The basic procedures for making a test with the Riehle tester are as follows:
1. Apply a minor load of 10 kilograms.
2. Set the penetration indicator to zero.
3. Apply a major load of 60, 100, or 150 kilograms (depending on the scale), and then reduce the load back to the initial 10-kilogram load.
4. Read the hardness directly on the penetration indicator.
The hardness reading is based on the measurement of the additional increment of penetration produced by applying a major load after an initial penetration has been produced by the minor load. In reporting a hardness number, the number must be prefixed by the letter indicating the scale on which the reading was obtained.
Removal and Replacement of a Penetrator
The penetrator is retained in the tester by means of a small knurled clamp screw extending from the top of
Fig. 1-29.-Barcol portable hardness tester.
5.5 BARCOL TESTER
The Barcol hardness tester, the upper clamp. To remove a penetrator, there should beat least 2 or 3 inches of space between the upper and lower clamps so that one hand can be placed underneath the upper clamp to catch the penetrator when it is released. Two or three turns of the clamp screw will release the penetrator. The two contact pins that extend through the penetrator on either side of the point are retained in the tester when the penetrator is removed.
To replace a penetrator, it must be turned so that the flat side faces the clamp screw, and the locating pin on the penetrator is in line with the slot provided to take the pin. The contact pins should be guided into their respective holes through the penetrator. With the penetrator in place, it should then be clamped securely by turning the clamp screw. Before you make an actual test, one or two preliminary tests should be made to properly seat the penetrator.
shown in figure 1-29, is a portable unit designed for testing aluminum alloys, copper, brass, and other relatively soft materials. Approximate range of the tester is 25 to 100 Brinell. The unit can be used in any
position and in any space that will allow for the operator’s hand. The hardness is indicated on a dial conveniently divided in 100 graduations.
Fig. 1-30-Cutaway of Barcol tester.
Figure 1-30 is a cutaway drawing of the tester, showing the internal parts and their general arrangement within the case.
The lower plunger guide and point are accurately ground so that attention need be given only to the proper position of the lower plunger guide within the frame to obtain accurate operation when a point is replaced.
The frame, into which the lower plunger guide and spring-tensioned plunger are screwed, holds the point in the proper position. Adjustment of the plunger upper guide nut, which regulates the spring tension, is made when the instrument is calibrated at the factory.
CAUTION
The position of this nut should not be changed. Any adjustment made to the plunger upper guide nut will void the calibrated settings made at the factory.
The leg is set for testing surfaces that permit the lower plunger guide and the leg plate to be on the same plane. For testing rivets or other raised objects, a block may be placed under the leg plate to raise it to the same plane. For permanent testing of this type, the leg maybe removed and washers inserted, as shown in the drawing. The point should always be perpendicular to the surface being tested.
The design of the Barcol tester is such that operating experience is not necessary. It is only necessary to exert a light pressure against the instrument to drive the spring-loaded indenter into the material to be tested.
Table 1-5.-Typical Barcol Readings for Aluminum Alloys
The hardness reading is instantly indicated on the dial. Several typical reading for aluminum alloys are listed in table 1-5. The harder the material, the higher the Barcol number.
To prevent damage to the point, avoid sliding or scraping when it is in contact with the material being tested. If the point should become damaged, it must be replaced with a new one. No attempt should be made to grind the point.
Each tester is supplied with a test disc for checking the condition of the point. To check the condition of the point, press the instrument down on the test disc. When the downward pressure brings the end of the lower plunger guide against the surface of the disc, the indicator reading should be within the range shown on the test disc.
To replace the point, remove the two screws that hold the halves of the case together. Lift out the frame, remove the spring sleeve, loosen the locknut, and unscrew the lower plunger guide, holding the point upward so that the spring and plunger will not fall out of place. Insert the new point and replace the lower plunger guide, screwing it back into the frame, Adjust the lower plunger guide with the wrench that is furnished until the indicator reading and the test disc average number are identical. After the lower plunger guide is properly set, tighten the locknut to keep the lower plunger guide in place, This adjustment should be made only after installing anew point; any readjustment on a worn or damaged point give erroneous readings.
