Eddy Current, and Ultrasonic techniques can be used to inspect bar and rod. The choice depends on the nonconforming conditions you wish to detect and the size and characteristics of the material. MAC instruments can handle a range of metal materials with a uniform cross section, including squares, rectangles, hex and round, in cut lengths or continuous production. Carbon steels, stainless alloys, aluminum, titanium and all other non ferrous metals can be inspected. Additional items such as markers, controls, demagnetizers, and components for mounting the encircling or sector test coils, saturation coils, rotaries, and for positioning and driving the material through the test, are combined with the instrumentation to make up a complete test system.
|Typical flaws and conditions that can be detected include:|
Testing Bars and Rods
|Testing Cold Finished Bars
MAC has systems for surface, subsurface and internal defects in aluminum, copper, non ferrous alloys, titanium, carbon, alloy steels, and stainless steel. Complete automated systems include encircling and spinning probe eddy current for surface and near surface flaws, and ultrasonic rotary for internal and subsurface defects. These technologies have also been applied to round and square billet inspection.
|Testing Hot Rolled Bars
The same techniques outlined for cold finished bars above apply to hot rolled bar. However, the size and type of defect that can be detected is often limited by variations that are typical of the hot rolled process such as the surface condition and dimensional variations, including straightness and ovality.
Testing Round and Square Billets
Automated eddy current and ultrasonic test systems are available that incorporate specifically designed mechanics to handle round and square billets at production line speeds. Systems include fast changeover times to accommodate different sizes.
|Testing Cut Lengths
With appropriate specialized mechanics and controls, the same techniques described above can be applied to testing cut lengths offline, on production equipment such as drawing, and peeling machines, and coil to coil or coil to bar. A wide variety of material that is processed even further as finished parts such as strut rods or piston pins can also be inspected by MAC
|Testing Continuous Bar at Elevated Temperatures
The Rotomac BQ encircling and spinning probe eddy current system can handle continuous bar in a rolling mill at elevated temperatures to detect longitudinal and transverse defects.
Detecting Flaws and Conditions in Rod and Bar
Short Surface & Subsurface Cracks
For detecting typical defects such as short surface and some subsurface cracks in carbon steel or non ferrous bar, a standard eddy current encircling coil instrument such as the MAC 400 is often selected. The MAC 400 can be supplied with up to four test channels. For the most demanding applications, the MultiMac”® provides optimum flaw discrimination with up to 8 test channels.
Internal Longitudinal and Transverse Flaws
When internal defects and inclusions need to be detected, ultrasonic inspection techniques are often the best choice. MAC’s multi channel Echomac FD-4 instrumentation and the Echomac rotary transducer assembly, with its unique rotating seal-less water coupling system permit UT inspection at high throughput speeds. The FD-4 can also be utilized with squirter couplants and existing water immersion systems.
Long Continuous Surface Defects
For detecting long, continuous surface defects such as seams and laps in cold drawn wire or cut length bar stock, the MultiMac”® used with rotary probe sensors is the most appropriate. By rotating multiple test probes at speeds up to 6000 RPM around the bar or wire, even relatively short flaws can be reliably detected in many applications, without sacrificing throughput speed.
Short and Long Continuous Surface and Subsurface Defects
For those applications that require the detection of both short and long continuous surface or subsurface defects, the new MultiMac”® multi mode eddy current tester would be the right choice. The MultiMac with up to 8 test channels, allows simultaneous detection of both types of defects in magnetic or nonmagnetic material.
Alloy and Hardness Detection
Variations in alloy, heat treatment, case depth and hardness can be successfully detected by MAC’s comparators. The Varimac® eddy current comparator can be used on a range of product types including non magnetic stainless bar. Variations in carbon steel or special alloy bar can also be detected with the Production Comparator low frequency electromagnetic comparator.
For applications where more than one of the conditions described above must be met, a multiple test NDT system using several testers or technologies can be assembled. In these cases, each tester or technology is used to find the types of defects or conditions that it is best suited to detect. The result is often a more accurate test and fewer rejects to allow more of your product to be shipped to your customer.