society of plastics engineers europe - vemet · society of plastics engineers europe...
Post on 15-Sep-2018
222 Views
Preview:
TRANSCRIPT
Wrijving en slijtage van kunststofproducten
Jan Spoormaker
Spoormaker-Consultancy in
Reliability and Liability of
Plastic Products
Society of Plastics Engineers Europe
Tribologie/polymeren
Friction and wear of plastic products
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Dictaat Hfdst. 3 tekst
Friction
Friction is a force that resist relative movements between two surfaces in contact.
Wear
Wear is a process in which interaction of surface(s) or bounding face(s) of a solid with
the working environment results in the dimensional loss of the solid, with loss of
material.
Friction and wear are system properties
Tribology
Science about friction, lubrication and wear
Tribotechnology
Engineering application of tribology
Tribological System according to Czichos
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Relative movement
Gliding, rolling
Load Fn
Velocity v
Ambient temperature
Friction force Fw
Friction coefficient f, μ
Wear h
Friction temperature
Noise
Loads &
environment
Loads &
environment
Tribological
quantities
Surface parameters
Roughness
Macro geometry
1. Body
2. Body
3. Substance
4. Environment
Dictaat Hfdst. 3 Fig. 3.1
- polymerisatie
- ketenopbouw en ketenlengte
- fysische eigenschappen
- kristallisatie
Spoormaker Consultancy in Reliability & Liability of Plastic Products
IO-2040-20081201
Polymeren
Plastics are fantastic, they can fail in many
unexpected ways
Polymeriseren en ketenlengte
additiepolymerisatie
Spoormaker Consultancy in Reliability & Liability of Plastic Products
IO-2040-20081201
Polymeriseren van etheen C2H4 PE
Spoormaker Consultancy in Reliability & Liability of Plastic Products
IO2070-20100215
Polymeriseren van etheen C2H4 PE
Spoormaker Consultancy in Reliability & Liability of Plastic Products
IO2070-20100215
onvertakt
vertakt
Ketenlengte
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Dictaat Hfdst. 3 Fig. 3.1
Ketenlengte
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Dictaat Hfdst. 3 Fig. 3.1
Ketenlengte van PE
Paraffine (500 g/mol ) lijmtube (105 g/mol) UHMW-PE (5.106 g/mol)
Spoormaker Consultancy in Reliability & Liability of Plastic Products
IO2070-20100215
Molecuulmassa - sterkte en viscositeit
Spoormaker Consultancy in Reliability & Liability of Plastic Products
IO2070-20100215
Amorf en semi-kristallijn
Spoormaker Consultancy in Reliability & Liability of Plastic Products
IO2070-20100215
tie-molecule
Kristallisatiesnelheid
Spoormaker Consultancy in Reliability & Liability of Plastic Products
IO2070-20100215parison
wrijving
slijtage
contactoppervlak
vervorming
cohesie en adhesie
Spoormaker Consultancy in Reliability & Liability of Plastic Products
IO-2040-20081201
Pwrijving en slijtage bij kunststoffen
Normal force, drag force and friction force
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Material combination μ, f
PA6 - PA6 (no lubrication)
1.20
PA6 – POM (no lubrication)
0.60
PA6 – PTFE (no lubrication)
0.10
POM – POM (no lubrication)
0.55Dictaat Hfdst. 3 Fig. 3.3
Wear
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Material combination wear factor k
POM – steel (Ra = 0.1 μm) 2 10-15 m2/N
POM – steel (Ra = 0.6 μm) 80 10-15 m2/N
h k p v t
Dictaat Hfdst. 3 Fig. 3.4
Micro contact surface
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Dictaat Hfdst. 3 Fig. 3.5
Deformation
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Dictaat Hfdst. 3 Fig. 3.6
Physical processes cohesion and adhesion
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Bonding forces
Cohesion
Adhesion ----------
Dictaat Hfdst. 3 Fig. 3.9
ruwheid
snelheid
stick-slip effect
Spoormaker Consultancy in Reliability & Liability of Plastic Products
IO-2040-20081201
Wrijving bij kunststoffen
Friction coeeficient as a function of roughness
Spoormaker Consultancy in Reliability & Liability of Plastic Products
High yield strength Low yield strength
Surface roughness Surface roughness
Dictaat Hfdst. 3 Fig. 3.10
Friction coefficient as a function of roughness for
POM and HDPE
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Roughness Ra (μm) Roughness Ra (μm)
Dictaat Hfdst. 3 Fig. 3.11
Friction coefficient as a function of speed
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Speed