Fig. 1-31.-Ernst portable hardness tester.
THE ERNST PORTABLE HARDNESS TESTER HAS A DIAMOND-TIPPED PENETRATOR AND READS IN ROCKWELL OR BRINELL SCALES.
NOTE : MATERIAL MUST BE SOLIDLY SUPPORTED FROM BEHIND. PRESS DOWN WITH A STEADY, EVEN FORCE.
5.6 ERNST TESTER
The Ernst tester is a small versatile tool that requires access to only one side of the material being tested.
There are two models of the tester-one for testing hardened steels and hard alloys and one for testing unhardened steels and most nonferrous metals. It has a diamond point penetrator, and it is read directly from the Rockwell A or B or the Brinell scales, depending on the model used. Figure 1-31 shows the Ernst portable hardness tester and its proper use.
The correct procedures for using the Ernst tester are as follows:
1. Solidly support the metal being tested by placing a bucking bar behind the metal. This will minimize flexing of the metal and yield a more accurate reading of hardness.
2. The handgrip must be pressed down with a steady, even force to ensure accurate readings.
3. Press down until the fluid column has stopped moving. The hardness value is given at the point where the fluid column has stopped moving on the scale.
As with other portable testers of similar type, the material must be smooth and backed up so there will be no tendency to sag under the load applied on the tester. The test block supplied with each tester should be used frequently to check its performance.
5.7 UNIVERSAL HARDNESS TESTER
For customers who require the flexibility of three hardness testing machines in one then Indentec's range of Universal Hardness Testers are an ideal choice.
The units are capable of Rockwell, Vickers and low load Brinell hardness tests, with the option of a hand held portable microscope or built in optical system for Vickers and Brinell indentation measurement.
If you need to eliminate uncertainty from Vickers and Brinell testing, you should check out our CAMS system. This computer-aided innovation replaces operator judgement with a CCD camera for distinguishing impressions. Through mouse-driven software, the indentation is electronically projected onto a PC monitor and measured automatically eliminating operator influence and reducing gang R+ R values. Available on all our Universal machines, CAMS makes Vickers and Brinell testing very easy and trouble free.
The multi-test facility makes the machine ideal for educational purposes in helping to demonstrate the three classical hardness tests.
The unit is supplied with UKAS accredited test blocks and indentors for each of the three test methods.
5.8 MICRO VICKERS HARDNESS TESTER
Our advanced line of QV-1000 Series Vickers hardness testers are low-cost and precise testing systems suitable for hardness analysis of metallic specimens in metallography laboratories or production environments.
Features
• Motorized turret
• High quality microscope with digital reading (QV-1000DAT Model)
• Fully automatic load control
• Easy operating system
• Two optical paths
• Built-in high speed thermal printer
• XY stage with minimum reading of 0.01mm
• QV-MONITOR or QV-CCD system (optional)
Micro Vickers Hardness Tester - Analogue with Auto Turret (motorized)
Standard configuration includes:
• Main unit
• Diamond indenter Vickers
• Objectives 10x, 40x
• Eyepiece 15x
• XY-stage with micrometers
• 3 adjustable feet
• 3 clamping devices
• Extension tube for CCD-camera
• Digital eyepiece incl. protection cover
• Spirit level
• Micro-Vickers test plates 2x
• Spare light bulb 12V-30W
• Spare fuses 2x
• Installation & user manual
• Portable tester
• If you can't bring the specimen to the tester, then you can take the test to the remote or large specimen with one of our handheld portable hardness testers.
• Producing on-the-spot readings and print-outs of any popular hardness scale, these pocket-sized instruments can be applied to any surface, from any direction, including upside down.
• Top models store up to 200 test results and display hardness, scale, time, material tested, number of tests, running average hardness, test direction and ultimate tensile strength.
• The units are totally portable, requiring no external power source cables and connect to a printer via an infra-red port.
• Instruments are supplied with an Indentec calibration certificate and a UKAS traceable test block.
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