Friability Test Apparatus : Basics and Calibration



It is the % loss in weight of a specified quantity of tablets when subjected to mechanical shock or attrition in a suitably designed apparatus. Friability of a tablet play important role from its manufacturing to its distribution to the customer.

% Friability =   Loss of weight (g)/  Initial weight (g)  x 100

Friability test is carried out to measure the mechanical strength of a compressed and uncoated tablet, and the apparatus use to measure the friability test is called as friabilator.

Friabilator is consist of a plastic drum attached with horizontal axis the internal diameter of drum is 287 to 291 mm and the depth of the drum is about 38 mm, it is made up of transparent synthetic polymer with polished internal surface.

Sample Quantity:

Tablet having weight 650 mg or less than this take 6.5 g of the weighed tablet to carry out the test; If the weight of a tablet is more than 650 mg, take 10 tablets to carry out the test and subjected to 25 rpm for 4 minutes or 100 time rotation.

How to load the sample in friabilator or operation procedure:

  • Check the Instrument for cleanliness and ensure that the instrument is in Calibrated state.
  • Load the assembly to set the friabilator.
  • Operate the instrument from its functional key provided on display screen.
  • Select the run mode generally there are two mode for operation of friabilator is employed time mode and count count mode.
  • Put the weighed tablet in the tray and enter the weight of sample and select the start to run test.
  • After completion of test remove the tablets from the holder situated at the bottom of the acrylic pan of the friabilator.
  • If the tablet shape, size is irregular or whenever specified perform the friability test after tilting the friabilator by 10 degrees.
  • Dedust the tablets and check for capping or breaking. Weigh the tablets and calculate its % friability by above given formula.


Acceptance criteria:

  • For uncoated tablet the % friability should not more than 1%.
  • For conventional compressed tablets % lose should be in between 0.5 % to 1%.
  • For effervescent and chewable tablets In house limit will be set because they undergoes higher weight loss when subjected to friability test.


In general friability test is run only for single time, if any tablet found to be broken, cleaved or cracked after completion of test or if the % loss is greater than the targeted value it establishes that the sample fails the test, and the test should be repeated twice on the fresh samples mean of the three test shall be calculated and % loss should be not greater than 1% to meet the acceptance criteria.


Calibration of Friabilator :

Calibration for number of rotation in 1 minute, 2 minutes and 4 minutes:      

  • Set the time by selecting the Time mode and set the time to 1 minute.
  • Then start the apparatus and check the No. of Revolutions in 1 minute.
  • Repeat the test by setting the time for 2 minutes, 4 minutes and check the No. of  Revolutions in 2 minutes, 4 minutes and record the result.
  • Each test to be performed in triplicate.


Acceptance criteria:

  • 24 to 26 rotations in 1 minute.
  • 48 to 52 rotations in 2 minutes.
  • 96 to 104 rotations in 4 minutes


Calibration for Time for 25 rotations, 50 rotations and 100 rotations:

  • Set the count by selecting count mode and set the count to 25 revolutions.
  • Start the apparatus and check the time with the help of stop watch complete 25
  • Repeat the test by setting the count to 50 revolutions, 100 revolutions and check the time with the help of stop watch to complete 50 revolutions, 100 revolutions and record the result.
  • Each test to be performed in triplicate.


Acceptance criteria:

  • 0:57 00 to 1:03 00 minutes for 25 rotations.
  • 1:54 00 to 2:06 00 minutes for 50 rotations.
  • 3:48 00 to 4:12 00 minutes  for 100 rotations.


Calibrate the instrument Monthly ±7 days / after completion of maintenance activity. Calibration of Timer and Revolution shall be done by outside party once in a year.


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