Method and blasting means for producing a sanitized finish on an aluminum substrate

Abstract

A method and a blasting material for producing a satinized surface on an aluminum substrate is provided. There is proposed a method for producing a satinized surface on an aluminum substrate, including the steps: providing an aluminum substrate; treating by blasting with a blasting material the surface regions of the aluminum substrate provided that are to be satinized; wherein there is used as the blasting material a mixture of angular and spherical particles having a grain diameter D.sub.90 of 0.3 mm.

Claims

1. A method for producing a satinized surface on an aluminium substrate, comprising the method steps: providing an aluminium substrate; treating by blasting with a blasting material the surface regions of the aluminium substrate provided that are to be satinized; wherein there is used as the blasting material a mixture of angular and spherical particles having a grain diameter D.sub.90 of 0.3 mm.

2. The method as claimed in claim 1, wherein a new grain blasting material particle mixture has: a) a content of angular new grain particles of between 80% by weight and 20% by weight or; b) a content of round new grain particles of between 20% by weight and 80% by weight; based on the total weight of the new grain blasting material particle mixture, wherein the total composition of the angular grain particles and the round new grain particles is 100% by weight.

3. The method as claimed in claim 1, wherein there is used as the blasting material a mixture of angular and spherical particles having a grain diameter D.sub.90 of 0.3 mm and 0.01 mm.

4. The method as claimed in claim 1, wherein the method comprises the following method steps: anodizing the surface regions treated by blasting; and sealing the surface regions to be anodized.

5. The method as claimed in claim 1, wherein the spherical particles have an average hardness of 250 HV and 500 HV.

6. The method as claimed in claim 1, wherein the angular particles have an average hardness of 600 HV.

7. The method as claimed in claim 1, wherein the blasting material particle mixture has an average content: a) of angular particles of 80% by weight and 20% by weight; or b) of spherical particles of between 20% by weight and 80% by weight, based on the total weight of the blasting material particle mixture.

8. The method as claimed in claim 1, wherein the blasting speed in the blasting process is on average from 30 m/s to 100 m/s.

9. The method as claimed in claim 1, wherein in the blasting process the pressure of the jet of particles at an outlet nozzle is from 2 bar to 10 bar.

10. The method as claimed in claim 1, wherein the substrate surface to be satinized is at least one of: deoxidized, deoxidized and pickled, or pickled, after the blast treatment and before anodization; and subjected to a polishing treatment after the blast treatment and before anodization.

11. The method as claimed in claim 1, wherein the blast treatment is carried out by means of a centrifugal wheel blasting device, an injector blasting device, or pressure blasting device.

12. A blasting material suitable for the blast treatment of aluminium surfaces by a method of claim 1, wherein the blasting material comprises a mixture of angular and spherical particles having a grain diameter D.sub.90 of 0.3 mm.

13. The blasting material as claimed in claim 12, wherein a new grain blasting material particle mixture has: a) a content of angular new grain particles of between 80% by weight and 20% by weight or b) a content of round new grain particles of between 20% by weight and 80% by weight; based on the total weight of the new grain blasting material particle mixture, wherein the total composition of angular and round new grain particles is 100% by weight.

14. The blasting material as claimed in claim 12, wherein a) the spherical particles have an average hardness of 250 HV and 500 HV; or b) the angular particles have an average hardness of 600 HV, in particular 640 HV.

15. The blasting material as claimed in claim 12, wherein the angular or spherical particles comprise iron-based metal alloys, wherein the angular particles comprise iron-based metal alloys which have a martensitic matrix with chromium carbides; and the angular particles comprise a chromium carbide-containing stainless steel; or wherein the spherical particles comprise a stainless steel, and the stainless steel has an austenitic microstructure.

16. The blasting material as claimed in claim 12, wherein the blasting material comprises a mixture of angular and spherical particles having a grain diameter D.sub.90 of 0.3 mm and 0.01 mm.

Description

BRIEF DESCRIPTION

(1) Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

(2) FIG. 1 shows a comparison of the surface structures produced by pickling according to the prior techniques and blast treatment according to the invention.

DETAILED DESCRIPTION

(3) FIG. 1 shows a comparison of the surface structures produced by pickling according to the prior techniques and blast treatment according to embodiments of the invention. As the comparison shows, the aluminium surfaces treated by blasting according to embodiments of the invention differ only insubstantially from the aluminium surfaces treated by pickling according to DIN 17611 E6, both in the normal view and in the microscopic enlargement. In fact, it is shown that the substrate surface treated according to embodiments of the invention no longer shows any web marks in the normal view. Substrate surfaces treated by blasting according to embodiments of the invention can readily be assembled with surfaces treated by means of the known pickling treatment without any visually perceptible difference between their surfaces.

Example 1

(4) Profile sections of extruded aluminium profiles of the alloy AlMgSiO.sub.5 were removed from a pressing plant for comparative tests. Sieve fractions of sieve sizes D.sub.90 of from 0.1 mm to 0.2 mm mesh size of both angular material and spherical material were produced from blasting materials of a German manufacturer. The round blasting material was stainless steel having a chromium content of 18% by weight 1% by weight and a nickel content of 10% by weight 2% by weight. The angular blasting material was stainless steel having a chromium content of 30% by weight 1% by weight and a carbon content of 2% by weight 0.1. The prepared profile sections were then blasted in a manual cabinet with variable compressed air pressure, mixtures of the spherical and angular sieve fractions also being used.

