Equipment Manual. for. Operation of Automatic Polishing Plate Control on the PM5 Precision Lapping & Polishing Machine.

Transcription

1 Equipment Manual for Operation of Automatic Polishing Plate Control on the PM5 Precision Lapping & Polishing Machine Ref: BE

2 PREFACE: PM5 auto-lap/pol MACHINES The PM5 auto-lap/pol features two independent systems offering automatic control of plate shape. Automatic lapping plate flatness control is facilitated by the use of an external monitor which constantly measures the plate shape and automatically corrects any deviations from that set by the operator. For further information on the operation of this system, please consult manual ref. no. BE Control of the polishing plate is provided by an internal monitor which measures plate deflection; the degree of the deflection is controlled by the machine s vacuum pump drive system, allowing the operator to make immediate changes at the touch of a button. The operation of this system is detailed in the following pages. CHANGING FROM AUTO-LAP TO AUTO-POL MODE As the two modes of PM5 auto-lap/pol operation are distinct from one another, so the software versions which govern these systems are different. On completion of the automatic lapping process, therefore, it is necessary to change to auto-polishing mode. This change is carried out as follows: 1. Switch the machine OFF at the "POWER ON/OFF" key on the control panel. 2. Remove jig, monitor, roller arms, slurry scraper, slurry chute and cylinder from the machine. Set the abrasive cylinder to one side and clean the other parts. Remove and clean the drip tray. 3. Remove the lapping drive plate by loosening the three Allen screws holding it in place, rotating the plate such that the screw heads are at the wide end of their locating grooves, and lifting it off. Fit the polishing drive plate in its place (see also BE section 2). 4. Refit the drip tray. Fit the O-ring in its groove in the drive plate, then mount the polishing plate, ensuring that it is properly seated. 5. Switch the machine on by holding down the far right key below the Process Data screen on the machine front panel, then pressing the "POWER ON/OFF" key. The Process Data Display will now display the software version titled "PM5 autolap/pol". Enter the polishing options, as described in the relevant section of the manual, by selecting [Polish]. Equally, to return to "auto-lapping" mode, it is necessary to power up the machine while holding the far right key down. If this key is not held down, the machine will re-enter the control branch in which it was previously functioning. Note: PM5 auto-lap/pol machines are supplied with two drip tray and slurry scaper assemblies. The deeper of the drip trays (and slurry scraper, Cat. no. ALP1-1005) is designed to be used when the machine is in lapping mode.

3 1. INTRODUCTION The PM5 auto-pol and PM5 auto-lap/pol feature a system which allows the operator automatic control of the polishing plate shape during processing. It allows the operator to programme the machine with the required plate shape, or, by using the Dynamic Target option, a start and end target can be set to be reached in a specific time. Equally, the machine allows precise control of the eccentric sweep facility used to polish samples on the PM5 range of lapping and polishing machines. All polishing parameters are controlled from the "Process Data" section of the machine control panel. The principle of operation of this system is extremely simple. The required plate shape (concave or convex) is input using the Process Data Display on the membrane panel and the plate set in motion. An Internal Monitor, situated below the top polishing plate, measures the actual shape of this plate and sends a signal to the microprocessor system. Using this as a datum, the deflection of the plate is altered to the value set by the operator. This control loop will continue to maintain the required shape. The system allows discreet changes to be made to the polishing plate shape at the touch of a button, while also permitting precise, repeatable control over the polishing parameters. PROCESS DATA DISPLAY MICROPROCESSOR CIRCUIT BOARD POLISHING PLATE O-RING PUMP CONTROL BOARD DRIVE PLATE INTERNAL MONITOR DEVIATION SIGNAL VAC PUMP PLATE SHAPE CORRECTING SIGNAL Figure D1: PM5 automatic polishing plate control system BE Page 3 of 14

