Cooperstock
Aluminum
- Joined
- Apr 13, 2015
Hello,
So I have been reading through posts on feeds and speeds. I know it is ALWAYS a reoccurring question. I am attempting to understand the underlying concept.
I have specifically been looking at 304SS which I see everything from 250SFM to 700SFM, and chip loading from .0015 IPT to .005
Lets just assume carbide as the cutter, Im not interested in HSS.
Q1. do carbide inserted tools need to be calculated differently than solid carbide?
I know for SS constant cutting engagement, (no slow feeds, or pauses which could cause work hardening)
I know that manufacturers of endmills provide suggested Feeds and speeds for their endmills. I believe this is driven by flute grind, Helix angle and quality of carbide material itself.
Q2. But why does SFM vary so greatly depending on machining method? Isn't SFM a property of the material itself and the heat the cutter can take (i.e. property of the cutting material)?
Someone mentioned that 40 taper machines should be run a 30%-40% less of the specs of those of 50 taper. This concept makes sense due to rigidity of the holder, but I rarely see this mentioned or asked. Is it assumed 50 taper for most posts?
I also see little comment on type of tool holder. It seems milling chucks and hydraulic chucks would allow for 'better numbers' due to their rigidity and runout. It seems like using a standard 'end mill holder' (with the set screw(s) on the side) would be a less ideal choice especially when in harder materials.
Q3. Does the SFM used in calculations depend on HP of the machine?
I thought the HP (or more specifically the RPM at which 'good' torque is produced) was the driving number for MRR. But RPM is SFM when combined with the tool diameter...so?
Since this topic does come up so often, feel free to direct me to posts that address these questions.
I just get tired of reading
"I don't machine this material much, but I tried this.... and it seemed to work ok"
So I have been reading through posts on feeds and speeds. I know it is ALWAYS a reoccurring question. I am attempting to understand the underlying concept.
I have specifically been looking at 304SS which I see everything from 250SFM to 700SFM, and chip loading from .0015 IPT to .005
Lets just assume carbide as the cutter, Im not interested in HSS.
Q1. do carbide inserted tools need to be calculated differently than solid carbide?
I know for SS constant cutting engagement, (no slow feeds, or pauses which could cause work hardening)
I know that manufacturers of endmills provide suggested Feeds and speeds for their endmills. I believe this is driven by flute grind, Helix angle and quality of carbide material itself.
Q2. But why does SFM vary so greatly depending on machining method? Isn't SFM a property of the material itself and the heat the cutter can take (i.e. property of the cutting material)?
Someone mentioned that 40 taper machines should be run a 30%-40% less of the specs of those of 50 taper. This concept makes sense due to rigidity of the holder, but I rarely see this mentioned or asked. Is it assumed 50 taper for most posts?
I also see little comment on type of tool holder. It seems milling chucks and hydraulic chucks would allow for 'better numbers' due to their rigidity and runout. It seems like using a standard 'end mill holder' (with the set screw(s) on the side) would be a less ideal choice especially when in harder materials.
Q3. Does the SFM used in calculations depend on HP of the machine?
I thought the HP (or more specifically the RPM at which 'good' torque is produced) was the driving number for MRR. But RPM is SFM when combined with the tool diameter...so?
Since this topic does come up so often, feel free to direct me to posts that address these questions.
I just get tired of reading
"I don't machine this material much, but I tried this.... and it seemed to work ok"