I'm using a TechnoCNC HD 4896 router to rout aluminum panels. Two questions:
(1) At panel thicknesses of .250" and thicker, I start getting this "tapering" effect where the side of the part gets wider on each successive pass. On a 0.250" thick panel, the part tapers out on one side 0.065" from the first pass to the last pass. Another side tapers outward 0.025". Two of the sides have no taper at all and came out perfect. Picture shows the tapering effect.
What is going on, and how do I fix? Is the only solution to feed slower, or is something else happening?
Details:
Material: 6061-T6 aluminum, .250" thick
Bit: 1/2" dia, 2 flute spiral cut, HSS
RPM: 15,000
Feed: 30-40 ipm (I manually adjusted it while cutting. Note that at 20 ipm, 12,000 RPM I don't get the tapering effect.)
Pass Depth: 0.015"
Coolant mist/air spray in use.
Hold Down: Custom mechanical jig that holds the stock panel above the table surface using clamps, and additional support spacer plates slid under the panel near the cut area to keep panel from sagging. (No vacuum hold-down available.)
I've also seen this problem for a different aluminum part using a 1/4" diameter cutter, 0.010 pass depth, 20 ipm, 12000 RPM.
(If I went by the numbers that one of the online calculators gives me, I should be able to use 12,000 RPM at about 96 ipm (feed per tooth = .004). Sounds way too fast to me.)
(2) Pass Depths: What is the deepest pass depth I should be using for cutting parts that are .250" to .625" thick? I've been using maximum of .015". With the size of some of the parts, it can take 5 or 6 hours to get one part cut out. Can I be going deeper (say, .100 or .250) to speed up?
Thanks for any advice.
Matt
(1) At panel thicknesses of .250" and thicker, I start getting this "tapering" effect where the side of the part gets wider on each successive pass. On a 0.250" thick panel, the part tapers out on one side 0.065" from the first pass to the last pass. Another side tapers outward 0.025". Two of the sides have no taper at all and came out perfect. Picture shows the tapering effect.
What is going on, and how do I fix? Is the only solution to feed slower, or is something else happening?
Details:
Material: 6061-T6 aluminum, .250" thick
Bit: 1/2" dia, 2 flute spiral cut, HSS
RPM: 15,000
Feed: 30-40 ipm (I manually adjusted it while cutting. Note that at 20 ipm, 12,000 RPM I don't get the tapering effect.)
Pass Depth: 0.015"
Coolant mist/air spray in use.
Hold Down: Custom mechanical jig that holds the stock panel above the table surface using clamps, and additional support spacer plates slid under the panel near the cut area to keep panel from sagging. (No vacuum hold-down available.)
I've also seen this problem for a different aluminum part using a 1/4" diameter cutter, 0.010 pass depth, 20 ipm, 12000 RPM.
(If I went by the numbers that one of the online calculators gives me, I should be able to use 12,000 RPM at about 96 ipm (feed per tooth = .004). Sounds way too fast to me.)
(2) Pass Depths: What is the deepest pass depth I should be using for cutting parts that are .250" to .625" thick? I've been using maximum of .015". With the size of some of the parts, it can take 5 or 6 hours to get one part cut out. Can I be going deeper (say, .100 or .250) to speed up?
Thanks for any advice.
Matt