Immersion inspection systems for production and laboratory

•     Systems from 0.3 to over 20 metres long

•     2 to 10 axis configuration

•     Contour following systems for complex curves

•     Multi probe systems for high throughput

•     PC based high gain - ultra low noise ultrasonics 

•    C scan and B scan, thickness mapping, volume scan

•     High speed automated production units

A wide range of immersion systems is available for inspection of discs, bars, forgings and fabrications - typical examples are shown below.

Six axis system for inspection of forged discs and other roto-symmetrical parts to Rolls Royce, Pratt & Whitney, GE and similar specifications. A full contour following capability is incorporated, with special software for simple implementation of daily calibration routines.

This is a simplified version of the system shown above - this time with 4 motorised axes (X, Y, Z and rotate) and a manual probe manipulator. The turntable has a raise / lower mechanism for ease of loading. This particular system has special software for processing C scan images generated from multiple gates, to highlight "real" defects  from other indications caused by surface blisters, for example.

This is one of many systems installed at Rolls Royce for inspection of titanium alloy fan blades during the production process. The tests carried out include inspection of the diffusion bonded interfaces at different stages, automated thickness mapping of the blades and bond inspection at the blade root. The particular machine shown above is a 4 axis system for thickness mapping, which uses a mechanical contact follower. Unlike machines supplied for inspection at earlier stages, programmed non contact following is not necessary for this application.

General purpose 7 axis system with X, Y, and Z linear axes, A and B probe manipulator axes, turntable and roller drive units. This unit was designed for a testing laboratory, but is equally suited to production applications. Optionally, it can be fitted with a Z axis yoke and squirters, for through transmission inspection of composite panels held vertically and scanned in an X-Z mode.

This system is installed at TWI, Port Talbot. You can get more information on TWI's general activities at http://www.twi.co.uk , or more specific information about the Port Talbot site on: http://www.twi.co.uk/j32k/unprotected/band_1/ndt_index.html

Large system for inspection of titanium alloy plate destined for engine fan blades. The system uses multi-channel ultrasonics and focussed probes for testing to stringent defect standards - typically 0.8mm FBH equivalent. The immersion tank is separated into two halves by a removable plate. The water can be pumped from one side of the tank to the other in a few seconds, to allow one side or the tank to be loaded whilst the other side is scanning.

6 axis system for production inspection of composite propeller blades, including full contour following and RF acquisition with real time B scan imaging. A dual axis "goniometric" manipulator is used, with the part shape programmed by a "teach and learn" procedure. In this case an additional follower can be used to compensate for small local variations in the surface profile. 

Some immersion testing applications require more specialised functions to facilitate the inspection of parts having an unpredictable shape. For example, in some some systems used for the inspection of SPFDB (superplastically formed - diffusion bonded) components, the scanning system is programmed to do a coarse scan over each part in order to measure the actual surface profile. This information is then used to automatically modify the main scanning program to suit the shape of each component. One of these systems is shown below.

Many of these systems require dual axis probe manipulators for programmed contour following - these have to be reliable for long periods with more or less continuous immersion. One such manipulator is shown below:

This typical manipulator includes double sealed motors and a Harmonic Drive ^TM zero-backlash gearbox. It is manufactured from machined stainless steel, or in some cases titanium alloy for light weight. Manipulators can be configured for tilt / tilt in two orthogonal axes, or tilt/swivel according to the requirements of each system. Where necessary, more than 360 degrees of angular movement is possible.

In other multi-channel systems, the surface profile of plates is measured ultrasonically and the angle of the array probe is adjusted in "real time". Also slight variations in plate thickness are accommodated by measuring the actual thickness during the scan and dynamically changing the monitor gate width to maintain a preset "near surface" and "far surface" resolution.

These pictures show a large tank installation, one of three on this site, for inspection of aerospace aluminium alloy plate up to 200mm thick.

The systems incorporate 6 scanning axes and a 2 axis mechanical scriber which is used to mark the position of confirmed defects.

Other features include detection of plate size and orientation, automatic following of random contours to maintain probe normality, 8 channel ultrasonics, "elastic" gates which follow the measured thickness of the plates and continuous back wall monitoring.

This is a 5 axis multi channel system for inspection of plate material. It is designed for use with a motorised immersion tank which can be driven outside the scanning unit for loading and unloading operations.

The scanning bridge and tank motions are interlocked so that there is no risk of collision if, for example the operator tries to move the tank when the Z axis manipulator is lowered. In addition, there is a collision protection ring around the probe array to avoid collision damage when scanning, if an incorrect scan plan is attempted.

System features 

Mechanical

Systems with 2 to 10 axes

Any combination of linear, manipulator, turntable, chuck rotate and bar rotate axes

DC or stepper motor drive

Rack and pinion, ballscrew or belt drive

High quality linear bearings (NSK type) giving long life under arduous conditions

Precision optical encoders - linear scale (Renishaw type) available on long linear axes

Resolution down to 2um, repeatability down to 5um (dependent on system type and application)

All immersed components are stainless steel or titanium alloy

Pulse echo and through transmission systems - simultaneous acquisition of data

Precision manipulators - gimbal/gimbal, gimbal/rotate and goniometric

 Ultrasonics

Fully integrated PC-based ultrasonics, data acquisition and motion control

Fully production hardened for noise immunity

Exceptional S/N ratio and near surface resolution

Digital A scan display with refresh rate >60Hz

Up to 8 independent gates per channel - amplitude, time of flight and phase monitoring

Single and multi-channel operation

Multi-channel, multi-gate data acquisition at PRF’s up to 20kHz. Higher PRF available with 2 or more pulser receivers

Frequency from <0.5MHz to >50MHz

Software

Windows 2000 with simple operation using pull down menus

A, B and C scan display in real time

Storage, recall and automatic setup for all test parameters

Programmed gate changes and auto gate setting

Display of images from multiple gates simultaneously

Full RF data acquisition and processing

On screen measurement and analysis

Multi axis motion control for complex shapes

Generation of scan profiles from CATIA files

Options for auto sensing of part shape and self teaching capability

Interfaces to factory network and mainframe computers

Custom software for special user requirements

Virtual Private Network (VPN) available for remote monitoring and support.