OCAI 70-Original Cerchar abrasiveness index tester - ASTM D7625-10


The OCAI-70 accurately determines the rock abrasivity index (CAI) employed for the classification of rock materials in terms of abrasivity. The CAI is a dimensionless unit obtained from measuring the wear on a HRC55 Rockwell Hardness steel stylus tip after it has been used to abrade a specimen with a 70N normal force. This instrument follows the ASTM D7625 method for determining the rock abrasiveness. The apparatus comprises a stationary stylus, a deadweight (70N) placed on top of the stylus. An articulated axis allows the user to place the stylus on the specimen. Then the movement of the axis will produce a reproducible stripe of length 10mm. The movement of the test is made by the operator at a speed of 1mm/second. Options include an indenter visualization system, spare indenters and a sharpening tool. The former encompasses a digital camera with indenter support and inspection software to reveal the wear amount which is then correlated to the abrasiveness index (CAI). The sharpening tool rapidly sharpens a worn stylus for subsequent scratch tests.

For more information, please visit Floxlab's website:  floxlab


Standard : ASTM D7625-10.
Manufacturer :
70 N
Maximum specimen height:
150 mm (6 inches)
Maximum specimen diameter:
76 mm (3.0 inches)
Scratch distance precision:
0.01 mm
Steel Stylus:
Rockwell Hardness HRC 54/56
25 kg
Dimensions (WxLxH):
260x 460 x 375 mm


* ASTM-compliant
* Easy manual handling, original version
* Features precision slide for smooth movement of the rock specimen over the required scratch distance
* Easy adjustment of the daylight for different specimen heights