What is the diameter tolerance? (determines rough or finish head)
What is the finish diameter of the bore? (determines connection diameter)
Is the bore a thru-bore, or step bore design? (75° lead = thru bore / 90° lead = step bore)
What is the material to be machined? (determines to insert code selection)
What is the machine spindle? (determines tool holder selection)
What is the finish depth of the bore? (determines length of shank & extensions)
What end of the spindle projection do you require? (determines length of shank & extensions)
Does the spindle have thru spindle coolant? Flood coolant? DIN “B”?
(if yes, calculate length of shank requirements)
What is the starting diameter of the bore?
What is the depth of cut requirement? Finish diameter – starting diameter / 2 = depth of cut (determines insert tool nose radius selection)
Misc: Select coolant through spindle based on connection diameter and bore depth requirements (question #7 above)
Speeds & Feeds
For best finish, generally, feed at 25% of nose radius. Optimal speeds & feeds depend upon a material, machine, tool overhang and setup conditions.
Insert Corner Radius
For heavy roughing use the largest available corner radius unless otherwise specified. For a finish, boring use the smallest corner radius to minimize lateral deflection, especially on long overhangs.
Depths of 5x diameter for rough boring and 3x diameter for finish boring using carbide tooling are achievable. At depths greater than that harmonic chatter and deflection may become a problem, causing you to adjust feeds & speeds. Changes in the amount of side block extension may require adjustment of feeds & speeds.
Depth of Cut
The depth of cut is a function of material and tool nose radius. Generally, the ideal minimum diameter depth of cut is equal to the insert nose radius. The maximum stock removal rate for rough boring may have to be decreased on very tough materials or extended overhangs and extended slide blocks.
Rough Boring 75° vs 90°
For maximum removal rates when a square shoulder is not required, use a 75° boring head. The 75° head self-centers in the hole for a more stable cut. However, if the hole is off-center or off-angle then use the 90° head because it will have less tendency to follow the existing hole.
Boring Bar Overhang
The maximum boring depth for steel boring bars is 5x bar diameter. For solid carbide bars 7x bar diameter. To maximize boring efficiency we recommend the shortest possible overhang be used
|Key to ordering boring heads by part number
A 22 75 400
A = finish heads, D = rough heads (see question #1 above)
|Key to ordering toolholders by part number
CT 330 22 100CT = type of shank (see question #5 above)
330 = taper size (see question #5 above)
22 = connection diameter (match head connection)
100 = boring depth (BD) (see question #6 above)