Manual 600MRD-L ROCKWELL HARDNESS TESTER

Transcription

1 Manual 600MRD-L ROCKWELL HARDNESS TESTER

2 CONTENT PAGE 1. GENERAL DESCRIPTION 2 2. TECHNICAL SPECIFICATIONS 5 3. INSTALLATION 6 4. FUNCTION OF COMPONENTS PREPARATION FOR USE OPERATION MAINTENANCE ABOUT HARDNESS SCALE, INDENTER, ANVIL, CONVERSION, AND MINIMUM THICKNESS OF CYLINDRICAL CORRECTION APPENDIX 25 Manual 600MRD-L 1

3 1. GENERAL DESCRIPTION The hardness tester is a measuring instrument for determining the hardness of materials. And the hardness test is one of the means, by which the quality of metal material or work-piece is decided. The hardness means that in certain condition the capacity of material of resisting indent pressed by another object, which is without remnant deformation. The more resisting capacity is, the higher hardness is, and conversely, the lower hardness is. In the tests of mechanical properties, the measurement of hardness is one of the easiest, fastest and the most economical methods. It is also one of the means of checking product quality, in manufacturing process. Because of the mutual corresponding relationships between metal hardness and other mechanical properties, the other metal properties of most metal materials can be calculated approximately by measuring hardness, for example, strength, fatigue, creep, abrasion and internal defect etc. (1) The basic principle of Rockwell hardness test At the beginning of the test, place the indenter of tester on the specimen surface, applies a preliminary load and establishes a reference point that a displacement transducer measures. Because the indenter penetrates into the specimen surface by means of preliminary load, surface roughness or irregularities do not affect the test. Next, the tester applies the main load. The larger force penetrates deeper into the specimen. Then, the tester removes the main load, meanwhile, still applying the preliminary load. At this point, the tester measures the depth of the indent relative to the established reference point. The linear depth of the indent is the basis for the Rockwell hardness number. A higher number represents a shallow indent, which indicates a harder material. Conversely, a low number represents a deep indent, which indicates a softer material. As showing Figure 1-1: Indenter Indenter depth from preliminary load Indenter depth from main load Specimen Linear measurement that forms the basis of Rockwell hardness tester readings Figure 1-1 Test principle 2 Manual 600MRD-L

4 (2) Rockwell hardness test formulas n1-n0 n1-n0 HRC.A=100- HRB= in which: n0 = Indenter depth from preliminary load n1 = Indenter depth from applies total test load F, then removes main load F1, but remains preliminary test load F0. (3) The introduction of the outline (Figure 1-2) and the components of Rockwell hardness tester (Figure 1-3): Digital panel Anvil Indenter Protection sleeve Capstan hand wheel Body Power control board Microprinter Load selector Leveling screw Figure 1-2 Outside component names Power level Automatically loading/unloading assembly Main axle system assembly Weight hanging rod Weight C Capstan hand wheel Weight B Weight A Power control board Figure 1-3 Elevating screw rod Internal component names Microprinter Manual 600MRD-L 3

5 Capstan system assembly: The capstan system is composed of the capstan hand wheel, elevating screw rod, an axle sleeve etc. When the capstan hand wheel is rotated clockwise, the elevating screw rod is elevated; When the Capstan hand wheel is rotated counter-clockwise, the elevating screw rod is returned down, and passed into the hole on the surface of work-bench. Between the top end of capstan hand wheel and upper end of elevating screw rod, the movable protection sleeve seals the upper end of elevating screw rod. And there is a hole at the center of upper end of the elevating screw rod; its main function is to support the anvil or special fixture. Cover: Two removable covers provide access to the internal components. Six cross- slot head screws fix the upper cover, so that to seal the power lever and the main axle system assembly. Two cross-slot head screws fix the rear cover on the back of tester base. Take off the rear cover; you can see the weight stack assembly. Weight stack assembly: The weight stack assembly is composed of a weight hanging rod and three Cylindrical Weights. A hook at the upper end of the hanging rod attaches to a hanging ring on the end of the power lever, one weight is fixed on the lower end of the rod, another two weights are hanged free on the rod, and rested on the supports. Power lever assembly: The power lever assembly extends from the main axle system assembly to the rear of the tester. A pivot hangs from the rear of the lever, and supports the weight stack. Mechanical linkage between the weight changer and dash pot assemblies control the amount and rate of force the lever generates. Weight changer: A Pair of bevel gears transmits the cam shaft to rotate, and to move the forks up and down, so that the weights release from or apply on the hanging rod, then change the force value. Automatic loading/unloading assembly: Automatic loading/unloading assembly is composed by servo motor, load cam, electric limit switch and elevating shaft. It works under the control of the electronic circuit to load and unload in order. Digital display: A digital display, on the front of the tester, contains LCD that indicates if the preliminary load is applied fully, and scales, the hardness value, dwell time. 4 Manual 600MRD-L

