“PVD coatings in transmissions: case studies” ”I rivestimenti PVD su

“PVD coatings in transmissions: case studies”
”I rivestimenti PVD su componenti di trasmissioni: esempi”
Paola Recanati – Oerlikon Balzers Italy- Precision Components Product Manager
Claudio Torrelli – Oerlikon Graziano – Head of Product Development
Agenda
1
Oerlikon – Company overview
2
The tribosystem
3
Surface engineering
4
PVD coatings
5
Application-tailored solutions
6
Gears, general
7
Case Study #1: Metallic sealing in off-road transmission
8
Case Study #2: Sports car gearbox
9
Case Study #3: Agricultural windrower
10 Case Study #4: IC engine piston pin
11 Case Study #5: Truck rear axle gear
12 Case Study #6: Differential pins
Company Overview – Four core competencies
Segment
Manmade
Fibres
Segment
Drive Systems
Segment
Vacuum
Segment
Surface
Solutions
The tribosystem
Pressure
Motion
Surrounding influences
Temperature
Relative humidity
Pressure
Component # 1
Roughness
Component # 2
Intermediate materials
Oil
Grease
Water
Particles
Contaminants
A tribosystem consists of many influencing parameters. Wear lifetime prediction
is therefore difficult and based on specific trials and experience.
Typical failure modes
Abrasive wear
Cause
Hard particles score the surface
Adhesive wear
Cause
Cold welding with material transfer
Surface fatigue (pitting)
Cause
Material fatigue with crack formation by dynamic
or cyclic load
Surface Engineering
Methods of coating deposition
• welding
• sintering
• melting
• dipping
•…
• roll cladding
• explosive cladding
• peening
•…
• flame spraying
• plasma spraying
• high-speed plasma spraying
•…
mechanical
mechanical-thermal
thermal
Coating
vapor deposition
Substrate
• Chemical Vapor Deposition
• Plasma Assisted CVD
• Physical Vapor Deposition
electrochemical
• chrom plating
• nickel plating
• zinc plating
• anodizing
•…
(0.001 µm … 10 mm)
chemical
• electroless nickel
• phosphatizing
• chromization
• sol-gel technique
•…
plating
Coating portfolio
Seizure protection
DLC
DLC STAR (Sliding
performance)
(friction coeff.)
WC/C
Bronze
CrC: Sliding &
Temperature
CrC
CNI Temperature
CNI thick: Corrosion
CNI
Ceramic
Nitriding Galvanic
Hard metal
Abrasion resistance
(Hardness)
Coating main clusters
Carbon Coatings
Nitride Coatings
BALINIT C/DLC/DLCS as examples
BALINIT A/CNI/AP as examples
Typical hardness: 1000-2500HV
Typical hardness: 1800-3200HV
Typical friction coefficient: 0,1-0,2
Typical friction coefficient: 0,2-0,5
Metals: Ti, Cr, Al
Graphite sp2
DLC sp2 & sp3
Diamond sp3
Non metals: C, N, B
Carbon Coatings - Dry running properties
X End of test due to adhesive wear
Coefficient of friction
0.8
x
x
x
0.6
AISI 52100 (DIN
1.3505), uncoated
AISI 4140 (DIN
1.7225), nitrided
Hard chrome
plated
0.4
BALINIT® C
(WC/C)
nearly no wear
0.2
0
0
100
200
300
400
Sliding distance [m]
BALINIT® C (WC/C) shows under dry running condition the lowest friction and highest wear life time
compared to conventional surface treatments.
Structure of the BALINIT® C – Coating
Total coating structure
WC/C-Section
0.1 µm
WC/C- coating
White lamella:
WC-rich
WC-coating
Cr-interlayer
Substrate material
Black lamella:
C-rich
Dual coating system BALINIT® DLC STAR
DLC for low friction and
wear resistance
CrN coating for
additional support
Base material for
component strength
«STAR» versions of BALINIT® C or DLC, have a CrN layer underneath. This CrN is very ductile and
gives excellent support properties, e.g. in cyclic loaded contacts like diesel injector needles.
