Five Things To Consider When Purchasing Product Inspection Equipment

Just as a family name is respected, a company&#;s brand must be protected. Choosing the right product inspection system for the detection of foreign material in your facility&#;s production line is a key step to protecting your brand.  

Link to AJR

The decision to install a new product inspection system or to upgrade an existing one is usually determined by one of two things: you either have the corporate commitment and financial resources to do what it takes to have the best inspection system for your particular product; or you have been mandated to do so in order to meet a specific regulatory requirement with financial constraints limiting your options. Regardless of why you&#;re exploring product inspection equipment, you should take into consideration each of the following tips before making any decision. 

Determine The &#;True&#; Cost of Ownership

It is highly recommended that you consider using one vendor that is able to provide magnetic, metal detection, x-ray, and check-weigh systems along with a comprehensive understanding and commitment to food safety and customer service. Your goal should not be to purchase the cheapest system that can do the job, but instead, to look at the long-term investment.

Initial purchase and installation- The least expensive part of your overall investment for electronic inspection equipment involves the up-front equipment purchase and installation cost, unlike other contaminant removal equipment such as magnets.

Equipment usability and adaptability- Consider the cost of &#;false&#; positive readings or rejects, the ongoing cost of maintenance and equipment validation, and the future adaptability of the system you choose. Understanding how a vendor&#;s equipment is supported as updates in software become available can keep existing electronic inspection equipment on the leading edge of technology, or result in obsolescence if it is not easily upgradeable.

Technical support- Ask if your vendor offers an annual technical support subscription. These programs can often include discounted rates for software upgrades, parts and service, not to mention annual third party re-certification.

Employee education- Consider and figure the on-going cost of training new employees. High turnover is inherent in the industry and is often the root cause of mistakes being made and recalls being issued. For example, the cost of recalling a product due to a &#;false&#; positive resulting from an employee error can damage your brand almost as much as actual particulate contamination. Once a recall is issued you cannot undo it, the damage is done and your brand has been tarnished.

Understanding Food Safety and Product Inspection Limitations

It is important that your vendor explain not only what their equipment can do, but what it cannot do. For example, magnets, when sized correctly and installed properly are very effective in capturing ferrous and weakly magnetic non-ferrous metals. In many cases, magnets can go beyond the capabilities of most metal detection and X-ray systems. Nonferrous or nonmagnetic metals, such as aluminum, will not be eliminated by a magnetic system. To control and capture these types of metals, metal detectors or X-ray systems should be considered.

Metal Detectors&#; Metal detector technology is based on a product&#;s &#;conductivity&#;. Highly conductive products like meats and baby food will be more challenging to sense smaller sized, specific types of metals. This typically results in a more generalized &#;metals sensing spectrum&#; to ensure quality standards are being achieved, while avoiding costly &#;false&#; positive rejects.

X-ray&#; X-ray technology is based on a product&#;s &#;density&#;. Some products are easier to inspect than others and some are not able to be screened by X-ray technology at all. If the targeted materials have a similar density of the products being inspected, such as non-calcified bones in chicken, the X-ray will be ineffective. 

Take the time to talk to more than one vendor. It is necessary that the vendor you choose not only understand, but is able to explain the technological limitations of the equipment. He or she should be able to present the physics-based principals for particulate detection in layman&#;s terms. You should come away from the assessment knowing at least one thing you didn&#;t know before and feeling confident in your new-found knowledge and the decision to be made.

Invest In Continuing Education

It&#;s important to select a vendor who will partner with your company in offering service packages that provide education, training, and periodic retraining for your employees. Technologies in this industry are constantly evolving, the goal being to make the detection of foreign material contamination in food ever better. On average, between 20 and 25 percent of recalls are due to detectable foreign matter such as bone, plastic, glass, or metal making its way to the consumer&#;s table. It is vitally important that the people responsible for monitoring and maintaining the detection equipment are knowledgeable on its operation and maintenance. Even without a high turnover rate, simple changes in mixtures or recipes can require a system calibration and reprogramming. In regards to electronic inspection equipment, one size does not fit all.

