Welcome to the Thread Turning CAM tip from our CAM Programming Tip Series. Thread Turning is an established and widely used threading technique for the threading of parts. We hope you find this video tip helpful to your thread turning processes for application in a variety of industries.
VIDEO TRANSCRIPT:
Thread Turning is an established and widely used threading technique for the threading of parts. It is commonly the 'first choice' technique for threading rotational parts because of it's high productivity and surface finish compared to other techniques shown here. (zoom in on thread turning pic in slide)
With thread turning there are 3 primary programming infeed methods: Modified Flank Infeed, Incremental Infeed (also known as Alternating Flank Infeed or Zig-Zag Infeed), and Radial Infeed.
With Modified Flank Infeed the insert is fed in at the angle relative to the thread profile. This angle is usually 1 to 5 degrees 3-5degrees for 'A' and 'F' insert Geometries and 1degree for chip breaker 'C' geometries. The advantage of this method is less heat generated, less vibration, and higher production reliability. This method should be a 'first choice' for most threading operations.
With Incremental infeed the insert is fed in at the angle of the thread profile, but here each leading flank pass is alternated with a trailing flank pass. The result is more even insert wear and longer tool life. Making this the ideal choice for larger thread profiles.
With Radial Infeed the insert is fed in a radial direction to the bottom of the thread. It does not follow the thread profile like that of Modified flank or Incremental. The benefit is even insert wear. This method is also simpler, easier, and more readily available as a programming option on machine tools and CAM software making it the most commonly used Infeed method.
In this example we can see for each of the separate infeed method nc codes shown, the Z values are different. In modified flank the insert follows the profile of the thread so that the Z values need to increase (or decrease) uniformly. For Incremental Infeed the z value alternates, and with radial infeed the z-value stays the same value -- illustrating why this method is easier to program and widely used even when one of the other methods would be the more productive choice.
For the infeed passes there are 2 options for programming -- constant depth per pass, and decreasing depth per pass. In constant depth per pass the passes are all equal depth, making for easier programming, but less productive machining.
For decreasing depth per pass the pass depth is gradually reduced at a specific value as so reduce the chip load on the insert and improve chip control and even insert wear. This should be the first choice for all thread turning operations.
To assist with thread turning Sandvik Coromant offers a calculator to output the correct # of passes and decreasing depth per pass for Modified Flank and Radial Infeed thread turning methods. Simply fill in the pull downs and fields for the type of thread profile and thread pitch parameters and the calculator will automatically output the ideal # of passes and decreasing depth per pass for radial infeed, and the z-offset per pass for modified flank. Note that for modified flank infeed be sure to specify the correct flank angle dependent on the insert geometry and thread profile angle being machinined.
To CAM Program this technique in Siemens NX6 CAM software, Use the 'Thread OD' or 'Thread ID' Operations for thread turning OD or ID threads. First in Modeling Mode establish the crest -- or upper limit of the thread and draw a line the length of the thread desired, then the root -- or lower limit of the thread and draw a line. Next draw a line perpindicular to the end point of the Crest line whre the thread will be terminated.
Next in Manufacturing Mode use the 'Thread OD' or 'Thread ID' Operation. Select the Crest Line at the side of the line where the start of the thread is desired. Next select the End Line and root line. Note that for tapered threads specify the 'depth and angle' instead of 'root line'. Fields will then become available to specify the depth and angle for the tapered thread.
While there is no 'canned op' to program the flank, and incremental infeed methods in NX, the radial infeed method can be programmed with a decreasing depth per pass using the 'individual' option set for 'cut depth' within the threading operation. Set the # of passes and depth of cut for each pass according to values in the Sandvik Coromant Threading Calculator.
Also note that solid model tools are available at www.Sandvik.coromant.com to be used in the toolpath verication of NX. Ideal for collision detection checking.
For more information about implementing this technique or any other CAM questions, please contact your local Sandvik Coromant representative.
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Coromant Capto® C10 - Heavy turning solution from Sandvik Coromantby sandvikcoromant2,389 views
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