Drilling SS316L tubesheet

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Drilling SS316L tubesheet

Postby khalid » Sun Jun 27, 2010 12:53 am

I am drilling holes with following specifications:
Material: SS316
Material thickness: 30mm
1- The HSS drill failed on the Second hole... I kept the RPM 800 and G73 cycle with Peck 6mm.. It simply toasted Flood coolant was On... 2min/hole

2- The second bit is used was Carbide, It ran for 30 holes and then suddenly break into 3 pieces... Again G73 peck cycle but with 2.5mm peck... 2 minute/hole

3- I then used HSCO drill and with G83 Cycle, lost it after 38th hole with 2.5mm peck... Coolant on.. 7minute /hole

4- Keeping all above experience in view, i again used HSCO drill but at this time G83 with 2mm peck (DOC) and after each 15 holes i sharpen the drill.. For this i added tool change command after each 15 holes in my Gcode.. i slightly changed the Gcode for downtime...
The above strategy went very good and i did above 100holes without breakage... 5minute /hole

5- I have HSS drills available, so i tried the same G83 cycle with them with 2mm peck and sharpening after each 15 holes..and i did 50 holes without loosing HSS drill.. 4.5min /hole

I have done 224 holes in 16.8 hours.
tubesheeet.jpg (65.31 KiB) Viewed 6636 times
2.JPG (132.73 KiB) Viewed 6637 times
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Postby Chris.Botha » Thu Jul 01, 2010 2:19 pm

cool! is it some sort of filter?
Wine me, dine me, tram my mill for me!
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Joined: Thu Apr 08, 2010 1:22 am

Postby juliao » Fri Jul 02, 2010 9:54 am

Hi khalid. I dont know that steel and dont know the rpm´s your machine can do but if it does 5000 rpm with a special drill(here in portugal is 4 or five times more expansive than HSS(about 30€) you can do each hole in less then 30 seconds.Last year i done a job with 6mm drill in stainless steel near weld and 25 mm depth and each one was made in 15 seconds..In picture your drill seems 8mm diameter so i say 30 seconds.Sometimes its better to spend a few more money but its a lot worthy.that 6mm drill ended 250 holes and you look at it and seems brand new..

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Location: Marinha Grande Portugal

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