GB/T 42951-2023 Timekeeping instruments - Watch external parts made of hard material - General requirements and test methods
1 Scope
This document describes the performance in terms of resistance to mechanical and thermal shocks, to corrosion, to scratches, to sunlight exposure and also to the wear of its components.
It applies to all elements made in massive material whose hardness is greater than or equal to 1200 Vickers.
This document concerns whole watches, in which all or some of the components of the external parts are made of hard material, with the exception of watch glasses.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 38020.2-2019 Watch-cases and accessories - Gold alloy coverings - Part 2: Determination of fineness, thickness, corrosion resistance and adhesion (ISO 3160-2:2015, MOD)
Note: There is no technical difference between the referenced content of GB/T 38020.2-2019 and the referenced content of ISO 3160-2:2015.
GB/T 38022-2019 Horology - Shock-resistant watches (ISO 1413:2016, IDT)
ISO 105-A02 Textiles - Tests for colour fastness - Part A02: Grey scale for assessing change in colour
Note: GB/T 250-2008, Textiles - Tests for colour fastness - Grey scale for assessing change in colour (ISO 105-A02:1993, IDT)
ISO 4892-1 Plastics - Methods of exposure to laboratory light sources - Part 1: General guidance
Note: GB/T 16422.1-2019, Plastics - Methods of exposure to laboratory light sources - Part 1: General guidance (ISO 4892-1:2016, IDT)
ISO 9227:2017 Corrosion tests in artificial atmospheres - Salt spray tests
Note 1: GB/T 10125-2021, Corrosion tests in artificial atmospheres - Salt spray tests (ISO 9227:2017, MOD)
Note 2: There are no technical differences between the content referenced in ISO 9227:2022 and the content referenced in ISO 9227:2017.
ISO/CIE 11664-4 Colorimetry - Part 4: CIE 1976 L*a*b*colour space
ISO 23160:2011 Watch cases and accessories - Tests of the resistance to wear, scratching and impacts
Note: GB/T 33725-2017, Watch cases and accessories - Tests of the resistance to wear, scratching and impacts (ISO 23160:2011, MOD)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
external part
part of a watch added to the movement and contributing to its external presentation, protection, fixing, control.
Note: For example, the watchcase, the bezel, the crown, the push buttons, the wristband and the clasp.
3.2
hard material
material whose Vickers hardness is equal to or higher than 1200 HV1
3.3
massive
having a composition that is macroscopically homogeneous across its entire section
3.4
brittleness
susceptibility to breaking, under the effect of a static or dynamic stress, without being significantly plastically deformed
4 Requirements, method of control and acceptance criteria
4.1 General
The requirements of this document apply to the elements of external parts of watches made in hard and massive material, according to the definitions in Clause 3.
Note: These materials can contain allergens or toxic materials such as nickel or cobalt.
The watch external parts made of hard material shall not present any shape which may be harmful for the user.
The control method and the acceptance criteria of these materials, constituting the prerequisites, are reported in Annex A.
In the case of tests involving mechanical solicitations (see 4.2, 4.7 and 4.8), the number of samples to be tested shall be sufficient to include the usually large dispersion of measurement inherent to the brittleness behaviour of hard materials. A statistical approach should be adopted (according to Annex C).
It is possible to apply all the tests or a selection of them to assemblies or to certain individual components. The definition of which components are to be tested and the test conditions to be achieved shall be given special attention in advance in order to highlight those parts that are typically sensitive under conditions of ordinary use.
In the case of hard materials that are additionally coated, the surface-related tests should be interpreted differently (wear, scratches, hardness, etc.).
The existence of porosity is admitted as long as the requirements of 4.2 to 4.9.
4.2 Mechanical shock resistance
4.2.1 Requirements and control method
The purpose of this test is to verify the mechanical behaviour of the tested elements or assemblies.
The external elements of watches made of hard material shall comply with the specific requirements of GB/T 38022-2019, 5.3. However, the height to be used shall be 0.75 m because of the lower shock resistance of hard materials, of which the consumer should be made aware.
4.2.2 Acceptance criteria
The examination of the elements made of hard material shall not reveal any permanent deterioration affecting its functions, its performance or its appearance (flaws or broken components).
The examination of the wristband shall not reveal any failure and not present any loss of components.
The assembly of the watch head, the wristband and its functional elements (clasp, loop, etc.) shall stay functional.
4.3 Thermal shock resistance
4.3.1 Requirements and control method
The purpose of this test is to evaluate the behaviour of assemblies containing at least one element made of hard material.
