Application Notes
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Mining Excavator Swing Shaft Inspections


Surface mining often entails the use of large trucks and shovels including massive Dragline excavators in large scale operations to remove overburden to access coal and other deposits of desired resources. Due to the size of this equipment many of the components are very thick resulting in challenging applications for ultrasound. In addition the preferred test methods are with the components in place and in operation which can mean limited access to the areas that need inspected. Phased Array can offer many benefits to these inspections.

Shaft and Pin Inspections

There are many shaft and pin components throughout an excavator. One critical component is the Swing shaft. There may be multiple of these components throughout a single excavator. Common lengths can be 200” plus and diameters of 22” or more. With the component in place there is limited access to the multiple areas that may require testing for fatigue cracking and other defects.  Conventional ultrasonics often utilize multiple angled wedges to inspect as much of the component as possible. Once defects are found the shafts are often removed and a complimentary 0 degree inspection from end to end of the shaft is conducted to further analyze the nature and extent of any defects. There are often many holes and other obstacles for a single beam 0 degree inspection.  Areas of prime interest include known stress areas, tapers and reductions of diameter areas. Because Phased Array offers multi-angle inspections from a single probe the limited access inspection area can be inspected much better and images and data can be stored if defects want to be monitored.

  Swing shaft in place and partially removed
Swing shaft in place and partially removed

Conventional and Phased Array Angle Beam Coverage. Red line shows possible limited access when component is in place

Inspection in field
Inspection i the field after shaft removed

Defect free shaft
Fatigue crack

Image from defect free shaft (corner of taper show) and fatigue cracked shaft

Related Shafts and Pins throughout a Dragline Excavator

Equipment Used

OmniScan SX or MX2

  • Portable for easy access inside cramped area of excavator
  • Conventional, Phased Array and TOFD capable
  • Manual or encoded data

Phased Array Probes and Wedges

  • Vary on application
  • 2.25 MHz common frequency
  • Shear and flat wedges
  • Contact wear faces for long 0 degree metal paths

Optional Software and Accessories

Olympus IMS

This new software is the most efficient and affordable option for OmniScan data analysis, and features the same analysis tools provided in the OmniScan onboard software, with the added flexibility of running on a personal computer.
The mini-Wheel Encoder is used for the positioning and dimensioning of defects in the scan axis. It can synchronize data acquisition with probe movement. It is also waterproof and compatible with Olympus standard PA wedges.
The single group, lightweight OmniScan SX features an easy-to-read 8.4 inch (21.3 cm) touch screen and provides cost-effective solutions. The OmniScan SX comes in two models: the SX PA and SX UT. The SX PA is a 16:64PR unit, which, like the UT-only SX UT, is equipped with a conventional UT channel for P/E, P-C or TOFD inspections.
The OmniScan MX2 now features a new phased array module (PA2) with a UT channel, and a new two-channel conventional ultrasound module (UT2) that can be used for TOFD (Time-of-Flight Diffraction), as well as new software programs that expand the capabilities of the successful OmniScan MX2 platform.
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