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1. March 2003 Conclusion Maintenance Manual Thermal expansion is a natural occurrence in any machining operation and when ignored can significantly impact accuracy and positioning By identifying and eliminating unwanted heat sources by calculating or measuring expansion effects and altering positioning accordingly by performing regular maintenance on the VMC and by adopting the machining practices outlined above the effects of thermal expansion can be reduced For higher accuracy requirements several options can be added to a standard VMC to further reduce expansion effects Thermal expansion itself is unavoidable but its undesirable effects can be eliminated Section 14 General Information 493 Fadal Maintenance Manual This page intentionally left blank 494 Section 14 General Information March 20032. differences are created Sunlight on a VMC will cause the side of the machine in the sun to expand at a different rate than the side in the shade Radiant heat sources such as ovens or hydraulic pumps will heat the side of the VMC closest to them significantly more than the side furthest from the radiant heat source Causing uneven expansion Cooling vents without diffusion gratings can blow cooler air onto one area of the VMC than another area once again Causing uneven expansion The goal is to surround everything with an even temperature A shop at 90 degrees will experience more thermal expansion than a shop at 70 degrees but a shop at 70 degrees with an air conditioning vent blowing directly on the VMC will experience more problems with uneven thermal expansion There are a few machining practices that can aggravate thermal expansion or its perceived effects and deserve special mention One is the use of rapid moves in a CNC program which can vastly increase the friction and therefore the thermal expansion on the ball screws The obvious drawback of reducing rapid moves is a slower production rate however this may be compensated for by increased accuracy and reduced scrap rates Another practice is using ceramic or other cutters without coolant and allowing the chips to sit on the table The chips absorb the majority of the heat from the cutting process and then transfer this heat to the table causing the table to expand independ
3. If a null modem is used that was supplied from FADAL the switch must be in the outward position away from the cable Use the mirror plug test as described in step 4 of the VMC section above to test each section of cable from the VMC to the computer replacing any section that fails What is the length of the cable a The longer the cable the slower the baud rate must be The faster baud rates may work for the longer cables but the chance of losing informa tion increases the faster the baud Try using a slower baud rate and if this works better this may be the best solution However this also may indicate an IO port at the computer with low voltage See the Computer and Computer IO Port section below Is the cable plugged into the proper port in the back of the computer a Some ports are marked COM or SER these are the proper ports lf the ports are unmarked a COM or serial port will be the male gender port the port with the exposed pins the female gender port will have sockets A gender changer plug may be needed if the gender on the cable will not plug into the proper COM or serial port Is the port active Is the cable on the inside of the computer cover attached to the port Check the voltage across pins 2 and 7 while transmitting a file use a file large enough to allow time to check the voltage while the transmis sion is in progress With the positive lead on pin 2 and the negative on pin 7 the
4. b DNCX using XMODEM e Baud rate This is variable and it must match the baud rate set at the VMC with the SETP command or with the CD command e Parity N None e Data Bits 8 Eight Stop Bits 1 One e EOB End Of Block CR LF ASCII 13 10 e Starting and ending character ASCII 37 e Packet Data Bytes 128 e Hardware handshaking disabled For more information see the file XMODEM DOC on FADAL s Bulletin Board 2 Use DOS to send a file bypassing the communications software in the computer If this works the software is in doubt a From the DOS prompt type the following two DOS commands shown in bold MODE COM2 2400 E 7 1 MODE port baud parity data bits stop bits MODE DOS command followed by a space port COM2 the is required DOS syntax baud 2400 the is required DOS syntax parity Even the is required DOS syntax data bits 7 the is required DOS syntax stop bits 1 TYPE C CNCDATA PN1234 NC gt COM2 TYPE pathnamefilename gt port TYPE DOS command followed by a space Section 14 General Information 481 Fadal Thermal Expansion Overview Recognizing Thermal 482 Expansion Accuracy and Repeatability Maintenance Manual pathname C CNCDATA substitute the drive and directories where the file being sent to the VMC is stored filename PN1234 NC substitute the name of the file sent to the VMC gt gt th
