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NC PROGRAM CNC TURNING TEST RUN

G10L2P1X0Z-257(G54)
G10L2P2X0Z-59.19(G55)
IF[#1000EQ1]GOTO1000
M64
(UDH 41MM)
G28U0B0
G50S2000
N2G54G99(OUT RUFF 0.8)
T0202G97S1800M03
G0X11Z.2M8M58
G1X-1.7F0.04
G0X10
G71U1.5R.3
G71P50Q55U.3W0.05F.2
N50G0X2.5
G1G42Z0.01F0.05
G1X3.9R0.05
G1Z-2
G1X4.92A120
G1Z-11
G1X8.8
G1Z-26.25
N55G0G40X10
G0X75Z75M9M59
M1

Estimated hours to repair CNC machine tools (Not including troubleshooting)

The below figures are only estimates for the amount of time it will take to repair your machine tool. When serious problems arise or parts are needed that will change everything. Most jobs should be scheduled for at least 2 days of downtime if possible. Many things can go wrong and will go wrong. If the machine is in operational and running in the current condition and you would like to run before the tech leaves to come back the next day, let him know immediately when he comes in the door. This may or may not be possible depending on the job. But I don't know how many times I've asked the customer this before I went to far and they thanked me for this since most people do not ask this question. Below you will find the average time from my experience to perform these jobs. Please remember every machine is different and sometimes you must remove an excessive amount of things in the way. If a bolt is stripped or something is damaged it could easily add another days worth of work. Also remember some alignments are required before doing others.

Average time for CNC Lathe repairs or adjustments Turret square alignment Upper turret (2-4 hrs), Lower turret(4-8) Turret Radial alignment (4-7 hrs) Spindle headstock alignment (3-6 hrs.) Subspindle Alignment (4-8 hrs.) Tailstock alignment (2-6 hrs.) Center line adjustment to grid shift axis (1 hr.) Backlash compensation adjustment per axis (15-min.) Grid shift per axis (15-30min.) Spindle replacement (min. 2-4 Days) Bearings replacement depends on machine and axis(4hrs-2 days) Drive replacement, and setting home- depends what axis(2-6hrs.) Axis Brake replacement (3-6hrs) Tool presetter adjustment per turret (2hrs.) Adjust level /square a machine (2-8hrs.)

Hydraulic troubleshooting and repair problems

Cartridge valve checks before replacement (check, flow control, solenoid, relief)

If its a cartridge valve pull out of the manifold and look at the nose of the cartridge. If there is a screen then see if its clean and try blowing compressed air on, in, and around it. If there is no screen then try pushing on the nose of the cartridge with a small screw driver (be careful not to damage anything). There may be only spring pressure holding it down. Actuate multiple times blowing compressed air into it to try cleaning any debris out. This will work if its a check valve, solenoid cartridge valve, flow control, or dump valve. To do on a relief valve you may have to back the control all the way out and reset the setting afterwards (this may be difficult if you do not understand hydraulic systems). Lathe Horizontal or Vertical machine center Make sure center cap on chuck is installed Chip tray clogged in back of actuator draw tube on opposite end of chuck. Check that the drain hose is not clogged and exit area is clear. Rotary table seals inside are bad Draw bar sometimes has hydraulics and coolant going through them, possible seals bad Low Hydraulic pressure

Machine tool backlash adjustment compensation parameters

What is Backlash? One of the main reasons your CNC machine loses its accuracy, is due to- you got it- backlash! Backlash is the mechanical loss of motion that can result from a mechanical or electrical problem. Basically backlash is the amount the screw has to rotate when reversing directions before the table or turret start to move. How is backlash compensated? Backlash can be tested with indicators, lasers, ballbars or other measuring devices to determine how much motion is lost when an axis reverses direction. This value is entered in the machines parameters, so when an axis changes direction, it compensates the amount in the parameter to determine when the axis will physically move. The value of the parameter is usually in millimeter. Below, are the common parameters and program to run backlash test. Remember to Write down original values first!!! Also, you may want to set the backlash comp first to zero to get the total amount of backlash to make sure it is not excessive. Reading should usually be below .008. Anything above .010 you might want to consider taking a closer look.

What exactly is machine backlash? Ballscrew backlash, ballscrew slop, bearing backlash and more.

Backlash is any non-movement that occurs during axis reversals. Say, for instance, the X axis is commanded to move 1 inch in the positive direction. Immediately after this X movement, the X axis is commanded to move 1 inch in the negative direction. If any backlash exists in the X axis, then it will not immediately start moving in the negative direction, and the motion departure will not be precisely 1 inch.

Backlash in the X or Y axis of machining centers is most obvious when milling full circles. If any backlash exists, there will be a nasty witness mark on each quadrant line (X+, X-, Y+ and/or Y- side of the circle). As you probably know, backlash is caused by normal usage, and checking for backlash (easily done with a dial indicator) should be part of your preventive maintenance program.

There is a feature called backlash compensation that electronically compensates for backlash. However, this feature (commonly set by parameters) simply causes the control to add the amount of backlash to each axis reversal. While this improves positioning accuracy, it does nothing to minimize the excessive vibration a machine will experience when performing powerful machining operations if the axis drive systems are not rigid The best way to correct (at least with box way construction) is to adjust the machine's gibs to eliminate the backlash all together.

Lathe tailstock alignment on CNC machinery and equipment

Tailstock alignments on CNC lathes are usually very simple. But do require that the main spindle or headstock be in perfect alignment first. Some people will use a coax indicator and clamp it in the main spindle and then sweep the center of the tailstock. This setup is only good to get it close and is not usually necessary. The correct way to align the tailstock is to chuck a piece of bar stock in the spindle at least 3" in diameter if possible and a minimum of a foot long. The diameter should be large enough that it does not deflect during cutting.