4 2. PREPARATION FOR POLISHING 2.1. LOCATION OF POLISHING PLATE (See also Figure D1.) Ensure that the Drive Plate and Polishing Plate surfaces are clean especially the grey, lapped faces. Clean the O-ring and fit it into the groove in the Drive Plate, ensuring that it is properly seated. Place the Polishing Plate centrally on the Drive Plate, ensuring there is an equal overhang over the Drive Plate. Press firmly on the top of the Polishing Plate to ensure that it is properly seated. NOTE: The Drive Plates for auto-polishing and auto-lapping differ - please ensure that the correct Drive Plate is used for each process, allowing the internal plate monitor to measure the plate shape during polishing. Ensure that for polishing, the protective cap covering the internal plate sensor is removed to allow the sensor to touch the back surface of the polishing plate. (Equally, if returning to lapping, replace this cap.) 2.2. SYSTEM CHECKS When switching on a PM5 auto-pol, the Process Data Screen will display the machine serial number and software version for three seconds, then the Polishing Menu Screen shown in Figure D2 below. When switching on a PM5 auto-lap/pol, the serial number and software version will also be displayed, but then the operator will be offered the choice between [Polish] and [Lap]. It is important to note that whenever the options [Set-up Sweep], [Polish] or [Lap] - but not [Set-up Sensors] - are selected for the first time (after switching on the machine), the machine will automatically carry out a short series of internal system checks, in order to set the workstation (and monitor support pillar, where applicable) to its mid position. This allows the roller arm(s) to be correctly positioned.(note: this only occurs after initial switch-on of the machine; it does not recur at any point during processing. However, should the emergency stop button be pressed, it will be necessary to switch the machine on again, and hence to carry out system checks.) NOTE: The machine s Process Data Display will prompt the operator to confirm that the System Checks may take place, by pressing the [Continue] key. This is to ensure that the checks are not carried out while sample holders are still within the roller arms. All jigs and fixtures MUST be removed from the roller arms before switching on the machine, i.e. before "System Checks" are run. This also applies when switching on the machine after the emergency stop button has been pressed. If the operator selects an alternative option, e.g. to alter the machine set-up, then returns to the initial menu screens, system checks will be carried out on selection of one of the options listed above. BE Page 4 of 14

5 To obtain the Polishing Menu screen (Figure D2) on a PM5 auto-lap/pol, simply select [Polish]. After the system checks are carried out, the Menu screen will be displayed. PM5 auto-pol [ Set-up ] [ Sensor ] [ Set-up ] [ Sweep ] [ Polish ] Figure D2: Polishing Menu Screen The polishing menu screen allows the operator either to set the internal plate sensor, to control or alter the speed or amplitude of the eccentric sweep movement, or to move directly to sample polishing CHECKING POSITION OF INTERNAL SENSOR It is now necessary to check that the height of the plate sensor or LVDT (Linear Variable Displacement Transducer), which measures the vertical movement or deflection of the centre of the polishing plate, is within the set tolerances. Select [Setup Sensor] from the screen shown in Figure D2 above. Set Plate Shape Sensor Current Intl Lvdt Offset = 234 [ Set Lvdt ] [ Set Lvdt ] [ Height ] [ Offset ] [ Exit ] Figure D3: LVDT Set-up screen Select [Set Lvdt Height] from the screen shown in Figure D3. This displays the internal LVDT position at the mid (half) vacuum level (see Figure D4 below). This is the most important value, as it is under mid vacuum that the plate should be at or near zero, i.e. flat. BE Page 5 of 14

6 Plate under half vacuum Actual vacuum: 509 mbar (Stable) Set point: 509 mbar Internal Lvdt: 257 [ Vac -- ] [ Vac ++ ] [ Vac Off ] [ Exit ] Figure D4: Set Internal LVDT screen Allow the "Actual vacuum" reading to settle at or near the "Set point" value. This is indicated by the appearance of the word "stable" beside the "Actual vacuum" reading. At this position, i.e. under mid vacuum, the Internal LVDT reading should be within the limits of +/ The machines and their plates are manufactured to ensure that on a day-to-day basis, the reading should always be within these values. If the position of the internal LVDT is such that it is outwith the tolerances of +/-500, it is necessary to manually adjust the position of the plate LVDT, to ensure that it is approximately at the centre of its range - see Section 2.4. A message to this effect will appear on the Process Data Display, indicating in which direction the adjusting screw should be turned (see below). If the internal LVDT value lies between -500 and 500, it is not necessary to manually adjust its position. Move to Section 2.5. IMPORTANT NOTE: The Display will still instruct the user in how to adjust the LVDT position. However, in this case the message can be disregarded, as the slight deviation will be offset by the machine software (see 2.5 below) SETTING LVDT MANUALLY Manual adjustment is accomplished by switching off the vacuum pump and performing slight adjustments to the height of the LVDT. The screen showing the half vacuum level (Figure D4) offers the operator the option [Vac Off] at the bottom of the screen. Press the touch panel key below the [Vac Off] display, which switches off the vacuum pump to allow the polishing plate to be removed. NOTE: the vacuum will reduce gradually, so wait a short while before attempting to remove the plate. BE Page 6 of 14