5. conditioned through some of the steps just mentioned the thermal stability of the table benefits even more There are several options that can be added to a standard VMC to help manage the thermal expansion problems Section 14 General Information 491 Fadal Probe Glass Scales Coolant Through Spindle Cooled Ball Screws 492 and Spindle Maintenance Manual A probe in the spindle can be used as a part of the program to discover what adjustments are required to compensate for thermal expansion The probe can be used to pick up the new home position at the beginning of each program or even at various times within the program A probe can quantify the rate of expansion in the Z axis and a change can then be made to the tool table The probe can also track the Y axis and X axis growth and by using a macro the fixture offsets can be altered without operator intervention Because the amount of expansion differs depending on where the fixture is located on the table each fixture should be relocated with the probe A consideration when using a probe is that if a chip is in the spindle or on the probe s holder the probe will indicate an incorrect position Because they are independent from the ball screws glass scales are more nearly accurate in positioning the table but they are affected by thermal expansion themselves generally from ambient temperature and they cannot combat the expansion of the head Keeping direct sunlight
6. off of the scale covers and maintaining the ambient temperature to plus or minus one degree from a target temperature should allow glass scales to perform well Still other steps must be taken to minimize the effects of thermal expansion on the head the spindle and the part material itself Glass scales are a good solution in a situation with multiple fixtures when a probe is not used FADAL s Coolant Through Spindle option is designed to work in conjunction with specific tooling with a hole in the center to allow coolant to be pumped deep into the part where normally coolant does not reach This significantly improves the rate at which heat is removed from the area of the cut reducing the expansion of the part material In addition there is less heat to be transferred through the tool to the spindle and the head so expansion of the spindle and the head is also significantly reduced improving Z axis positioning and accuracy The only effective way to greatly reduce the thermal expansion of the ball screws is to provide coolant through the center of the screws Building on the Coolant Through Spindle concept machines equipped with this feature pump a fluid through the screws and the spindle A refrigeration unit coupled to a thermostat is used to control the temperature of the fluid which consequently conditions the temperature of the screws and spindle as the fluid flows through them Section 14 General Information March 2003 Fada
7. only accepted characters allowed before the initial percent sign are DNC DNCX or TA 1 In addition no O words are allowed in DNC mode Example DNC b Atwo second dwell is required between the DNC command and the first percent symbol If the software being used to transmit the program cannot support this dwell time remove the DNC DNCX or TA 1 com mand from the file and type the command at the VMC before starting file transmission 3 When a file is posted for a paper tape or when a paper tape is read and placed on a disk it may have leader characters before the initial percent sign they need to be removed 4 If some of the file can be transmitted but some of it cannot check for syntax errors a Examine the area in the file for syntax errors and repair them For example double motion words or missing words are syntax errors Section 14 General Information 475 Fadal 476 Maintenance Manual Example X1 23 X4 5 Double motion words Y2 3 Incorrect placement of minus 534 No word at all Use the TA 1 1 command for program transmission so that the control will halt transmission and display the line where the syntax error occurs 5 If a word processor or editor is used to write the program it must be saved in a text only format Some processors will add formatting characters to the file which will disallow communications VMC 1 Check to see if the grounding wires are properly attache
8. voltage should range between 10 and 12 volts Any voltage below 10 volts could result in interrupted communications A FLUKE meter or equivalent used to measure voltage must be set to AC to obtain a reading When the computer was set up did any interrupts interfere with the communications port A qualified computer setup person will be able to confirm that the port is free of other interrupts Section 14 General Information 479 Fadal Maintenance Manual 4 If an IBM compatible computer has a serial mouse is the mouse plugged into the proper port a Usually the serial mouse is used in COM1 or serial port one Move the mouse to COM1 and the VMC cable into COM2 and try to communicate again If the mouse is not to be used during the DNC process remove the mouse software commands from the CONFIG SYS and or AUTOEXEC BAT file s and then reboot the computer CAUTION Only a person familiar with altering these files should perform this operation as these files are necessary for startup of an IBM compatible computer Refer to the DOS manual for any questions regarding these files and how to properly modify them 5 Some screen saver software can interrupt communication change the baud rate or transmit an odd hidden character when the screen saver starts to display Remove or disable the screen saver software and try to communicate again 6 The quality of the IO board must be considered Multipurpose IO boards are us
