Virtual Laboratory Instrument Training Series

Web Site Design
by
Dr. Glen A. Stone
South Dakota School of Mines and Technology
501 East Saint Joseph Street * Rapid City, SD 57701
(605)394-1284 * FAX (605)394-3369

© 2002 - Dr. Glen A. Stone - SDSM&T


Instrument: Wilson Rockwell Hardness Tester

Unsupervised Use of This Instrument Requires Passing an Instrument Usage Quiz
Instrument Location: MI 125

Hardness profile obtained from a MET 231 laboratory study of the Hardenability of Steels.

  1.  Vocabulary associated with this instrument.

Interrogate the instrument by placing the curser over various regions of the instrument.
Pop-up boxes will appear.
One of several anvils designed to support specimens being tested. This small diameter anvil is suggested for small specimens with gentle curvature. Such a specimen is placed with the center of curvature up One of several anvils designed to support specimens being tested. This small diameter anvil is suggested for small specimens with gentle curvature. Such a specimen is placed with the center of curvature up Dial gauge that is calibrated to provide Rockwell hardness numbers. There are two scales on the gauge: red and black. The correct scale is defined in Table 5 of ASTM standard E 18. This table is reproduced later in this presentation. Dial gauge that is calibrated to provide Rockwell hardness numbers. There are two scales on the gauge: red and black. The correct scale is defined in Table 5 of ASTM standard E 18. This table is reproduced later in this presentation. Oil displacement dashpot: This dashpot controls the rate of major loading on the specimen being tested. This loading control prevents the full major load from being applied instantaneously. Oil displacement dashpot: This dashpot controls the rate of major loading on the specimen being tested. This loading control prevents the full major load from being applied instantaneously. This is the load hanger. There are three possible loads applied during a Rockwell test: 60 kgf, 100 kgf, and 150 kgf. The instrument currently has 100 kgf on the hanger. This is the load hanger. There are three possible loads applied during a Rockwell test: 60 kgf, 100 kgf, and 150 kgf. The instrument currently has 100 kgf on the hanger. This handle allows the operator to start the application of the major load. A gentle clockwise rotation raises the loading beam over the top of a cam lobe. As soon as the operator senses the top of the cam lobe, release the handle. The dashpot will then control the rate of major loading of the sample and indenter. This handle allows the operator to start the application of the major load. A gentle clockwise rotation raises the loading beam over the top of a cam lobe. As soon as the operator senses the top of the cam lobe, release the handle. The dashpot will then control the rate of major loading of the sample and indenter. This four-handle wheel allows the operator to control the space between the anvil and the indenter. In addition this handle is used to apply the minor load. This four-handle wheel allows the operator to control the space between the anvil and the indenter. In addition this handle is used to apply the minor load. This four-handle wheel allows the operator to control the space between the anvil and the indenter. In addition this handle is used to apply the minor load.

  2.  Who uses this instrument?

MET 231, MET 331, and MET 441/541 Lab Classes, CAMP, CAAN, AMP, and Researchers

  3.  Who are the responsible faculty?

Mechanical Properties Laboratory Mentors
Dr. Dana Medlin
Office: MI 104

  4.  Safety!

  • There are no safety issues of concern associated with the Wilson Rockwell Hardness Tester. However, this is a crowded laboratory space. There are furnaces, the Fenn Rolling Mill, the Charpy Impact apparatus, the Jominy End-Quench apparatus, and the 20 kip MTS machine. Always be aware of who is around you and what they are doing.
  • Students are not allowed to work alone in the lab. There must always be a lab partner present when any equipment is being used in this laboratory.
  • Some instruments have a logbook. A logbook is not maintained for the Wilson Rockwell Hardness Tester.

  5.  Report Injuries

Report any injury, no matter how minor, to the person supervising the laboratory. If this person is not available find the department chair or the department secretary. If there is a major injury requiring medical attention:
call 0-911
The nearest phone is located in the main entrance stairwell.

  6.  Past Damage -- Wilson Rockwell Hardness Tester

The most common error leading to damage is not checking the position of the loading cam.
Check the position of the loading cam before attempting to apply the minor load to a specimen in the Wilson Hardness Tester.
Attempting to apply the minor load with the loading cam rotated clock-wise from its correct position can generate sufficient compressive load to crush the ball chuck. The 1/16-inch diameter steel indenter ball because of compression overloading of the assembly has crushed the right ball chucks in the two images.
Damaged Hardness Standards
  • Only the top surface of a Rockwell Standard Block is certified. By attempting to calibrate the Wilson Hardness Tester using the back of the block creates errors in your results and destroys the standard.
  • Never place a hardness indentation on the back of a standard!
  • Also this standard block has been exposed to the elements – allowed to get wet. Take care of the standard hardness blocks!