Dictaat Hfdst. 3 Fig. 3.12
Mass-spring model
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Dictaat Hfdst. 3 Fig. 3.13
Stick-slip effect
Spoormaker Consultancy in Reliability & Liability of Plastic Products
time
Dictaat Hfdst. 3 Fig. 3.14
deformatie
adhesieve slijtage
abrasieve slijtage
pitting
Spoormaker Consultancy in Reliability & Liability of Plastic Products
IO-2040-20081201
slijtage bij kunststoffen
Boundary and deformation zone
Spoormaker Consultancy in Reliability & Liability of Plastic Products
• Boundary zone
• Deformation zone
Hard roughness
asperity top
Dictaat Hfdst. 3 Fig. 3.15
Adhesive wear
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Dictaat Hfdst. 3 Fig. 3.16
Abrasive wear
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Dictaat Hfdst. 3 Fig. 3.17
Shear stress for rolling contact
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Dictaat Hfdst. 3 Fig. 3.18
Pitching as a result of fatigue
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Fatigue cracks Pitting
Dictaat Hfdst. 3 Fig. 3.19
Knieprothese
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Knieprothese
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Putvorming in UHMPE
Spoormaker Consultancy in Reliability & Liability of Plastic Products
slijtage – ruwheid
meten van slijtage
vlaktedruk – pv waarde
warmte-ontwikkeling
PTFE
Hardheid
Spoormaker Consultancy in Reliability & Liability of Plastic Products
IO-2040-20081201
Lagers
Wear as a function of roughness for POM and HDPE
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Dictaat Hfdst. 3 Fig. 3.20
Wear as a function of roughness and pressure for PA6.6
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Dictaat Hfdst. 3 Fig. 3.21
Wear as a function of pressure
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Dictaat Hfdst. 3 Fig. 3.22
Different wear tests
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Dictaat Hfdst. 3 Fig. 3.23
Pin on disk
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Dictaat Hfdst. 3 Fig. 3.24
Calculation of average bearing pressure and wear
Spoormaker Consultancy in Reliability & Liability of Plastic Products
p 43MPa
h k p v t
FT D
p
Extra
Heat flux and Average Bearing Pressure
Spoormaker Consultancy in Reliability & Liability of Plastic Products
2(W/m )h f p v
- heat flux
f – friction coeficient
p – average bearing presure
v - velocity
Dictaat Hfdst. 3 tekst
Critical pv-values
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Dictaat Hfdst. 3 Fig. 3.25
Prediction of wear
Spoormaker Consultancy in Reliability & Liability of Plastic Products
h k p v t
k – wear factor
p – average bearing presure
v – velocity
t - time
Dictaat Hfdst. 3 tekst
Coefficients of friction and wear rates
Spoormaker Consultancy in Reliability & Liability of Plastic Products
1 1h k p v t 2 2h k p v t
Extra
Effect of PTFE content on wear
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Extra
PTFE & silicone to reduce friction and wear
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Extra LNP Lubricomp
Effect of hardness on wear
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Extra LNP Lubricomp
Effect of shaft finish on wear (micro-inches!)
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Extra LNP Lubricomp
warmte-ontwikkeling
vermoeiing
Spoormaker Consultancy in Reliability & Liability of Plastic Products
IO-2040-20081201
Tandwielen
Failure analysis
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Extra
Failure analysis
Spoormaker Consultancy in Reliability & Liability of Plastic Products
Extra
Guidelines for plastic bearings
Spoormaker Consultancy in Reliability & Liability of Plastic Products
• Metal bearing surfaces must be smooth (< 1 μm), hard and corrosion
resistant.
• Wear particles must be collected in grooves.
• Bearing clearance must account for high thermal expansion and absorption
of water (PA)
• The average bearing pressure should preferably be not higher than 1 N/mm2
and at most 5 N/mm2.
• The out-of-roundness of bearings should be as small as possible and film
gates are preferred.
• Bearing plastics with PTFE are preferred especially for applications without
lubrication.
• Boundary lubrication is must better than running dry.
• Grease or oil can affect plastic bearings (swelling & ESC)
Dictaat Hfdst. 3 tekst
top related