Presentation of various pretreatment methods for Aluminum

Transcription

Presentation of various
pretreatment methods for
Aluminum
Automotive Cycle
Mark Wolf, PWT/VFT, Bad Nauheim, 17.April.2012
Pretreatment of Aluminum
Agenda
•Whey is a pretreatment of aluminum surfaces necessary?
•Aluminum pretreatment process chain
•Pretreatment methods of Aluminum
•Worldwide Local sourcing
•Abstract
2 Pretreatment of Aluminium | Mark Wolf PWT/VFT | 17.April.2012
Whey is a pretreatment of aluminum surfaces in regard to the used
joining technique necessary?
• The aluminum oxide layer does have an high influence in quality of
joinings
- Adhesive bonding :
long-term durability of boning (bond line corrosion)
- Arc welding (MIG welding):
start of weld arc, process stability of welding arc
(position of welding seam)
- Spot welding:
process stability, wear of welding tip
• For thermal joining techniques the aluminum surface have to be
lubrication free to achieve
a high
quality joining.
(porosity,
hydrogen
Adhesive
bonding
Laser
fillet weld
embrittlement)
Einflus Al-Vorbehandlung [ AC 120 ]
ungealtert
35
SST 3000h
33,0
Zugscherspannung [ MPa ]
30
25
20
15
10
5
0
4,0
31,0
Entfettet
34,0
Gardoclean 299
beölte
Process chain
Process chain
Reasons for carrying out
aluminum pre-treatment
Before adhesively bonding aluminum
• To remove fouling, grease and oil
Press shop
Pre-treatment
of Al pressings
Bodyshop
Finishing/
paintshop
• To establish a defined oxide layer
• To activate the surface
• To enhance resistance to aging on
bonding layer
Before welding aluminum
• Surface free of dirt and grease
• Defined oxide layer thickness
• Uniform volume and
contact resistance
When reworking aluminum
• Extraction systems not designed for
oil-laden grinding swarf
• In some cases better surface finish
evaluation when surface is clean
Pretreatment methods of Aluminum
Anti-corrosion oil
Defined oxide layer
Aluminum
Single part
pretreatment:
Coil pretreatment:
• Facility:
• Facility:
-
in dipping bath
Continuous pretreatment
-
-
Coil coating
• Raw products:
• Raw products:
-
Ti/Zr
-
Coil metal
Stamping parts
Casts
Extrusion
-
Special racks
Additional handling
-
No additions process
In body shop cell
• Raw products:
-
-
• Logistics:
-
• Facility:
-
• Logistics:
-
Local pretreatment:
Stamping parts no
stamping oil
Casts
Extrusion
• Logistics:
-
Additional handling in body
shop
single part pretreatment
Henkel Alodine 2040 (Ti)
Degreasing I
55-60°C pH 9.5-11
Gardoclean 299/4:
• Compatible with all joining
techniques
• Short process
• No stainless steel racks
Degreasing II
55-60°C pH 9.5-11
Rinsing I
Industrial water (non-drinking)
Chemetall Gardoclean 299/4 (Si)
Rinsing II
Industrial water (non-drinking)
Pre-degreasing / passivation
80-85°C, 12 min, pH 10-12
Rinsing III
D.I. water
Degreasing / passivation
80-85°C, 12 min, pH 10-12
Deoxidizing Alodine 2040 (Ti)
35-40°C pH 1.2-1.5 Tif
Rinsing I
D.I. water
Rinsing IV
D.I. water
Rinsing II
D.I. water
Rinsing V
D.I. water
Rinsing III
D.I. water
Rinsing VI
D.I. water
Force drying
Force drying
100°C, 20 min
100°C
Alodine 2040:
• Compatible with all joining
techniques
• Best surface cleaning
• Best surface insulation
resistance
Conclusion:
• Best system for stable
body shop processes
• High cost
Coil pretreatment
Process flow for
aluminum pretreatment
Method for pretreatment of
coils
Adhesive
Deep-drawing compound
Anti-corrosion oil
Defined oxide layer
Aluminum
Al supplier Press shop Bodyshop
Ti/Zr
Coil pretreatment
Adhesive
Anti-corrosion oil
Defined oxide layer
Aluminum
TiZr conversion coating for semi structural bonding:
•
Temporary corrosion protection (predominantly Zr)
•
Prevention of re-formation of oxide layer
=> same surface resistance as before (for the moment) (predominantly Ti)
=> improved weld ability
•
Produced by Chemetall as Gardobond X 4591
•
At most European supplier available
•
Risk of read-through after Zink phosphate bath in paint shop
Ti/Zr
Coil pretreatment
Adhesive
Anti-corrosion oil
Anodized layer
Aluminum
Thin anodized film for structural bonding:
In the anodizing methods, the aluminum surface is cleaned and the natural aluminum oxide
layer removed. Then a defined, firmly adhering oxide layer is built up, consisting of a thin
barrier layer, only a few nm thick and free of pores, and a porous surface film.
•Description of the method:
- Degrease/de-oxidize (acidic)
- Anodize
•Patent bended
•Special equipment is necessary
•No spot-welding
Coil pretreatment
Oxsilan MM 0705 conversion coating
for structural bonding:
•
Same application equipment as TiZr Coating
•
Same high level performance after aging like TAF Coating
•
No patent bending for oxsilan application at aluminum supplier
•
No marking in paint shop after Zink phosphate bath
•
Spot-welding possible
Adhesive
Hotmelt
Defined oxide layer
Aluminum
Oxsilan
Local pretreatment
Drawing oil
Anti-corrosion oil
Undefined oxide layer
Aluminum
Adhesive
Press shop Bodyshop
Plasma pre-treatment:
•
Burn off lubricants
•
Activate the surface
Laser pre-treatment :
•
Burn off lubricants
•
Micro structure of surface
Quelle: PlasmaTreat
Conclusion:
•
Local pretreatment no on stamping parts
(Stamping oil)
•
Potential for castings and extrusion for welding
•
No potential for structural bonding with
actual technology
Quelle: CleanLaser
Worldwide Local sourcing
Europe:
•
Pretreatment of aluminum in Europe available
Rest of world:
•
Pretreatment not available ,
no standard process at local OEM’s
Conclusion:
•
World wide production of aluminum structure in body in white needs new sources for
aluminum pretreatment.
•
New logistic concepts has to be developed
Single part pretreatment
Gardoclean 299/4
Single part pretreatment
Alodine 2040
Coil pretreatment
TAF
Coil pretreatment
TiZr / Oxsilan
Deutschland (Europa)
In house
Suppliers
Suppliers
Novelis
Novelis, Hydro, Aleris,
Alcan
Süd Afrika
In house
China
In house
USA
Kobe-Steel
Fa. Novelis
Abstract
• Pretreatment of Aluminum is necessary for good joining quality
and stable processes
• Depending on the joining technique and material process chain, different
pretreatments are necessary.
• For sheet, metal coil pretreatment is the most economic method.
• Worldwide Local sourcing of pretreated aluminum is difficult. Therefore
new sources have to be established and new logistic concepts have to
be proven.
Thank You

Presentation of various pretreatment methods for Aluminum

Transcription

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