(5) After blasting, the profile sections were first cleaned in a cleaner for aluminium surfaces from ALUFINISH, product ALFICLEAN, then pickled gently for one minute in a dilute sodium hydroxide solution (50 g/l at 60 C.), and then deoxidized in an acidic solution of 150 g/l of sulfuric acid and a peroxidic additive (ALFIDEOX from ALUFINISH; 1 g/l) and then anodized in a bath containing 180 g/l of sulfuric acid. A current density of 1.5 A/dm was used; the anodization time was 40 minutes until a layer thickness of 20 m was achieved. Between each of the above-mentioned treatment steps, the profile sections were rinsed, and a rinsing operation of at least one minute in tap water was also carried out after the anodization. The oxide layers produced were then sealed for one hour in hot water at 96 C. to 98 C., a so-called sealing aid from ALUFINISH, product ALFISEAL, being added to the water in a concentration of 2 g/l. The profile sections were then subjected to a comparative assessment.

(6) In addition, after the above-mentioned cleaning and pickling, some blasted profile sections, instead of being deoxidized as mentioned above, were polished in a solution of 75% sulfuric acid, 15% phosphoric acid and 10% water at a temperature of >100 C. for one minute and then likewise anodized as described. The results of the evaluations are described briefly below:

Example 1a

(7) In the case of the profile sections treated with the spherical blasting material particles, the web marks and welding seams on the surfaces were still wholly visible and not covered.

Example 1b

(8) In the case of the profile sections treated with angular blasting material particles, a decoratively troublesome whitish coating was observed throughout after anodization; the surface finish of surfaces later treated with the same blasting material particles was significantly different from the first tests with fresh blasting material particles. The coverage of web marks and welding seams was significantly reduced.

Example 2

(9) Mixtures of the angular and spherical blasting agent particles in the range of 30% spherical material and 70% angular material and 30% angular and 70% spherical blasting material particles gave a significantly more decorative surface finish, and both the web marks and the welding seams were covered to the greatest possible extent. In addition, the surface finish was reproducible in a plurality of repeat tests.

Example 3

(10) In the case of the profile sections subjected to a polishing treatment instead of deoxidization, the surfaces treated with the mixture of spherical and angular blasting material showed an attractive, glossy, satin-like finish.

Example 4

(11) The tests were repeated in a so-called centrifugal wheel system with some different blasting material particle mixtures. The same surface finish as had been achieved in the manual cabinet with compressed air was found, even when the pressure was varied.

Example 5

(12) Angular new grain particles, for example of the mark Grittal obtainable from Vulkan Inox GmbH, having a grain diameter D.sub.90 in the range of from 0.1 mm to 0.2 mm and an average hardness of 750 HV were used as blasting material. As spherical new grain particles, particles having a grain diameter D.sub.90 in the range of from 0.1 mm to 0.2 mm and an average hardness of 450 HV were used as the blasting material. Spherical new grain particles having an average hardness of 450 HV can be obtained, for example, using particles of the mark Chronital obtainable from Vulkan Inox GmbH, by pre-rounding or compacting the spherical grains beforehand in a machine so that the spherical test material has a hardness of 450 HV. The angular and spherical new grain particles were mixed as indicated in Table 2.

(13) The blasting material mixture in question, see Table 2, was delivered in a blast cabinet of type Normfinish, manufacturer Leering Hengelo BV, of series DP 14, with continuous blasting material cleaning for the treatment of an extruded standard aluminium window frame profile, for example ALMG SI 0.5, under the following conditions:

(14) The results are shown in Table 2.

(15) Sieve fraction D.sub.90: <0.2 mm and >0.1 mm

(16) Nozzle diameter: 10 mm/

(17) Blasting pressure: 2 bar

(18) Distance nozzle to blasting material: 300 mm

(19) Blasting angle: 80

(20) Amount of Blasting Material

(21) delivered: 7.2 kg/min.=432 kg/h

(22) Blasting speed 1 m/min

(23) TABLE-US-00002 TABLE 2 Blasting Blasting material in material in each case each case sieve fraction sieve fraction D.sub.90 < 0.2 mm D.sub.90 < 0.2 mm and and Finish assessment of extruded standard >0.1 mm >0.1 mm aluminium window frame profiles Test angular spherical ALMG SI 0.5 Evaluation 1 0 100 Some pressing marks not covered; welding seams more glossy than the finish of the aluminium surface; web marks visible; 2 20 80 Some pressing marks not covered; /+ welding seams and web marks almost no longer visible; 3 30 70 Pressing marks largely covered; + welding seams and web marks no longer visible; 4 40 60 Pressing marks completely covered; ++ welding seams and web marks not visible; very uniform finish; smooth aluminium surface; virtually E6 finish; 5 50 50 Pressing marks completely covered; +++ welding seams and web marks not visible; E6 finish; 6 60 40 Pressing marks completely covered; ++ welding seams and web marks not visible; very uniform finish similar to point 4; smooth aluminium surface; virtually E6 finish; 7 70 30 Pressing marks completely covered; + welding seams and web marks not visible; finish is more matt compared to point 4 and 6; 8 80 20 Pressing marks, welding seams and web /+ marks not visible, but matt and rough surface; when viewed obliquely there is a whitish finish; 9 100 0 Pressing marks, welding seams and web marks not visible, surface is more matt and more rough than in point 8; when viewed obliquely there is a whitish finish Evaluation: +++ = very good correspondsto E6 finish ++ = good corresponds almost to E6 finish + = satisfactory, better than E5 finish /+ = slightly better than E5 finish = acceptable, E5 finish and poorer = unsatisfactory

(24) Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

(25) For the sake of clarity, it is to be understood that the use of a or an throughout this application does not exclude a plurality, and comprising does not exclude other steps or elements. The mention of a unit or a module does not preclude the use of more than one unit or module.