GB/T 22638.2-2016 Test methods for aluminium and aluminium alloy foils – Part 2: Determination of pinhole
1 Scope
This part of GB/T 22638 specifies the determination method for pinhole of aluminium and aluminium alloy foils.
This part is applicable to determination of the number and diameter of pinholes in aluminium and aluminium alloy foils.
This part is also applicable to the determination of roller hole diameter of aluminium and aluminium alloy foils.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
GB/T 8170 Rules of rounding off for numerical values & expression and judgment of limiting values
GB/T 26492.4-2011 Defects for wrought aluminium and aluminium alloys ingots and products - Part 4: Defects for foils
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 26492.4-2011 and the following apply. For the convenience of use, the term and definitions in GB/T 26492.4-2011 is listed below.
3.1
pinhole
irregular holes visible on the surface of aluminium and aluminium alloy foils, of which the maximum diameter is usually not more than 0.2 mm
Note: It is modified from GB/T 26492.4-2011, 2.24.
4 Principle
Based on the light transmittance of pinholes of aluminium and aluminium alloy foils, the number and diameter of pinholes are determined under the specified environment and light source of lamp box.
5 Apparatuses
5.1 Observation room and pinhole box
5.1.1 See Figure 1 for the schematic diagram of observation room and pinhole box.
Key:
1——observation room;
2——pinhole box;
3——test surface.
Figure 1 Observation room and pinhole box
5.1.2 The pinhole box should be made of wood. The upper surface of the box shall be a piece of frosted glass with a thickness of 5 mm. The surface of the frosted glass shall be provided with a determination surface of a suitable area, which should not be less than 0.1 m2 and shall be opaque.
5.1.3 There is a light source in the pinhole box, and the transmitted illumination of frosted glass shall be 1,000 lx to 1,500 lx, and the light shall be evenly distributed on the determination surface.
5.1.4 The ambient illumination of the observation area above the determination surface of the sample shall be 20 lx to 50 lx.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Apparatuses
6 Samples
7 Test procedures
8 Result expression
9 Test report