Ensure Technical Support Is Readily Available

There are few things worse than buying a product, not having it work properly, and then being unable to get the level of technical support needed. Most commonly the barriers to product support are language or distance, and often, both. You may find that a U.S.-based company will be more willing and able to provide the technical support that goes with its products. The ideal situation is to purchase from a vendor that services what they sell, even if that may mean paying a premium price. Technical support means providing an understanding of the system that goes well beyond its installation. This may include system validation, programming requirements, preventative maintenance, or reports required to fulfill a regulatory requirement. This support also needs to be easily accessible. Waiting hours will be a major inconvenience, but waiting days or weeks could cost you an unimaginable amount in lost revenue. Ask the tough questions, and get it in writing.

Opt For Sanitary Design

With the FDA&#;s recent elevated focus on food safety, sanitary design is a wise consideration. First, you want to look for a design that eliminates the need for disassembly in order to be cleaned. If it must be disassembled, it should be quickly accomplished and preferably require no tools. Food processing is a dirty business. Be it wet or dry, food matter can find the smallest nook and cranny in which to collect and grow colonies of potentially deadly germs. Nuts, bolts, and screws are all capable of harboring pathogens, as are the tools used to remove them. Routine cleaning is a fact of life, one that will be included in any comprehensive hazard analysis and critical control points (HACCP) plan. It is a chore that is time-consuming and messy, which is why it is often not completed properly and/or on schedule, if at all. Investing in a built-in, well-thought-out sanitary design will more than pay for itself over time.

Critical thinking before making a decision to purchase is necessary. Know what foreign materials are risks to your product line, and find the vendor that can address each of those risks. Be aware that it may take more than one piece of equipment to adequately provide optimal detection, and be open to weighing all of your options. This, in all likelihood, will render the cost of ownership more manageable and leave you with more trust and satisfaction in your product inspection system.

 

 

Magnetic Products, Inc. (MPI), is a family-owned, U.S.-based company established in . Offering complete metal contamination control, MPI has a diverse product portfolio that features magnetic and non-magnetic material separation and handling equipment, metal detectors, check-weighers, and x-ray inspection equipment. MPI President, Keith Rhodes, attributes MPI&#;s continued success in the market to the company&#;s ability to keep pace, often supplying custom integrated solutions to meet unique customer needs. Rhodes is proud of his company&#;s tradition in advancing product performance and its ever expanding line of material handling and metal-control systems.

 

When Do You Need to Perform Magnetic Particle Testing?

What is Magnetic Particle Testing Used For?

Table of Contents

1.

What is Magnetic Particle Testing (MPT)?

1.1.

How Does Magnetic Particle Testing (MPT) Work?

2.

What is Magnetic Particle Testing Used For?

2.1.

Common Application of Magnetic Particle Testing

2.2.

When Do You Need to Perform Magnetic Particle Testing?

3.

Magnetic Particle Inspection Process Overview

3.1.

Wet Suspension Inspection

3.2.

Dry Particle Testing

3.3.

Final Inspection Steps

4.

Pros and Cons of Magnetic Particle Testing

5.

Magnetic Particle Testing Equipment

5.1.

Contour Magnetic Probes

5.2.

Magnetic Particles

5.3.

Lights

5.4.

Other Accessories

6.

Alternatives to Magnetic Particle Testing

For more Brinell Hardness Tester Suppliersinformation, please contact us. We will provide professional answers.

Although invisible, magnetic fields tell us a lot about our surroundings. Birds were lucky enough to evolve special iron-based receptors, and now they use them to detect Earth&#;s magnetism for intercontinental navigation.

For us, it took decades of experiments and a great deal of equipment to harness the power of magnetic fields. First, we invented an artificial &#;magnetic receptor,&#; aka compass, to help us navigate the world. Later, William Hoke invented a new asset inspection method to locate the tiniest defects.

In the s, Hoke noticed how metal shavings accumulated around vehicle cracks. Such keen observation spurred Hoke&#;s research and eventually led to the patenting of magnetic particle testing, a method of locating defects in materials almost at the microscopic level.

What is Magnetic Particle Testing (MPT)?