Fields of application for BALINIT® coatings
Engines
Diesel
injection
pumps
Leisure &
Domestic
Applications
Mobile
phone
Racing
Machine
tools
Printing &
Packaging
Watches
Aerospace
Compressors
Precision
Mechanics
Guns
Roller
bearings
Hydraulics
Oil & Gas
Medical
Instruments
Gears
Textile
machines
Motorcycle
Medical
Devices
Highly loaded fast running gear
Tooth flank stress [N/mm2]
2100
2000
Uncoated
BALINIT®
C (WC/C)
1900
1800
Test method:
FZG-C-test
case hardened steel,
62 HRC, RZ = 3 µm
1700
1600
1500
2
4
6
8 107
2
4
6
8 108
2
Stress cycles
BALINIT® C (WC/C) increases load carrying capacity (fatigue endurance limit) of case hardened gears by 10-15%.
The reason is the reduced hertzian stress due to lowering of the friction and running in of the coating.
Case studies
Case Study #1: Metallic sealing in off-road transmission
Case Study #2: Sports car gearbox
Case Study #3: Agricultural windrower
Case Study #4: IC engine piston pin
Case Study #5: Truck rear axle gear
Case Study #6: Differential pins
Case study #1: Metallic sealing
Compact wheel loader transmission
Turning
Rotary valve
Fix
Housing
Confidential
Main function = Sealing between outer and inner area
Max. pressure difference: 450 bar
Case study #1: Metallic sealing
Compact wheel loader transmission
Counter piece: Valve block
Surface grinded and lapped
Confidential
Shim fixed in the rotary valve
Case study #1: Metallic sealing
Compact wheel loader transmission
Contamination of
•
pump
•
high pressure hoses
•
tank
•
filter
Replace of
• transmission
• pump
• filter
Confidential
Cleaning of
• hoses
• tank (150l)
Estimated total cost app. 10K€
BALINIT® C guarantees the sealing functions and prevents/prolongs very difficult and expensive
maintenance operations.
Case study #2: Aston Martin Lagonda One-77
Coating of the cylindrical & bevel gears
One-77 is the high performance version of AML Vanquish
580Nm (510 HP)
750Nm (750 HP)
Gears contact stress is the gearbox limit to the increase of performances.
Due to development time constraint it wasn’t possible to develop a dedicated new gearbox
Case study #2: Aston Martin Lagonda One-77
Coating of the cylindrical & bevel gears
Test stopped
@ 200% lifetime
BALINIT® C increased the resistance to contact stress, doubling the life of the bevel set pinion.
Similar results were obtained on cylindrical gears.
Case Study #3: Torque Hub ® final drive windrower
BALINIT® C2VLT doubled life of sun gears
Case Study #4: Piston pins
Reduction of power consumption [W]
700
Cylinder peak pressure
45 bar
65 bar
90 bar
115 bar
135 bar
155 bar
600
500
400
300
200
100
0
800
2000
1600
2000
2400
Engine speed [Rev/min]
BALINIT® DLC reduces the power consumption of the truck engine up to 600 W. DLC coating of wrist
pins is also used to substitute the bronze bushing.
Case Study #4: Piston pins
Specification example (Diesel engine, no bushings)
Coating
Thickness
Process
Film Hardness
a-C:H on CrN support layer
2.5 ± 0.7 µm
a-C:H ≥ 0.8 µm (1.2 µm nominal)
PVD/PACVD
≥ 24 Gpa
Adhesion
Roughness
HF 1 – 4 (VDI 3198)
Ra before / after coating 0.05 / 0.07
Coating
hard functional layer with low friction and
low adhesion tendency (e. g. a-C:H)
intermediate layer or functional layer with
low friction (e. g. CrC/a-C:H)
tough / ductile functional and / or support
layer (e. g. CrN)
adhesion layer (e. g. Cr)
substrate
Case Study #4: Piston pins
Typical “wear” at areas with
• highest load (edges con-rod)
• lowest lubrication (piston periphery)
• highest temperature (piston periphery)
• “wear” stops (intentionally) at interface
to CrN – support-layer
Case Study #5: Truck rear axle gear
Power [kW]
1.0
0.8
0.6
0.4
0.2
0.0
40
50
60
70
80
90
100
110
Oil Temperature [°C]
rear axle power loss due to splash and oil quality in function of
oil temperature. Axle type = U177E; ratio = 2.93; 1100 rpm
Bevel gears of vehicle axes have a rather high sliding ratio. This causes frictional losses.
BALINIT® C (WC/C) coating of a truck rear axle gear reduced frictional losses by 1.5 kW.
Case Study #6: Differential pins
Differential for Combine Agricultural transmission.
BALINIT® C (WC/C) coatings could be used to replace bronze bushings between the pins and the
planet gears