ASTM C1495 Test for Effects of Surface Grinding on Flexure Strength of Advanced Ceramics

Scope:

ASTM C1495 method determines the effects of different grinding conditions on flexural strength. For this, advanced ceramics are tested under different grinding conditions to measure their effects on flexural strength. This test can be used to rank different materials based on their response to one or more different grinding conditions. All these measurements can be used to develop an optimum grinding process. They can also be used to develop ceramic materials which are more tolerant of grinding damage. This ASTM C1495 test is also used for quality control purposes to ensure the consistency of a grinding process.

This test applies to grinding methods that generate a planar surface, such as a flat surface. It does not apply to grinding methods that generate non-planar surfaces, for instance, cylindrical.

Flexure test methods that are used to determine the effect of surface grinding are ASTM C1161 (Test Method for Flexure Strength of Advanced Ceramics at Ambient Temperatures) and C1211 (Test Method for Flexure Strength of Advanced Ceramics at Elevated Temperatures). Materials tested in this standard are those that are specified in the standards C1161 and C1211.

ASTM C1161 and C1211 require test specimens that have a rectangular cross-section, flat surfaces, and that are fabricated with specific dimensions and tolerances.

Test Procedure: 

The detailed procedures for conducting ASTM C1495 flexure tests are given in C1161 and C1211. C1161 and C1211 cite procedures for conducting tests in both three-point and four-point flexure, but only the four-point flexure test applies to this standard. 

Depending on the objective of the measurements, two procedures, A and B, are available in ASTM C1495. 

Procedure A is restricted to linear grinding processes obtained, for instance, by a horizontal spindle, reciprocating-table surface grinder. Procedure A is used to determine the effects of different grinding conditions on flexural strength. And it determines the response of a material to surface grinding. All these measurements are used in developing an optimum grinding process and in material development. 

Procedure B is not restricted to linear grinding. It applies to any grinding method that produces a flat surface. As in Procedure A, the baseline flexural strength is compared with inherent flexural strength. Procedure B is primarily intended for quality control purposes but it can also be used for process development.

Video 01: Flexural test (3-point bend test)

Specimen size:

The specimen dimensions and tolerances for ASTM C1465 are specified in the flexure test standards ASTM C1161 and ASTM C1211. 

Data:

In ASTM C1465, flexure strength values for each test specimen are determined from break force, specimen width and thickness, and flexure span as described in C1161 and C1211.

The strength of a beam in four-point 1⁄4-point flexure is calculated by:

σ_f = flexural strength,

 P = break load, 

L = outer (support) span of the test fixture,  

b = test specimen width, and 

d = test specimen depth. 

Conclusion:

ASTM C1495 method determines the effects of different grinding conditions on flexural strength.