Magnetic Particle Testing (MPT) is a non-destructive testing (NDT) method that uses magnetizing force to locate on-surface and sub-surface defects.

Because MPT relies on magnetic fields, it only works for assets made of ferromagnetic metals like iron, cobalt, and nickel. Such materials are highly susceptible to magnetic fields and can retain magnetic properties even when removed from the external force.

Magnetic particle testing is a visual NDT method. But unlike unaided inspections, MPT can reveal tiny, even microscopic cracks, pores, voids, and discontinuities an inspector may otherwise miss. Also, MPT delivers quick results, letting you see the defect&#;s location, size, form, and severity in real-time.

The surface defects are highly visible when exposed to magnetic fields and UV light. Source: MDPI

How Does Magnetic Particle Testing (MPT) Work?

Magnetic particle test requires two essential components: a testing tool with magnetic poles on both ends and a colored substance with magnetic particles. The device generates a magnetic field and sends magnetic flux through the test material, with two possible outcomes:

• No defects: The magnetic flux flows freely through the material, indicating a homogenous surface.

• Defect present: The crack causes the magnetic flux to divert from its path. This creates a separate flux leakage field with greater magnetic power than defect-free areas.

The flaw will not be visible, though, without the application of colored magnetic particles across the test area. These particles accumulate on the flux leak, allowing us to see the crack, delamination, or another irregularity.

The figure illustrates how the magnetic flux spreads across the tested areas without and with defects. Source: The National Board of Boiler and Pressure Vessel Inspectors

What is Magnetic Particle Testing Used For?

Magnetic particle testing is the primary inspection method for assets made of iron, nickel, cobalt, and their alloys (especially steel). It&#;s a common NDT method for weld, pipe, tube, rails, and boiler inspections.

Because magnetic particle testing requires direct visual observation and surface contact for particle application, it&#;s most suitable for easily accessible assets.

Common Application of Magnetic Particle Testing

IndustriesDefect typesAssets1. Aerospace
2. Automotive
3. Oil and gas
4. Petrochemical
5. Manufacturing
6. Power generation
7. Railroad1. Surface cracks
2. Subsurface cracks
3. Lack of fusion
4. Inclusions
5. Pores
6. Holes
7. Discontinuities
8. Laps1. Welds
2. Pipelines
3. Boilers
4. Heat exchangers
5. Turbine blades
6. Gears and shafts
7. Automotive components

When Do You Need to Perform Magnetic Particle Testing?

MPT is often used post-production to determine if the manufactured objects meet quality and safety requirements. Additionally, it&#;s used for industrial asset inspection as part of condition monitoring programs.

For planned routine checks, the National Board Inspection Code (NBIC) describes the following use cases of magnetic particle testing:

• Tests of the internal and external surfaces of the boiler and pressure vessels
• Checks of vessels in liquid ammonia service for stress corrosion cracking
• Analysis of fire-damaged components to determine if they retained their strength
• Crack detection in plates of locomotives and steam boilers
• Identification of cracks during baffle clip welding of pipes, valves, and manholes
• Defect location in welded joints and adjacent heat-affected zones

As per ISO standards, magnetic particle tests are also used to detect:

• Inhomogeneities in coolant circuit components of light water reactors (ISO -2:)
• Discontinuities in railway rolling stock material (ISO :)
• Imperfections in seamless and welded steel tubes (ISO -5:)
• Defects in welds (ISO :)
• Discontinuities in steel and iron castings (ISO :)
• Imperfections on the body and the end/bevel face at the ends of steel tubes (ISO -5:)

Magnetic Particle Inspection Process Overview

Magnetic particle inspection is a seemingly straightforward process, but it requires thorough preparation. Namely, asset owners must hire a certified inspector (in line with ISO standards).

The inspector will select a fit-for-purpose test device (e.g., a portable yoke, stationary desk) and the type of magnetic particle inspection (wet or dry). They will also choose a magnetic substance with the right properties (color, particle size, temperature use).

To get accurate results, you must ensure parallel mounting between the test object and the magnetic field (at least 45-90 degrees) and illuminate the test area properly (lamp or UV light). Also, remove all other items with ferromagnetic properties from the test area to prevent interferences.

