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Case | Application Example of Spindle Fault Diagnosis for a Double Spindle Inverted Car

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Case | Application Example of Spindle Fault Diagnosis for a Double Spindle Inverted Car

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Project background:

The machine tool is an EMAG double spindle inverted car with a maximum spindle speed of 6,500 rpm and a maximum speed of 5,000 rpm. The customer has not identified any specific problems, which is ready to report them to the machine manufacturer for repair.

I. Test Situation

Field testing of Montronix diagnostic installations:

Left side spindle Right side spindle

To determine the source of the fault, comparative measurements were taken on each of the two spindles to check the performance condition of each spindle.

II. Comparison and Analysis of Test Data Display

Spindle measurement data for machine tool No. 33.

Fig. 1 - Spindle left measurement with machine tool No. 33

The spindle on the left was tested at 0-5000rmp, in 500rmp increments. We can see from the raw vibration data that the overall operation of the spindle is very unstable (fluctuating on a curve at a fixed speed), indicating that the spindle is rotating with uneven forces. As an example, at 4500 rmp, a clear resonance (large yellow arrow) appears when the frequency is 4500 rpm / 60s = 75 Hz and the red arrow shows the tested rpm. Although the amplitude is not large from the spectrum, the vibration acceleration (i.e. the force on the spindle) is clearly abnormal and its suspected to have a resonance. At the same time, there is a homogeneous vibration in the high frequency region in all three directions, at around 854 Hz. This frequency is 11.38 times the operating frequency of the spindle, which suggests that the spindle bearing may be abnormal.

Fig. 2 - Spindle to the right of the machine tool No. 33

Looking at the left spindle, the same running condition, the comparison is very obvious. It is graphically obvious that the two are so different that no experience is needed here. When we check at 4500 rpm, there is no noticeable vibration on the image and the acceleration is smooth, with no arcing (compare Fig. 2 and the area marked by the blue circle in Fig. 3), indicating that the right-hand spindle performance is in a stable state.

In order to compare the measurement results, we also introduced another machine tool of the same construction and type, No. 27, which is a normal machining machine tool. And we tested it in the same way as the previous machine.

Measurement data for the spindle of the machine tool No. 27:

Fig. 3 - Spindle to the left of machine tool No. 27

The intuitive feeling is that the graphics are cleaner, which means that the spindle is running very stable. The vibration becomes larger at the last 5000 rmp which is related to the spindle warming up (the spindle not warming up causes high vibration at high speed), but overall there is no arcing and the forces are well balanced.

Fig. 4 - Spindle to the right of machine tool No. 27

The right-hand spindle is stable and well balanced by the forces. It is only at 4500 rpm that the spindle has a noticeable amplitude in the Z and Y axes at twice and three times the working frequency (75*2=150Hz, 75*3=225Hz), indicating that the spindle may be slightly misaligned in the Z and Y directions, but both amplitudes are small (<0.4μ).

A brief explanation of the misalignment is as follows.

Theoretically, the spindle's axis should be in a straight line. In practice, however, the spindle is a highly complex mechanical compound and deviations are inevitable for various reasons. These deviations are very slight. Generally we consider it to be satisfactory as long as it meets the standard. In the case of misalignment, there are several cases in practice (Figure).

According to feedback from the customer on site, the spindle has a sharp high frequency sound when running at no load, most likely caused by the spindle being misaligned, but the problem has not affected the actual process for the time being.

III. Summary
In comparison, both spindles of the machine tool No. 33 are in unsatisfactory condition. The spindle on the left is in worse condition and further analysis shows that the bearings are worn. The spindle is likely to be scrapped. Also, the spindle is in an unstable condition, which makes it difficult to guarantee machining accuracy and needs to be repaired immediately. The spindle on the right is in better condition than the left, but it is significantly different from the 27 and also has a large amplitude problem. So it is also recommended that it be serviced immediately.

IV. Feedback Validation
A week after the test, the customer took the initiative to provide feedback that machine 33 had been reported to the EMAG factory for repair (as it could no longer be processed). The factory test determined that the spindle bearing had worn out and had to be replaced and repaired, with the repair cycle taking about a month, which was a good verification of the diagnosis.

V. Inspiration
Through the above case, we can see that the diagnostic instrument can display the mechanical data very well, with data and images, anyone can intuitively make comparisons, so that the mechanical data is no longer so invisible and untouchable and dependent on experience. If there are discrepancies, we can look deeper into the source of the discrepancies, and if there are no discrepancies, we can look for other parts of the problem. This simple judgement can help our equipment personnel to quickly narrow down the scope of troubleshooting and focus on the trouble spots, greatly enhancing the efficiency of troubleshooting and lowering the technical threshold of equipment maintenance.

