critical threads are required, the blanks may be produced by
other means like turning, extruding, or heading. The blank
diameter of a rolled thread is at the pitch diameter, a
theoretical point between the major diameter and minor diameter."
The following quote is from: Rolled Threads Unlimited, LTD., 1404
Pearl Street, Waukesha, WI 53186, URL,
http://www.thomasregister.com/olc/rolledthreads/custom.htm#top
"In thread rolling, the material is compressed, not cut away,
creating a stronger thread, and obtaining a much higher
micro-finish on the flanks. These diagrams indicate a rolled
thread's superior resistance to stripping. The rolled thread's
grain structure is not severed in any way, but is, instead,
reformed in unbroken lines that follow the thread's contours.
Therefore, for a shear failure to take place, it must occur
across, rather than with the grain."
Also try http:\\www.edsmfg.com
In several sites that were checked regarding grading of bolts,
nothing was mentioned about difficulties with rolled threads.
Now, George, where is there information showing that rolled
threads are inferior?
Blake
http://albums.photopoint.com/j/AlbumIndex?u=1536873&a=11674710
|