Evident LogoOlympus Logo
자료실
Application Notes
자료로 돌아가기

배빗 베어링 라이너의 초음파 검사


Application

bearing being tested

Testing the bond between Babbitt metal bearing liners and steel or bronze bearing shells and measuring the liner thickness.

Background

Babbitt metal, first formulated in 1839, is an alloy of tin or lead, copper, and antimony that is commonly used as a rolling contact surface in friction bearings because of its low coefficient of friction, good load-bearing and lubrication properties, and resistance to galling. Babbitt bearings typically consist of a relatively thin layer of Babbitt cast over a steel or bronze shell that provides structural strength. Proper bonding between the Babbitt liner and the steel or bronze shell is essential for performance, and the thickness of the Babbitt is often of interest as well. Babbitt bonding and thickness can be readily tested with ultrasonic flaw detectors if the Babbitt layer thickness is greater than approximately 0.2 mm (0.008 in.).

Equipment

Any Olympus flaw detector can be used for this test. These include the EPOCH® 6LT, and EPOCH 650 instruments. Selected contact or delay line transducers can be used as described below.

Procedure

(a) Bond test from the outer surface of a bearing

In cases where the outer surface of the bearing shell is accessible and concentric with the inside diameter (ID), the simplest procedure is to test from the outside with a small contact transducer, typically in the frequency range from 10 MHz to 2.25 MHz. Common choices include the V112-RM (10 MHz), V110-RM (5 MHz), and V106-RM (2.25 MHz) transducers. If the liner is bonded, a small echo from the shell/liner boundary will be followed by a larger echo from the liner ID. If the liner is disbonded, there will be only a large echo from the inner surface of the shell.

The waveforms below show a typical response from a 2 mm (0.080 in.) Babbitt liner inside a 17.75 mm (0.700 in.) steel shell, using a V112-RM contact transducer. In the waveform example below, on the left, the small negative echo in the red gate followed by an echo in the blue gate represents a bonded condition. In the waveform on the right, the much larger negative echo in the red gate and the absence of an echo in the blue gate represents a disbond.

Typical indication from good partTypical flaw indication, echo in red gate
Typical waveform from a bond Typical waveform from a disbond

(b) Bond testing from the inner surface of a bearing

Liner bonding can also be tested from the ID using a small-diameter delay line transducer, typically with a broadband delay line that has been radiused to conform to the ID curvature for optimum coupling. Frequency ranges from 20 MHz for very thin Babbitt (under 0.5 mm [0.020 in.]) to 2.25 MHz for thick Babbitt (5 mm [0.200 in.] or greater). Common choices include the V208-RM (20 MHz), V202-RM (10 MHz), V206-RB (5 MHz), and V207-RB (2.25 MHz) transducers with radiused delay lines. This test is based on both echo phase and amplitude. If the Babbitt is bonded, there will be a positive polarity reflection from the liner/shell boundary. If the Babbitt is disbonded, the echo will be negative and significantly larger. This is due to the relative acoustic impedances of the two metals. The waveforms below show a typical response from a 2 mm (0.080 in.) Babbitt liner inside a steel shell, using a V202-RM delay line transducer. In the waveform on the left, the small positive echo in the gate represents a bonded condition. In the waveform on the right, the much larger negative echo followed by multiple reflections represents a disbond.

Typical indication from good partTypical flaw indication, echo in red gate
Typical waveform from a bond Typical waveform from a disbond

(c) Babbitt thickness measurement

Babbitt thickness can be measured from the outside or inside diameter. Thickness measurement uses the same transducers as the bonding test and can be performed simultaneously. The waveform below shows a typical thickness measurement from the ID of a bearing. Note that Babbitt metal is very soft and thus has a very slow sound velocity for a metal—typically about 3350 m/s (0.1315 in./µs) for tin-based Babbitt alloys and about 2285 m/s (0.0900 in./µs) for lead-based Babbitt.

Typical indication from good part
Babbitt thickness measurement

For further information on Babbitt bearing testing or any other ultrasonic test applications, contact Olympus.

Olympus IMS

이 애플리케이션에 사용되는 제품
EPOCH 6LT 휴대용 초음파 결함 탐상기는 한 손 작업에 최적화되어 있으며 로프 접근 및 고소 작업이 필요한 고휴대성 응용 분야에서 탁월한 성능을 제공합니다. 가볍고 인체 공학적 디자인으로 사용자의 손에 단단히 고정시키나 로프 접근이 필요한 응용 분야에서는 다리에 묶을 수 있습니다.
EPOCH 650은 다양한 응용 분야에 대한 우수한 검사 성능과 유용성을 갖춘 재래식 초음파 결함 검출기입니다. 이 직관적이고 견고한 장비는 인기 있는 EPOCH 600 결함 탐상기 후속작이며 추가 기능을 갖추고 있습니다.
죄송합니다. 이 페이지는 해당 국가에서 사용할 수 없습니다.
아래 양식을 작성하여 원하는 내용을 알려주십시오.
죄송합니다. 이 페이지는 해당 국가에서 사용할 수 없습니다.