6 2. TECHNICAL SPECIFICATIONS The tester dimensions and total weight show as Figure 2-1: Figure 2-1 Dimensions Table 2-1 Dimensions and Weight. Dimension mm A. Height 715(approx.) B. Width 227 C. Length 516 D. Test Space Height protection sleeve) 84 (Without protection sleeve) 170 E. Test Space Depth 165 Weight (kg) 85 Voltage 220V/110V Dwell time 2~99s Table 2-2 Capacities of test Loads Preliminary Load N (kgf) Total Load N (kgf) 98 (10) 588 (60) 98 (10) 980 (100) 98 (10) 1470( 150) Table 2-3 Rockwell hardness scales, indenter, and test load Rockwell Indenter Preliminary Total Hardness Mm (in.) Load Load Scale N (kgf) N (kgf) A Diamond Cone 98 (10) 588 (60) B Ball Ø (1/16) 98 (10) 980 (100) C Diamond cone 98 (10) 1470 (150) D Diamond cone 98 (10) 980 (100) E Ball Ø (1/8) 98 (10) 980 (100) F Ball Ø (1/16) 98 (10) 588 (60) G Ball Ø (1/16) 98 (10) 1470 (150) H Ball Ø (1/8) 98 (10) 588 (60) K Ball Ø (1/8) 98 (10) 1470 (150) L Ball Ø 6.35 (1/4) 98 (10) 588 (60) M Ball Ø 6.35 (1/4) 98 (10) 980 (100) P Ball Ø 6.35 (1/4) 98 (10) 1470 (150) R Ball Ø 12.7 (1/2) 98 (10) 588 (60) S Ball Ø 12.7 (1/2) 98 (10) 980 (100) V Ball Ø 12.7 (1/2) 98 (10) 1470 (150) Manual 600MRD-L 5

7 3. INSTALLATION Installing procedure of hardness tester: Unpack the tester. Lift the hardness tester onto the work-bench. Install four leveling screws. Install weights. Before you install the hardness tester, check for the following conditions: The workbench is capable of supporting the tester and any other accessories, the bench top must have a hole for the elevating screw rod to travel through the metal top as Figure 3-1 illustrates. The floor supporting the workbench is free of mechanical vibrations from other machinery. There is adequate clearance between the tester and surrounding walls, to allow for routine service. Procedure 1: Unpacking (a) Shear off the packing straps with the pincers. (b) Disassemble four nuts with the wrench, then remove the packing case upwards. (c) Remove the plastic packing bag from the tester. (d) According to the packing list, inventory all items. Some accessories may be in the package with the tester or in separate packages. Procedure 2: Lifting the hardness test onto the workbench. Cautions: Do not lift the test manually by yourself. Otherwise, person will be injured. Because of the tester weight and dimensions, it is difficult to move the tester, you should lift the hardness tester by means of mechanical lifting equipment. According with the correct lifting methods, only the experienced persons are permitted to move the tester. Do not use the cover or the capstan screw rod to lift tester, otherwise the components and tester accuracy will be damaged. Before moving the tester, remove the weight stack, if not, the movement of hanging weight in tester base will damage the tester. Use extreme care when lifting the tester. The tester is top heavy and could topple over. When lift and move tester, check if the weight stack has been removed. (a) Tie up the tester with a lifting strap rated for twice the weight of the tester, as Figure 3-2 illustrates. Figure 3-2 Lifting tester 6 Manual 600MRD-L

8 (b) Use a mechanical lifting device to slowly lift the tester onto the workbench, and then remove the lifting strap. Procedure 3: Installing four leveling screws After the tester is moved onto the workbench, install four leveling screws, then adjust them to make the tester anvil be horizontal. It ensures that the weights are hung correctly, and prevent tester from rocking. Before you start, the following tools should be prepared: Lifting strap Mechanical lifting device Spirit level Adjustable open-ended wrench or plate forceps Flat anvil (from accessory case) Four leveling screws (from accessory case) Before you start, assure that the workbench for supporting the tester is stable. (a) Support the tester with a mechanical lifting device, while you carefully tilt the tester base up as Figure 3-3 illustrates. (b) Thread a leveling screw in each corner of the base. Figure 3-3 Installation leveling screws (c) Remove the foam shipping block. (d) Install a flat anvil. (e) As Figure 3-4 illustrates, place the spirit level on the anvil, then level the tester front to back. (f) Use the wrench to adjust the level of the base as Figure 3-4. Figure 3-4 Leveling the base (g) Rotate the spirit level 90º. (h) Adjust the level of the tester with the wrench side to side. (i) Remove the lifting strap. Manual 600MRD-L 7

