Fragmentation Test For Glass

Fragmentation Test Method / Procedure for tempered glass

Fragmentation Test (Ref : IS 2553-1990)

Principle : Toughened glass is broken by giving it a sudden punch and no of broken particle per unit area are counted.
Procedure :

i)                    Three glasses from each lot having the same thickness are to be tested for this purpose. The specimen shall be supported as far as possible over its whole area, means being provided to prevent any substantial spreading of the fragments.

ii)                  The three glasses shall be broken by means of a centre punch of  0.20 ±0.05 mm in radius of curvature at its tip by giving a severe blow to cause fracture.

iii)                The particle count determination on any one piece of glass sheet shall be completed before 3 minutes of the fracture of that glass. No magnifying lense or other aid to vision shall be used when making the particle count.

iv)                The broken particle in a square of side 5 cm shall be counted. A fragment on the side line of the square shall be counted as half. The particle count shall be made in the region of the coarsest fracture excluding the areas, within 20 mm from the periphery of the glass and within 75 mm in radius from the point of impact.

Interpretation Of Results :
The material shall be taken as having satisfied the requirement of the tests if:
a) Glasses up to 4 mm thickness:

i)                    There are not more than 400 particles and not less than 40 particles in a square of side 5 cm in the coarsest area.

ii)                  If the count is between the limits of less than 40 but not less than 30 per 25 cm square, the count in the embracing square of side 10 cm is not less than 160 particles.

b) Glasses above 4 mm thickness

iii)                There are not more than 400 particles and not less than 60 particles in a square of side 5 cm in the coarsest area.

iv)                If the count is between the limits of less than 60 but not less than 40 per 25 cm square, the count in the embracing square of side 10 cm is not less than 240 particles.

If the fragmentation of any glass proves to be unsatisfactory, three additional glasses shall be taken from the lot and test repeated.

Resistance To Shock Test

Principle : The toughened safety glass is given a sudden shock with a smooth surface steel ball of 63.5 mm in diameter from a height of 100 cm.

Apparatus:

A steel ball of about 63.5 mm in dia  and  weighing 1040±2 gm with smooth surface.   

Test Specimen :

The test specimen for use in the test shall be tampered glass about 610 x 610 mm square having the same thickness ,

Testing Frame :

i)                    The test specimen shall be supported with an iron frame.

ii)                  A mean of droping the ball freely from a height of 100 cm so as to strike the specimen within 25 mm from the centre is required. An electromagnet to be used for this.

Procedure :

i)                    Place the test specimen on testing frame. The steel ball is placed at a height of 100 cm from the surface, allowed to fall towards the centre of the surface of test specimen from standstill state without any force applied. The presence of breaking is observed.

ii)                  The number of impact per test specimen shall be limited to one time and the test shall be carried out at ordinary temperature.

iii)                Five specimen are to be tested for the test

Interpretation Of Results :
The product shall be accepted when not more than one sheet is broken and rejected when 3 or more sheets of them are broken. When two sheets are broken, another sample of 5 sheets shall be tested and lot accepted if all 5 sheet pass the test.