Guide to leeb hardness testers


Rebound hardness testers , otherwise known as “ Leeb Hardness Testers ” are the alternative to traditional counter hardness testers , installed in laboratories . The revolution represented by rebound hardness testers is primarily related to their portability combined to very high precision and to the type of non-destructive test which are able to make .
This method is based on the Leeb principle introduced by Dietmar Leeb in 1975. Conceptually it’s defined as the ratio between impact speed and impact body rebound velocity , then multiplied by 1000 . Depending on metal type the Leeb method indicates hardness value that can be converted to other scales ( for example HB , HV , HRC etc. ) . Using the same principle is also possible to measure tensile strength in relation to steel . The operating principle is based on the application of a certain force to an impact body of a certain weight , that will go to touch the measuring surface .
The instrument respectively measure impact and rebound velocity when  spherical striker  is located to 1mm from the measuring surface . The calculation formula is the following:

HL=1000×(VB/ VA)

HL → Hardness value HLD
VB → Rebound speed of impact body
VA → Penetrator impact velocity

With this method we can measure many materials , like :

• Steel and fusions ;
• Cold work tool steel ;
• Stainless steel alloys ;
• Gray cast iron ;
• Nodular cast iron ;
• Mergers and aluminum alloys ;
• Brass alloys / zinc brass alloys ;
• Bronze alloys ;
• Copper alloys

Application areas of rebound hardness testers are many , some examples :

• Control and approval of incoming goods (input) ;
• Quality control on production line (output ) ;
• Stress measurement of material ( maintenance ) ;
• Testing tensile strength ;
• Molds cavity ;
• Bearings and other parts ;
• Troubleshooting pressure pots ;
• Steam generators and other equipment ;
•  Possibility of operation on large parts ;
• Assembled parts measurement ;
• Small areas measurement .


• Probes : Rebound hardness testers supports various types of probes according to inspection conditions and the tested material . Here are some models:




Tipo D

Standard model, ideal for 90% of measurements

Tipo S

Same application field of type D probe with impact body wear resistance 10 times greater

Tipo E

For hard metals

Tipo DC

Probe in size to operate in restricted spaces

Tipo D+15

Prolonged probe for bores measurements

Tipo DL

Probe with narrow profile for specific measure ( eg. Gears)

Tipo G

Increased impact probe

Tipo C

Low-impact probe to measure thin or sensitive to indentation samples.

Adaptor rings for convex and concave surfaces

Another important accessory is the set of adapter rings ,  that allows inspection of all surfaces , concave or convex . The adaptor ring , chosen by sample characteristics that should be measured , is substituted for the standard one included with probe . Here are kit adapter rings full specifications:



Ring type




For external cylindrical surfaces R10÷R15



For external cylindrical surfaces R14.5÷R30



For external cylindrical surfaces R25÷R50



For internal cylindrical surfaces R11÷R13



For internal cylindrical surfaces R12.5÷R17



For  internal cylindrical surfaces R16.5÷R30




For external cylindrical surfaces SR10÷SR15



For external cylindrical surfaces SR14.5÷SR30



For internal cylindrical surfaces SR11÷SR-13



For internal cylindrical surfaces SR12.5÷R17



For internal cylindrical surfaces SR16.5÷SR30






Universal adapter for exterior surfaces, variable radius R10÷∞

Integrated / external printer

The evolution of rebound hardness testers , according to market needs , grown through a series of  products specifically designed to deal with needs of productive sector . To give opportunity to write measurement reports in real time the vast majority of rebound hardness testers can be connected to an external printer or possess an integrated one . This solution is particularly indicated for operators who have to travel frequently and leave a tangible record of the inspection.

Pc interface

The increasing use of personal computers had a positive impact even in the world of rebound hardness testers . Today is possible to make communicate rebound hardness tester and a personal computer through simple and intuitive interfaces that allow less experienced operator to manage data and process them in several respects .


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