  7.  Maintenance

  • Regular Scheduled Maintenance
    • The Materials and Metallurgical Engineering Department schedules an annual service of all the Rockwell Hardness Testers. This service is provided by Washington Calibration, Inc.
  • Maintenance Expected of Student and Staff Users
    • Each student using the equipment must put all standards away, and clean the area around the instrument.


    After the spring 2002 semester the image to the right was the state of affairs around this and other instruments in this laboratory. Space is provided in the drawer below the machine or in storage block designed to hold specific items. Items not cared for:

    • Standards left on the bench
    • Several hardness indenters left lying on the bench -- not put away in the storage block
    • Anvils are not put away in the storage block
    • Lab samples left lying here and there
    • Table surface dirty

    Fault lies with both faculty and students. Lets bring an end to this disrespect for our laboratories!



  • Report Damage
    • Contact Dr. Medlin if an instrument is damaged. Leaving an instrument after it has been damaged is a disservice to those that follow. Please report damage as soon as it happens!

  8.  Instrument Operation Instructions

Quick Links to Instrument Operation Topics
  1. Getting Started
  2. Weight Configurations on a Wilson Hardness Tester
  3. Rockwell Hardness Tester Indenters Available in the Laboratory
  4. Animated Gif of Hardness Measurement Steps
  5. Set Minor Load
  6. Apply Major Load
  7. Video Illustrations
Getting Started
Prepare the Sample for Rockwell Hardness Measurement
Never attempt to conduct a hardness test on hollow tubes or samples mounted in Bakelite or other types of plastic mounting compounds.

The reason is the Rockwell test uses the motion of the indenter, not the surface area of the indentation to measure hardness. Because a hollow tube or plastic has a lower stiffness (modulus) than a solid metal an error in the reported hardness number will result.
ASTM E18 Defines the Proper Industry Standard for the Rockwell Hardness Test
For a valid Rockwell hardness measurement the surface finish and sample thickness must conform the ASTM E18.

Visit the Reference Section of the Library
Typical Sample
All samples must be solid metal. For sheet samples make sure both sides are flat and parallel to each other. Cylindrical samples can be tested provided the correct anvil is selected.
Several Anvils Available in the Laboratory
Select an anvil such that the sample will not move or shift in any way as the minor load is applied.

Weight Configurations on a Wilson Hardness Tester
Select and fix the load to 60 kgf, 100 kgf or 150 kgf, whichever applies for the hardness scale expected.
60 kgf 100 kgf 150 kgf
The Permanent Weight Hanger Provides the 60 kgf load.

Add the 40 kgf Weight for 100 kgf Load

Add the 40 and 50 kgf Weights for 150 kgf Load

Rockwell Hardness Tester Indenters Available in the Laboratory
Select and mount on the machine the correct indenter. Consult the sophomore laboratory Hardness Testing Handout for additional information.

Animated Gif of Hardness Measurement Steps




1. Apply Minor Load
2. Apply Major Load
3. Remove Major Load
4. Record Hardness Number

Photograph Sequence Illustrating How to Set Minor Load
Rotate four handled wheel counter-clockwise to create sufficient space between the anvil and indenter. Rotate four handled wheel clockwise to bring anvil and indenter in contact. Rotate four handled wheel clockwise until minor load is applied. Minor load is set when small dial is aligned with the dot.
If the large dial hand is not exactly over the zero, it is permissible to rotate the outside ring to make it so.

Apply Major Load: Gently rotate cam clockwise until its motion is controlled by the dashpot.
Gently rotate the cam clockwise until the cam moves on its own. The dashpot now controls the rate the major load is applied. After the cam's clockwise rotation stops it is usual to maintain the major load for a predetermined time. The same elapse time for major load application is used for each of the following hardness measurements. Major load is set. The large dial may move slowly as the indenter continues to penetrate the sample by a process called creep.
  • Remove Major Load: Gently rotate the cam counter-clockwise until it stops.
  • Read the appropriate hardness scale. See Illustration below.
  • Remove the sample by rotating four-handled wheel counter-clockwise.

Gently rotate the cam counter-clockwise until the cam stops. Read the Rockwell hardness number.
This test used 100 kgf and the 1/16-in ball.
Thus the red dial is used.
The hardness is HRB 94.

Video Illustrations
↓ Play Video Illustration ↓
Rockwell Hardness Test
DSL or Cable
Dial Up Modem
↓ Play Video Illustration ↓
Gauge Movement During a Test
DSL or Cable
Dial Up Modem

  9.  Link to Quiz and Web Site Evaluation Form

  • If you are enrolled in MET 231, 331 or 441/541 the Username and Password is your student ID number.
  • If you are working on a CAMP, CAAN or AMP project and enrolled as an graduate or undergraduate student, contact Dr. Medlin via email. Your Password and Username will set as your student ID number.
  • If you are a visitor, email or contact Dr. Medlin directly. A temporary Username and Password will be provided.
Unsupervised use of this equipment requires personal certification by Dr. Medlin, or passage of the qualifying quiz with a grade of 100%