GB2105257A

GB2105257A - Improvements in or relating to a material to be engraved by a laser

Info

Publication number: GB2105257A
Application number: GB08217423A
Authority: GB
Inventors: Wladimir Wladimiroff
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-06-17
Filing date: 1982-06-16
Publication date: 1983-03-23
Also published as: JPS5816077A; DE3222449A1; SE421880B

Abstract

A material to be engraved by a laser comprises a metal substrate (2), with a reaction layer (3) laminated to one surface, there being a further metal layer (4) on the reaction layer (3). The material is engravable with a laser beam of lower power than would be required to engrave the substrate above, the surface metal layer forms a radiation barrier during the initial stage of the laser engraving process. The reaction layer reacts with the laser beam, to change and/or volume, or to form a product which reacts with the hot edge of the line being engraved, or melts and partially vaporises to form a hard curing foam, or which carbonises under the influence of radiation penetrating the metal surface layer. <IMAGE>

Description

SPECIFICATION Improvements in or relating to a material to be engraved with a laser This invention relates to a material that is to be engraved with a laser, and more particularly to such a material consisting of two or more layers on a metal substrate.

Laser engraving utilising ordinary metal often gives low contrast. This is a drawback especially in the case of laser-engraving of frontplates. Such laser-engraved frontplates must often be treated after the laser engraving step to improve contrast.

The treatment can involve rubbing black wax into the frontplate surface or can involve chemical etching of the laser-engraved surface. After such a treatment the engraved surface must be cleaned and polished and so the time gained by utilising a laserengraving process is lost again in the subsequent after treatment.

The possible expedient of increasing the engraving depth and thereby as in the case of a reliefincreasing contrast, leads to longer engraving times or demands a more powerful laser-engraving system, both involving higher cost.

According to the broadest aspect of this invention there is provided a material suitable for being engraved by a laser, said material consisting of a metal substrate laminated with at least one reaction layer and at least one metal surface layer on the side of the reaction layer remote from the substrate, the reaction layer or layers being selected to react with a laser beam of considerably lower power density than is necessary for reaction with the substrate.

Preferably the metal surface layer is made to have a thickness and vaporization energy such that the surface layer forms a radiation barrier during the initial phases of a laser-engraving process using a laser with a power density matched to the sensitivity of the reaction layer.

Convenientlythe metal surface layer comprises two or more superimposed layers.

Advantageously the material comprises a reaction layer which, under irradiation with a laser beam having a power density sufficient to penetrate the metal surface layer, changes colour or volume or both colour and volume.

In one embodimentthe reaction layer is made to form a hard curing foam or porous substance.

Advantageously the reaction layer is made to form one or more products under laser irradiation, which product or products react with the hot edges of the surface layer along the engraved line, the reaction product or products giving increased contrast of said line.

Preferably at least one reaction product etches the edges of said metal surface layer along the engraved line In a preferred embodiment the reaction layer is made to melt and partially vaporize under irradiation with a laser beam having a power density sufficient to penetrate the metal surface layer so that a hard curing foam is pressed out of the engraved line to cover the hot edges of said surface layer along said line.

It is to be understood that the reaction layer may be made to carbonize as a result of irradiation with a laser beam having a power density to penetrate said metal surface layer.

In another embodiment there are two or more reaction layers which each have the properties of the reaction layers as defined above, or have such properties synergistically.

This invention also relates to a material as defined above whenever engraved and to a method of engraving comprising the steps of directing a laser beam onto a material as defined above.

A preferred embodiment of the present invention is a material with a metal surface that is suitable for being engraved by a laser. When engraved the material gives a good contrast of the engraved information, even when engraved with comparatively moderate laser powers. In the preferred material good contrast is obtained as an immediate result of the laser-engraving progress and not as the result of some after treatment.

The invention thus seeks to provide a material which, apart from giving good contrast of the engraved information, also allows a relatively high laser-engraving speed. The preferred material has good temperature and aging stability.

In order that the invention may be more readily understood, and so that further featu res thereof may be appreciated, the invention will now be described by way of example with reference to the accompanying drawings in which Figures 1, and 3 are cross sectional views of a material in accordance with invention during the various steps of a laser engraving process, and Figures 2 and 4 are cross sectional views of alternative materials in accordance with the invention.

