Klingelnberg gear advantages

[Tmoose]

Reading and talking I'm getting different stories about advantages or characteristics of spiral bevel gears made with the Klingelnberg system. These are some of the things I've heard -

- Can be "hard" machined (skiving possible on gears up to RC 65, finishes per AGMA 9-12, 25-40 rms finish) which is a big time saver compared to having to finish grind. But Drago's book seems to indicate other gear machines can use skiving tools, too.
- "Better" more accurate gears - For the rolling mills I'm working with, a little quieter gear is of no consequence
- Better finish - if the finish had an impact on surface durability, it would have some merit, but in Section 13-21 Dudley "Gear Handbook" 1st edition says the surface-condition factor Cf depends on finish, related to cutting vs shaving vs grinding vs shot-peening, etc. But then he says the surface finish factor can be taken as unity (Cf=1.0), "unless tests or field experience indicate otherwise."
- limited gear size - K'berg gears are also described as being uniform addendum and dedendum, which can set a limit on the number of minimum teeth on a gear. So K’berg can be at a disadvantage.
- Fuller radius at tooth root possible – legitimately stronger teeth, but there is plenty of room in this app for bigger gears, so that seems less of an across-the-board advantage

 

[Matt51]

Both Gleason and Klingelnberg offer a full range of machines. It used to be, before Klingelnberg offered grinding machines, they would skive finish gears on their generating machines. Conventional gears were face milled, the Klingelnberg gears were face hobbed. This is what you are referring to. These gears have unground roots. My understanding is the AGMA rating was the same for either type of gear, hard finished face hobbed, or ground face milled. Philadelphia Gear sold their Klinglenberg machines to Overton? in Chicago.
There is no difference in minimum numbers of teeth. You can get a very good gear either way. It allows a shop to buy one machine instead of two. It used to be easier to develop patterns on the face hobbed tooth form, but with the latest computer tools, there is not much advantage here.
Pattern spreads from the center, in both directions, towards the heel and toe. In face milled gears, the pattern spreads from toe to heel.
There was some preliminary testing at NASA that indicated face hobbed gears might be quieter.
Get quotes both ways, and see if you can save money.