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Hi
[email protected] / [email protected] ICMCTF 2016, April 25 - 29, San Diego
Dedicated PVD Coating Development for High-Performance Gear Hobbing A. LÜMKEMANN1, M. BEUTNER2, M. MORSTEIN1, T. CSELLE1, B. KARPUSCHEWSKI2
1 PLATIT AG, Switzerland 2 UNIVERSITY OF MAGDEBURG, Germany
Motivation o Increasing global gear production
(approx. 90 million units in 2014)
o Gear hobbing is the commonest
green manufacturing process
o Specific characteristic of hobbing are
continously changing chip thicknesses
o Sophistcated demands for the coated cutting edge
Multilayer with Nanolayered Substructure
Coating Thickness & EdgePrep o Edge rounding by wet blasting
o Increased surface roughness for
higher radii
o High tool life time possible for
wide radius range
Coating of Fly-Hobbing Teeth
Multilayer Structure:
o Alternating hard & tough
AlCr based layers
o Composition by
ARC control
o Alternating Al and
Si or Ti content
o Periode: 50 – 100 nm
Test Setup and Conditions
workpiece
rotation
Hobbing Fly-Hobbing Test
workpiece
rotation
axial
feed
o To investigate wear behaviour in gear hobbing an analogy test is used
o Wear behaviour of a full hob can be reproduced using only a single tooth
gear type Europe Japan
module mn 2.7 mm 2,31 mm
pressure angle α 22.5 ° 14,5°
tool diameter da0 100 mm 90 mm
number of starts z0 2 5
number of gashes i 19 14
substrate PM-HSS
helix angle β 24.5 °
number of teeth z2 41 48
face width b 25 mm 29 mm
gear material AISI 5120
tensile strength Rm 590 N/mm²
lubrication none
LF TF
500 µm
rake face LFC = 10,4 m/tooth
-120 -60 -40 -20 -0 [µm]
Maximum Load of all GP‘s
GP‘s
in
tra
ns
ve
rse
se
cti
on
o Tests were conducted on a
Liebherr LC180 hobbing
machine using a manual
transmission gear geometry
o A gap of a gear is generated
via multiple generating
positions (GP‘s)
o The wear of a tooth is
caused by superpositioning
of all GP‘s
AlCr
Al Ti Cr
Nanolayered Substructure by:
o Deposition rate
o Carousel rotation speed
o Ratio rpm tree : rpm carousel
o NL in the range of d = 5-15 nm
o AlCrN based Multi- / Nanolayer prevents crack propagation
Analogy test Japan: mn = 2.31 mm, vc = 150 m/min, fa = 1.69 mm/rev, zo = 5, dry
Analogy test Europe: mn = 2.7 mm, vc = 220 m/min, fa = 3.6 mm/rev, zo = 2, dry
AlCrN-ML 27 m/tooth Opt. AlCrN-ML 32 m/tooth
Optimized
ML / NL
o Base coating: CrN, columnar
o All4 = AlCrN+AlCrTiN: Fine columnar
o nACRo4 = AlCrN+AlCrN/SiNx: Very fine structure
o All4 with Ti doped top layer inhibits crater wear best,
shows lowest flank wear and highest tool life!
Testing Nanostructured QuadCoatings4
HR-TEM: nACRo (AlCrN/SiNx)
Nanolayer + Nanocomposite
0
25
50
75
100
4,5 5,4 6,3
coating thickness [µm]
life time
Roughness Rpk
[A.U
.]
0
25
50
75
100
14 19 24
edge radius [µm]
life time Roughness Rpk
[A.U
.]
ground
0
40
80
120
160
0 10 20 30 40 50
flan
k w
ear
[µm
]
tool life [m/tooth]
Market JP: AlCr(Si)N
AlCrN-ML
opt. AlCrN-ML
AlCrN + AlCrN/SiN
AlCrN + AlCrTiN
shadowing hob
tooth
decreasing
coating thickness
mounting device for
blasting & coating
coating
unit
o Edge prep & Coating of fly-hobbing teeth like a real hob
o Realistic shadowing during micro blasting & PVD process
o Very high coating thickness
induce drops in life time due to
cracks inside the coating
0
2
4
6
8
10
12
14
13
,0
12
,4
10
,5
13
,6
too
l lif
e [
m/t
oo
th]
AlCr based
Benchmark
AlCrN
high Bias
AlCrN+ AlCrTiN AlCrN+ AlCrTiN
high Bias
Bias + 70 %
100 µm
+Ti
+Si
opt. NL
High Bias Voltage
blasted
o All tested coatings with 4 µm coating thickness
o High Bias: Top layer with +70% increased Bias voltage
50 nm
1 µm
AlC
r-b
ased
A
lCrN
-ML
“ML“
APT analysis
Cr
Al
Sou
rce:
J.M
. Sch
nei
der
, O. H
un
old
, K.G
. Pra
dee
p, M
Ch
RW
TH A
ach
en
GP-11
Al
Cr
2,3 m/tooth 6,5 m/tooth
Calotest
13,6 m/tooth 12,4 m/tooth 13,0 m/tooth
100 µm 6,5 m/tooth 2,3 m/tooth
10,5 m/tooth
30 µm 20 µm