Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
GB/T 14235 comprises the following parts under the general title Low temperature pattern wax materials for investment casting:
—— Part 1: Testing methods for physical properties;
—— Part 2: Testing methods for usability properties.
This is part 2 of GB/T 14235.
This part is drafted in accordance with the rules given in GB/T 1.1-2009.
This part replaces GB/T 14235.2-1993 Testing methods for bending strength of pattern materials in investment casting, GB/T 14235.5-1993 Testing method for surface hardness of pattern materials in investment casting, and GB/T 14235.9-1993 Testing method for thermal stability of pattern materials in investment casting, this part is an integrated revision of GB/T 14235.2-1993, GB/T 14235.5-1993 and GB/T 14235.9-1993. The following main technical changes have been made with respect to the 3 replaced standards:
—— the application scope of the standard is modified (see clause 1);
—— the testing method is added for wetting angle between pattern materials in investment casting and binder (see clause 6);
—— the clause is added for test report (see clause 7);
—— Annex A gives a comparison of the differences between this part and the 3 replaced standards.
This part was proposed by and is under the jurisdiction of SAC/TC 54 the National Technical Committee on Foundry of Standardization Administration of China.
The previous editions of this standard are as follows:
—— GB/T 14235.2-1993;
—— GB/T 14235.5-1993;
—— GB/T 14235.9-1993.
Low temperature pattern wax materials for investment casting - Part 2: Testing methods for usability properties
1 Scope
This part of GB/T 14235 specifies the test methods for usability properties such as bending strength, surface hardness, thermal stability and wetting angle of investment - binder.
This part is applicable to the determination of the usability properties such as bending strength, surface hardness, thermal stability and wetting angle of investment - binder.
2 Terms and definitions
For the purposes of this document, the following term and definition apply.
2.1
bending strength at ambient temperature of low temperature pattern wax materials
strength of the load obtained from static bending to brittle fracture at a certain loading speed
3 Testing of bending strength
3.1 Overview of testing method for bending strength at ambient temperature
The prepared paste or liquid pattern wax materials is pressed into a strength specimen with a specified dimension. After the specimen is placed at a certain temperature for 24 h, the load peak value of the static bending brittle fracture is tested by a flexural properties tester, and the bending strength of the specimen is calculated with the mechanical formula.
3.2 Instruments and apparatus
Instruments for bending strength testing:
—— Flexural property tester: see Figure.1 for the specimen holder installed on the flexural property tester, with a fulcrum spacing of 30 mm.
—— Mercury-in-glass thermometer: the temperature measuring range is 0 ℃ to 200 ℃ with an accuracy of 1 ℃.
—— Surface thermometer: the temperature measuring range is 0 ℃ to 100 ℃ with an accuracy of 1 ℃.
—— Thermostatic water bath: temperature control accuracy is ±1 ℃.
—— Vernier caliper: the measuring range is 0 mm to 150 mm with an accuracy of 0.02 mm.
—— Injection-profiling machine: pneumatic or hydraulic piston injection-profiling machine or wax injection machine.
In: mm
Figure 1 Schematic diagram for specimen holder
3.3 Preparation of specimen
3.3.1 See Figure 2 for the dimension and shape of the profiled cavity and die orifice.
3.3.2 Test block dimensions: 20 mm × 40 mm × 6 mm.
In: mm
Figure 2 Schematic diagram for specimen profiling
3.3.3 The injection temperature shall be the best temperature value determined in actual production, and the fluctuation range of injection temperature shall be controlled within ± 1 ℃.
3.3.4 The injection pressure is (1.18 ± 0.02) MPa, and other injection pressures, if adopted, shall be indicated in the test report.
3.3.5 The profiling temperature is (28 ± 1) ℃ and the holding time is (100 ± 10) s.
3.3.6 Load the pattern wax material into the cylinder preheated to the injection temperature for injection-profiling, which can only be carried out once for each loading, after injection, the thickness of the remaining material in the wax cylinder shall not be less than 20 mm.
3.3.7 The specimen shall be free of defects such as cracks, air holes, mechanical damage, cold shut, etc. When subject to perspective inspection under light, the specimen shall be free of holes inside.
3.3.8 More than 9 acceptable specimens shall be made.
3.3.9 Place the specimen in a thermostatic water bath at (20 ± 0.5) ℃ for 4 h, take it out and dry it for testing. The specimen shall not be flexurally deformed during storage.
3.4 Test procedure
3.4.1 Measure the dimension of the specimen with a vernier caliper.
3.4.2 Place the specimen on the fixture bracket of the tester, and it shall not be skewed or inclined. Fix the indenter on the loading rod with its cutting edge parallel to the two cutting edges on the bracket, and it shall be placed in the middle position.