9. 20 04 2000 11 0020 For reference the old serial number scheme Year of Machine Month of Example 9911020 99 11 020 Manufacture Section 14 General Information March 2003 Fadal Communications Troubleshooting Environment March 2003 File Maintenance Manual For communication problems several factors must be examined Review the environment then check the file the VMC the cables the computer and finally the computer s communications software Any one of these systems can propagate a communication problem In areas where lightning strikes are common communications can be interrupted when or after lightning has struck a power line The lightning may affect the memory of the CNC control which would then have to be zeroed from the DI mode It is suggested to call a service person or see the maintenance manual for this zeroing procedure e An RS 232 surge suppressor adds protection in this kind of environ ment 1 Has the file ever successfully been transmitted to the VMC before If the file has been transmitted before has it recently been edited and has something been introduced into the file Use an editor or word processor which will show hidden characters If hidden characters are present in the file remove them 2 If the file has not been successfully transmitted use an editor or word processor which will show hidden characters If hidden characters are present in the file remove them a The
10. Fadal Maintenance Manual Section 14 General Information Helpful Formulas Temperature Degrees Fahrenheit F 9 5 x degrees C 32 Degrees Celsius C 5 9 x degrees F 32 Conversion Factors Inch in millimeter x 0 03937 Inch in centimeter x 0 3937 Millimeter mm inch x 25 4 Centimeter cm inch x 2 54 Liter gallon U S x 3 7854 Gallon U S liter x 0 2642 Bar Pounds per Square Inch psi x 0 0689 Pounds per Square Inch psi Bar x 14 5 Newton metre N m pound foot x 14 5939 Pound foot Newton metre N m x 0 0685 Newton metre N m ounce inch x 0 00706 Ounce inch newton metre N m x 0 1416 Electrical References Formulas from Ohm s Law Amperes I Volts E Resistance R Resistance R Volts E Amperes I Volts E Amperes I x Resistance R Single Phase Kilovolt Amperes KVA Volts x Amperes 1000 Three Phase Kilovolt Amperes KVA Volts x Amperes x 1 73 1000 Expansion Formula Coefficients Expansion amount Coefficient x distance x degree of temperature change Fahrenheit Coefficients Steel 00000633 Cast Iron 00000655 Aluminum 00001244 March 2003 Section 14 General Information 473 Fadal Maintenance Manual Fadal Machining Centers Serial Numbers 474 The new serial number scheme is as follows oo 99 9999 99 9999 Machine Number 01 VMC 02 Rotary 03 Re Man Year of Month of Manufacture Manufacture Example 0420001100
11. d a The only proper and acceptable primary ground is a single continuous copper wire attached from the ground bus in the junction box of the VMC to the main power box of the building A green sticker in the junc tion box further expounds the grounding requirement Any other meth ods of grounding such as grounding to the conduit or to a ground rod are not acceptable and will lead to communication problems See the Pre Installation section for grounding procedures Check to see if the screws attaching the ground wire to the VMC are tight at both ends The ground wire of the RS 232 DB25 plug on the inside of the CNC con trol cabinet must be attached from the RS 232 port to the inside of the CNC control cabinet This wire is attached to pin 1 of the DB25 plug and is used to shield the cable at the VMC end ONLY see the FADAL VMC Users Manual for proper pin configuration If the paint has not been removed from this area scrape the paint away and re attach the wire 2 Check the cable from the RS 232 port on the inside of the CNC control cabinet to the1030 board a Sometimes this cable will work itself out of the plug Press the plug into the board to confirm a good connection Examine the cable for cuts or kinks and replace it if there is evidence of damage 3 For VMCs with a phone modem make sure that the DB25 plug on the inside of the CNC control cabinet is NOT plugged into the back of the Section 14 Genera