The elements of external parts of watches made of hard material shall meet the specific requirements according to the following method:
——Place the samples in a thermal chamber stabilized at 70 °C ± 2 °C without humidity contribution during 2 h.
——Soak them immediately in deionized water at 5 °C ± 2 °C during 30 s minimum.
——Repeat this cycle five times minimum. Samples shall be dried after each cycle.
——Observe the horological external parts and record visible variations.
Other heating methods can be used but shall be specified in the report.
4.3.2 Acceptance criteria
No visible degradation shall be observed on the components or assembly tested.
4.4 Corrosion resistance
4.4.1 Requirements and control method
The purpose of this test is to evaluate hard material elements or assemblies against corrosive agents.
The elements of external parts of watches made of hard material shall meet the specific requirements, concerning the following tests, of ISO 9227:2022, 5.2.2 and GB/T 38020.2-2019, 7.4.
4.4.2 Acceptance criteria
To be determined by the concerned parties.
4.5 Wear resistance
4.5.1 Requirements and control method
The purpose of this test is to evaluate the potential degradation of the element made of hard material due to random wear.
The elements of external parts of watches made of hard material shall meet the specific requirements of ISO 23160:2011, 4.1.
4.5.2 Acceptance criteria
To be determined according to ISO 23160:2011, 4.1.6.
The wear resistance shall be high due to customers' expectations.
4.6 Scratch resistance
4.6.1 Requirements and control method
The purpose of this test is to evaluate the potential degradation of the element made of hard material. Due to customers’ expectations, the abrasive load shall be adapted in order to provide more discriminating tests than those described in ISO 23160:2011, 5.3.
The elements of external parts of watches made of hard material shall meet the specific requirements of the ISO 23160:2011, 5.2, 5.3 and 5.4, using sharp edge alumina abrasive (Corundum F70), see Table 1.
4.6.2 Acceptance criteria
To be determined according to ISO 23160:2011, 5.6.
The scratch resistance shall be high due to customers’ expectations.
Standard
GB/T 42951-2023 Timekeeping instruments―Watch external parts made of hard material―General requirements and test methods (English Version)
Standard No.
GB/T 42951-2023
Status
valid
Language
English
File Format
PDF
Word Count
7500 words
Price(USD)
225.0
Implemented on
2024-3-1
Delivery
via email in 1~3 business day
Detail of GB/T 42951-2023
Standard No.
GB/T 42951-2023
English Name
Timekeeping instruments―Watch external parts made of hard material―General requirements and test methods
GB/T 42951-2023 Timekeeping instruments - Watch external parts made of hard material - General requirements and test methods
1 Scope
This document describes the performance in terms of resistance to mechanical and thermal shocks, to corrosion, to scratches, to sunlight exposure and also to the wear of its components.
It applies to all elements made in massive material whose hardness is greater than or equal to 1200 Vickers.
This document concerns whole watches, in which all or some of the components of the external parts are made of hard material, with the exception of watch glasses.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 38020.2-2019 Watch-cases and accessories - Gold alloy coverings - Part 2: Determination of fineness, thickness, corrosion resistance and adhesion (ISO 3160-2:2015, MOD)
Note: There is no technical difference between the referenced content of GB/T 38020.2-2019 and the referenced content of ISO 3160-2:2015.
GB/T 38022-2019 Horology - Shock-resistant watches (ISO 1413:2016, IDT)
ISO 105-A02 Textiles - Tests for colour fastness - Part A02: Grey scale for assessing change in colour
Note: GB/T 250-2008, Textiles - Tests for colour fastness - Grey scale for assessing change in colour (ISO 105-A02:1993, IDT)
ISO 4892-1 Plastics - Methods of exposure to laboratory light sources - Part 1: General guidance
Note: GB/T 16422.1-2019, Plastics - Methods of exposure to laboratory light sources - Part 1: General guidance (ISO 4892-1:2016, IDT)
ISO 9227:2017 Corrosion tests in artificial atmospheres - Salt spray tests
Note 1: GB/T 10125-2021, Corrosion tests in artificial atmospheres - Salt spray tests (ISO 9227:2017, MOD)
Note 2: There are no technical differences between the content referenced in ISO 9227:2022 and the content referenced in ISO 9227:2017.
ISO/CIE 11664-4 Colorimetry - Part 4: CIE 1976 L*a*b*colour space
ISO 23160:2011 Watch cases and accessories - Tests of the resistance to wear, scratching and impacts
Note: GB/T 33725-2017, Watch cases and accessories - Tests of the resistance to wear, scratching and impacts (ISO 23160:2011, MOD)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
external part
part of a watch added to the movement and contributing to its external presentation, protection, fixing, control.
