scientizt
Plastic
- Joined
- Dec 27, 2009
- Location
- Netherlands
Hi guys and gals,
I was wondering if you could please share some thoughts with me on this one.
I am planning to do some gundrilling 4140 on the lathe. I have the tools and setup all ready to go (I've already made a chip box, a deep hole coolant through insert reamer using Mapal carbide inserts, a high pressure cooling / lubrication system, and I even built a diamond wheel toolgrinder, especially for sharpening carbide tools including gundrills).
But before I start drilling, I am wondering about what the optimal hardness of 4140 should be in HrC, for the very best drilling and reaming results. Should it be dead soft, or do carbide drills and reamers prefer a higher hardness?
I might be mistaken, but my gut tells me it should have some hardness to prevent tearing and clogging up the cutting edge. But what are the numbers?
I plan on using Gühring and ElDorado carbide tipped gundrills, mostly around 7mm to 10mm, with a stock N8 nose grind for as long as it lasts, and then probably regrinding the drill to an F8 facet grind. Speeds, feeds and lubrication etc. are also sorted out and should be alright.
I believe my 4140 as delivered from te supplier is around 32HrC, but I can heat treat it any way I like.
Thank you, best regards from The Netherlands,
Scientizt
I was wondering if you could please share some thoughts with me on this one.
I am planning to do some gundrilling 4140 on the lathe. I have the tools and setup all ready to go (I've already made a chip box, a deep hole coolant through insert reamer using Mapal carbide inserts, a high pressure cooling / lubrication system, and I even built a diamond wheel toolgrinder, especially for sharpening carbide tools including gundrills).
But before I start drilling, I am wondering about what the optimal hardness of 4140 should be in HrC, for the very best drilling and reaming results. Should it be dead soft, or do carbide drills and reamers prefer a higher hardness?
I might be mistaken, but my gut tells me it should have some hardness to prevent tearing and clogging up the cutting edge. But what are the numbers?
I plan on using Gühring and ElDorado carbide tipped gundrills, mostly around 7mm to 10mm, with a stock N8 nose grind for as long as it lasts, and then probably regrinding the drill to an F8 facet grind. Speeds, feeds and lubrication etc. are also sorted out and should be alright.
I believe my 4140 as delivered from te supplier is around 32HrC, but I can heat treat it any way I like.
Thank you, best regards from The Netherlands,
Scientizt