Chrome Replacement on Hydraulic Actuators 18. Huynh Busak and Shamban Hcat Feb 2007
Transcript of Chrome Replacement on Hydraulic Actuators 18. Huynh Busak and Shamban Hcat Feb 2007
CHROME REPLACEMENT ON HYDRAULIC ACTUATORS
UPDATE ON HVOF SEAL TESTING AND EXPERIENCE
PRESENTED BY:SON HUYNH
Senior Aerospace Application Engineer
Presentation Outline
Seal Testing and Experience on HVOF Coating
Surface Finish
Recommendations
High Pressure Material - Aerospace Case Study
HARDWARERod (HVOF) – < 5uin. Ra max.Housing (Bare Steel) – 8uin. Ra max.
MOTIONReciprocating – with Dither
APPLICATIONS5000 psi Development Program
SPECIFICATIONSMedia Phosphate EsterSpeed 3 to 4 HzStroke Length (in.) 4” Max.Pressure 0 to 5000 psiTemperature Range -65F to 275F
LEAKAGE MEASUREDZero (insufficient to form a drop)
Turcon VL Seal Turcon Excluder DC
Commercial Aircraft - Aerospace Case Study
SPECIFICATIONSMedia Phosphate EsterSpeed n/aStroke Length (in.) 2.95Pressure 0 to 3000 psiTemperature Range -65F to 275F
LEAKAGE MEASUREDZero (insufficient to form a drop)In service since early 2000. Performed to 30,000 Flight Hours.
Turcon VL Seal Turcon Excluder DC
MOTIONReciprocating – with high Hz dither
HARDWARERod (HVOF) – 4uin. Ra max.Housing (Bare Steel) – 8uin. Ra max.
APPLICATIONSOutboard, Inboard Aileron and Elevator Actuators
Commercial Aircraft - Aerospace Case Study
SPECIFICATIONSMedia Phosphate EsterSpeed n/aStroke Length (in.) .020” to 4”Pressure 50 psi min
5000 psi maxTemperature Range -65 to 275F
Turcon VL Seal Turcon Excluder DC
APPLICATIONSFlight Controls
LEAKAGE MEASURED1 drop every 31,899 cycles
MOTIONReciprocating with dither
HARDWARERod: HVOF apply Wc-Co-Cr Surface finish: per B+S recommendation
Basic Characteristics of Surface Texture
TypicalTraversing
Length
Lay
RoughnessAverageRa
Centerline
WavinessSpacing
WavinessHeightPeaks
RoughnessSpacing
Roughness sampling Length or Cutoff
valleys
PTFE
Elastomer
Influences:Sealing performance, wear and life time
Surface Finish
1
2
A
B
Abrasion – Dry Running
• Particles (2) are torn out of the
soft surface (B) due to peaks of
the hard surface (A)
• Hard particles (1) are removed from the surface
due to wear, corrosion or system non-cleanliness.
These particles become embedded into the soft
surface (B) and cause scratches in the hard surface (A)
• Premature seal wear/failure
• Hardware damage scratching and scoring
• Excessive leakage
• System failure
Improper Surface Preparation can lead to…..
Surface Finish Roughness: Ra
Ra = 1L
Z(x) dx∫L
o
Roughness Average Ra – the area between the roughness profile and it’s mean line, or the integral of the absolute value of the roughness profile height over the evaluation length
Ra is not enough to define a Dynamic Sealing Surface
Rz5Rz1 Rz2 Rz3 Rz4
Lm = 5 x sl
sl
Surface Finish Roughness: Rz
Rz =15 (Rz1+Rz2+Rz3+Rz4+Rz5)
Lm
Rt
Surface Finish Roughness: Rp, RtRp
Material contact area: Tp (Mr)
L1 L2 L3 L4 L5
C
Lm
L1+L2+L3+L4+L5LmTp = x 100 (%)
Definition: Material percentage at defined
depth (C)
Surface Finish Bearing Ratio: Tp (Mr)
Surface Finish Bearing RatioSimply expressed, at a given depth the profile is sliced (horizontally) and the material percentage is reported
Tp = 39%
Tp = 79%
Surface Finish Effects
Wear rate
Leakage rate
Seal friction
High
Medium
Low
32 µin Ra(0,8 µm Ra)
16(0,4)
12(0,3)
8(0,2)
4(0,1)
2(0,05)
Surface Finish
0(0,0)
Aerospace std.
Profiles Rt Ra Mrc=.25 ABBOTT Curves
1
1
1
1
1
1
1
9
9
8
8
3
8
12
75%
15%
85%
20%
7%
25%
38%
Surface Finish Profile Comparison
Static, ExternalDynamic, Internal
Dynamic, External
Surface Finish Recommendations
Surface Finish Recommendations – Static, Internal
The following is Busak+Shamban Aerospace surface finish recommendation for static seals on cylinder (bore) inside diameters (I.D.) and other static locations:
Measurement Std. Recommendation
Ra 32 μin maximum
The following is Busak+Shamban Aerospace surface finish recommendation for dynamic pistons seals on cylinder (bore) inside diameters (I.D.):
Measurement Std. Recommendation
Ra ≤ 16 μin
Surface Finish Recommendations– Dynamic, External
The following Busak+Shamban Aerospace surface finish parameter recommendations for dynamic rod seals or dynamic external sealson HVOF applied coatings:
Measurement Std. Recommendation
Ra < 5μin
Rp ≤ 8μin maximum
Rz (Rtm) 40μin maximum
Tp (Mr)> 70% @ depth of p =
0.25 Rz relative to reference line = 5 %
Rsk -0.1 to –3
Thank You For Your Attention
Contact Information:Son Huynh
Phone: 260-748-5729Email: [email protected]