9 Procedure 4: Installing the weights. The weights are removed prior to shipping. Install the weights after the tester has been leveled. Before you move the tester to another site, remove the weights from the tester, leaving the weights in the tester, can damage the internal mechanisms. Before starting, check the following conditions: The tester is horizontal. The elevating screw rod is in its lowest position. You need the following tools: Cross-slot screwdriver. Slot screwdriver. Shears. (a) Remove the six screws with screwdriver from upper cover, as Figure 3-5 illustrates. (b) Remove the upper cover. (c) Remove the rear cover with screwdriver, as Figure 3-5 illustrates. 6-M3 screw Upper cover Rear cover 2-M6 screw Figure 3-5 Removing upper, rear cover. (d) Remove the foam in the body. (e) Turn the load selector knob to the 588N (60kgf) position. (f) Remove the hanging rod carefully, assemble weight A with hanging rod, and place the weight A onto the weight supporting plate. Then return the hanging rod back lifting ring in the base, as Figure 3-6 illustrates. Finally, insert two weights into the hanging rod carefully, and use the studs to hang the weights onto the fork slots, as Figure 3-7 illustrates. (g) As you turn the load selector knob one revolution, check if the weights are centered on the rod supports and if the studs rest in the weight changer forks. (h) Replace the upper and rear covers. 8 Manual 600MRD-L

10 Hanging ring Fork Weight A Figure 3-6 Hanging rod and weight "A" installation Weight C Weight B Figure 3-7 Weights "C" "B" installation Manual 600MRD-L 9

11 4. FUNCTION OF COMPONENTS. (0) System Setup There are 5 dip switches corresponding to different functions on the control circuit board under the upper cover (see Figure 4-1 for detail position information). Before you set up them, the hardness tester should be powered off ;or you can set up them then press RESET key. Figure 4-1: Control Circuit Board (1). Switch NO.4 of DK1: selects one from the testing hardness mode or testing force mode In ON position, the system is ready for testing hardness. In the OFF position, the system is ready for testing force, and only RESET, CLEAR,, are valid, is for the motor rotating with testing force loaded and is for the motor rotating to the unload position. (2).Switch NO.3 of DK1: selects the force unit In ON position, the force unit is N. In OFF position, the force unit is Kgf. (3) Switch NO.2 of DK1: sets the date/time In ON position, North America format MM DD YY HOUR minute (AM/PM) (12 Hours) In off position, Europe format DD MM YY HOUR minute (24 HOURS) (4) Switch NO.1 of DK1: selects conversion table In ON position, the scale complies with Europe standard In OFF position, the scale complies with North America standard (5) Switch NO.1 of DK2: switchs sound on/off In ON position, sound is on In OFF position, sound is off. (6) Operating instructions of keypad. Refer to Figure 4-2: Whether the following keys are valid or not depends on the state of the hardness tester. When the key is valid and pressed, the buzzer beeps out the sound of "du"; when the key is invalid and pressed; the buzzer beeps out the sound of "dilinlin" to inform the user. Figure 4-2 :Keypad 10 Manual 600MRD-L

12 1 ESET key - restores the system to the original state of the factory. The state is that: SCALE is HRC without limitations and not for conversion (in NONE state), dwell time is 4s. 2 CLEAR key-sets the displacement to zero. Press the key when the tester is in the testing state, the displacement will be reset (the new origin value). 3 ESC key- cancel key. If you want to cancel any operation, you can press the key. The key is invalid when the brightness being adjusted. 4 DELETE key- the "delete" key Deletes the result of current test. Press it for 4 minutes until buzzer beeps, then test number of times is set to zero (NO: 00). 5 PRINT KEY- It is invalid when the number of tests is zero. You can output data in one of the modes (INTERNAL PRINTER, TO RS232C NO STATS, TO RS232C WITH STATS). 6 SCALE KEY- scale selection key. The key is valid only when the test number of times is 0 and the tester is in testing state. The selectable SCALE, the corresponding TEST FORCE and INDENTER is brightened showing that the scale is selectable now, see Figure 4-3. Press the, keys to select the scale. The total 29 scales are: HRC HRBs HRB HRA HRD HREs HREw HRFs HRFw HRGs HRGw HRHs HRHw HRKs HRKw HRLs HRLw HRMs HRMw HRPs HRPw HRRs HRRw HRSs HRSw HRVs HRVw Custom1 Custom2 Figure 4-3 : Scale Selection TEST FORCE and INDENTER are changed with the scale. After selecting scale, press OK for confirming, press ESC to cancel changing the scale and restore the latest scale. 7 MENU key- for setting the menu. The key is invalid in the process of testing. The menu is composed of 5 items and accessed by pressing the MENU key. See Figure 4-4. The setting of menu is memorized even if the power is off. Figure 4-4 : Setting The Menu Press the, keys, select the corresponding menu. Notice: 1). When the HARDNESS CONVERSION is selected, OK is invalid if the scale does not exist in corresponding table. 2). If the test number of times (NO) is not zero, DWELL TIME is invalid. Manual 600MRD-L 11

