Thread rolling 3/4-10 x 5.75"L in Turning Center?

[red beard]

I received an RFQ for several hundred parts with 5.75" long 3/4-10 threads. Material is A36 hrs (or whatever low carbon steel I want to use). I have no experience thread rolling, but it would seem like the best way to make these parts in a turning center. It would be run on a Hyundai Hit-18s.

If I was just doing a few parts I would single point them or set up a Geometric die head in the Turret lathe, but I at this quantity, I want something that will run consistently and reliably. It seems like rolling the threads would be a better option. I'm looking at the LMT/Fette axial rolling heads. (There are a couple on ebay the right size.)

Does this sound doable? Any other tips or input would be appreciated.

 

[Guest]

I have only thread rolled brass. My logic says a few things. First for several hundred if you factor in the full cost of a tool that someone else probably already has chances are you won't get the job. Also if your turret is a little out of alignment or the tool is miss set you may get some nasty effects on a thread of that dimension. I single point long threads using my live center all the time and with the right insert would expect 150 or so of your parts before replacing and maybe an offset every 50. I would think single pointing would take around 60 seconds. I don't think this job is a good one to try to learn something new on. Unless of course if there is an extreme and expensive learning curve the money isn't coming out of your pocket. How much for the rolling head and new rollers? Also am curious the time rolling saves and I wonder how much HP it takes.

 

[Finegrain]

I received an RFQ for several hundred parts with 5.75" long 3/4-10 threads. Material is A36 hrs (or whatever low carbon steel I want to use).

12L14 and single-point them.

Regards.

Mike

 

[apoc_101]

Could go either way with this, if the thread rolling tooling is worth adding to your capabilities you could pay a nice chunk of it off with this job without inflating the quote. I'd quote based on what it will cost you to turn the threads with single point cutting, which should be somewhere between "free machining steel and less inserts" and "cheap steel and more inserts".

sleep on it and consider that more threading work in the future could benefit from thread rolling capability... but most thread jobbing is still single point cut due to the flexibility of the process (thread rolling is a tighter process, with specific dies and careful setting and initial diameters to achieve production threading capacity)

 

[Red James]

Rolled threads require close attention to the diameter of the material to be rolled, i.e. you will have to turn your bars and hold a couple of thou on size before learning how to roll. Cut-off with a chamfer and de-tit the end, then advance the material, face & repeat. 3/4" bar thru spindle needs a lot of support, especially outside of the machine. Does not sound fun. Buy thread roller, rolls, some sort of material support, material. Cost each?

OTOH you can buy 12' lengths already threaded (McMaster price 36.25), saw, face chamfer 2x and be done. Sounds like a $5.50 part or $550 per hundred. Now you can think about whether it's worth the learning costs.

 

[red beard]

Thanks for the input guys. I realize I wouldn't be able to put the whole cost the the head into the quote, but it is something I think I could use in the future. I'm always looking for ways to improve my capabilities.

Rolled threads require close attention to the diameter of the material to be rolled, i.e. you will have to turn your bars and hold a couple of thou on size before learning how to roll. Cut-off with a chamfer and de-tit the end, then advance the material, face & repeat. 3/4" bar thru spindle needs a lot of support, especially outside of the machine. Does not sound fun. Buy thread roller, rolls, some sort of material support, material. Cost each?

OTOH you can buy 12' lengths already threaded (McMaster price 36.25), saw, face chamfer 2x and be done. Sounds like a $5.50 part or $550 per hundred. Now you can think about whether it's worth the learning costs.

There is more to this part than the thread, otherwise I would use threaded rod. (We cut thousands of pieces of threaded rod every year for a fastener distributor.) This part starts at 1.25"dia and the end has some milling and cross holes in it.

Now my customer says that it can be made as a weldment using threaded rod and rectangular crs, so that's looks like the rout I'm going to take.

 

[sfriedberg]

If you are using B7 threaded rod for that weldment, thread it as 4140HT for pre-/post-heat purposes.