7 O-ring Adjusting screw Locking screw Internal LVDT Figure D5: Drive Plate showing LVDT adjusting screw With the Polishing Plate removed, firstly ensure all surfaces are clean. Using an Allen key, loosen the locking screw, then adjust the position of the adjustment screw slightly to bring the reading within the tolerances stated above. It must be stressed that only slight movements - adjustments of less than a quarter of a turn - are necessary. NOTE: If the sensor display is initially negative, adjust the clamp screw clockwise; if positive, adjust the clamp screw anticlockwise. This instruction will be given on the Process Data Display. Reposition the Polishing Plate on the Drive Plate, ensuring it is correctly seated. Press [Vac On] to set the vacuum pump in operation. Observe the internal LVDT reading under Half Vacuum; if it requires further adjustment, carry out the procedure described above once again. Always allow the reading a few seconds to settle before making another adjustment. When a correct reading is obtained, tighten the locking screw. NOTE: The internal LVDT is set by Logitech prior to delivery of the machine, and so little further adjustment should be necessary on the part of the operator. At this point the user should check the shape of the polishing plate s top surface. This is accomplished by zeroing the single dial gauge on the master flat block supplied, then transferring it to the polishing plate. Note that due to the nature of polishing plates, the reading gained will be approximate. Very small deviations from zero at mid vacuum may be corrected by adjusting the pump drive; however, it should be noted that this will result in a reduction in the range of available plate deflection at one end of the scale. To adjust the plate shape to zero, use the [Vac --] and [Vac ++] keys. If the plate (as seen on the dial gauge) is slightly concave, it is necessary to reduce the vacuum; observe the "Actual vacuum" reading and the dial gauge, and use the keys to obtain a zero value on the dial gauge. If the plate is slightly convex, increase the vacuum until a zero reading is obtained. BE Page 7 of 14

8 Larger deviations may be removed by conditioning the plate, using the diamond smoothing block, to ensure a flat surface. For further information on the maintenance and preparation of expanded polyurethane plates, consult manual ref. no. BP When the internal LVDT and vacuum level are correctly set, press [Exit] to return to the Polishing Menu Screen (Figure D2) ZEROING THE INTERNAL PLATE SENSOR On a day-to-day basis, the operator simply requires to zero the internal plate sensor or LVDT. This is converted by the machine s microprocessor system into a plate shape reading on the Process Data Display, representing the plate shape over a 5 inch (127mm) diameter (representing a standard Logitech holding fixture). To zero the sensor, select [Set-up Sensor] from the Polishing Menu screen (Figure D2), then [Set LVDT Offset] from the LVDT Set-up screen shown in Figure D3 above. The "Monitor Set-up" screen shown in Figure D6 is then displayed. This should come in to within the limits of +/-500, i.e. +/- 5? m. Press [Set] to zero the sensor. The display changes from that shown in (a) in Figure D6 to that shown in (b) for a moment, to confirm that the sensor has been zeroed, then returns to the LVDT Set-up screen Monitor: 2.3? Convex Auto-Zero: OFF Monitor Set-up (a) [Set] [Exit] Monitor Set-up Monitor: 0.0? Flat Auto-Zero: ON (b) Figure D6: Monitor Set-up Screen At this point the user should check the shape of the polishing plate s top surface, by zeroing the single dial gauge on the master flat block supplied, then transferring it to the polishing plate. Note that due to the nature of polishing plates, the reading gained will be approximate. However, it will be sufficient to allow the user to gauge whether conditioning of the plate top surface is necessary, using the diamond smoothing block, to ensure a flat surface. For further information on the maintenance and preparation of expanded polyurethane plates, consult manual ref. no. BP BE Page 8 of 14

