Krautkramer phased array ultrasound technology helps to improve productivity and quality

GE Inspection Technologies and its Krautkramer ultrasonic products is at the front of using phased array technology in high-speed operations.

Copperweld Automotive Group has installed the latest generation of Krautkramer phased array equipment to ultrasonically inspect tube for any welding defects created during production.

Freedom from defects is key to tube production for automotive industry
Ensuring that components are defect free is a key concern in all manufacturing industries. This is especially true when these components are used in situations where their failure could cause serious accident or injury. In the automotive industry there is a constant drive towards reducing weight while also increasing strength.

Two technologies that are paying dividends in these areas are hydroforming and swaging. In the first process, welded steel tubes are pressure formed in a die to the shape of the finished component. This process is typically used for frame and chassis components, and gives increased strength while reducing weight. In the second process, tubes are shaped to give varying diameters, for typical use in axles or steering components. This process can give great strength with reduced manufacturing cost. Previously these components were machined to give their final shape.

However, both of these techniques subject the tube to high stresses in the forming processes, which could enlarge any incipient defects. This means that the tubes need extreme care and control at the welding stage to ensure their integrity.

Copperweld Automotive Group
Copperweld Automotive Group (Woodstock, Ontario, Canada) supplies high quality, low cost welded steel tube fabrications for the automotive industry. Not only does Copperweld manufacture tubing and fabricate tubing components, but with the recent addition of hydroforming technology Copperweld can now produce much more varied shapes their customers demand. Copperweld began making welded tube at the Woodstock facility in 1919, and now employs almost 900 people. It has considerable experience in tube making, tube fabrication and has always been innovative in its approach, continually seeking to improve its processes and the level of manufacturing quality.

Krautkramer solution
As part of its tube manufacturing process, Copperweld has installed the latest generation of Krautkramer equipment to ultrasonically inspect tube for any welding defects created during production. This new equipment is installed close to the welding operation, to give fast feedback to the mill personnel in the event of problems.

A key feature of the new system is the use of phased arrays to generate the sound beams used for the test. The phased array technique is based on the principle of interference. From basic physics we are familiar with the experiment in which two point sources magically seem to produce "rays" or beams of waves. By combining several ultrasound sources (typically 16, 32, 64 or 128) in an array and adjusting their phases by electronic means, it is possible to produce a single, tightly-focused beam. The advantage is that very fast, very accurate control of the beam direction and focus can be achieved electronically, without any moving parts.

With phased arrays, not only can the sound be accurately focused to suit any tube size, but it can also be scanned, so that the entire weld area is inspected. Also, because of the precise beam location, defects on both the inside and outside of the tube can be clearly differentiated - an important feature in analysing problems.

With the phased array system two sensor heads are mounted in water chambers, which ride on the tube. The heads scan the tube from two sides to ensure the detection of defects regardless of their orientation The ultrasonic beams are electronically precisely focused for each tube size to be tested, and electronically scan the welded area.

Head-to-head comparison
As part of the introduction plan for the new equipment, Copperweld ran a conventional fixed probe ultrasonic system and the new equipment together for a six-month period, so that results from the two systems could be compared. This direct comparison clearly showed the benefits of the new equipment, including fast, reproducible set-ups, and consistently reliable defect detection and identification.

A further feature of the new equipment is that the in-process test information is analysed and reported both to QA and to manufacturing personnel. The information includes details of any defects found, with a summary report for each tube size. Readout screens are available both at the tube manufacturing line and in the QA lab, so that all personnel can be aware of any developing issues, and can react to them before they become serious. This remote operation is also available at the GE Inspection Technology service centre, for analysing any issues with the test equipment or remotely installing any software updates.

The tube weld integrity test system has proved the benefits of Phased Array Ultrasonic testing, both by giving better consistency of results and in presenting the test data in a form more useful to the customer. The final outcome is greater reliability, quality and safety.