Predator Probe Theory and Operation

Transcription

1 Predator Probe Theory and Operation VM Products, Inc. Specialists in Eddy Current Probes, Reference Standards, Applications, Research & Development P.O. Box 44926, Tacoma, WA Tel: (253) / Fax: (253) * sales@vmproducts.net 1

2 The Predator probe is a multi-coil arrangement that acts as a self balancing system which greatly reduces the unwanted signal created by probe movement and uneven inspection surfaces. This design creates a directional probe that gives optimum results when scanned in specific directions. It has also been found that this self balancing advantage allows the operator to go from one material to another without significant changes in the instrument settings. Now, one probe can be used for crack detection on various materials such as Aluminum, Steel & Titanium without time consuming instrument set-up adjustments. 2

3 The Predator Probe operates best when used as a Reflection (driver/pick-up) probe. Select a Reflection cable, such as the VM99L16R-102F, when using the Predator Probe with the Nortec 2000D+. Typical preliminary instrument *settings for the Nortec 2000D+ are as follows: Frequency 100 khz Angle Approximately 8 Degrees or adjust so flaw signal is vertical up Gain Approximately 58 db Probe Drive HIGH Low Pass Filter 100 Hz High Pass Filter - OFF *Exact settings may vary slightly between probes. 3

4 This signal is produced by a deep EDM notch in 7075-T6 Aluminum. The phase angle is adjusted to display the signal in a vertical direction Deep EDM Notch Aluminum Fig Deep EDM Notch Titanium This signal is produced by a deep EDM notch in 6AL-4V Titanium. The settings are the same as those used for the Aluminum. The signal is very good considering the 100 khz frequency. Fig. 2 4

5 This signal is produced by a deep EDM notch in 4340 Steel. Again, the settings are the same as those used for Aluminum and Titanium Deep EDM Notch 4340 Steel Fig. 3 All Three Materials This display shows all three materials using the same settings. The probe was balanced in air, not on the materials. There is very little signal offset between materials when the coils are closely balanced. Fig. 4 5

6 The VM2502RA-P125-1/2 x 6 Predator Probe is scanned across transverse and longitudinal EDM notches in the radius of the VM30889-C1A reference standard. #1 #2 Fig. 5 Notch #1 Notch #2 Probe Movement When these two notches are scanned, they will produce signals which travel in opposite directions. This feature can aid in determining the orientation of the flaw. Fig. 6 6

7 Normal scanning is in the direction of the probe axis as shown on page 9. This display shows a signal from a scan across a deep EDM notch in aluminum. The phase is adjusted to give an upward motion. Fig. 7 Fig. 8 Turn the probe 90 degrees from its original orientation and scan across the same notch in the same direction of travel as the first. This will produce a signal that is 180 degrees from the original. This helps verify the flaw and its location. 7

8 Fig. 9 CAUTION: The Predator is designed as a directional probe. It should be scanned in the directions indicated on the probe. If the probe scan orientation is somewhere between these scan marks, a reduced signal will result. The display above shows a scan where the probe is rotated at 45 degrees from normal. This almost completely eliminates the flaw response. 8

9 Fig. 10 #1 #2 Scan direction is normal to the axis of the probe. Scan direction is across the flaw. Ref. Fig. 7 Fig. 11 #1 #2 Probe orientation 90 degrees from normal. Scan direction the same. This will produce a Signal 180 degrees out from the normal. Ref. Fig. 8 Fig. 12 #1 #2 Probe angle is between normal and 90 degrees. At 45 degrees the signal is almost completely eliminated. Ref. Fig. 9 9

10 Predator-.325 Straight Version / 3 ½ long, dia. shaft with ¼ wide tip &.200 diameter coil. Predator-.125 Straight Version / 3 ½ long, dia. shaft with ¼ wide tip &.125 diameter coil. PREDATOR N Predator N Right Angle Version / 3 ½ long, dia. shaft with ¼ wide tip &.200 diameter coil. 3/8 Drop with head in line with the shaft. PREDATOR W Predator W Right Angle Version / 3 ½ long, dia. shaft with ¼ wide tip &.200 diameter coil. 3/8 Drop with head perpendicular to the shaft. 10

11 PREDATOR N Predator N Right Angle Version / 3 ½ long, dia. shaft with ¼ wide tip &.125 diameter coil. 3/8 Drop with head in line with the shaft. PREDATOR W Predator W Right Angle Version / 3 ½ long, dia. shaft with ¼ wide tip &.125 diameter coil. 3/8 Drop with head perpendicular to the shaft. PRED N-1.5 Predator N-1.5 Right Angle Version / 1 ½ long, dia. shaft with ¼ wide tip &.200 diameter coil. 3/8 Drop with head in line with the shaft. PRED W-1.5 Predator W-1.5 Right Angle Version / 1 ½ long, dia. shaft with ¼ wide tip &.200 diameter coil. 3/8 Drop with head perpendicular to the shaft. 11

12 PRED N-1.5 Predator N-1.5 Right Angle Version / 1 ½ long, dia. shaft with ¼ wide tip &.125 diameter coil. 3/8 Drop with head in line with the shaft. Predator W-1.5 Right Angle Version / 1 ½ long, dia. shaft with ¼ wide tip &.125 diameter coil. 3/8 Drop with head perpendicular to the shaft. VM2530RA-P125-3/4X7 Stainless Steel Shaft Right Angle Probe / 7 long with.165 dia. shaft &.125 diameter coil. 3/4 Drop head. Optional sizes are available. Please contact VM Products for Price and Delivery (253)