9 2.6. USING ECCENTRIC SWEEP Eccentric sweep is employed in polishing to give even higher quality results, increasing the area of the plate or pad which comes into contact with the sample. The optimum eccentric sweep movement to use during sample preparation depends on the material being processed; the PM5 machine s Process Data display allows precise control over the sweep amplitude and the sweep speed, to allow these parameters firstly to be optimised and subsequently to be repeated. To set or to alter these parameters, select [Set-up Sweep] from the Polishing Menu Screen (Figure D2). (See also Section 2.2 "System Checks"). Three screens are available when setting parameters for the eccentric movement - see Figures D7 to D9 below. These are: "Set Inner Sweep Limit" - to set the innermost limit of the eccentric movement. "Set Outer Sweep Limit" - to set the outermost limit of the eccentric movement. "Set Sweep Speed" - to set the rate at which the workstation oscillates. A fourth screen displays all the set parameters; press [Next] to move to Figure D7. The screens appear in a cycle, so press the [Next] key to move on to the next screen in sequence. When setting the sweep parameters, only the parameter to which the individual screen applies is displayed and can be altered - the others are hidden. So, for example, the sweep speed cannot be changed from the "Set Inner Limit" screen - the operator must press [Next] twice to move to "Set Sweep Speed". Set Inner Sweep Limit In Out Inner: 20% Outer: Speed: Sweep mode: [-] [+] [Next ] [Exit ] Figure D7: "Set Inner Limit" screen Set Outer Sweep Limit In Out Inner: Outer: 90% Speed: Sweep mode: [-] [+] [Next ] [Exit ] Figure D8: "Set Outer Limit" screen BE Page 9 of 14

10 Set Sweep Speed In Out Inner: Outer: Speed: 75% Sweep mode: [-] [+] [Next ] [Exit ] Figure D9: "Set Sweep Speed" screen To adjust the inner or outer limits, press the [ - ] or [ + ] keys as appropriate. The band of blocks on the display screen (Figure D7 - D9) shows the width of the sweep selected as a percentage of the maximum sweep width available. After the key has been released for approximately two seconds, the workstation will change position to demonstrate the new limit which has just been selected, allowing the operator to gauge whether the sweep range is appropriate. (NOTE: The machine will instruct the user to start the plate to allow these parameters to be set.) NOTE: When a new inner or outer limit is set, and the workstation is moving to demonstrate this new position to the operator, the touch panel keys below the Process Data Screen will not operate until this movement has been completed. In order to set the sweep speed, the third screen in the cycle should be used (see Figure D9). Here the [ -] and [+] keys will simply increase or decrease the percentage of the maximum speed to be used, allowing the desired value to be chosen. When the operator has found the optimum values for the sweep movement, pressing the [Exit] key will take the machine straight into sample polishing, using the last static target set by the operator. This avoids the need to reselect [Polish] from the Polishing Menu Screen. For further information on setting targets, see Section 3. NOTE: During polishing, pressing the [Exit] key will bring the eccentric sweep movement to an end but will not stop the plate. This means that the holding fixture will stop at the end of the current sweep - whereas simply pressing the "STOP" key on the membrane panel will halt both the plate and the eccentric movement at once, in whichever position on the plate track they are at the time. BE Page 10 of 14

11 3. SAMPLE POLISHING The operator may begin sample polishing by selecting [Polish] from the Polishing Menu screen (see also the note on System Checks, Section 2.2). The Process Data Screen will offer the operator the option of setting a static or a dynamic target. A static target is simply a value which is retained by the plate throughout processing; dynamic targets allow a start and end target to be set to be reached over a specific time SETTING A STATIC TARGET PLATE SHAPE Select [Static] as the target type required. The static target can be altered by pressing the touch panel keys below the Process Data Screen, either to make it convex, concave or to return it to a flat target (see Figure D10). The position of the "-T-" demonstrates the value being set in relation to the zero value. Set Target Plate Shape T - Target: 0.0? Flat (start plate to begin processing) [] [] [Set] [Exit] (i) Target set to zero Set Target Plate Shape T - Target: 4.0? Convex (start plate to begin processing) [] [] [Set] [Exit] (ii) Target set convex Set Target Plate Shape T - Target: 2.5? Concave (start plate to begin processing) [] [] [Set] [Exit] (iii) Target set concave Figure D10: Setting Target Plate Shape BE Page 11 of 14

