Your supplier of high pressure laboratory instruments

Your supplier of high pressure laboratory instruments

OCAI-70 Original Cerchar abrasivity 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.



ASTM D7625-10.


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)

260 x 460 x 375 mm


ASTM-compliant, original version

Easy manual handling

Features precision slide for smooth movement of the rock specimen over the required scratch distance

Easy adjustment of the daylight for different specimen heights

Video presentation:


Une réalisation