13 1 The two HARDNESS CONVERSION tables are selected by switch NO.1 of DK1. Press the,,, keys, select the corresponding scale, press OK for confirming and ESC for cancel, then return to main screen. Switch NO.1of DK1 is on (Europe standard) Figure 4-5: Changing the scale Switch NO.1 of DK1 is off (North America standard) 2 DWELL TIME Dwell time is selectable in a range of 2~99 S. You can press the, key to carry out adding or reducing the value. Pressing the, key continuously can add or reduce the value rapidly. Press OK for confirming or ESC for cancel, then return to main screen. Figure 4-6: Setting the dwell time 3 LIMITS GO/NG set, high and low hardness limits, see Figure 4-7 MAX and MIN can be set by pressing the, keys to carry out adding or reducing. Pressing the, keys continuously can add or reduce the value rapidly. Setting MAX or MIN can be switched with the, keys. If you want to switch off the setting of LIMITS, press the DELETE key then press OK for confirming. After the setting is finished, press OK for confirming or ESC for canceling, then return to main screen. Figure 4-7: Setting the LIMITS 12 Manual 600MRD-L

14 4 DATA OUTPUT there are three items to be selected, see Figure 4-8. You can select by pressing the key, then press OK key for confirmation, or press ESC key for cancel, then return to main screen. The baud rate of RS232C is 2400bps. Figure 4-8: Data output mode selection 5 DATE/CLOCK/BRIGHTNESS you have two choices. See Figure 4-9. Access to setting the items by pressing the, keys,then press OK. Press ESC key for cancel, then return to main screen. Figure 4-9: SETTING THE DATA/CLOCK/BRIGHTNESS SUB-MENU - By setting switch NO.2 of DK1, Europe format or North America format has been selected, see Figure After DATA/CLOCK is accessed, day, month, year, hour, minute is selectable with the, keys, You can press the, key to carry out adding or reducing the value. Pressing the, key continuously can add or reduce the value rapidly. Press OK for confirming and ESC for cancel, then return to main screen. Switch NO.2 of DK1 is on (North America Standard) Figure 4-10: Setting the time Switch NO.2 of DK1 is off (Europe Standard) Manual 600MRD-L 13

15 - BRIGHTNESS brightness setting, You can press the, key to adding or reducing the brightness, see Figure There are 32 steps of brightness, which can be set. It is invalid to exceed 32 steps. Press OK for confirming and return to main screen, ESC key is invalid. Figure 4-11: Setting The Brightness (6) The load selector is a ratcheting knob on the side of the tester as Figure 4-12 illustrates. Test Load Setting Values N (kgf) 1470 (150) 980 (100) 588 ( 60) Figure 4-12 Load Selector Warning: Do not adjust or rotate the load selector while the tester is applying the main load or in remaining load time. The load selector can not adjust or rotate until the main test load has been relieved, otherwise the precision of the load selector will be confused. (7) The capstan hand wheel is used for screw rod elevating, as Figure 4-13 illiterates. By turning the hand wheel clockwise or counter clockwise, you raise or lower the elevating screw rod to change the rod height, you can either install or remove specimen, and apply or remove the preliminary load. Caution: Do not strike the indenter with the anvil. Striking the indenter with the hardened anvil could damage both components. Do not move the capstan nut while the tester is applying the total load. Doing so will invalidate the test result. Figure 4-13 Elevating Screw Rod 14 Manual 600MRD-L

16 5. PREPARATION FOR USE a. Installing an Anvil, as Figure 5-1 illustrates. Elevating screw bore for anvil installing Figure 5-1 Installing an Anvil (1) Before installing, lower the elevating screw rod, so that there is enough space for installing anvil. (2) According to the dimensions and shape of the specimen, select the proper anvil. (3) Before installing, clean the anvil installing bore on the elevating screw rod (clean the thread of anvil). (4) After installed, perform a few hardness tests on a test block for several times, so that the anvil is installed steady on the elevating screw rod. b. Installing an Indenter (1) Clean the handle of the indenter and main axle bore, then insert the handle into the bore, align the machined flat with the screw on the site of main axle, as Figure 5-2 illiterate: Main axle Main axle bore screw Indenter shoulder Machine flat of indenter handle Indenter tip Figure 5-2 Installing Indenter (2) Do not strike the indenter tip with the anvil, otherwise, the both parts will be damaged. (3) Insert the indenter handle into main axle bore until the indenter shoulder contacts the shoulder of the main axle bore tightly. Then fix the screw of the main axle bore slightly when testing, after applying the preliminary load, loose the screw of main axle bore, and then apply the main test load, fix the screw slightly again, so that the indenter is proper installed on the main axle. Manual 600MRD-L 15

