Sonntag Universal Impact Machine

Prepared by:

Laraba Kendig


Dow 2231


The following materials and equipment associated with this procedure present exposure or physical health hazards. Safety precautions are prudent and mandatory.

The head of the impact tester is very heavy and moves at high velocity. Be diligent about keeping all body parts of our of the path of the swinging head.


Prior to performing this procedure, the following safety equipment must be accessible and ready for use: (e.g. chemical fume hood, biological safety cabinet, laminar flow hood, chemical spill kits)


Protective Equipment:

Prior to performing this procedure, the following personal protective equipment must be obtained and ready for use: (e.g. acid resistant gloves, safety eyewear, lab coat, chemical splash apron)

You must wear safety glasses at all times in the Impact Tester laboratory

Waste Disposal:

This procedure will result in the follow regulated waste which must be disposed of in compliance with environmental regulations.



In the event that a hazardous material spills during this procedure, be prepared to execute the emergency procedure below.

Not Applicable


Note: The Impact tester is currently set up with a heavy head. Use the correct chart on the Impact tester to determine the toughness of each fractured specimen.

  1. Lift the head up to either half or full height, depending on how tough your sample is. If your sample is quite brittle, you may want to use the half height (100 ft.-lbs.). If it is very tough, use full height (240 ft.-lbs.). You will have to move the head to the correct position for the head to be latched. The latch clicks into holes at the base of the pendulum. Move the lever from "release" to "latched" when the head is lifted to the correct position.
  2. Put your sample into the sample holder. You may either use an Izod set-up or a Charpy set-up. See Callister's Materials Science and Engineering book for details on the differences between these two methods. Tighten the screw on the sample holder so that your sample is held securely. WARNING: At this time, the head is suspended in the air above your head. You may want someone to "spot" the head as an added precaution against having it give way unexpectedly. If it did give way (but it shouldn't), you could be hurt quite badly since you are in the path of the pendulum while securing the sample.
  3. On the toughness scale, move the toughness marker to the 100/240 position. Read the directions near the scale for assistance in this.
  4. Stand back and make sure that no one is in the path of the pendulum.
  5. Pull the lever from "latched" to "release". The pendulum will swing down and the head will smash into your sample, breaking it.
  6. Wait for the pendulum to stop swinging. You can move the lever from "release" to "brake" to slow it down faster. BE CAREFUL not to put your hand in the path of pendulum to stop it. It may still be moving with a lot of force.
  7. Read the toughness off of the scale. The toughness is indicated by how far the marker moved when the pendulum came down the first time.
  8. Remove your sample.
  9. Clean up any broken pieces of sample in the sample holder and around the base of the Impact Tester.


Last Revision:

Jun 24, 2024