MWF FEED
21st April 2020, 02:21 PM
I'm looking for some input on what I've done wrong here.
IMG_6063.png (https://metalworkforums.com/attachment.php?attachmentid=385985&d=1587433540)
It happened when I was parting this workpiece:
IMG_6065.png (https://metalworkforums.com/attachment.php?attachmentid=385986&d=1587433696)
The OD on either side of the parting cut is 38mm and 32mm, the lathe was running at 360RPM feeding by hand at a low feed rate and coolant was on. The "Big Bang" occurred when I was about 11mm down into the cut with about 21mm diameter still left to cut. It appears one of the chips refused to eject and got stuck, "fused" into the parting gap and just snapped off the blade.
The "fused" chip can be seen in this postmortem photo:
IMG_6070.png (https://metalworkforums.com/attachment.php?attachmentid=385987&d=1587434244)
A bit more detail on the operation:
The recommended surface speed for this parting tool is 80-170m/min, at fatal diameter the speed was about 22m/min. The recommenced feed rate is 0.08-0.3mm/rev, manual feed was not very consistent and a bit jerky but would have been below the recommended maximum at all times.
I checked the tool height adjustment afterwards and found the tool was about 1mm over centre height. The insert was changed a day ago and has only been used to part a few Aluminium parts, so it would have had very little wear.
Chips on this parting tool tend to curl up into pig tails before breaking off. At the start of the cut the chips fall away easily but the deeper the cut gets the more reluctant the chips are to exit the parting groove. It is only the next chip that pushes the previous chip outwards. As the chips build up and refuse to exit I regularly withdraw the tool to clear the chips.
This little incident was a good reminder why I always wear a safety rated full face shield when parting ....
Luckily the blade has two usable sides, so I was able to finish the parting operation like this:
IMG_6068.png (https://metalworkforums.com/attachment.php?attachmentid=385988&d=1587435527)
Two side by side grooves, cut one side 5mm deep, then the other 10mm, then another 10 on the first side and so on. This ensures there is always room for chips to exit.
Where did I go wrong? What should I have done differently? How do you part a 30 or 40mm workpiece?
Thanks for looking at my post
Attached Images
https://metalworkforums.com/images/attach/png.gif IMG_6063.png (https://metalworkforums.com/attachment.php?attachmentid=385985&d=1587433540) (546.6 KB)
https://metalworkforums.com/images/attach/png.gif IMG_6065.png (https://metalworkforums.com/attachment.php?attachmentid=385986&d=1587433696) (499.6 KB)
https://metalworkforums.com/images/attach/png.gif IMG_6070.png (https://metalworkforums.com/attachment.php?attachmentid=385987&d=1587434244) (677.1 KB)
https://metalworkforums.com/images/attach/png.gif IMG_6068.png (https://metalworkforums.com/attachment.php?attachmentid=385988&d=1587435527) (451.1 KB)
Read the full thread at metalworkforums.com... (https://metalworkforums.com/showthread.php?t=204897&goto=newpost)
IMG_6063.png (https://metalworkforums.com/attachment.php?attachmentid=385985&d=1587433540)
It happened when I was parting this workpiece:
IMG_6065.png (https://metalworkforums.com/attachment.php?attachmentid=385986&d=1587433696)
The OD on either side of the parting cut is 38mm and 32mm, the lathe was running at 360RPM feeding by hand at a low feed rate and coolant was on. The "Big Bang" occurred when I was about 11mm down into the cut with about 21mm diameter still left to cut. It appears one of the chips refused to eject and got stuck, "fused" into the parting gap and just snapped off the blade.
The "fused" chip can be seen in this postmortem photo:
IMG_6070.png (https://metalworkforums.com/attachment.php?attachmentid=385987&d=1587434244)
A bit more detail on the operation:
The recommended surface speed for this parting tool is 80-170m/min, at fatal diameter the speed was about 22m/min. The recommenced feed rate is 0.08-0.3mm/rev, manual feed was not very consistent and a bit jerky but would have been below the recommended maximum at all times.
I checked the tool height adjustment afterwards and found the tool was about 1mm over centre height. The insert was changed a day ago and has only been used to part a few Aluminium parts, so it would have had very little wear.
Chips on this parting tool tend to curl up into pig tails before breaking off. At the start of the cut the chips fall away easily but the deeper the cut gets the more reluctant the chips are to exit the parting groove. It is only the next chip that pushes the previous chip outwards. As the chips build up and refuse to exit I regularly withdraw the tool to clear the chips.
This little incident was a good reminder why I always wear a safety rated full face shield when parting ....
Luckily the blade has two usable sides, so I was able to finish the parting operation like this:
IMG_6068.png (https://metalworkforums.com/attachment.php?attachmentid=385988&d=1587435527)
Two side by side grooves, cut one side 5mm deep, then the other 10mm, then another 10 on the first side and so on. This ensures there is always room for chips to exit.
Where did I go wrong? What should I have done differently? How do you part a 30 or 40mm workpiece?
Thanks for looking at my post
Attached Images
https://metalworkforums.com/images/attach/png.gif IMG_6063.png (https://metalworkforums.com/attachment.php?attachmentid=385985&d=1587433540) (546.6 KB)
https://metalworkforums.com/images/attach/png.gif IMG_6065.png (https://metalworkforums.com/attachment.php?attachmentid=385986&d=1587433696) (499.6 KB)
https://metalworkforums.com/images/attach/png.gif IMG_6070.png (https://metalworkforums.com/attachment.php?attachmentid=385987&d=1587434244) (677.1 KB)
https://metalworkforums.com/images/attach/png.gif IMG_6068.png (https://metalworkforums.com/attachment.php?attachmentid=385988&d=1587435527) (451.1 KB)
Read the full thread at metalworkforums.com... (https://metalworkforums.com/showthread.php?t=204897&goto=newpost)