17 6. OPERATION Before running a test, please check as following. - Ensure that the proper anvil has been installed in the bore of the elevating screw rod. - Ensure that the proper indenter has been installed in the bore of the main axle bore. - Ensure that the proper load has been selected with the load selector. - Ensure that the time of loading has been set - Ensure that the scale conversion has been set. (If there is no need of conversion, do not set) - Ensure that the space between the anvil and indenter is enough for specimen placing. Test procedure: (1) Turn on the power (2) When the NO is zero, press SCALE key,, key select the scale and the corresponding load, indenter according to the display. (3) When the NO is zero, dwell time can be set, conversion scale can also be set if necessary. (4) After the power is turned on, the tester is restored to the status of the latest test. The hardness results of the latest test have been saved. The DELETE key should be pressed for 4s, or RESET key should be pressed before initiate a new test. The test points can't exceed to 63 points in each test procedure. (5) Place the specimen or test block on the anvil. Before doing so, ensure there are no dust, crevices, and pits on the surface of the specimen. The surface between the specimen and the anvil should be clean enough, so good contact can be achieved. The depth of specimen should be greater than 10 times the depth of the indentation. (6) Clockwise rotate the capstan hand wheel slowly. When it touches the specimen, rotate more slowly. At this time, the light bar on the upside of the LCD goes from the PROLOAD area to the OK area, signifies that the preload 98N has been applied, see Figure 6-1. Just at this time, don't rotate the hand wheel any more, (if not, the light bar will go to OVER area, and the buzzer will beep continuously. On this condition, the test is invalid. You should rotate the hand wheel count-clockwise and make the elevating rod go down until the light bar disappears on the upside of the LCD, then test again). At the same time, automatically the motor applies the load, delays for a period of time, removes the load. In testing process, TESTING, load, dwell time, unload are displayed. In the end, the hardness value corresponding to the scale is displayed. Figure 6-2 is the display of the LCD: the 6th test, the current test value is 62.9HRc,the mean value of six times (x) is 63.0HRc, the deviation (S.DEV) is 0.2, the repeatability(r) is 0.4, no conversion scale. When LIMITS is active, if the hardness value is in the range having been set, the buzzer beeps out the sound of 'du', and GO is displayed, otherwise NG is displayed and the buzzer beeps out the sound of 'dilinlin'. When LIMITS isn't active, the buzzer beeps out the sound of 'du', and GO and NG aren't displayed. Now you can get the readings from the screen. The data can be output optionally. Figure 6-1: The Display of LCD when preload being applied 16 Manual 600MRD-L

18 Figure 6-2: Displaying the test results (7) Count-clockwise rotate the capstan hand wheel to make the elevating rod go down, release the preload 98N, at this time, the bright bar disappears, and this is the end of one test procedure. The hardness of latest test is reserved until the next test. (8) If you want to go on with the new test, the hardness value will be set to zero, repeat the procedure 5-7. (9) Data output modes and information Press MENU key, access to main screen, select DATA OUTPUT with arrow keys, enter sub-menu by pressing OK key, select one of the three output modes in the same way. You should test for twice or more (the first test value should be deleted). A.INTERNAL PRINTER mode: turn on the power of the printer, after this mode is selected, press OK, press PRINT key, then the printer begins to work. See Figure. 6-1,print format is: :63.0HRc NO :06 S.DEV :0.2 MAX :63.2 MIN :62.8 R :0.4 CONV: HRC HRC HRC HRC HRC HRC -mean value of harness N0-amount of test S.DEV-deviation MAX- hardness maximum value MIN-hardness minimum value R- repeatability CONV-mean hardness value of conversion scale B. TO RS232C NO STATS: simple information output mode Select the mode, press OK, press PRINT, then simple information output is initiated. In this mode, only the test data are transmitted out. C. TO RS232C WITH STATS: simplex information output mode. Select the mode, press OK, press PRINT, initiate simplex information output. In this mode, not only the test data but the statistic data are also transmitted out. Manual 600MRD-L 17