Previous : Case | 1ms Response! Choose the Airbag of the Machine Tool World

Next : Masterlink Universal Add-on 4/5 Axis Drive Control System

Previous : Case | 1ms Response! Choose the Airbag of the Machine Tool World

Next : Masterlink Universal Add-on 4/5 Axis Drive Control System

Case | Application Example of Spindle Fault Diagnosis for a Double Spindle Inverted Car

Views:









Project background:

The machine tool is an EMAG double spindle inverted car with a maximum spindle speed of 6,500 rpm and a maximum speed of 5,000 rpm. The customer has not identified any specific problems, which is ready to report them to the machine manufacturer for repair.

I. Test Situation

Field testing of Montronix diagnostic installations:

Left side spindle Right side spindle

To determine the source of the fault, comparative measurements were taken on each of the two spindles to check the performance condition of each spindle.

II. Comparison and Analysis of Test Data Display

Spindle measurement data for machine tool No. 33.

Fig. 1 - Spindle left measurement with machine tool No. 33

The spindle on the left was tested at 0-5000rmp, in 500rmp increments. We can see from the raw vibration data that the overall operation of the spindle is very unstable (fluctuating on a curve at a fixed speed), indicating that the spindle is rotating with uneven forces. As an example, at 4500 rmp, a clear resonance (large yellow arrow) appears when the frequency is 4500 rpm / 60s = 75 Hz and the red arrow shows the tested rpm. Although the amplitude is not large from the spectrum, the vibration acceleration (i.e. the force on the spindle) is clearly abnormal and its suspected to have a resonance. At the same time, there is a homogeneous vibration in the high frequency region in all three directions, at around 854 Hz. This frequency is 11.38 times the operating frequency of the spindle, which suggests that the spindle bearing may be abnormal.

Fig. 2 - Spindle to the right of the machine tool No. 33

Looking at the left spindle, the same running condition, the comparison is very obvious. It is graphically obvious that the two are so different that no experience is needed here. When we check at 4500 rpm, there is no noticeable vibration on the image and the acceleration is smooth, with no arcing (compare Fig. 2 and the area marked by the blue circle in Fig. 3), indicating that the right-hand spindle performance is in a stable state.

In order to compare the measurement results, we also introduced another machine tool of the same construction and type, No. 27, which is a normal machining machine tool. And we tested it in the same way as the previous machine.

Measurement data for the spindle of the machine tool No. 27:

Fig. 3 - Spindle to the left of machine tool No. 27

The intuitive feeling is that the graphics are cleaner, which means that the spindle is running very stable. The vibration becomes larger at the last 5000 rmp which is related to the spindle warming up (the spindle not warming up causes high vibration at high speed), but overall there is no arcing and the forces are well balanced.

Fig. 4 - Spindle to the right of machine tool No. 27

The right-hand spindle is stable and well balanced by the forces. It is only at 4500 rpm that the spindle has a noticeable amplitude in the Z and Y axes at twice and three times the working frequency (75*2=150Hz, 75*3=225Hz), indicating that the spindle may be slightly misaligned in the Z and Y directions, but both amplitudes are small (<0.4μ).

A brief explanation of the misalignment is as follows.

Theoretically, the spindle's axis should be in a straight line. In practice, however, the spindle is a highly complex mechanical compound and deviations are inevitable for various reasons. These deviations are very slight. Generally we consider it to be satisfactory as long as it meets the standard. In the case of misalignment, there are several cases in practice (Figure).

According to feedback from the customer on site, the spindle has a sharp high frequency sound when running at no load, most likely caused by the spindle being misaligned, but the problem has not affected the actual process for the time being.

III. Summary
In comparison, both spindles of the machine tool No. 33 are in unsatisfactory condition. The spindle on the left is in worse condition and further analysis shows that the bearings are worn. The spindle is likely to be scrapped. Also, the spindle is in an unstable condition, which makes it difficult to guarantee machining accuracy and needs to be repaired immediately. The spindle on the right is in better condition than the left, but it is significantly different from the 27 and also has a large amplitude problem. So it is also recommended that it be serviced immediately.

IV. Feedback Validation
A week after the test, the customer took the initiative to provide feedback that machine 33 had been reported to the EMAG factory for repair (as it could no longer be processed). The factory test determined that the spindle bearing had worn out and had to be replaced and repaired, with the repair cycle taking about a month, which was a good verification of the diagnosis.

V. Inspiration
Through the above case, we can see that the diagnostic instrument can display the mechanical data very well, with data and images, anyone can intuitively make comparisons, so that the mechanical data is no longer so invisible and untouchable and dependent on experience. If there are discrepancies, we can look deeper into the source of the discrepancies, and if there are no discrepancies, we can look for other parts of the problem. This simple judgement can help our equipment personnel to quickly narrow down the scope of troubleshooting and focus on the trouble spots, greatly enhancing the efficiency of troubleshooting and lowering the technical threshold of equipment maintenance.

Previous : Case | 1ms Response! Choose the Airbag of the Machine Tool World

Next : Masterlink Universal Add-on 4/5 Axis Drive Control System

Previous : Case | 1ms Response! Choose the Airbag of the Machine Tool World

Next : Masterlink Universal Add-on 4/5 Axis Drive Control System