What is the Significance Cupping Test?

Cupping test is a significant test to assess the ductile properties of the metal. In this test, a punching force is applied to the metal sheet of thickness from 0.2mm to 2mm. A visual inspection is done to see if the test material has developed any cracks or deformity. The force applied on the sample is displayed by the gauge.

It is very simple to perform this test but it tells very crucial aspects about the test sample. The testing machine conducts this test on the principle that a cup-shaped depression is created in the sheet by applying force through a punch on the clamped test material until a visible deformation occurs. What is the depth of the cup with respect to the applied force is measured.

This is a manually performed test. The highly calibrated scale is needed to measure the force applied on the sheet.

Why is Cupping Test Important?

When we talk about cupping testing procedure, there is a minor confusion about its important. If it is important for testing properties of metal sheets or for testing properties of coatings? Well, for both. Different industries use cupping test machine for assessing different quality factors. For metal, it is done to adjudge the ductile properties. For some applications, it becomes important that metal should bear the punch to a certain extent without getting cracked. E.g. automobiles with metal bodies must pass this test. As vehicles are prone to dents due to external impacts, the metal body should be ductile enough not get cracked.

Again, in the automobile industry, this cupping test is performed to check the elongation of the coating done on the body of the vehicle. The paint should not chip off or cracked when a dent is formed due to the punch. If coating gets removed, the metal underneath would become prone to corrosion.

What Precautions Needed to Be Taken?

This is a very simple to perform the test and a very simple cupping test machine is used to conduct this test. But to get the precise results, you need to take some precautions to increase the efficiency of the test. As such you don’t need any specified conditions.

• Clamp the sample tightly on the blank holder so that it should not slip when punch applies force to it.
• Once you start the test, do not allow the punch to be moved, else the depression created by it would not be ideal to check the actual behavior.
• Force is applied to the sample until a crack develops that allows the light to pass through
• Measurement should be started when punch just touches the surface initially.