Feeds & Speeds - Drilling

[RJS100]

I am finishing up my first project in 1018 steel. Everything worked great, but I was surprised to have issues with the simple drilling operation. I drilled a 1/4" hole pilot hole followed by a 3/8". In both cases the drills got wrapped with chips like a birds nest. The holes were drilled with YG1 jobber length 135-degree TIN coated drill bits. I used a FogBuster for MQL lubrication.

I used the G-Wizard speeds and feeds calculator to determine the rpm and feed. I tried two options:

.375 drill bit - 1 inch deep hole
s/f calculated for a TIN coated drill bit. - 978 rpm and 2.4 ipm plunge rate
s/f calculated for a non coated drill bit. - 815 rpm and 1.85 imp plunge rate

In both cases, the drill bit looked like the attached image. I tried increasing the feed rate a bit, but it did not help at all. Any suggestions as to how to avoid this?

Best... Richard

[suntravel]

Go with the feedrates from YG1, they know there tools

for 3/8"
1100 rpm 6.6ipm in mild steel

Predrilling should not be larger than the core of the next drill, otherwise it is begging for birds nests.

I avoid predrilling unless the drill is very big and the machine is not strong.

Use peck drilling tho keep chips short and unload the flutes with deep holes.

Uwe

[RJS100]

Thanks Uwe,

I looked high and low but could not find the chip load and surface speed recommendations from YG1. I did use a peck depth of .100" Should I use a smaller peck depth?

In comparison to the speeds and feeds that GWizard suggests, I need to push it to the most aggressive settings to come up with a feed rate of 6 ipm. Their suggested rpm is still only 897. Your Feeds and speeds seem much more aggressive... but I will give it a try.


I put a call in to YG1 to get more info.

Best... Richard

[suntravel]

1100 rpm and 0.006 in/rev in YG1 table for a 9mm drill jobber with TIN Coating...

But mild steel is not known for good chip breaking anyway.

Uwe

[RJS100]

Thanks so much. I was able to locate the YG1 feeds and speeds for these drills. Everything worked out great.

I think this was my first and hopefully last project with 1018 steel. While all the features machined perfectly, and I was able to machine the slot within a half thou... I just don't like working with this stuff. I will search the internet in hopes to find some other alloy that machines like aluminum with some of the strength properties of steel before I touch this stuff again

Thanks as always for your help... Richard.