CLEANING OF ALUMINIUM

Transcription

1 Protection upgraded CLEANING OF ALUMINIUM A Demanding Process Described Using the Example of Aerosol Cans Aluminium 2000, June 2017 Peter Volk May 18,

2 CLEANING Often an Underestimated Process Substrate Contamination Steel Zinc (Plated Steel, Cast) Aluminium (Sheets, Extrusion, Cast) Magnesium Titanium Hard Metals (W/Co, WC, TiC, TiN) Copper, Brass Stainless Steel Glass, Ceramics Oil, Grease (synthetic, native) Lubricants Pigments, Dust, Chips Release Agents Metal Soaps Fingerprints Salts Corrosion Products Inhibitors May 18,

3 CLEANING Properties of the Surface Residues at the Surface Contamination Layer, < 1 µm Binding Energy Sorption Layer, nm Reaction Layer, nm Deformed Boundary Layer, >1µm Bulk Material May 18,

4 CLEANING Mechanism SINNER Circle Application Time: 5 min ( min) Temperature 60 ºC (RT - 80 ºC) Assist the Cleaning: Wiping Brushing Spraying Ultra sound Air or part agitation Flooding Builder Substances: Hydroxide Silicate Phosphate Carbonate Borate Alkanol amine fatty acids Surfactants: NaOH, KOH Non-ionic surfactants Anionic surfactants Na 2 H 2 SiO 4 5 H 2 O K 5 P 3 O 10, K 4 P 2 O 7 Na 2 CO 3 Na 2 B 4 O 7 10 H 2 0 May 18,

5 CLEANING Mechanism Builder substances Adjusting and maintaining the ph-value Complexing effect (oxides, scale, rust) Dispersing (smallest particles) Inhibiting (Al, brass etc.) Conductivity (electro degreasing) Surfactants Reducing surface tension Degreasing Emulsifying or demulsifying Oil separation Foam abilities application May 18,

6 CLEANING Mechanism Synergism of Builder and Surfactant May 18,

7 CLEANING Mechanism Schematic: hydrophobic particles (coal, soot) hydrophilic particles (oxides) builder chips fat, wax, oil, lubricant surfactant May 18,

8 CLEANING Control of the Cleaning Bath Builder: Surfactant: Titration, Conductivity Photometric analysis May 18,

9 CLEANING Control of the Cleaning Bath Surfactant: Bubble Pressure Tensiometer σ = p r 2 p (t) t B t May 18,

10 CLEANING Quality and Control Desired Result: Oils, corrosion protection, soaps, pigments are removed High surface energy Wettability of the Surface indicates the Quality of the Cleaning Clean: surface can be wetted by test ink water Not clean: test ink rolls off Hill GmbH May 18,

11 AEROSOL CANS Attractiveness May 18,

12 AEROSOL CANS Processing From Slugs to Cans More than cans are produced worldwide per year. May 18,

13 AEROSOL CANS Cleaning Special tasks for the aluminium aerosol cleaning High amount of residual lubricants on the surface Rather small cleaning bathes compared to high surface areas Short process times High pressure applications with no allowance of foam No attack or matting of the surface allowed May 18,

14 AEROSOL CANS Cleaning Results - Surface Tension Generally, after the cleaning the surface was wettable with water (water break free surface) Name Surface tension measured with test ink [mn/m] Surface before cleaning SurTec 148 >56 SurTec 006 >56 SurTec 147/086 >56 Before Cleaning <28 Surface after cleaning Right: Surface Tension inside of the tubes Left/Bottom = Test Ink 56 mn/m Left/Top = Test Ink 48 mn/m Right/Top = Test Ink 44 mn/m Right/Bottom= Test Ink 41 mn/m May 18,

15 AEROSOL CANS Cleaning Results - Residual Carbon after Cleaning Cleaner SurTec 148 SurTec 006 SurTec 147/086 Before cleaning Properties Residual Carbon XRF [weight %] Inside Outside Surface as after forming Surface after grinding Surface as after forming Surface after grinding Surface as after forming Surface after grinding Surface as after forming 19, Surface after grinding May 18,

16 AEROSOL CANS Evaluation of pigment residues adhesive tape Name after forming after grinding Inside outside Inside outside SurTec 006 SurTec 147/086 SurTec 148 uncleaned May 18,

17 AEROSOL CANS Evaluation of pigment residues wiping with white cloth Name after forming after grinding Inside outside Inside outside SurTec 006 SurTec 147/086 SurTec 148 uncleaned May 18,

18 AEROSOL CANS Cleaning Production Foam Control Drag in of metal soaps and high pressure application bear the danger of foam formation. Suitable cleaners and surfactant blends need to be chosen carefully to fight foam. Normal Appearance Undesired and Stable Foam May 18,

19 SUMMARY Aerosol Can Cleaning Cleaning in General Cleaning often is underestimated It is an important step within the value chain of producing parts The ingredients of the cleaner need to be well chosen, to fit to the substrate, the contaminant and the application method Control and maintenance are mandatory Cleaning of Aerosol Cans Cleaning is extremely important; often it is the basis for subsequent painting The cleaning of aerosol can holds special demands Short cycle times High pressure High drag in of impurities Foam is critical and needs to be save against stable foam May 18,

20 Protection upgraded Thank you. May 18,