Analysis Of Problems in EDM Machining

Broken Wire

1. Poor discharge status

Decrease the value of P. If the value of P is lowered and the wire is still broken, consider reducing the value of I until the wire is not continuous. This operation will reduce the processing efficiency. If the wire breaks frequently, please refer to the following to find out the root cause of the wire breakage.

2. The flushing state is not good. For example, the upper and lower nozzles cannot be used for veneer processing, or during open processing, the wire breakage is usually located in the processing area.

Lower the P value and check whether the upper and lower spray nozzles are damaged. If damaged, please replace it in time.

3. The conductive block is severely worn or too dirty, and the broken wire is usually located near the conductive block.

Rotate or replace the conductive block and clean it.

4. The guide wire part is too dirty, causing wire scraping, usually the broken wire is near the guide wire part.

Clean the guide wire parts.

5. Too much tension

Lower the wire tension FW in the parameters, especially when taper cutting.

6. There is a problem with the quality of the electrode wire and workpiece material.

Replace the electrode wire, reduce the P and I values, until the wire is continuous.

7. The waste silk in the waste silk bucket overflows and contacts the machine tool or the bottom surface, causing a short circuit. Usually, the silk breaks just after the processing is started.

Put the overflowing waste silk back into the waste silk bucket, and clean the waste silk bucket in time.

8. Broken wire at the take-up wheel

Check the wire pressing ratio of the take-up wheel, the standard value is 1:1.5～1.6.

9. Insufficient cooling water for the conductive block, usually the broken wire is located near the conductive block

Check the cooling water circuit.

10. The conductivity of deionized water is too high, usually the broken wire is in the processing area

Check the conductivity of the water. If it is out of tolerance, replace the resin in time.

11. The quality of deionized water is poor, and the broken wire is usually in the processing area.

If the water in the water tank has turbidity or peculiar smell, or there is a problem with the pure water added to the machine, the water tank should be cleaned in time and the filter paper core should be replaced.

12. The wire is broken, there is waste wire embedded in the ceramic guide wheel of the lower head, or the guide wheel bearing does not run flexibly.

Clean and re-adjust and install the ceramic guide wheel, and replace the guide wheel bearing if necessary.

13. The balance wheel shakes too much and the wire is not smoothly transported.

Correct the wire speed and use a tensiometer to correct the wire tension.

Low Machining Speed

1. Not processed according to the standard process, the upper and lower nozzles are more than 0.1mm away from the workpiece

Veneer processing as much as possible.

2. The created process file is incorrect.

Input the relevant processing requirements correctly and generate reasonable process documents.

3. Modify the processing parameters, especially if the P and I values ​​are reduced too much, the processing speed will be greatly reduced.

It is necessary to modify the discharge process parameters reasonably.

4. The flushing state is not good enough to reach the standard flushing pressure.

If the veneer processing is indeed not possible, the processing speed must be correctly understood.

5. Deformation of the workpiece leads to unstable discharge state during machining, especially trimming.

Reasonably arrange the process to control material deformation.

6. If ACO (Automatic Process Optimization) is selected in the parameters, the processing efficiency will be reduced in the case of unstable processing.

In the case of stable cutting, the ACO function can be cancelled.

7. For workpieces with many corners, using high-precision parameters can obtain higher accuracy, but it will reduce efficiency.

Properly reducing the STR value of the corner strategy can increase the processing speed.

8. Mode 30 processing, the discharge stability is not good, the speed is slow

Modify the parameter UHP to increase 2 values.

9. The trimming speed is slow.

The relative processing volume of each cut can be changed to be smaller. If you want to increase the speed of trimming one, you can reduce the offset of the main cut by 0.005mm～0.01mm.

10. The main cutting efficiency is lower than before.

Maintain the machine tool in time.

Silk Marks On The Surface

1. There is a problem with the quality of the electrode wire.

It is recommended to use original consumables.

2. The workpiece material is problematic, or the material contains impurities.

Replace the workpiece material.

3. The release of local internal stress in the internal tissue of the workpiece will cause wire marks to occur in individual positions of the workpiece.

Optimize the processing technology to reduce the internal stress and deformation of the material.

4. The temperature of the working fluid is too high or the temperature changes too much.

A refrigerator must be used to control the liquid temperature and ensure a proper ambient temperature.