12 NOTE: ENSURE THAT [SET] IS PRESSED EACH TIME A NEW TARGET IS CHOSEN, OTHERWISE THE EXISTING VALUE WILL BE RETAINED. IT SHOULD BE NOTED THAT THE PLATE SHAPE WILL TAKE A SHORT WHILE TO STABILISE AT THE TARGET VALUE SET. THIS IS QUITE NORMAL AND CAN BE OBSERVED BY WAY OF THE POSITION OF THE BLOCK ON THE PROCESS DATA SCREEN DISPLAY. Polishing T- Target: 0.00? m flat Vacuum: 509 mbar [Targ - ] [Targ + ] [Exit] Figure D11: Actual plate shape displayed during processing Note that during sample processing, the operator can alter the shape of the plate at any time by simply pressing the [Targ -] and [Targ +] keys SETTING A DYNAMIC TARGET The Dynamic Target function permits the operator to set an initial and a final plate shape, and the time taken for the transition between these two targets. This allows, for example, the initial plate shape to be matched to that of the sample, and this to be gradually altered during polishing to the final shape required. Select [Dynamic] from the "Select Target Type" screen. The next screen to be displayed (see Figure D12) allows you to either [Start] or [Resume] a process which has already been programmed in. To create new dynamic targets, select [Next]. Choice: Start at Initial Target/Resume Start: -4.00? End: 1.00? Time: 40 mins [ Start ] [ Resume ] Figure D12: Dynamic Target Screen This will take the operator to the cycle of screens shown in Figure D13 below. As with the eccentric sweep parameters, only the parameter to which the individual screen applies is displayed and can be altered. For example, the transition time cannot be changed from the "Set Start Target" screen - the operator must press [Next] twice to move to "Set Transition Time". BE Page 12 of 14

13 Set Start Target Start: -4.00? End: Time: [ + ] [ - ] Set End Target Start: End: 1.00? Time: [ + ] [ - ] Set Transition Time Start: -4.00? End: 1.00? Time: 40 mins [ + ] [ - ] Figure D13: Setting Dynamic Target Screens NOTE: The minimum Transition Time which may be set is 20 minutes, the maximum is 4 hours. Once the three values have been set, press the [Next] key to return to the Dynamic Target Screen shown in Figure D12, and press [Start]. Locate the sample holding fixture within the roller arm, if this has not already been done, then start the plate. If the operator stops the process at any time, selecting [Start] will begin the process again from the start. To continue processing from the point where the process was halted, select [Resume]. During processing, the actual (current) target is displayed at all times - that is to say that it will change during processing from the initial target and move to the final target during the transition time. On completion of the transition time, the machine will maintain the End Target, effectively continuing to polish with a Static Target. NOTE: When polishing with a Dynamic Target, the [Targ -] and [Targ +] keys will not function. Changes can only be made by stopping the process and programming in the new value. BE Page 13 of 14

14 PM5 auto-pol PM5 AUTO-POLISHING FLOWCHART [ Set-up ] [ Sensor ] [ Set-up ] [ Sweep ] [ Polish ] SENSOR SET-UP (System checks) TARGET SETTING Set Plate Shape Sensor Current Intl Lvdt Offset = 234 [ Set Lvdt ] [ Height ] [ Set Lvdt ] [ Offset ] [ Exit ] (System checks) Current Type: Static [ Static ] [ Dynamic ] Set Target Variation With Time Plate under half vacuum Actual vacuum: 509 mbar (Static) Set Point: 509 mbar Internal Lvdt: Monitor Set-up Monitor: 2.3 m Convex Auto-Zero: OFF Choice: Start at Initial Target/Resume Start: -4.00m End: 1.00m Time: 40 mins [ Vac -- ] [ Vac ++ ] [ Vac Off ] [ Exit ] [Set] [Exit] [ Start ] [ Resume ] ECCENTRIC SWEEP Set Start Target Polishing Sweep Parameters In Out [ + ] Start: -4.00m End: [ - ] Time: Inner: 0% Outer: 100% Sweep mode: ON Speed:100% [Edit ] [Exit ] Set End Target Set Inner Sweep Limit In Out [ + ] Start: End: 1.00m Time: [ - ] Inner: 20% Outer: Speed: Sweep mode: [-] [+] [Next ] [Exit ] Set Transition Time Set Outer Sweep Limit In Out Inner: Outer: 90% Speed: Sweep mode: [-] [+] [Next ] [Exit ] [ + ] Start: -4.00m End: 1.00m Time: 40 mins [ - ] Set Sweep Speed In Out Inner: Outer: Speed: 75% Sweep mode: [-] [+] [Next ] [Exit ] Set Target Plate Shape T - Target: 0.0m Flat (start plate to begin processing) [] [] [Set] [Exit] Polishing T - Target: 0.00mm flat Vacuum: 509 mbar [Targ - ] [Targ + ] [Exit] BE BE Page 14 of 14