What’s the Best Method for Detecting Surface Cracks?

Introduction 

Surface cracks can be a serious issue in a variety of industries, as they can compromise the integrity and strength of a material or structure. In order to identify and address these cracks, it is important to have a reliable method for detecting them. Detecting and addressing surface cracks is important for ensuring the structural integrity and safety of products, as well as for maintaining their performance and lifespan. While there are numerous methods of identifying surface cracks, non-destructive testing methods have been found to be most efficient and cost effective and this article will be examining the best method for detecting surface cracks. So, let’s go.

I. Which methods are available for the detection of Surface cracks?

There are various methods in the industry today for detecting surface cracks, the most popular of which have been highlighted below. 

• Visual Inspection (VT) – Generally considered a basic form of inspection, visual inspection is the first point of call when determining the quality of a component or a production process. Its major tools of inspection are the eyes, simple magnifying glasses and microscopes. There are several advantages to using visual inspection as a method for detecting surface cracks. It does not require sophisticated equipment or setting up processes which is a huge advantage. In addition, visual inspection can be performed quickly, making it an efficient method for identifying cracks in a timely manner. But most importantly, it does not require destroying the test sample in the process of identifying cracks making the sample useful after the test. Nevertheless, there are also some limitations to using visual inspection for detecting surface cracks. One of the main limitations is that it is subjective, as it relies on the observer’s ability to identify cracks based on their appearance. This can lead to variations in the accuracy of the inspection, as different observers may have different levels of experience or expertise in identifying cracks.
  There are two techniques that can be used for visual inspection, including direct visual inspection which involves looking at the surface of the material with the naked eye or a magnifying device, such as a microscope or borescope. There is also indirect visual inspection which uses a light source, such as a flashlight or lamp, to illuminate the surface of the material. 
• Dye penetrant testing (PT) – This method has an extensive application in solid material testing finding usage in industries like the manufacturing sector to ascertain product integrity and safety. Its main advantage is the simplicity of tools and process in its detection of surface cracks. There are two main types of dye penetrant testing: visible and fluorescent. In visible dye penetrant testing, a red or orange penetrant is used, and a white developer is applied. This makes the defects easy to see against the white background. In fluorescent dye penetrant testing, a penetrant that is invisible to the naked eye is used, and a developer that fluoresces under ultraviolet light is applied. This makes the defects visible under UV light.
• Eddy current testing (ECT) – In a practical sense ECT relies on the conductibility of the tested material using an electromagnetic field generated by an alternating current. This electromagnetic field induces an eddy current once the conductive material and a conductor are in close proximity. These eddy currents, in turn, generate their own electromagnetic fields, which can be measured and analyzed to determine the presence and location of any surface cracks or other defects. Surface cracks detection is a common application of ECT especially for tiny cracks found in conductive materials. This type of testing is typically performed using a handheld probe or a scanner system, which is moved over the surface of the material being inspected. The probe or scanner generates an electromagnetic field, which is used to induce eddy currents in the material. Any surface cracks or defects will disturb the eddy currents and cause changes in the electromagnetic field, which can be detected and analyzed to identify the location and size of the cracks. 
  

II. What’s the advantage of ECT in detection of surface cracks? 

One main advantage of eddy current testing is its speed. It can be used to scan large areas in a short amount of time, making it ideal for testing large components or structures. Eddy current testing can also be performed on-site, allowing for quick and convenient testing without the need to disassemble or transport the component.

Another advantage of eddy current testing is its accuracy. It can detect surface cracks as small as 0.1mm in depth, and it is highly sensitive to changes in the material’s surface. Hence, it is very helpful in identifying defects that may be hard for the naked eye to identify. Eddy current testing is also a cost-effective method for detecting surface cracks. It does not require the use of consumables or special preparations, and it can be performed by a single operator. This means that there are no additional costs associated with the testing process, making it a cost-effective option for companies looking to ensure the quality and safety of their products.

In addition to its speed, accuracy, and cost-effectiveness, eddy current testing has several other advantages. It is non-destructive, so it does not damage the material being tested. It is also non-intrusive, meaning that it does not require the material to be disassembled or modified in any way. This makes it a preferred method for testing components that are critical to the function of a system or that are difficult to access.

III. What’s the advantage of Portable Surface Array ECT Devices?

Portable surface array ECT devices, also known as eddy current testing devices, are a type of non-destructive testing (NDT) equipment that are used to detect cracks and other defects in metallic surfaces. These devices are especially useful for industries such as aerospace, automotive, and manufacturing, where the integrity of metal components is crucial.

One of the main advantages of using a portable surface array ECT device for surface cracks detection is its portability. These devices are designed to be lightweight and compact, making them easy to carry and use in a variety of locations. This is especially useful for inspecting large and hard-to-reach surfaces, such as those found in aircraft or industrial machinery.

Another advantage of portable surface array ECT devices is their high accuracy and sensitivity. These devices use eddy currents to detect defects in metallic surfaces, which allows them to detect even the smallest cracks and other abnormalities. This ensures that potential problems are identified and addressed before they can cause further damage or compromise the safety of a product or system.

In addition to their high accuracy, portable surface array ECT devices also offer fast and efficient testing. These devices can quickly scan a large surface area and provide results in a matter of seconds, which helps to minimize downtime and improve productivity. This is especially important for industries that rely on fast turnaround times for inspections and repairs.

Finally, portable surface array ECT devices are relatively easy to use and require minimal training. These devices typically come with user-friendly software that guides the operator through the testing process and provides clear, easy-to-understand results. This makes them accessible to a wide range of users, including those who may not have extensive training or experience in NDT.

Overall, portable surface array ECT devices offer a number of advantages for surface cracks detection, including portability, accuracy, efficiency, and ease of use. These devices are an invaluable tool for industries that rely on the integrity of metal components, and their use can help to prevent costly failures and improve overall safety and reliability.

Conclusion

In conclusion, visual inspection is a simple and cost-effective method for detecting surface cracks. While it has some limitations, it can be an effective tool for identifying cracks and ensuring the integrity and strength of materials and structures. By following best practices and using appropriate lighting and viewing conditions, operators can effectively identify and evaluate cracks on the surface of components and products, helping to ensure their safety and reliability. More importantly, using sensitive and accurate tools like a portable surface array ECT devices which are also portable can be very effective.