12. e gt is required DOS syntax to redirect file to COM2 port COM2 e Note Before typing these two lines the VMC should be in the TA 1 mode ready to receive the program at 2400 baud Refer to the DOS manual for answers to additional questions about the DOS commands used here 3 Running DOS based software from Windows may not work for communica tions Thermal expansion is a natural occurrence in materials subject to heat and there are several sources of heat in any machining operation In addition different materials react to heat at different rates and different subsystems of the VMC react to specific machining operations to different degrees further complicating matters Finally some machining practices designed to save time may actually aggravate the expansion problem Fortunately there are a number of ways in which the unwanted effects of thermal expansion can be reduced to acceptable tolerances Changes in positioning can have many causes and correctly identifying the cause is the key to solving the problem Thermal expansion has a unique signature which can aid in recognizing it as the culprit in a given situation Position changes that are due to thermal expansion occur gradually over time and continue to move in one general direction at a more or less constant rate The best way to combat thermal expansion is to accept the inherent nature of it in a machining operation and to take corrective measures like those sug
13. ently from any other part of the VMC A third practice is the use of cutting oil in place of water soluble coolant Although cutting oil does reduce friction at the surface of the cut coolant does a much better job of carrying away the heat of the cut and minimizing the effects of thermal expansion resulting from that heat Yet another practice that deserves mentioning is machining parts at temperatures significantly different from those at which the parts are inspected If the inherent expansion of the part material from the heat of the machining process is outside tolerance once the part has cooled to inspection temperatures the problem can only be resolved by correcting for the heat generated during machining so as to keep the part material closer to inspection temperatures while the part is being machined Along those same lines it is important to use a gauge at approximately the same temperature as the temperature at which the gauge was calibrated Finally the use of blanks for which the outside dimensions have been established prior to cutting is another practice which aggravates the effects of Section 14 General Information March 2003 Fadal Non Uniform Expansion Material Differences Fixtures Sub Plates Machine Assemblies March 2003 Maintenance Manual thermal expansion Since the blank is going to expand locally from the heat of cutting the actual distance from edge to feature may change The differing rates o
14. epts that will aide the troubleshooting process The first discussion will be number systems We all use the Decimal System or base 10 which is based on ten so when ten 10 counts are reached the next one causes a carry to the next column and each count in this column has a value of 10 times the previous column Each place has a value ten times greater than the next place to the right We use ten numerals 0 to 9 for this system One Hundred Twenty eight 128 Sixty four l 64 Thirty two 32 Sixteen 16 Eight gt lt D D M M OK OK M 00m oo 1 Decimal equivalent total 147 Section 14 General Information 487 Fadal 488 Maintenance Manual The other numbering systems work the same way they just have different base numbers By having a different base number they also have a different number of numerals and the columns have different weights The Binary System or base two 2 is the basic system used by computers Each place has a value twice as great as the next place to the right Two numerals or digits 0 and 1 are used and they are referred to as bits Millions 1 000 000 Hundred Thousands 100 000 Ten Thousands 10 000 X3 X 3 X 4 Thousands 1 000 X 0 Hundreds 100 X 1 J EN Tens 10 X 2 1X7 3 340 12 7 lt 4 Ones To determine the decimal value add the results of each column column value multiplied by column weight Computers use binary number systems because they have two distinct s
15. f expansion by unlike materials further complicate the problems created by the heat generated in the machining process This applies both to parts stock like aluminum and to fixtures and sub plates often also made of a material like aluminum Aluminum s coefficient of expansion is nearly twice that of steel or cast iron the primary VMC materials which means the aluminum will expand nearly twice as much as the ball screws head spindle or table Fixtures or sub plates of material other than the steel cast iron of the VMC will cause the greatest problems in this area unless the bottom of the fixture or sub plate is flat within 001 please note that parallel is not the same as flat and flatness is the key in this area For example a sub plate made of aluminum has an expansion coefficient nearly double that of the table to which it is secured If the flatness is not within 001 the heat of the machining process causing the sub plate to expand at twice the rate of the table will result in the sub plate actually bending the VMC s table This will cause binding which will both affect position accuracy and cause undue wear on the mating surfaces under the table Various assemblies of the VMC itself will be affected by different sources of heat in the machining process and the effect of each assembly on positioning will vary accordingly For instance the head will expand from two heat sources the spindle heat and the ambient temperatu