3.4.3 Start the tester to load with a loading rate of 1.5 N/s to 2 N/s.
3.4.4 Record the load when the specimen breaks.
3.4.5 If the fracture is defective, the test is invalid.
3.5 Calculation of test result
3.5.1 Substitute the test results into Formula (1) to obtain the bending strength of the pattern wax materials.
(1)
where,
σw—— the bending strength, MPa;
F—— the load when the specimen breaks, N;
L—— the spacing between two fulcrums of specimen, mm;
b—— the specimen width, mm.
h—— the specimen thickness, mm.
3.5.2 Calculate the standard deviation (σ) of the bending strength test results of the pattern wax materials, and then calculate the arithmetic mean after excluding data other than 3σ to express the bending strength value of the pattern wax materials. At least 9 specimens shall be used to calculate the arithmetic mean
3.6 Measurement accuracy and error
3.6.1 Repeatability
For the same specimen of pattern wax material tested by the same operator in the same laboratory, the difference between the two results shall not be greater than 0.6 MPa.
3.6.2 Reproducibility
For the same specimen of pattern wax material tested by different operators in different laboratory, the difference between the two results shall not be greater than 1 MPa.
4 Testing of surface hardness
4.1 Overview of testing method for surface hardness
The surface hardness of the low temperature pattern wax material is expressed in needle penetration, which refers to the depth of the standard needle inserted into the pattern wax material in the vertical direction within 5 s under a load of 100 g at a temperature of 20 ℃, in 10-1 mm.
4.2 Instruments and apparatus
Instruments for surface hardness testing:
—— Penetrometer or automatic penetrometer and its accessories shall be adopted.
—— Surface thermometer: the temperature measuring range is 0 ℃ to 100 ℃ with an accuracy of 1 ℃.
—— Mercury-in-glass thermometer: the temperature measuring range is 0 ℃ to 200 ℃ with an accuracy of 1 ℃.
—— Thermostatic water bath: the temperature control accuracy is ± 1 ℃.
—— Flat-bottom heat preservation dish: the capacity and depth are no less than 1 L and 50 mm respectively.
4.3 Specimen
4.3.1 Specimen containing ring
The specimen containing ring is made of stainless steel, and its shape and dimension are shown in Figure 3.
Foreword i 1 Scope 2 Terms and definitions 3 Testing of bending strength 4 Testing of surface hardness 5 Testing of thermal stability 6 Testing of wetting angle of investment - binder 7 Test report Annex A (Informative) Comparison of the differences between the new and previous standards Bibliography
Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
GB/T 14235 comprises the following parts under the general title Low temperature pattern wax materials for investment casting:
—— Part 1: Testing methods for physical properties;
—— Part 2: Testing methods for usability properties.
This is part 2 of GB/T 14235.
This part is drafted in accordance with the rules given in GB/T 1.1-2009.
This part replaces GB/T 14235.2-1993 Testing methods for bending strength of pattern materials in investment casting, GB/T 14235.5-1993 Testing method for surface hardness of pattern materials in investment casting, and GB/T 14235.9-1993 Testing method for thermal stability of pattern materials in investment casting, this part is an integrated revision of GB/T 14235.2-1993, GB/T 14235.5-1993 and GB/T 14235.9-1993. The following main technical changes have been made with respect to the 3 replaced standards:
—— the application scope of the standard is modified (see clause 1);
—— the testing method is added for wetting angle between pattern materials in investment casting and binder (see clause 6);
—— the clause is added for test report (see clause 7);
—— Annex A gives a comparison of the differences between this part and the 3 replaced standards.
This part was proposed by and is under the jurisdiction of SAC/TC 54 the National Technical Committee on Foundry of Standardization Administration of China.
The previous editions of this standard are as follows:
—— GB/T 14235.2-1993;
—— GB/T 14235.5-1993;
—— GB/T 14235.9-1993.
Low temperature pattern wax materials for investment casting - Part 2: Testing methods for usability properties
1 Scope
This part of GB/T 14235 specifies the test methods for usability properties such as bending strength, surface hardness, thermal stability and wetting angle of investment - binder.
This part is applicable to the determination of the usability properties such as bending strength, surface hardness, thermal stability and wetting angle of investment - binder.
2 Terms and definitions
For the purposes of this document, the following term and definition apply.
2.1
bending strength at ambient temperature of low temperature pattern wax materials
strength of the load obtained from static bending to brittle fracture at a certain loading speed
3 Testing of bending strength
3.1 Overview of testing method for bending strength at ambient temperature
The prepared paste or liquid pattern wax materials is pressed into a strength specimen with a specified dimension. After the specimen is placed at a certain temperature for 24 h, the load peak value of the static bending brittle fracture is tested by a flexural properties tester, and the bending strength of the specimen is calculated with the mechanical formula.
3.2 Instruments and apparatus
Instruments for bending strength testing:
—— Flexural property tester: see Figure.1 for the specimen holder installed on the flexural property tester, with a fulcrum spacing of 30 mm.
