[How do I?] Will opening up bores with radius end mill wear out the radius corners

mrproduxn

mrproduxn

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I retired from the trade with 40+ years. I am a seasoned machinist, with years of manual and cnc time, as well as 13 years in management and support roles. I have made thousands of parts in my home shop. I have a tooling question. I make hundreds of the same parts monthly on my floor drill press, P-M manual and cnc vertical mills. I work entirely with grade 6061 aluminum. After nearly 4 years of making these parts I am curious if I am using too many steps in a process. I have a 1/16" deep pocket that I finish mill with a radius corner end mill. In the center of the pocket is a thru hole. I always pre-drill the hole 1/16" undersized on the drill press, then on the cnc I g83 an on size square corner carbide end mill thru to finish the bore 1" deep with a nice finish, come up and rough the pocket. I then change to my same size carbide end mill, with a 1/8" corner radius, and finish the inside diameter of the pocket. I would like to use 1 tool to do both of those operations, saving 3 minutes per part, but I worry about prematurely wearing out my radius corners on the end mill. I try to minimize my tooling budget, use quality brand uncoated carbide end mills, and run conservative chip loads, feeds and speeds. Am I overly concerned. Should I use the radius corner end mill to bore out the hole and rough/finish the pocket in one operation. I just never felt like the ground radius corners are as strong as the original square corners on end mills. I would be mad if my pocket walls have lines from wear caused by boring with the same tool. I do use coolant for boring and for washing away chips during machining. I would appreciate any input. I don't want to rush into a change that will shorten cutter life. Thank you.
 
Zero production experience here but, I thought radius corners were stronger than square? Would a radius in the bottom corner of the bore make a difference? I'm in for the answers too.
 
Radius is fine when milling in x and y. Not an issue. The hole is a thru hole. I just don't want any radius corner breakdown cutting in z that will show any marks in the x/y radius walls of the pocket. Boring in z, or using the g83 peck cycle, seems to cause no breakdown on the square corners.
 
If the pilot hole is smaller than the minor diameter of the flute radius, how would it cause more wear in z than milling in x or y. When milling, are you cutting deeper than the corner radius on each pass?

I'm not trying to be confrontational, just interested in how this works in the real world.
 
The hole is drilled 1/16" smaller and within 0.010" of true position on a drill press. The end mill opens up the hole on true position using a g83 peck cycle, within 0.0005" accuracy in x and y, with a nearly polished finish. Only 25% of the 1/8" radius edges will be cutting. The parts have a beautiful finish the way I have always machined them. I don't want to risk scoring the end mills radius edges, by boring with it, and that is why I asked the question. Quality carbide 5/8" end mills, with a 1/8" corner radius, are not cheap to replace. I take pride in the surface finish, dimensional consistency and overall quality of the parts I sell. I do not ship anything that is more than 0.001" out of my designed tolerance. I do not ship anything with a poor surface finish. That is why am reluctant to change my proven processes. I have made and sold a variety of nearly 10,000 parts (~$160k gross) over the past 3.5 years. I always receive compliments on the appearance and function of my automotive products.
 
But if you can be more efficient you should be able to make more profit.
Joe
 
If you are making these in production, how hard would it be to do a test. Use the Radius end-mill for all operations and see how it performs? I realize that you will have to create a new g-code program so you will have to weigh the cost of that with the potential benefits.
 
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