Clean the surface area of grease, oil, and rust. Ensure the thickness of the paint coating does not exceed 0.05 millimeters. The thicker coating will reduce test sensitivity.

The inspector will then select the right magnetic flux density (minimum 1T) and strength (between 30 and 60 gauss) and perform the inspection. The next steps will vary based on the type of magnetic particle inspection.

Wet Suspension Inspection

Wet suspension inspection assumes dispersing water-based magnetic particles over the test area. Wet inspections are perfect for finding even very small imperfections for two reasons. First, magnetic particles in a wet state are extremely small (0. mm). Second, in a flowing agent, they are easily dispersed and evenly distributed.

Wet suspension testing steps:

1. Disperse the suspension on a tested area
2. Evenly apply the magnetic field in two or three short busts (1/2 second)
3. Locate areas with magnetic particles in high concentrations
4. Demagnetize and clean the inspected area

Dry Particle Testing

Dry magnetic particle testing involves sprinkling magnetic powder on the test surface. Most often, portable probes generate pulsating magnetic fields. By moving the dry powder around, these pulses make it easier for particles to stick to defects. Therefore, this method can be used to inspect irregular surfaces, inclusions, weld discontinuities, and even subsurface defects.

Dry particle testing steps:

1. Evenly apply the magnetic field
2. Spread the thin layer of powder on a tested area
3. Slowly blow the excess powder away
4. Remove the magnetic field
5. Analyze areas with magnetic particles in high concentrations
6. Demagnetize and clean the inspected area

Final Inspection Steps

The MPT inspector provides a cartography of defects, their descriptions, and severity rankings. For external certifications, the technician must also outline the entire procedure (surface tested, magnetization method, equipment used, testing materials, results, and decisions made post-testing).

Pros and Cons of Magnetic Particle Testing

A variety of magnetic particle testing devices make lab assessments, factory inspections, and field tests possible. The test provides immediate results and a detailed representation of all defects.

However, MPT is not a universal form of NDT since it&#;s limited to ferromagnetic materials. Also, if nonferrous metal or thick paint covers the test asset, the measurement will likely be inaccurate.

Advantages of magnetic particle testing:

• Low equipment and inspection costs. Magnetic probes are cheaper than ultrasonic probes or radiography devices.

• Tests can be done on smooth and rough surfaces with equal accuracy rates.

• Visualizes the size, location, and number of defects fast, allowing for quick remediation.

• Suitable for both on-surface and near-surface defects detection with different probes.

• Can detect even microscopic surface cracks, locating wear and corrosive influences early on.

• Highly portable, the magnetic probe can be easily connected to a battery power supply for field inspections.

Disadvantages of magnetic particle testing:

• Limited use: Only works with ferromagnetic materials and their alloys and doesn&#;t reveal defects deep within the asset.

• Requires extensive preparations (Lighting, installation, protective gear, paint and rust removal, etc.).

• Coating removal may be required. More than 0.05 mm of coating may skew the results. Also, requires demagnetization of the test asset.

• It causes a mess at the operating premises. Liquid particles spill all around the test object and stain the surface.

• In non-ventilated rooms, some particle suspensions and powders can be hazardous and even flammable.

Magnetic Particle Testing Equipment

Magnetic particle testing equipment falls into two categories: stationary and portable.

Stationary equipment (like a magnetic wet bench) is used for lab tests that require a certain amount of space, artificial light, and a mounting surface. Tests on stationary equipment are most often conducted using wet fluorescent particles for more reliable flaw detection.

On the downside, stationary MPT equipment is immobile, making it impractical for in-service assets. So, let&#;s examine the portable options.

Contour Magnetic Probes

Contour probes (also called yokes) are portable, handheld devices that produce a magnetic field between their two magnetic poles. Since they have two operating modes&#;AC with alternating currents and DC with direct currents&#;they can be used for both surface-level and near-surface defect detection.

Contour magnetic probes are available in other configurations, including:

• Prods: handheld electrodes that should be manually pressed to both sides of the test object. This device creates a circular magnetic field, aiding in better detection of lengthwise cracks. The prod works in pulses, with the inspector regularly turning it on and off.