16. f the system part fixture VMC In its simplest form any solution designed to combat thermal expansion must reduce friction reduce ambient influences or increase heat removal through radiation convection or evaporation A complementary approach is to simply compensate for the changes brought on by thermal expansion In a real life situation a balance of approaches is required Section 14 General Information March 2003 Fadal Ambient Sources Sunlight Cooling Systems Radiant Heat Binary Numbers Number Systems Four x Two 8 4 2 10010011 4 One 1 8 6 2 March 2003 Maintenance Manual Do not allow direct sunlight on the VMC Window shades that diffuse sunlight can be acceptable but any source of warmth that only heats one side of the VMC at a time will cause uneven warming and further complicate thermal considerations Diffusion gratings on air conditioning vents can be used to prevent any air from directly blowing on the machine or part Again an unevenly heated part or machine will cause the heated or cooled portion of the part or machine to expand at rates different from the rest of the part or machine If an operator can detect the radiant heat from other devices a protective wall needs to be erected between the machine and the device radiating the heat This type of heat source will cause the machine to heat up on one side and Cause uneven expansion There are some mathematical conc
17. ffected by the heat of machining It will expand but it takes longer to heat or cool the entire table In addition the use of coolant tends to stabilize the temperature of the table at or close to coolant temperature A machining operation using rapid moves and low spindle speeds with additional cooling at the part through FADAL s servo coolant subsystem will generate much more thermal expansion in the ball screws and hence the X axis and Y axis than will be seen in the Z axis from the spindle or in the part material from the cutting An operation using very high RPM spindle speeds with slower interpolated moves would experience more Z axis expansion but would experience less expansion in the X axis and Y axis and might actually experience less expansion in the part material because the high rate of chip removal carries much of the heat away from the part Each machining operation has a unique combination of factors that apply to predicting and managing the thermal expansion inherent in machining Finding the right solution is a matter of combining various approaches many of which are outlined in the pages that follow A simplified description of the thermal environment in machining would state that heat is generated through friction and also input through ambient factors That heat is transferred among the system components and is either removed from the system through radiation convection and evaporation or absorbed by the components o
18. gested in this document ahead of time lt should be noted that when accuracy and repeatability are quoted for a machine thermal expansion is not considered These values are measured and recorded only when the machine and all of its components are thermally stable usually by limiting test repetitions and time duration so that thermal Section 14 General Information March 2003 Fadal Expansion Coefficients Heat Sources March 2003 Friction Maintenance Manual growth does not have a chance to come into play For example a typical industry test for linear repeatability involves only seven to ten moves away from and back to a position The rate of expansion of any particular material due to temperature can be measured This rate of expansion is referred to as the expansion coefficient and is measured per degree per inch Using this rate of expansion and the temperature of the material the effects from heat can be predicted l Expansion Material Location Usage soe Coefficient Steel Ball Screws Spindle Fixtures Sub 00000633 Plates Tooling part stock Cast Iron Head Table Column Glass Scales 00000655 part stock Aluminium Fixtures Sub Plates part stock 00001244 Formula coefficient distance degrees of temperature change expansion amount For example if a nut is 23 inches from the motor mount and the temperature of the screw has changed 20 degrees the screw length wo