Note: For example, the watchcase, the bezel, the crown, the push buttons, the wristband and the clasp.
3.2
hard material
material whose Vickers hardness is equal to or higher than 1200 HV1
3.3
massive
having a composition that is macroscopically homogeneous across its entire section
3.4
brittleness
susceptibility to breaking, under the effect of a static or dynamic stress, without being significantly plastically deformed
4 Requirements, method of control and acceptance criteria
4.1 General
The requirements of this document apply to the elements of external parts of watches made in hard and massive material, according to the definitions in Clause 3.
Note: These materials can contain allergens or toxic materials such as nickel or cobalt.
The watch external parts made of hard material shall not present any shape which may be harmful for the user.
The control method and the acceptance criteria of these materials, constituting the prerequisites, are reported in Annex A.
In the case of tests involving mechanical solicitations (see 4.2, 4.7 and 4.8), the number of samples to be tested shall be sufficient to include the usually large dispersion of measurement inherent to the brittleness behaviour of hard materials. A statistical approach should be adopted (according to Annex C).
It is possible to apply all the tests or a selection of them to assemblies or to certain individual components. The definition of which components are to be tested and the test conditions to be achieved shall be given special attention in advance in order to highlight those parts that are typically sensitive under conditions of ordinary use.
In the case of hard materials that are additionally coated, the surface-related tests should be interpreted differently (wear, scratches, hardness, etc.).
The existence of porosity is admitted as long as the requirements of 4.2 to 4.9.
4.2 Mechanical shock resistance
4.2.1 Requirements and control method
The purpose of this test is to verify the mechanical behaviour of the tested elements or assemblies.
The external elements of watches made of hard material shall comply with the specific requirements of GB/T 38022-2019, 5.3. However, the height to be used shall be 0.75 m because of the lower shock resistance of hard materials, of which the consumer should be made aware.
4.2.2 Acceptance criteria
The examination of the elements made of hard material shall not reveal any permanent deterioration affecting its functions, its performance or its appearance (flaws or broken components).
The examination of the wristband shall not reveal any failure and not present any loss of components.
The assembly of the watch head, the wristband and its functional elements (clasp, loop, etc.) shall stay functional.
4.3 Thermal shock resistance
4.3.1 Requirements and control method
The purpose of this test is to evaluate the behaviour of assemblies containing at least one element made of hard material.
The elements of external parts of watches made of hard material shall meet the specific requirements according to the following method:
——Place the samples in a thermal chamber stabilized at 70 °C ± 2 °C without humidity contribution during 2 h.
——Soak them immediately in deionized water at 5 °C ± 2 °C during 30 s minimum.
——Repeat this cycle five times minimum. Samples shall be dried after each cycle.
——Observe the horological external parts and record visible variations.
Other heating methods can be used but shall be specified in the report.
4.3.2 Acceptance criteria
No visible degradation shall be observed on the components or assembly tested.
4.4 Corrosion resistance
4.4.1 Requirements and control method
The purpose of this test is to evaluate hard material elements or assemblies against corrosive agents.
The elements of external parts of watches made of hard material shall meet the specific requirements, concerning the following tests, of ISO 9227:2022, 5.2.2 and GB/T 38020.2-2019, 7.4.
4.4.2 Acceptance criteria
To be determined by the concerned parties.
4.5 Wear resistance
4.5.1 Requirements and control method
The purpose of this test is to evaluate the potential degradation of the element made of hard material due to random wear.
The elements of external parts of watches made of hard material shall meet the specific requirements of ISO 23160:2011, 4.1.
4.5.2 Acceptance criteria
To be determined according to ISO 23160:2011, 4.1.6.
The wear resistance shall be high due to customers' expectations.
4.6 Scratch resistance
4.6.1 Requirements and control method
The purpose of this test is to evaluate the potential degradation of the element made of hard material. Due to customers’ expectations, the abrasive load shall be adapted in order to provide more discriminating tests than those described in ISO 23160:2011, 5.3.
The elements of external parts of watches made of hard material shall meet the specific requirements of the ISO 23160:2011, 5.2, 5.3 and 5.4, using sharp edge alumina abrasive (Corundum F70), see Table 1.
4.6.2 Acceptance criteria
To be determined according to ISO 23160:2011, 5.6.
The scratch resistance shall be high due to customers’ expectations.