More specifically: FIGURE 1 shows a cross-section of a material according to the invention, in which a metal substrate 2 is laminated with a reaction layer 3 and a metal surface layer 4. During the engraving process a laser beam 1 is focussed onto or just below the surface layer 4; FIGURE 2 shows a cross-section of a material according to the invention in which two reaction layers 6 and 7 are provided, the two layers being such that they react under laser irradiation and give a hard curing foam 5, which is made to flow out over the edges of the engraved line; FIGURE 3 shows a cross-section of a material according to the invention as shown in Figure 1, in which the reaction layer 3 has changed to a darker colour and decreased in volume, giving good contrast as a result of both relief effect and colour change; and FIGURE 4 shows an enlarged cross-section of a material according to the invention, in which the reaction between the laser beam and the reaction layer 3 has resulted in the etching away of the metal surface layer 4 in the viciniilf of the engraved line. By choosing the appropriate colour for the metal surface layer and the reaction layer a good contrast is obtained as a result of such a laser-engraving process.

In the above illustrated embodiments the reactive layer or layers consist of a material reacting upon irradiation with a laser beam having a considerably lower power density than is necessary to obtain a reaction with the substrate. The thickness and vaporization energy of the metal surface layer is chosen such that, given a certain power density of the laser beam e.g. a sensitivity matched to the sensitivity of the reaction layer, that is to say powerful enough to cause the reaction layer to react, but not powerful enough to cause the substrate to react, the surface layer forms a radiation barrier during the initial phases of the laser-engraving process. The metal surface layer is preferably anodized or electrochemically treated (before laser-engraving) to obtain a pleasing surface texture and colour.The radiation barrier function of the metal surface layer ensures a well defined engraving line and therefore high engraving precision.

The reaction layer is chosen to consist of materials which readily interact with the laser radiation and thereby either change colour, volume or both. In one embodiment of the invention the reaction layer forms a foam or similar porous, hard curing substance after laser irradiation.

It is also feasible to choose the materials in the reaction layer such that, upon reaction with the laser beam, products are formed which react with the hot sides of the engraved line. This reaction is chosen to give increased contrast of the engraved line. An example of such a reaction is the information of reaction porductswhich etch or dissolve the metal surface layer in the vicinity of the engraved line.

Choosing the appropriate composition of the reaction layer laser irradiation can be made to melt and partially evaporizethe material, which consequently increases in volume so that the reaction product is pressed out of the engraved line or flows over the edges of the line.

Claims

1. A material suitable for being engraved by a laser, said material consisting of a metal substrate laminated with at least one reaction layer and at least one metal surface layer on the side of the reaction layer remote from the substrate, the reaction layer or layers being selected to react with a laser beam of considerably lower power density than is necessary for reaction with the substrate.

2. A material according to claim 1, wherein the metal surface layer is made to have a thickness and vaporization energy such that the surface layers forms a radiation barrier during the initiai phases of a laser-engraving process using a laser with a power density matched to the sensitivity of the reaction layer.

3. A material according to claim 1 or 2, wherein the metal surface layer comprises two or more superimposed layers.

4. A material according to any one of the preced ing claims, wherein the material comprises a reac tion layer which, under irradiation with a laser beam having a power density sufficientto penetrate the metal surface layer, changes colour or volume or both colour and volume.

5. A material according to any one of the preced ing claims, comprising a reaction layer which is made to form a hard curing foam or porous sub- stance.

6. A material according to any one of the preceding claims comprising a reaction layer which is made to form one or more products under laser irradiation, which product or products react with the hot edges of the surface layer along the engraved line, the reaction product orproductsgiving increased contrast of said line.

7. A material according to claim 6, in which at least one reaction product etches the edges of said metal surface layer alongthe engraved line.

8. A material as claimed in any one of claims 1 to 5, comprising a reaction layer which is made to melt and partially vaporize under irradiation with a laser beam having a power density sufficientto penetrate the metal surface layer, so that a hard curing foam ia pressed out of the engraved line to coverthe hot edges of said surface layer along said line.

9. A material according to any one of claims 1 to 8, comprising a reaction layer which is madetocar- bonize as a result of irradiation with a laser beam having a power density to penetrate said metal surface layer.

10. A material according to any one of the preceding claims, comprising two or more reaction layers which each have the properties defined in one or more of said claims, or which such properties synergistically.

11. A material substantially as herein described with reference to and as shown in Figures 1 and 3 of the accompanying drawings.

12. A material substantially as herein described with reference to and as shown in Figure 2 of the accompanying drawings.

13. A material substantially as herein described with reference to and as shown in Figure 4 of the accompanying drawings.

14. A material according to any one of the preceding claims when engraved by a laser.

15. A method of engraving comprising the steps of directing a laser beam onto a material as claimed in any one of claims 1 to 13.

16. Any novel feature or combination of features disclosed herein.