—— Mercury-in-glass thermometer: the temperature measuring range is 0 ℃ to 200 ℃ with an accuracy of 1 ℃.
—— Surface thermometer: the temperature measuring range is 0 ℃ to 100 ℃ with an accuracy of 1 ℃.
—— Thermostatic water bath: temperature control accuracy is ±1 ℃.
—— Vernier caliper: the measuring range is 0 mm to 150 mm with an accuracy of 0.02 mm.
—— Injection-profiling machine: pneumatic or hydraulic piston injection-profiling machine or wax injection machine.
In: mm
Figure 1 Schematic diagram for specimen holder
3.3 Preparation of specimen
3.3.1 See Figure 2 for the dimension and shape of the profiled cavity and die orifice.
3.3.2 Test block dimensions: 20 mm × 40 mm × 6 mm.
In: mm
Figure 2 Schematic diagram for specimen profiling
3.3.3 The injection temperature shall be the best temperature value determined in actual production, and the fluctuation range of injection temperature shall be controlled within ± 1 ℃.
3.3.4 The injection pressure is (1.18 ± 0.02) MPa, and other injection pressures, if adopted, shall be indicated in the test report.
3.3.5 The profiling temperature is (28 ± 1) ℃ and the holding time is (100 ± 10) s.
3.3.6 Load the pattern wax material into the cylinder preheated to the injection temperature for injection-profiling, which can only be carried out once for each loading, after injection, the thickness of the remaining material in the wax cylinder shall not be less than 20 mm.
3.3.7 The specimen shall be free of defects such as cracks, air holes, mechanical damage, cold shut, etc. When subject to perspective inspection under light, the specimen shall be free of holes inside.
3.3.8 More than 9 acceptable specimens shall be made.
3.3.9 Place the specimen in a thermostatic water bath at (20 ± 0.5) ℃ for 4 h, take it out and dry it for testing. The specimen shall not be flexurally deformed during storage.
3.4 Test procedure
3.4.1 Measure the dimension of the specimen with a vernier caliper.
3.4.2 Place the specimen on the fixture bracket of the tester, and it shall not be skewed or inclined. Fix the indenter on the loading rod with its cutting edge parallel to the two cutting edges on the bracket, and it shall be placed in the middle position.
3.4.3 Start the tester to load with a loading rate of 1.5 N/s to 2 N/s.
3.4.4 Record the load when the specimen breaks.
3.4.5 If the fracture is defective, the test is invalid.
3.5 Calculation of test result
3.5.1 Substitute the test results into Formula (1) to obtain the bending strength of the pattern wax materials.
(1)
where,
σw—— the bending strength, MPa;
F—— the load when the specimen breaks, N;
L—— the spacing between two fulcrums of specimen, mm;
b—— the specimen width, mm.
h—— the specimen thickness, mm.
3.5.2 Calculate the standard deviation (σ) of the bending strength test results of the pattern wax materials, and then calculate the arithmetic mean after excluding data other than 3σ to express the bending strength value of the pattern wax materials. At least 9 specimens shall be used to calculate the arithmetic mean
3.6 Measurement accuracy and error
3.6.1 Repeatability
For the same specimen of pattern wax material tested by the same operator in the same laboratory, the difference between the two results shall not be greater than 0.6 MPa.
3.6.2 Reproducibility
For the same specimen of pattern wax material tested by different operators in different laboratory, the difference between the two results shall not be greater than 1 MPa.
4 Testing of surface hardness
4.1 Overview of testing method for surface hardness
The surface hardness of the low temperature pattern wax material is expressed in needle penetration, which refers to the depth of the standard needle inserted into the pattern wax material in the vertical direction within 5 s under a load of 100 g at a temperature of 20 ℃, in 10-1 mm.
4.2 Instruments and apparatus
Instruments for surface hardness testing:
—— Penetrometer or automatic penetrometer and its accessories shall be adopted.
—— Surface thermometer: the temperature measuring range is 0 ℃ to 100 ℃ with an accuracy of 1 ℃.
—— Mercury-in-glass thermometer: the temperature measuring range is 0 ℃ to 200 ℃ with an accuracy of 1 ℃.
—— Thermostatic water bath: the temperature control accuracy is ± 1 ℃.
—— Flat-bottom heat preservation dish: the capacity and depth are no less than 1 L and 50 mm respectively.
4.3 Specimen
4.3.1 Specimen containing ring
The specimen containing ring is made of stainless steel, and its shape and dimension are shown in Figure 3.
Contents of GB/T 14235.2-2018
Foreword i
1 Scope
2 Terms and definitions
3 Testing of bending strength
4 Testing of surface hardness
5 Testing of thermal stability
6 Testing of wetting angle of investment - binder
7 Test report
Annex A (Informative) Comparison of the differences between the new and previous standards
Bibliography
