Introduction
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 .
Accessories:
• Probes : Rebound hardness testers supports various types of probes according to inspection conditions and the tested material . Here are some models:
|
Probe |
Scope |
|
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:
|
Nr |
Type |
Ring type |
Description |
|
1 |
QE-15 |
|
For external cylindrical surfaces R10÷R15 |
|
2 |
QE.5-30 |
For external cylindrical surfaces R14.5÷R30 |
|
|
3 |
QE-50 |
For external cylindrical surfaces R25÷R50 |
|
|
4 |
QI11-13 |
|
For internal cylindrical surfaces R11÷R13 |
|
5 |
QI12.5-17 |
For internal cylindrical surfaces R12.5÷R17 |
|
|
6 |
QI16.5-30 |
For internal cylindrical surfaces R16.5÷R30 |
|
|
7
|
CE10-15 |
|
For external cylindrical surfaces SR10÷SR15 |
|
8 |
CE14.5-30 |
For external cylindrical surfaces SR14.5÷SR30 |
|
|
9 |
CI11-13 |
|
For internal cylindrical surfaces SR11÷SR-13 |
|
10 |
CI12.5-17 |
For internal cylindrical surfaces SR12.5÷R17 |
|
|
11 |
CI16.5-30 |
For internal cylindrical surfaces SR16.5÷SR30 |
|
|
12
|
UN |
|
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 .
Copyright by © SAMA Tools All rights reserved
