Hi,
Hoping someone can help, I am using a semi-auto gear cutting machine to cut straight spur gears. I am using a 3 module 20 PA HSS hob to cut various spur gears.
The machine is quite old but new to me. I have cut approx 75 different gears to date ranging from 25 teeth up to 97 teeth. The problem I am having is when I cut 25 teeth up to about 55 teeth my surface finish is really good. When I get into larger number of teeth, I am getting a real bad surface finish, it is like I am getting lines though the tooth (feed is too course) becasue of the rotation of workpiece in relation to the hob RPM (I think).
I have tried a couple of different settings. My main settings to date have been 100 RPM with table feed of 2.45 mm/min (this is the slowest table feed according to my chart). With the smaller no. of teeth this has worked really well. With larger number of teeth I have tried 160 RPM and 200 RPM which helped a little but I am concerned about the life of the hob. The hob is still nice and sharp, I have good clamping and good oil supply. If anyone can help with desired speeds and feeds etc would be great.
HELP NEEDED PLEASE.
Thanks Matt
Hoping someone can help, I am using a semi-auto gear cutting machine to cut straight spur gears. I am using a 3 module 20 PA HSS hob to cut various spur gears.
The machine is quite old but new to me. I have cut approx 75 different gears to date ranging from 25 teeth up to 97 teeth. The problem I am having is when I cut 25 teeth up to about 55 teeth my surface finish is really good. When I get into larger number of teeth, I am getting a real bad surface finish, it is like I am getting lines though the tooth (feed is too course) becasue of the rotation of workpiece in relation to the hob RPM (I think).
I have tried a couple of different settings. My main settings to date have been 100 RPM with table feed of 2.45 mm/min (this is the slowest table feed according to my chart). With the smaller no. of teeth this has worked really well. With larger number of teeth I have tried 160 RPM and 200 RPM which helped a little but I am concerned about the life of the hob. The hob is still nice and sharp, I have good clamping and good oil supply. If anyone can help with desired speeds and feeds etc would be great.
HELP NEEDED PLEASE.
Thanks Matt