Check alignment of lathe tailstock to spindle

1. Perform head stock alignment first!! (Under .0004" taper over 6 inches approx.)
2. Chuck up a minimum 3" material to prevent deflection from tool pressure. Use a test piece long enough to simulate your actual part
3. You may want to consider checking the machine level before making the adjustment. Especially if it is a long bed machine.
4. Engage tailstock
5. Make short program to turn and entire length of part
6. Measure diameter at each end and subtract the large end from the small end to determine how much taper is present
7. Also check in middle of the part to verify there was no deflection when the part was machined.

Spindle Orientation adjustments, and parameters

What is spindle orientation and how is it determined? Spindle orientation is when the spindle finds its home position just like a regular machine tool axis accept that its called orientation. Orientation is often needed to align the tools up properly in order to perform a tool change. Orientation could miss position for a number of reasons. Crash, sensor, axis misalignment causing a crash are the most common. Orientation is usually set with either parameters or a pot on the circuit board or drive. Remember axis alignment at tool change position must be correct before adjusting orientation alignment. Orientation is often set parallel with an axis. Make sure you check the tool changer arm alignment slowly rotating through before running a tool change at full speed.

How to adjust spindle orientation? Basically its relatively simple. Just change the parameter, usually only press reset and then orient the spindle again and check the alignments with the tool changer arm. Move the tool changer arm manually by either turning the fan on the back of the motor or sometimes there is an allen wrench or wrench flat. Depending on the machine and if it is a servo motor driven then it sometimes can be rotated by the hand wheel.

Turret Alignment

Learn how to check the Turret alignment on a lathe and make turret adjustments on your CNC. Lathe Turret alignments become necessary for many reasons. Machine crashes are the only reason for needing a turret alignment. The alignment of the turret controls how square your drills will run in your broing bar pockets. The ensure that they run parallel with Z-axis as well as cut on center with the part. If either alignment is out excessive tool wear or breakage will occur as well as sizing problems.. That is why a properly aligned turret is critical to any machining process.

For this turret alignment procedure you will need a magnetic base and an indicator. First, check the squareness of the turret by mounting the indicator in a place where you can sweep across the face of the turret. The indicator should not move when this axis is moved. If it does, you will have to try mounting it on the tailstock, sub spindle or main spindle. In general this should be under .0001 if you are performing the alignment. Depending on tolerance of parts will determine if it is necessary to perform a alignment. If the lathe is doing on center drilling this alignment is much more critical. When a machine is crashed the metal can become distorted so you may want to check multiple stations to confirm you are aligning it to the average tool face. This test checks that the turret face is parallel to the Z-axis slide. This will affect how true your drills and boring bars run.

Pallet change alignment procedures for CNC

Rotary type CNC pallet changers

There are many different designs but the following sequence of events are usually somewhat the same. These type of pallet changers usually are on Horizontal machining centers with a B axis

1. Check the alignment of each pallet when at Zero in the machine. Notice any difference This difference should be repaired first. This can often be caused by crashes which change the mechanical alignment with the pallet and engagement ring found underneath.
2. Next if the indicator reading across the front of the pallets is not true a B axis alignment will be required. This can be a difficult procedure and varies greatly.
3. If it is straight many pallet changers use a lifting type system. Often there is a set of tapered cones or round rod protruding into recesses in the pallet. These pins or cones will often have some bolts that can be loosened to adjust cones center position.
4. Move the machine to pallet change position. Note: you may have to adjust the axis home position if the misalignment is off equal for all cones or alignment pins.
5. To adjust actuate the pallet changer in the motion to move it up and down and view any rotation of the pallet or movement as the pins slide into the holes. Many times you can just loosen the cones and move the pallet changer up and down to self center them.
6. Make sure you check and adjust both pallets.

Lathe Head stock or spindle Alignment

Check spindle alignment by chucking up a piece of material and performing a cut. The material should be a minimum diameter of 2" and around 9" in length. You only want about 6" extended from the face of the chuck jaws. If the diameter of the material is too small or the material is too soft, it could deflect. Unless you want to perform an alignment twice. Once the material is chucked up safely, make a program to turn a 6" length and start cutting. Make sure the cuts are not too heavy, and make sure to clean up the part completely.

Then, measure the piece with a micrometer at both ends. The readings generally should be under .0004" of each other, but check with the builder for their specs. More tolerance may be acceptable depending on what parts are made on the machine. If the chuck side is larger, then your spindle is tilted up towards the upper turret. If the chuck side is smaller, then your spindle is tilted down. Before adjusting anything mount an indicator on the end of the bar and record the reading.

As far as performing the spindle head alignment. This can be fun. Most headstocks have two sets of push pull screws and 6 to 8 Large bolts used to lock down the headstock. First I would tighten the push pull screws down tight opposing each other, but not too tight that you strip them out or bend the bolts. Then I would loosen the hold down bolts. The push pull screws will hold the headstock in relatively the same place. Read your indicator and adjust the push pull screws to jog the head around. Use your indicator to make an estimate as too how much you should move it. Then tighten bolts, no need to really crank them down yet. Now take another test cut and repeat above until you are within tolerance. I like to get it under .0002".

Once you are within tolerance don't forget to crank down the bolts and take one more test cut to make sure it stayed within tolerance. Then loosen push pull screws a little so they do not get damaged in the event of a crash.

Order of which spindle head alignments should be performed
1st- Headstock & turret squareness
2nd-Radial turret, tailstock or subspindle align and part transfer between main spindle