There are two types of testing in CNC machining: destructive and non-destructive. Methods that examine and/or evaluate parts by damaging or destroying materials might be ideal for some processes, but for not all. In fact, many industries rely on non-destructive testing methods to collect crucial data in a less aggressive way.
What is non-destructive testing?
Non-destructive testing, or NDT, in CNC machining, involves a wide range of diligent yet gentle inspection techniques. It’s a type of assessment that allows machinists to gather important data about a material, component, and/or design without damaging its integrity. NDT is also used to evaluate fabrication and assembly systems for high-tolerance projects.
This method goes by many names as well, including NDE (non-destructive examination) and NDI (non-destructive inspection). Thus, NDT is often used as an umbrella term to describe the many tools and techniques required. Either way, the goal of non-destructive testing is to guarantee a part’s critical geometries so that no catastrophic accidents ever occur.
How is NDT used?
NDT methods are used worldwide for a plethora of industries, including oils and gas, mining, and even HVAC. Modern medicinal uses are quite common as well. For example, ultrasounds, X-rays, and MRIs use NDT techniques to check a patient’s health condition without causing an injury.
In much the same way, non-destructive testing in inspects various features without doing damage to the infrastructure of a part. Thus, it’s most frequently used in the following sectors:
NOTE: These methods can also be used for DIY projects and prototypes to help perfect concepts before production.
Common non-destructive testing methods
Interestingly, this critical inspection doesn’t always require special tools to complete. Well-trained CNC machinists can simply look at a component, material, tool, or machine to gather the information they need. Visual examinations fall under the NDT resignation because they don’t damage anything but still provide data. However, more intense evaluations are common too.
Regardless, each one requires a unique set of skills, tools, preparation, and training. That’s because some NDT techniques are used for a complete volumetric evaluation while others only provide surface data about an object. Meanwhile, these are the 8 most common non-destructive testing methods in CNC machining:
1. VT (Visual)
VT, or visual testing, collects information about a part or material based on the simple act of looking at it with the naked eye and sometimes a flashlight or Remote Visual Inspection (RVI) camera.
2. UT (Ultrasonic)
UT, or ultrasonic testing, uses high-frequency sound waves to penetrate a material for the purposes of discovering and/or evaluating property changes after fabrication or assembly.
3. RT (Radiographic)
RT, or radiography testing, uses targeted gamma-rays (or X-rays) to pinpoint design or infrastructure imperfections without making direct contact with the material.
4. ET (Electromagnetic)
ET, or electromagnetic testing, utilizes electrical currents to create a measurable determination about a material’s possible defects and/or strengths.
5. MT (Magnetic)
MT, or magnetic particle testing, reveals problems by measuring disruptions in the part’s magnetic field – generally from weak spots, hollow points, or negatively charged ions.
6. AE (Acoustic)
AE, or acoustic emission testing, harnesses the power of acoustic waves to discover defects and strengths of a material, part, or system.
7. PT (Penetrant)
PT, or penetrant testing, uses a harmless liquid coating to reveal holes, breaks, and cracks in a part or material, usually before mass production.
8. LT (Leak)
LT, or leak testing, is a simple process that involves studying a part, material, or vessel to reveal problematic features, defects, or potential weak spots.
The ideal non-destructive testing method always depends on several factors, including materials, geometries, and design. So, regardless of the industry, it’s always a good idea to consult the pros. In many cases, a technician must be NDT certified to do the work.
The top 3 benefits of NDT
Non-destructive testing is the lifeblood of any legitimate CNC machine shop. The methods are consistent, repeatable, and reliable if performed by a qualified Pioneer Cuts expert. With that comes the promise of experience, integrity, and accuracy plus these three bonus advantages:
Nearly all NDT techniques are safe for machinists. Every method except for RT uses harmless tools to gather data about a part or material. At the same time, expert inspections can help increase the safety protocols of a component or project, which then ensures quicker certifications.
This crucial step in the manufacturing process can help save money. That’s because it allows time for an object to be examined before mass manufacturing. If it can come out unscathed, then the design and construction are ideal, and no further corrections have to be made.
NDT methods provide the opportunity for thorough examinations in record time. This is especially important when deadlines are tight, but protocols are tighter. Moreover, these techniques help prolong the lifespan of machines and tools while also making machining much easier.
Contact Pioneer Cuts experts for more information on how non-destructive testing techniques can help save time, money, and resources.
Understanding the limitations and capabilities of your parts, materials, and vessels can spell the difference between success and failure when it comes to manufacturing. Therefore, it’s crucial to take advantage of NDT techniques when fabricating components for any industry.