• Coils and conductive cables are great for spherical objects. When wrapped around the test object, the coil produces a magnetic field parallel to the test object, revealing longitudinal cracks. Coils are often used in a setup with a magnetic wet bench.

• Electromagnets: devices that emit electric currents to create a strong magnetic field. They consist of an electric coil wrapped around a soft piece of steel.

Magnetic Particles

Magnetic particles are nanosized parts of ferromagnetic material that attract flux leaks and thus visualize defects. There are two types of magnetic particles: dry and wet.

Dry Particles

Dry particles are a mixture of milled magnetic powders and a color pigment. Depending on the manufacturer, a dry magnetic powder can have a variety of properties:

• Particle size: between: 0.05 &#; 0.15 mm
• SAE sensitivity: 6-8
• Usage temperature: 0°&#; 427°C
• Colors: black, red, grey, yellow, brown, or fluorescent green.

Dry particles are best for testing irregularly shaped rough surfaces.

Wet Particles

Wet particles are suspended in a water-based material and mixed with color pigment. On the market, particle suspensions are available in the form of liquid, gels, sprays, and inks.

Depending on the manufacturer, they have the following characteristics:

• Size: starting with as small as 0.mm
• SAE sensitivity: 6-7
• Usage temperature: -10°&#; 80°C
• Colors: black, white, fluorescent green or yellow.

Wet particles are best for finding small, almost microscopic cracks.

Lights

Good lighting is essential for magnetic particle testing. The setup will depend on the inspection type.

For traditional wet and dry inspection, use a lamp at a color temperature between and K (as per ISO ). For fluorescent inspecting, you will need mercury discharge lamps, halogen lamps, xenon lamps, or LED arrays to generate UV light, also called blacklight. For your safety, check that the UV light is no greater than 365nm in intensity (as per ISO ).

Other Accessories

For efficient and quick inspection, you might need additional tools:

• Cleaning agents to remove dirt, grease, or oil from the test area
• Wire brushes to remove rust from the test area
• Solvents to remote paint coatings
• Power bulb or powder blower for clearing powder from the test area
• Demagnetizing equipment to magnetically de-energize the test area

Alternatives to Magnetic Particle Testing

The simplicity and affordability of MPT make it an attractive choice for testing ferromagnetic materials, but it falls short for other types of assets. Moreover, MPT can&#;t detect defects deeper than 2 mm.

Other non-destructive inspection methods, like ultrasonic or eddy current testing, can provide better accuracy, flexibility, sensitivity, and depth of detection.

Ultrasonic testing (UT) has great penetration power, detecting flaws deep inside large assets like storage tanks and wind turbines. It works for almost all materials, including metals, polymers, plastics, ceramics, fiberglass, and glass. Plus, UT discloses the defect&#;s orientation aside from its size, shape, and location. To accomplish this, the MPT technician must reapply the magnetic field from a different angle (and perhaps change the mounting system).

EMAT testing &#; a UT method combined with the force of a magnetic field. Contrary to magnetic particle testing, EMAT provides high-precision detection deep within assets without the need to touch the surface. EMAT is an excellent tool for testing in confined spaces, hot areas, and potentially hazardous locations.

Eddy current testing (ECT) is a better solution for testing large structures in one go. It doesn&#;t require direct contact with the test specimen and can still penetrate deeper into the material (up to 40mm). Unlike MPT, ECT doesn&#;t need chemical liquids with particles, some of which are harmful to workers. Furthermore, ECT is capable of testing both ferromagnetic and nonferrous metals.

To achieve even greater speed and flexibility for all these methods, you can use drone-mounted UT, ECT, and EMAT probes.

Purpose-built for inspections, Voliro&#;s omnidirectional drone helps test assets of any shape, height, and dimension at faster speeds. No scaffolding or cherry-picker required &#; inspectors stay firm on the ground, while collecting high-fidelity data for analysis. By changing probes, you can customize Voliro T for multiple, making it an all-in-one solution for most non-destructive testing tasks.