19. git Nibble four 4 bits or binary locations Byte eight 8 bits or binary locations Word Sixteen 16 bits or binary locations Double Word Thirty two 32 bits or binary locations These grouping are used for many reasons The most common are Data Addressing and Status Reading a status in a computer can be very helpful for troubleshooting Status is uSually a byte or a word The status is normally represented in hexadecimal To demonstrate how a status byte is decoded the command 1 byte in the diagnostics display switches will be used Each binary bit in the status byte will represent one relay in this case Because Fadal uses negative logic a value of zero 0 turns the relay on activates it BO is the right most bit Each Hexadecimal digit is representing four 4 binary bits BO M68 M69 B1 High range Idler B2 Unused B3 Drawbar Geneva Slide Enable B4 Drawbar B5 Air indexer B6 Coolant 1 On B7 Coolant 2 On Section 14 General Information 489 Fadal VMC Maintenance Cabinet Fans Lubrication Machining Practices 490 Warm Up Maintenance Manual For example if the command 1 displayed BD then the binary equivalent would be 1 0 1 1 1 1 0 1 To decode remember that 0 is On In this example B1 the high range idler would be On and Coolant 1 would be On The fans in the cabinets must be functioning properly The purpose of the fans in the cabine
20. l Information March 2003 Fadal March 2003 Maintenance Manual modem if it is it will interrupt normal communications through the RS 232 port Use the mirror plug to test the 1030 board The mirror plug is stored in the bottom of the CNC control cabinet when the VMC is shipped The plug is a DB25 plug with no wires coming from it On the inside of the plug pins 2 and 3 are crossed to complete the communications path Plug the mirror plug into the RS 232 port on the outside of the back of the CNC control cabinet a Use the diagnostics mode to complete the test 1 Move to the cold start position 2 From the command mode type DI then press ENTER Type GO 3000 and press ENTER to enter the test menu Press 4 to select the RS 232 1030 test Select a baud rate generally the baud rate used in normal communications 6 Observe the screen 5 4 5 Numbers next to the word TESTING should be changing constantly If this occurs the1030 board has passed the test The numbers at the end of the other sentences should all be zero If any numbers appear at the end of these sentences it is an indication that the 1030 board is faulty assuming the cable was checked in step 2 above Note The 1030 is rarely faulty If the diagnostics test passes then it is safe to conclude that the VMC is not at fault for a communication problem 7 Press the manual button to end the communication test 8 Power off the VMC wait 10 sec
21. onds then power on again 5 Has the proper baud rate been selected at the VMC a The CD command is used to select a baud rate The MU command has a list of each baud in the menu or see the users manual for the same list b The SETP command for the VMC parameters can be used to select a baud rate as default The CD command will temporarily override the selection in the SETP parameter page Section 14 General Information 477 Fadal 478 Cables 1 9 Maintenance Manual Verify that all connections between the communications cable and both the VMC and the computer are firmly seated including surge suppressors gender changers and couplers Pick up the cables and physically confirm that each connection is properly together Loose cable connections are one of the most common causes of com munication problems If a switch box is used determine if the switch is in the proper position a Examine the cable connections to see if they are in the correct ports b Turn the switch handle back and forth a few times Sometimes the con tacts are corroded and turning the handle will temporarily correct the problem e f turning the handle corrects the problem it is suggested to clean the contacts or replace the switch box with a new one If the cable is coiled because the cable is too long it is suggested to get a shorter cable The coiling may cause intermittent problems The shorter the cable the le
22. rature of the screws change The operator can follow the home position changes throughout the production run and change the fixture home position and offsets accordingly Using soluble and synthetic coolants that are mixed with water is the single most effective factor in removing the heat generated during cutting Coolant is formulated specifically to absorb a great deal of heat within its molecular structure without having to radiate that heat onto the next material it contacts Cutting oils are formulated for cutting and lack the cooling quality of soluble and synthetic coolants mixed with water Flood coolant is a better choice than either mist coolant or cutting oils because it benefits the cutting process in addition to providing heat removal The temperature of the coolant can be conditioned further through any of a few simple actions Bags of ice floating in the coolant tank can be used to maintain the temperature Pumping the coolant through a radiator or through a copper coil in the coolant tank or through a copper coil placed in a small refrigerator can all be used to condition the temperature of the coolant One side benefit of coolant is its cooling effect on the table as well as the part As it is splashed around the coolant s direct contact and its evaporation tends to keep the table at or near the temperature of the coolant directly compensating for the effect of hot chips falling on the table If the coolant temperature is being