19 D Value Precision Adjustment If you learn the structure and work principle of the tester, you can make an appropriate adjustment to it, as Figure 6-3 illustrate. Figure 6-3 precision adjustment Remove the upper cover. If the hardness value you got is lower than the standard specimen, loosen screw-cap (II), thread screw (III) clockwise little by little. Then screw the screw-cap (II). You can repeat the above process until the test value is in the range of the deviation. If the hardness value you got is higher than the standard specimen, thread the screw (III) count-clockwise. 18 Manual 600MRD-L

20 7. MAINTENANCE The tester is a precision instrument that requires periodic cleaning. How often you clean the tester depends on the working environment and cleanliness. For non-metallic surface, wipe clean with a soft cloth dampened with a mild liquid cleaner. Do not use too much cleaner. It could seep inside the tester and cause the components damage. For metallic surfaces, wipe clean with a soft cloth dampened with a light oil. Do not use too much oil. Excessive oil attracts dirt and other debris. Clean the mating surface between the elevating screw rod and anvil, and the indenter shoulder, the main axle surface, as Figure 7-1 illustrates. Dirt, oil, metal chips or other debris between these surfaces could compress during testing and cause inaccurate results. Cleaning Cleaning Figure 7-1 Cleaning Keep the elevating screw rod clean. A collapsible cover protects the elevating screw above the capstan nut from dust and dirt. (1) Lubricating the Elevating Screw Rod You should periodically use mobile oil to lubricate the elevating screw rod. Lubricating the rod can prevent screw from binding Note: Before lubricating, check for the following conditions: - There is not any specimen, anvil or indenter installed in the tester. - The elevating screw rod is completely extended. Procedure (a) Remove the protective cover, as Figure 7-2 illustrates. Figure 7-2 Removing the Protective Cover (b) Inspect the screw threads for any dirt, fibers or other debris. If you find any, use a cloth to remove it. (c) Apply some oil to each thread sparingly. Do not apply oil too much. (d) Use a cloth to wipe any excess oil Caution Small pieces of fibers or other debris can cause the elevating screw rob to bind. After lubricating the screw, remove all traces of lint from it with a soft brush. (e) Remove any lint or fibers with a soft brush. (f) Replace the protective cover. (g) Run the screw rod up and down several times to distribute the oil evenly. Manual 600MRD-L 19

21 (2) Care of Indenter Figure 7-3 illustrates a diamond cone indenter and a ball indenter. Indenter handle Ball Diamond cone indenter Indenter cap Figure 7-3 Diamond Cone Indenter (left) Ball (middle, right) Note: Do not use a worn or damaged indenter. (a) Diamond Cone Indenter Inspect the Diamond cone indenter for damage every month. If the conical surface of the metal body has many dents, it means that the operator has probably struck the indenter against the hardened anvil. Inspect the indenter under a 10x power magnifier. If there is significant damage, replace the indenter. In order to avoid damaging the indenter, protect it with your finger when remove the anvil and specimen. (b) Ball Indenter Inspect the ball indenter for damage daily. If there is sign of wear or deformation, replace the ball. Method of replacement: Unscrew the cap by turning it. Remove the old ball and install a good one. Screw on the cap and install the indenter. (3) Test Block Verification Test block verification is an easy means of check the accuracy of the tester. The procedure is a simple comparison. You install the test block, perform a hardness test on it, then compare the resulting hardness value with the number engraved on the test block. This comparison indicates if the tester needs serving. Note: As usual, in often - use condition, you should inspect the tester accuracy daily. Test Block Before verification, please pay attention as following: (a) Use the top surface of the test block. If use the bottom or side surface, you can not get the correct hardness velue. (b) Use a test block that is in good condition. Do not use a test block if there is not at least 2.5 times the indent diameter between indents. (c) Do not use a test block that has had the old indents ground off, you can not be sure that the newly machined surface has the same hardness value as the original one. (d) If you use the tester throughout a given scale, check the high, middle and low range of scale. If you only use one or two ranges, choose test block that fall above and below the hardness numbers of those ranges. (e) Caution Items: You should at least test five times on a block's working surface (the first point does not record), the standardized hardness value is engraved on the working surface. Compare the average value with the standardized value. If the deviation is in the allowable range, it will be qualified. 20 Manual 600MRD-L

