Barcol Impressor

Barcol lmpressor is an indentation hardness tester originally made in the USA. It has 3 models in series. 934-1 is the typical model which is in widest application.

Barcol lmpressor is mainly applied in two areas: One is aluminum fabrication industry, to test pure aluminum, soft aluminum alloys, thick aluminum alloys, aluminum belts, aluminum alloys extrusions, bars, castings, forgings and assembled aluminum alloy parts (e.g. Al-alloy door &window, curtain wall etc.) Relevant standard is American standard ASTM 8648-00 《Test Method for Indentation Hardness of Aluminum Alloys by Means of a Barcol lmpressor》;the other is fiber reinforced plastics industry, most of the domestic and abroad fiber reinforced rlastics products are required to test Barcol hardness. Relevant standard is American standard ASTM D2583-07 《Test Method for Indentation Hardness of Rigid Plastics by Means of a Barcol lmpressor》.

Principle and Structure

Barcol Impressor is a kind of indention hardness tester. It uses a special shape indenter impressed into the
specimen by a standard string pressure and measures the indentation depth to obtain hardness value.
Barcol hardness value is:
HBa=100-h/0.0076
HBa—Barcol hardness value
h——indentation depth (mm)
0.0076—–indentation depth for one unit of Barcol hardness
The structure of Barcol Impressor is illustrated in Fig.1.
The main testing system of Barcol Impressor is set in the frame. The indenter is in the full scale adjusting screw
(indenter sleeve) with a plunger loaded by load spring on top. The test force applied on indenter by load spring
through plunger is adjusted by load adjusting screw. The plunger moves up and down along with indenter, thus,
the dial indicator shows hardness reading through the lever. The legs fixed at the back of the frame can insure the
indenter be perpendicular to test surface. The enclosures at both left and right sides protect the inner system from
being damaged and changed.
The top of indenter is 0.76mm, equivalent to 100 degrees upper on the top surface of full scale adjusting screw when the
impressor is under nonworking condition. The indicator pointed on zero at this moment.

Technical Parameters

Indenter:
26°panhead cone, head face diameter 0.176mm
Testing Range: 0~100HBa，equivalent to 25~150HBW
Resolution: 0.5HBa
Indication error: hardness range
42~52HBa, ±2HBa
hardness range 84~88HBa ±1HBa
Repeatability error: hardness range 42~52HBa, ±2HBa
hardness range 84~88HBa ±1HBa
Net weight:
0.5kg

Test Times

The error of Barcol Impressor is bigger than Brinell hardness tester and Rockwell hardness tester. In order to reduce the test error, test for several times and take the average reading . The softer specimen i s, the more test times need to be carried out. The test times should be even more when testing composite material The recommended test times according to different hardness value on homogeneous material and heterogeneous material are shown as table 1 and table 2.

Table 1 Recommend test times for aluminum alloys materials (according to ASTM B648-2000)

Barcol Hardness	Min. Test Times
50	6
60	5
70	4
80	3

Table 2 Recommend test times for fiber reinforced plastics and rigid plastics (according to GB/T3854-2005)

rigid plastics		fiber reinforced plastics
Barcol Hardness	Min. Test Times	Barcol Hardness	Min. Test Times
20	9	30	29
30	8	40	22
40	7	50	16
50	6	60	10
60	5	70	5
70	4
80	3

Model Selection

There are 3 models in Barcol series.

Model 934-1 which is equipped with standard load spring and standard indenter is in widest application. It is used to test aluminum and aluminum alloys, copper and copper alloys, fiber reinforced plastics, other reinforced plastics and unreinforced plastics etc. Its testing range is equivalent to 25-135HBW (500kg, 10mm).The typical Barcol hardness of aluminum and aluminum alloys of different grades and conditions are shown as table 3:

Table 3 Typical Bracol hardness of aluminum alloys

Alloys and heat treatment	1100-0	3003-0	3003H14	2024-0	5052-0	5052H14	6061T6	2024T3
Barcol Hardness	35	42	56	60	62	75	80	85

Model 935 which is equipped with softer load spring and standard indenter is used to test softer plastics, soft metals such as lead and tin and wood materials like floor etc. Its testing range is equivalent to 50-110HRR.

Model 936 which is equipped with softer load spring and indenter with bigger cone angle is used to test even softer materials such as leather, felt and soft wood etc.

Standard Package

Tester Leg

Standard hardness block (2 pcs) Spare indenters (2 pcs) Calibration wrench

Carrying case

Optional Accessories

High value Standard hardness block Low value Standard hardness block Spare indenters