5. The external environment of the machine tool is harsh and the vibration is large.

Improve the external environment of the machine tool.

6. The conductive block is severely worn.

Rotate or replace the conductive block.

7. Insufficient cooling water for upper and lower conductive blocks.

Clean relevant parts.

8. The guide wire is too dirty.

Maintain the guide wire section.

9. The working fluid is too dirty.

Clean the liquid tank and water tank, and replace the working fluid.

10. Observe whether the discharge state is stable, and whether there is a short-circuit back-off phenomenon during trimming.

If there is a short circuit in the trimming, the UHP value can be increased by 1~2.

11. If the discharge current and voltage are normal when trimming, but the speed is very low.

The relative offset can be reduced.

12. The flushing state is not good, and it cannot reach the standard flushing pressure and jet shape.

Check whether the upper and lower nozzles are damaged. If they are damaged, they should be replaced in time.

13. Silk tension is unstable.

Calibrate the wire speed and tension.

The Surface Is Not Polished

1. The relative offset is too small.

Increase the relative offset appropriately.

2. The deformation of the workpiece material causes uneven cutting speed during trimming.

Reasonably arrange the process to reduce material deformation.

3. The quality of the electrode wire is poor. It is recommended to use original consumables.
4. The guide wire is too dirty.

Maintain the guide wire section.

5. The conductive block is severely worn. Rotate or replace the conductive block.
6. Wrong selection of process parameters.

Input the relevant processing requirements correctly and generate reasonable process documents.

7. The flushing state is not good, and it cannot reach the standard flushing pressure and jet shape.

Check whether the upper and lower nozzles are damaged. If they are damaged, they should be replaced in time.

Large Cutting Shape Error

1. When cutting corners, the lag of the electrode wire will cause the corners to collapse.

For workpieces with high corner accuracy requirements, parameters with corner strategies should be selected.

2. In order to reduce the deformation during the processing of larger workpieces, the processing technology can be improved:

(A) Die:

Make two main cuts, first increase the compensation amount of the main cut by 0.1mm～0.2mm on one side for the first main cut, let the stress release, and then use the standard offset for the second main cut.

(B) Punch:

1) Two or more temporary stays should be reserved, and open processing is used during programming.

2) Arrange a reasonable starting position and supporting position. Try to punch holes and avoid cutting directly from the outside of the material.

3. The wire is not vertical.

Perform wire calibration again.

4. The external environment of the machine tool is harsh and the vibration is large.

Improve the external environment of the machine tool.

5. The quality of electrode wire and workpiece material.

It is recommended to use original consumables and materials without quality problems.

6. The distance between the workpiece clamping position and the upper and lower nozzles is too large.

Adjust the clamping method.

7. The wire speed or wire tension is unstable.

Adjust or calibrate the wire speed and tension.

8. The flushing conditions have changed significantly, causing the wire to vibrate greatly.

Check the upper and lower spray nozzles. If the spray nozzles are damaged, they should be replaced in time.

9. Whether the axis of the machine tool and the upper and lower arms collide, causing the mechanical accuracy to change.

If the shaft or the upper and lower arms collide, resulting in abnormal accuracy, please contact service personnel for repairs in time.

Workpiece Concave or Bulging

1. Concavity in the middle of the workpiece: you can reduce the Ssoll value of the main cutting and trimming parameters, increase the wire speed and tension, increase the last cut constant-speed cutting speed, and increase the relative offset between trim 1 and the main cut.
2. The bulge in the middle of the workpiece: the opposite of the method of processing the concave center of the workpiece.

The Two Ends Of The Straight Body Are Different

1. The quality of the electrode wire is poor.

It is recommended to use original consumables.

2. Optimize the parameters.

1) Increase the wire speed and slightly increase the wire tension.

2) Adjust the parameter CCON.

3) When programming, add taper compensation in the program.

Wire Mark At The Cutting Edge Of The Die

1. Adopt arc cut-in-arc cut-out method.

When programming, the arc cut-in-arc cut-out method is adopted, and the arc size is 0.5mm.

2. Adopt the cut-in-cut-out point separation method.

When programming, set each entry point to a different position to avoid entering and exiting from the same point.