Thread Machining Breakdown
Breakdown 1: Thread cutting failure
| Breakdown Causes | Solutions |
| Non installation of spindle encoder causes system thread cutting failure | Install spindle encoder, ensure encoder line number matches the system |
| Spindle encoder damaged | Change new spindle encoder |
| Disconnection between spindle encoder and system or wrong connection | Use multimeter to measure if the encoder signal line is cracked |
| Circuit breakdown of system internal thread receiving signal | Send to the manufacturer for maintenance or change the mainboard |
| Loose contactor between spindle encoder and the system or bad connection | Ensure tight connection between contactors in two ports and tight welding in the place of bad connection |
Breakdown 2: Wrong thread cutting pitch, nonalignment
| Breakdown Causes | Solutions |
| Wrong parameter setting | Check if fast movement speed is too fast, check the time constant of linear acceleration and deceleration, thread acceleration and deceleration constant, acceleration and deceleration lower limit of thread axes index, time constant of feeding acceleration and deceleration and the lower limit for low speed of feeding acceleration and deceleration |
| Electronic gear ration is not set up step angle is not modulated | If use 980T system or DA98 servo drive, check if electronic gear ration is correctly calculated and set up. If use step driver, check if the step angle and transmission ratio is correct |
| System or driver steps out | See if step motor or driver steps out through phase lamp or dial indicator. Servo drive can be check through pulse display on the driver or dial indicator; program dry run, see if there is any change in dial indicator after tool post returns to machining starting point; If no, check the parameter and the device |
| Line parameter of system encoder doesn’t match the encoder | There are 1200 and 1024 line parameter selection in 928TC, modify parameter based on spindle encoder line number and make sure system matches spindle encoder |
| Performance overload | There is upper limit for the multiplier of spindle speed and screw pitch. If exceed this upper limit, it may cause abnormal machining. Make sure all performance indexes are within reasonable range |
| Wrong operating mode or wrong programming format | Read operating instruction, get familiar with programming format and operating mode; wrong thread machining pitch for 928TA, 928TC (V2.13), add K value into thread machining instruction |
| Mechanical breakdown or motor failure | Measure if the location precision is qualified, measure screw clearance and see if use system parameter eliminate the clearance; check motor bearing and ballscrew, tightness of tool post location precision in overload situation, check spindle, fixture and tool installation, tool alignment and compensation |
| Spindle encoder signal line is interfered | Please use shielding signal line of spindle encoder and ensure reliable connection of shielding contactor between two ports |
| Unstable spindle speed | Eliminate external interference, check mechanical transmission stability |
| Mismatching between workpiece material and tool | Use matching tool to avoid sticking to the tool |
Breakdown 3: Nonalignment of the first few threads, the rest are normal
| Breakdown Causes | Solutions |
| Due to speed ascending and descending, there is incorrect lead in thread starting and finishing parts. Therefore it’s necessary to reserve dry run distance which varies with parameter | Method 1: adjust system parameter. Please refer to the configuration of 980T with step driver: No.22：200; No.23：4000; No.24：400; No.25：400; No.26：100; No.27：8000; No.28：100; No.29：100; No.30：100; Method 2: adjust machining process by programming. Change thread machining instruction G92 into G32, run G32 at F feeding speed by G01 instruction so as to reduce the impact caused by speed ascending and descending |
Breakdown 4: Run out of thread, wrong path
| Breakdown Causes | Solutions |
| Wrong programming format or operating mode | Read instruction and get familiar with programming format and operating mode |
| System soft failure | Initialize the system. If it still doesn’t work, send it to the manufacturer for maintenance |