22 If the average value of five values is out of the Rockwell test block limits: - Inspect the indenter, replace the ball or inspect the tip of the diamond indenter under a at least 10x power magnifier. If there is significant damage, replace the indenter. - Check the mating surfaces of the indenter and the main axle if they are clean and free of dirt, chips, and oil. These items prevent the indenter from seating properly and cause invalid test results. After replacing the indenter or anvil, do several adaptive tests, so that the components are installed steady. (4) Troubleshooting To help you when a problem develops, Table 7-1 suggests a probable cause and recommends an action. Do not operate the tester if you are unable to solve the problem, contact with service office. Table 7-1 Troubleshooting Guide Problem Cause Solution Elevating screw rod binds Rust or debris Clean and lubricate the screw rod Tester applies total load inconsistently Low oil level in dash pot reservoir Oiling the reservoir Tester could not apply total load Weights are not properly hung Check if weights are properly hung. Incorrect hardness values Unknown. Verify the tester with test block [Refer to page 25-(4)] Incorrect hardness values Wrong load. Check if you are using proper load for the hardness scale. Incorrect hardness values Wrong indenter Check if you are using the proper indenter for its hardness scale. Incorrect hardness values Indent distance Check if the distance between indents is at least 2.5 times the diameter of indent. Incorrect hardness values Damaged indenter Replace the damaged indenter. Incorrect hardness values Anvil or indenter installs unsteady Check if the anvil and indenter are seated Incorrect hardness values Anvil not appropriate for specimen Select the correct anvil that supports specimen. Incorrect hardness values vibrations Isolate the tester from environmental vibrations. Incorrect hardness values Specimen is too thin The thickness of specimen should be 10 times more than indent depth. Incorrect hardness values Specimen angle Adjust specimen surface, so that the indenter is 90 to the specimen. Incorrect hardness values Non - homogenous specimen Use an indenter with a larger area. Light could not be turn on. 1.Problem with power supply 1.Check if the power supply switch is on 2.Fuse short circuit 2.Change the fuse. Motor could not stop 1.Interfered by the outside circuit. Turn off the power, lower the elevating 2. Misoperation screw rod. Wait for a while then turn on. The hardness value 1.Tester is not level, weight 1.install the weight again. is error. rubs in the body. 2.weights are not in order. 2.change the position of the weights in order. Manual 600MRD-L 21

23 8. ABOUT HARDNESS SCALE, INDENTER, ANVIL, CONVERSION, CYLINDRICAL SPECIMEN CORRECTION AND MINIMUM THICKNESS OF CYLINDRICAL CORRECTION. (1) Select a Rockwell Scale. Before testing a specimen, you must first determine which Rockwell scale is suitable. Each scale requires a specific combination of loads, and an indenter. In most cases, a hardness tolerance specification for a material is indicated on a technical drawing. If the material you wish to test has no specification, or you doubt the scale for a particular specimen, consider the following limiting factors: - Specimen Material - Specimen Thickness - Scale Limitations (2) Specimen Material Table 8-1 gives a list of all regular Rockwell scales and typical material for these scales. And the table includes only the regular Rockwell scales, this information can be helpful for your test. Note: As usual, you should use the heaviest load as possible. Table 8-1 Typical Scale Application Scale Symbol Application A Cemented carbides steel and deep case-hardness steel. B Copper alloys, soft steels, aluminum alloys, malleable iron C Steel, hard cast iron, titanium, and deep casehardened steel and prelatic malleable iron. D Thin steel, medium casehardened steel, and perlitic malleable iron. E Cast iron, aluminum and magnesium alloys, bearing metals. F Annealed copper alloys, thir soft sheet metals. G Phosphor bronze, beryllium copper, malleable irons. H Aluminum zinc lead. K Bearing metals and other soft or thin material including plastic. L Bearing metals and other soft or thin material including plastic. M Bearing metals and other soft or thin material including plastic. P Bearing metals and other soft or thin material including plastic. R Bearing metals and other soft or thin material including plastic. S Bearing metals and other soft or thin material including plastic. V Bearing metals and other soft or thin material including plastic. (3) Specimen Thickness In order to avoid the influence of cold-worked, the material thickness should be at least 10 times the indent depth. Use the minimum thickness ration of 10:1 as an approximation. (4) Scale Limitations - Results below 20HRC with diamond cone indenters Do not use a diamond indenter when readings fall below 20HRC since there is a loss of sensitivity. Diamond cone indenters are not calibrated below 20HRC. With softer materials, try using the B scale. Note: Do not test tungsten carbide on the C scale. This material could either fracture or reduce the life of the indenter. 22 Manual 600MRD-L

