DeFelsko’s PosiTector BHI Barcol Hardness Impressor is designed for testing the hardness of rigid plastics and soft metals such as aluminum, aluminum alloys, copper, and brass. Comparable to 934-1 Barcol hardness Tester, the PosiTector BHI features an easy-to-read digital display, onboard memory, and includes a user-adjustable measurement timer with on-screen countdown.
For nearly 80 years, the Barcol Hardness test has been used to measure the hardness of materials. Conceived during World War II as a way to ensure aircraft rivets had not been sabotaged with inferior quality metal, the Barcol Hardness Impressor is still used today for a variety of applications including aluminum production, fiber and glass reinforced plastics, duro or hard thermo plastics, and to measure the degree of cure in composite materials.
Hardness is a measure of a material’s ability to resist permanent deformation such as bending, scratching, abrasion, or cutting. Quality Assurance and Quality Control demands require each material to meet a specific standard of hardness—often determined by tests like those done with a Barcol hardness tester.
Indentation hardness testers such as the PosiTector BHI Barcol Hardness Impressor and the PosiTector SHD Shore Hardness Durometer use a precisely-shaped tip/indentor connected to a calibrated spring, and measure how far the tip penetrates into the material. The greater the indentation, the lower the hardness.
Barcol hardness testing is a crucial step for quality assurance and quality control of materials such as rigid plastics, aluminum, aluminum alloys, copper, and brass. Each material needs to meet a specific standard of strength. Testing the Barcol hardness of a material determines its ability to resist deformation.
For some plastics and fiber-reinforced polymer composites, Barcol Hardness Testers can also be used to measure the degree of curing and cross-linking. Hardness increases as cure progresses until a maximum for the resin type is reached.
Barcol hardness is measured with a portable, hand-held unit like the PosiTector BHI, consisting of an indicating device (display) and an indentor. Per ASTM B648, “the indentor [is a] hardened steel truncated cone having an angle of 26° with a flat tip…”. One unit of Barcol hardness is equivalent to the indentor moving 0.0076 mm (0.00030 in.). A reading of zero means that the indentor penetrated the full 0.76 mm (0.03 in.) into the surface, without compressing the spring compress. A reading of 100 means that the indentor did not penetrate into the surface at all, and that the spring is fully compressed. A higher reading indicates a harder material.
The PosiTector BHI Barcol Hardness Impressor is a modern update to the Model 934-1, originally created over 75 years ago. The digital hardness tester minimizes the chance of operator error. These instructions are written for the PosiTector BHI, but can be used with any model of Barcol Hardness tester.
Step 1: Identify a Test Location
The Barcol hardness tester should be used on a hard, firm surface. If the material is thin or otherwise likely to deform, place it on a firm surface for the duration of the test.
Impressions should not be made within 3 mm (1/8 in.) of the edge of the part, or of other impressions.
Step 2: Take a Measurement
Ensure that the tester is perpendicular to the surface being tested, using shims to raise the ‘leg’ on irregular or small parts, if necessary. Press the probe down onto the material to be measured until the indentor foot is in full, flat contact with the surface. The test timer will begin counting down. When the timer reaches 0s, the gage will display the measurement value. If memory is enabled, the gage reading will be stored into onboard memory.
At the beginning and the end of each work shift, check the accuracy of the meter with the included test disks and leveling plate. On a hard, flat surface, place the Barcol hardness tester’s legs on top of the leveling plate and the test disk under the indentor tip. Once the gage is positioned, press the PosiTector BHI firmly down. Observe the measurement on the easy-to-read digital display. Take 3-5 readings on each disk to verify accuracy, ensuring at least 3 mm (1⁄8 in.) of distance from previous impressions.
The easy-to-read digital display takes the guess work out of reading analog scales, reducing the likelihood of operator error.
Each digital reading is stored into memory for future review and reporting. The on-screen statistics display makes it easy to identify trends and average readings. When measurement is complete, use the built-in USB port to download readings to a PC or Mac.
DeFelsko offers four free and unique ways to view, analyze, and report Barcol hardness data using PosiSoft Solutions. Select from a powerful desktop version, an easy-to-use mobile app, cloud storage, or PosiSoft USB – a simple gage interface similar to a flash drive. To learn more about our PosiSoft Solutions follow the link here.
The PosiTector BHI features an on-screen timer when measuring the hardness of a material. Set the timer to the desired limit, and it will automatically start counting down once the indentor is pressed firmly down on to the surface.
When enabled, the PosiTector BHI will continuously display hardness readings. Continuous Reading mode is ideal when a test timer is not required or when performing a calibration verification.
On-screen statistics like average, standard deviation, and min/max hardness are continually updated and displayed while measuring. All readings and statistics can be recorded into memory for further analysis and reporting.
The HiLo Alarm on the PosiTector BHI allows the gage to audibly and visibly alert the user when the readings exceed user-specified limits.
The Auto Sub-Batch automatically creates a new sub-batch in the Advanced model of the PosiTector BHI after the necessary number of readings are stored.
The following standards are used to determine the Barcol hardness of a material.
ASTM B648 guides the user through measuring the hardness of aluminum alloys. It defines proper techniques and procedures for measuring aluminum.
“1.1 This test method covers the determination of indentation hardness of aluminum alloys using a Barcol Impressor…”
“5.2 The Indentor shall consist of a hardened steel truncated cone having an angle of 26 degrees with a flat tip 0.157 mm (0.0062in) in diameter.”
*Refer to ASTM B648 for a complete description of the test standard.
ASTM D583 standard test method determines the indentation hardness of both reinforced and non-reinforced rigid plastics using a Barcol Hardness Impressor.
“1.1 This test method covers the determination of indentation hardness of both reinforced and non-reinforced rigid plastics using a Barcol Impressor…”
“4.1 A material’s surface hardness is determined through the use of a Barcol Impressor. The relative depth of penetration of the Impressor’s indentor provides a comparative measure of the material’s hardness.”
*Refer to ASTM D2583 for a complete description of the test standard.