23. re The effects of thermal expansion in the head will be seen in the directions of the Y axis and the Z axis but not in the X axis with the Y axis expanding away from the column toward the operator and the Z axis expanding down toward the table Meanwhile the Y axis itself will be expanding away from the column due to the expansion of the ball screw which will compensate for the effect of the head s expansion in the same direction The ball screws will expand due to the friction of the nut The effect will increase with the distance of the nut from the motor mounts the effective length of the screw and will be in the direction away from the motor mounts Thermal growth of the ball screws is independent of growth in the head or the table The spindle experiences heat not only from the actual cutting which is transferred through the tool but also from its bearings The spindle also Section 14 General Information 485 Fadal Solving the Thermal Expansion Problem 486 General Considerations Maintenance Manual transfers most of this heat to the head and the thermal growth is reflected in the head position as mentioned above and is independent of changes in the ball screws or table The table receives most of its heat secondhand through the heat of the nut the heat from the part through the fixture or sub plate and the heat carried by hot chips that lay on the table Because of its large size the table seems less a
24. rections needed are for the expansion of the part material as each successive part feature is machined Locate fixture offsets and establish tool length offsets after the machine has attained the optimum operating temperature Avoid using moves or spindle speeds that exceed those used in the part program In addition to running a warm up routine at the beginning of the production shift the same kind of routine can be run during breaks This will maintain the VMC at operating temperature especially the two subsystems that heat up or cool down the most the spindle and the ball screws Section 14 General Information March 2003 Fadal Rough Cut Cool Down Finish Cut Monitoring Position Changes Coolant VMC Options March 2003 Maintenance Manual A complement to the warm up of the VMC is the use of a rough cut to remove most of the material from the part Although the part material heats up the material can then be cooled to a stable temperature Then a series of finish cuts can complete the part in a short time so that the material doesn t have time to expand beyond acceptable tolerance This process is also effective for inspecting parts By cooling the part prior to the finish cuts the temperatures at final cut and at inspection can be brought closer In this situation the target temperature should also be close to the temperature at which the gauge is calibrated The home position of the part will change as the tempe
25. ss chance a parity error will occur Check to see if the cable is draped over fluorescent lights or wrapped around or connected on the high voltage line for the power to the VMC or other machines This can cause RF noise and inductive voltages on the cable and communications will be interrupted from time to time a Welding machines and EDM machines close to the VMC or the cable will also cause communication problems These machines also cause RF noise which interrupts communications Open the DB25 plugs to see if the solder on the pins have been applied properly Cold solder joints for these wires will need to be soldered again 6 Check to see if the wires are connected to the proper pins See the Communication section of the User Manual for the proper pinout Confirm that with shielded cable pin one is connected to the shield at the VMC side only Pin one cannot be connected at the computer side 7 If straight cable is used then a null modem is required A null modem cable can be purchased from the FADAL Parts Department part 4537 or from any computer store A null modem is a short portion of cable or ribbon cable that has pins 2 and 3 crossed The crossover and the proper jumpers on each end can be found in the Communication section of the User Manual Section 14 General Information March 2003 Fadal Computer and Computer IO Port March 2003 fee 1 No WN a Maintenance Manual