24 - Tungsten Carbide Although there is no limitation to the material hardness that you can test with the diamond indenter, the A scale is the accepted one by the carbide industry. - Readings above 100 with ball indenters. Although scales using the ball indenter range to 130, do not be accept readings above 100, except under special conditions. Values between 130 and 100 use the very tip of the ball, because of the indenter's blunt slope, the sensitivity of most scales is poor in this region. Also, with the smaller diameter indenter, there is a danger of flattening the ball under the high pressure developed on the small contact area. For consistent results, change the balls frequently. (5) Cylindrical Specimens When you test a cylindrical or curved surface, the test result requires a cylindrical correction factor. Correction factors are based on whether the indent is on the inside or outside surface of the specimen, as Figure 8-1 illustrates. Inside diameter correction Indent location Indent location Outside diameter correction Figure 8-1 Cylindrical Specimens 6) Selecting an Indenter Depend on the material and scale, a test may require either a cone or steel ball type indenter. Table 8-2 details the indenter and load combinations for regular Rockwell tests. Table 8-2 hardness scale Scale Symbol Indenter mm (in.) Load N (kgf) A Diamond Cone 588 (60) B Ø Steel Ball (1/16) 980 (100) C Diamond Cone 1470 (150) D Diamond Cone 980 (100) E Ø Steel Ball (1/8) 980 (100) F Ø Steel Ball (1/16) 588 (60) G Ø Steel Ball (1/16) 1470(150) H Ø Steel Ball (1/8) 580 (60) K Ø Steel Ball (1/8) 1475 (150) L Ø 6.35 Steel Ball (1/4) 588 (60) M Ø 6.35 Steel Ball (1/4) 980 (100) P Ø 6.35 Steel Ball (1/4) 1470 (150) R Ø 12.7 Steel Ball (1/2) 588 (60) S Ø 12.7 Steel Ball (1/2) 980 (100) V Ø 12.7 Steel Ball (1/2) 1470 (150) (7) Select an Anvil It is important that you select an anvil that supports the specimen and does not introduce any error, which will cause an inaccurate test result. Figure 8-2 illustrates the common types of anvil. Manual 600MRD-L 23

25 Figure 8-2 Anvil (1) Anvil (2) Anvil (3) Anvil (4) Anvils The plane anvil is suitable for the tests of middle or small specimen with a stable bottom. The pedestal anvil has a small elevated flat spot. The small contact point reduces the possibility of irregular specimen shapes from introducing erroneous hardness values. If the specimen is not flat, place it on the anvil with the more convex side down. This method makes better contact with the anvil at the test point. The plane anvil has a large flat surface. Use this anvil for testing heavy flat bottom specimens. The standard V has a deep groove, which keeps rounded specimens in place. Use this anvil for testing cylindrical specimens with diameter of 6 mm or larger. The Relationships Between Specimen Minimum Thickness and Hardness HRC-HRB. 24 Manual 600MRD-L

26 9. APPENDIX (STANDARD) About HRC Correct Factors for Out-Cylindrical Surface Table C.1, C.2, C.3, C.4 are used for the correct factors of convex out-cylindrical surface. Table C.1 - Use for the tests with diamond cone indenters (scale A, C, and D). HRC Specimen Radius (mm) Observed Reading Note: The correct factors more than 3 HRA, HRC, HRD are not considered, so have not been listed in above table. Table C.2 - Use for mm ball indenter tests (Scale B, F and G). HRC Specimen Radius (mm) Observed Reading Note: The correct factors more than 5 HRA, HRC, HRD are not considered, so have not been listed in above table. Manual 600MRD-L 25

27 Table C.3 - Rockwell Hardness Tests (Scale N) a.b HRC Specimen Radius (mm) Observed Reading (6)d (5.5)d (5.5)d (5)d (4.5)d (4)d (3.5)d (3.5)d a. These correct factors are approximate values, or indicate the mean values of actual testing values on most above listed radial surfaces, reach to the accuracy about 0.5 unit of HRC hardness. b. While testing on the convex cylindrical outside surface, the testing accuracy I great affected by the alignment between elevating screw rod, V shape anvil and indenter, and surface roughness, linearity of cylindrical specimen. c. About the other radii unlisted in above table, the correct factors can be obtained by linear inserting method. d. If not allowed, adoption of the value in the brackets is not permitted. Table C.4 - Rockwell Hardness Tests (Scale T) a.b HRC Specimen Radius (mm) Observed Reading (13)d (9)d (6)d (4.5)d (3.5)d (11.5)d (7.5)d (5)d (4)d (3.5)d (10.5)d (6.5)d (4.5)d (3.5)d (8.5)d (5.5)d (4)d (6.5)d (4.5)d (5)d (3.5)d a. These correct factors are approx., values, or indicate the mean values of actual testing values on most above listed radial surfaces, reach to the accuracy about 0.5 unit of HRC hardness. b. While testing on the convex cylindrical outside surface, the testing accuracy I great affected by the alignment between elevating screw rod, V shape anvil and indenter, and surface roughness, linearity of cylindrical specimen. c. About the other radii unlisted in above table, the correct factors can be obtained by linear inserting method. d. If not allowed, adoption of the value in the brackets is not permitted. 26 Manual 600MRD-L

28 W03-193