I was wondering what everyone thinks is the best method for machining an O.D. thread. Single pointing is the only thing I currently use but we have a job coming up that may benefit from a different method like thread milling or thread whirling for example. The only print I could pull up was the part that had a 1/2-13 thread on it but I know there are smaller ones as well. These parts would be running in a L20 and an A32 and made from 1144 stress proof.
Thanks
Thread whirling? That is a new one. Mind if I use it? I think you mean thread rolling or thread forming.
The best method depends on soooo many factors, one could not fully explain in a life time.
Size of thread
Length of thread
Type of thread
Specifications of thread
Final use of thread
Type of material
Machines available
Horsepower available
Tools available
Rigidity of work piece
Coolant/lubrication available
http://www.kirkcon.com/
No I meant thread whirling (Genevieve Swiss Industries - Tooling & Accessories for Swiss-Type CNC Machines - pt#cit-btw100-u9.1) Now I have never used one of these before and I've only seen them used for bonescrews but I'm told they can be used for normal threads too. I know there are many factors when it comes to threading, I'm just looking to see what method others prefer in general.
Ok. Looks like segmented die threading to me. They probably call it whirling to "brand" it and trademark it for their products only.
On a lathe, my preferred method of cutting OD threads is single point threading. One tool covers a large range of threads.
On a mill, my preferred method of cutting OD threads is "single point" thread milling. One tool covers a large range of threads.
My only consideration for varying from these methods would be extreme difficulties encountered using these methods or if production numbers were so high that the per part time savings would justify the additional tool cost and set up time to switch methods.
http://www.kirkcon.com/
Never heard of thread whirling? You've got to be kidding me :haha:
No, I was not kidding. Found it after some digging:
Marubeni Citizen-Cincom, Inc.
"There’s not much new about whirling. It’s been used in Europe to machine helical parts for more than 50 years. It’s time-tested, and it’s proven to machine screws and thread forms at speeds often as much as four times faster than traditional thread milling or hobbing, and typically without the need for secondary finishing operations. But that’s in Europe.
What’s new is whirling’s recent and growing acceptance in the United States. It has become widely used in the manufacturing of “large” parts, such as steering gears, worm gears, acme threads, ballscrews and other threaded parts. To make these, however, has required installation of large, costly and dedicated whirling machines.
Now there’s an alternative. It’s a new whirling attachment that’s designed specifically for use on Citizen-Cincom Swiss turning centers. This new tool brings the advantages of whirling to the production of “small” parts, such as bone screws and threaded surgical implants. It also introduces this new application to a non-dedicated machine tool, while preserving the machine’s multi-axis turning, milling and drilling versatility."
Looks like Star also has a unit available.
I have never operated a Citizen-Cincom Swiss turning center. I have never worked for a company that had a dedicated whirling machine. The required tool looks to be very expensive and the initial set up quite time consuming. Definitely looks like something I will avoid unless I start getting machine screw orders of 10,000+ per year.
http://www.kirkcon.com/
Yep, it's thread whirling and it does a great job if you can afford the attachment. Think of it as turning and threading at the same time and smooth threads , no burrs at all. As an option over single point threading outside of that, we have used geometric dieheads. Much faster even at lower rpm's but, not as nice as single pointing. Just use it like your rigid tapping or floating. I find chasers to be sub par these days and it really effects how the dieheads work. Hope this helps?
We roll a lot of threads here, and it works great. Unfortunately a 1/2-13 thread is way to big to roll on an L20 IMO. Whirling might be the way to go if you are making a lot of the parts.
Well....I just looked at Genevieve, their whirling attachments for the L20 are 12mm and below, so it looks like 1/2" thread is out. They don't sell the attachment for the A20.
www.atmswiss.com
Is it possible to turn the blanks then get them sub contract thread rolled on a horizontal thread rolling machine ,normally quite a cheap 2nd op and always looks good if you cant roll on op 1
This would be a great option, if and only if, there are no axial holes in the part. Rolling the threads of, say, a socket set screw will crush the socket, if they are rolled as a second operation.Originally Posted by micky316
Also, you would have to take into account part elongation when the treads are rolled since the rolling process displaces material. The part will grow in length.
Mike
Last edited by gizmo_454; 02-28-2012 at 11:29 AM. Reason: Added part elongation...
Due to some of the parts being too large in diameter for our L20 I think I am going to run all the different parts in our A32. There is no whirling tool available for this machine yet so it looks like thread rolling is what I'll be looking into now. The parts do not have an axial hole so crushing will not be a problem. As for rolling as a second op we really try to avoid any 2nd op's cause with the additional handling of the parts comes the risk of scraping them.
If the parts are all of a standard OD, why not just single point them? As I am typing this, Our Citizen E32 is chugging along making M16x1.5x59mm socket set screws. They are about 2-5/16" long. No second op threading. The idea behind the swiss is to keep the second ops to a minimum.
As to rolling the threads, you can try that. You mentioned 1/2-13 as one of the possible threads. I'll tell you that I thread rolled M12x1.25 threads in our 15HP Haas SL-10 lathe. The material was A-311 Stressproof. It did it, but it was quite a load on the spindle. 1.25 pitch threads are roughly equivalent to a 20 pitch, and M12 is smaller than 1/2". Let me know how it goes! I would be interested to see.
Mike
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