26. tates The two states are variously called true and false high and low ON or OFF or 1 and O Two different voltage levels are used to represent the two states Binary Coded Decimal BCD is a numbering system used to represent a decimal number using a group of four 4 bits Hexadecimal Hex is a numbering system using base sixteen 16 This is a very common number system in computers It uses sixteen 16 numerals 0 to F to represent the numbers The following are examples of the numbering system provided to show the differences Decimal Binary Binary Coded Decimal Hexadecimal 0 0000 0000 0000 0000 00 1 0000 0001 0000 0001 01 2 0000 0010 0000 0010 0 2 5 0000 0011 0000 0011 0 3 4 0000 0100 0000 0100 04 5 0000 0101 0000 0101 05 6 0000 0110 0000 0110 06 7 0000 0111 0000 0111 07 8 0000 1000 0000 1000 08 9 0000 1001 0000 1001 09 Section 14 General Information March 2005 Fadal Binary Number Groupings Reading Status Group March 2003 0000 1010 0000 1011 0000 1100 0000 1101 0000 1110 0000 1111 0001 0000 0001 0001 0001 0010 0001 0011 0001 0100 0001 0001 0001 0001 0001 0001 0001 0001 0001 0001 0010 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 0000 Maintenance Manual PrRrPrPrFPOCGMCOOMCOOO ARWNOPFPOTMMUOWDS Since the Binary Numbering System is the one used by computers there is a need to define the grouping of binary numbers Bit one 1 binary location or di
27. ts is to cool the electronics and to move the heat out the vents An excessive amount of heat in the cabinets from clogged holes or nonfunctional fans will transfer to the column and cause it to expand as well as damaging the electronics On a regular basis remove and clean the vent hole grates as the vents occasionally become clogged with dust or other particles and inspect the fans to see that they are working Lubrication is essential for the free motion of the table saddle and head as well as for the nut on each ball screw Each way must be lubricated and the ball screws greased to minimize both the wear on the machine and the excess heat generated by friction The lubrication system must be inspected and serviced regularly Inspect all of the ways to confirm that each way is getting lubricated The lubrication system may need to be flushed by a qualified service person to remove any contaminants on the inside of the tubes and joints The first step in combating thermal expansion effects is also the simplest Run the machine through a series of moves at feeds and speeds equivalent to what will be encountered in the production run long enough to reach an equilibrium that is where the amount of heat being generated is balanced by the amount of heat being removed via convection evaporation or absorption through expansion of material After that point is reached the effect of thermal expansion in the VMC stabilizes and the only cor
28. ually not recommended High quality boards dedicated to only IO functions are recommended DigiBoard and Quad Tech are examples of companies which produce high quality IO boards These boards are specific to the operating system used by the computer one board is used for DOS another for Windows and another for micro channel IBM PS 2 These boards usually test 12 volts across pins 2 and 7 at the computer for the best quality transmission A FLUKE meter or equivalent used to measure voltage must be set to AC to obtain a reading 7 If a network board is installed in the computer the computer technician who installed the board must check for conflicting interrupts and I0 addresses 8 The FADAL Assist software has in its utility menu an RS 232 tester Use the mirror plug in the port and follow the instructions on the screen for test number one Software 1 Check the communication parameters in the software a 480 TA DNC and PU using Xon Xoff Baud rate This is variable and it must match the baud rate set at the VMC with the SETP command or with the CD command Section 14 General Information March 2003 Fadal March 2003 Maintenance Manual e Parity E Even e Data Bits 7 Seven Stop Bits 1 One e EOB End Of Block CR LF ASCII 13 10 Starting and ending character ASCII 37 e Xon Xoff Software handshaking disabled for TA enabled for DNC and PU e Hardware handshaking disabled
29. uld have expanded 0029118 inches 00000633 23 20 0029118 It comes as no surprise that the primary source of heat in machining is friction however some of the sources of friction and all of the areas affected by a given friction source may not be readily apparent Additionally the effects on the ambient temperature from various heat sources in the machine shop are often overlooked The most obvious heat source from friction is the cutting of material itself Heat is transferred to the chips which then can transfer their heat to the table Heat is also transferred to the tool and then to the spindle and then to the head Finally heat is transferred to the part material itself and from there to any fixture or sub plate holding the blank Movement of the table and of the head also generates heat from the friction The ball screws turning produces friction between the nut and the screw heating the screw and causing expansion with the Y axis of the machine experiencing more thermal expansion than the X axis because the Y axis is moving more weight than the X axis The movement of the table on the ways produces friction which can increase the expansion of the ball screws Section 14 General Information 483 Fadal Ambient Temperature Machining Practices 484 Maintenance Manual The general temperature of the shop environment will affect the machining process but the most significant effect will be seen when temperature
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