May 3 2021
Visual inspection is a very common technique used by maintenance professionals in physical asset management. It is also the last step in the production line for most goods.
While engineers are constantly finding new ways to automate widely used repetitive actions, visual inspections have remained an invaluable tool for finding issues, especially in the field of equipment maintenance.
In this post, we explain the value of visual inspection for a variety of purposes and cover the most common modern use cases. And of course, because visual inspections can give varying results due to their subjective nature, we will share some essential steps you can take to standardize your inspection process.
The definition of visual inspection
Visual inspection is a very basic inspection method used in manufacturing quality control and asset maintenance. It is the method of looking for flaws or imperfections using the naked eye and non-specialized inspection equipment.
Quite often, there is no empirical formula for finding defective products or inspecting a piece of equipment. Therefore, the experience of the person that is performing visual inspection plays a significant role in determining the efficacy of the process.
Looking for anomalies with the naked eye is the most common method of visual inspection. But it is not necessarily limited to that. Using other senses for inspection also falls under the broad umbrella of visual inspection. The basic tenet is that an experienced person is using his sensory capabilities to identify problems with objects they inspect.
For instance, experienced professionals can assess the quality of materials like wood and metals by judging the sound produced by them. They can just knock on the object and make a judgment based on the sound produced by it.
Similarly, a maintenance technician might smell a gas leak, hear that something is loose inside the asset, or even feel that a piece of equipment vibrates more than it should or radiates excessive heat. All while performing a visual inspection.
Visual inspections in physical asset management
Visual inspection is an integral part of physical asset management. Maintenance professionals use it on a daily basis as part of their routine maintenance activities.
Occasionally, an organization will train machine operators to perform visual inspections instead of maintenance techs. This practice is commonly referred to as autonomous maintenance.
Regular inspections help maintenance teams spot signs of wear and tear that can lead to equipment failure. Minor issues are corrected on the spot if the technician has access to the right tools and parts. Otherwise, they will leave a note about the detected issue. The maintenance manager or supervisor will later add a new task to the preventive maintenance plan so the problem doesn’t go unaddressed.
While they can be very useful, visual inspections come with a couple of downsides. Machines often need to be shut down so a technician can perform a visual inspection. As you can imagine, this reduces equipment uptime and can hurt the bottom line. The other problem is that visual inspections can sometimes spot the problem too late. If you detect noise, heat, or smoke, the failure might already be in progress.
To combat these issues, more and more organizations are using condition monitoring sensors and equipment to monitor asset health and performance in real-time. This technology allows them to notice deterioration signs much earlier than it would otherwise be possible. This is neatly represented in the graphic below.
These sensors allow organizations to run advanced maintenance strategies like condition-based maintenance and predictive maintenance. Such strategies reduce the need for visual inspections but are far from making them obsolete. Sensors are still fairly expensive and can only detect specific deterioration signs. It means that manual testing methods like visual inspections are not only necessary but a more cost-effective option, especially for inexpensive assets.
Visual inspections in quality control
Visual inspection is the oldest non-destructive testing (NDT) method for quality control. In its original form, visual inspection is used to observe the surface of an object and look for cracks, scratches, misalignments, corrosion, and other physical defects.
Big brands, especially those that produce expensive products, have a lot to lose if they send out a whole line of defective products. Visual inspection is a great way to quickly filter out items with obvious defects.
For instance, automakers like Rolls-Royce give extreme importance to the fit and finish of each component that goes into their cars. Their internal research shows how roughly 70% of all faulty components are rejected because of discrepancies found during visual inspection.
This is not to say that visual inspections are reserved only for luxury goods. A good counter-example comes from the food and beverage industry. Here, visual inspections are performed to ensure there aren’t any foreign objects in the product, that packages are uniform and properly sealed, and that the products are not mislabeled. Because of the fairly straightforward nature of these inspections, many food manufacturers are starting to adopt machine vision systems for quality control.
An example of an automated visual inspection system (Image source)
Broadly speaking, visual testing for quality control can be done in three different ways:
- Random sampling: Quality checks are performed on randomly selected products. Products can be checked right at the production line for obvious visual defects. More complex inspections (like testing the interior of a product) are usually carried out at special testing areas.
- Full manual sampling: All products are inspected manually. This can be a physically demanding job with a lot of repetitive actions. To maximize the health and productivity of workers performing the inspections, organizations should look to provide the necessary tools and ergonomic equipment.
- Automated visual inspection: Products are inspected using cameras, image processing methods, and machine learning algorithms. More on this later in the article.
The automated systems for visual inspection seem to be gaining more traction as the private sector develops industry-specific solutions. It remains to be seen how fast will manufacturers adopt this technology.
Modern visual inspection techniques
Incremental technological improvements in camera quality and machine learning are starting to change how we think about visual inspections. Maintenance techs now have the ability to perform visual inspections at hazardous and hard-to-reach places, while being miles away from the objects they are inspecting. Quality control specialists, on the other hand, have more and more access to automated visual inspection solutions.
Remote visual inspections for asset maintenance
These days, technicians can use robots and drones to view otherwise inaccessible areas. We are talking about inspecting objects at great heights, very confined spaces, hazardous places like storage tanks, and similar.
Images or videos can be viewed from a remote location, even thousands of miles away from the location of the inspection site – hence the name remote visual inspection. The captured data can be accessed in two different ways:
- Live stream: Robots or drones can relay data of the location to the base station where the inspector can watch the live feed. In this case, the robot or drone can also be controlled from the remote terminal. It can only be used in cases where there is constant wireless communication between the equipment that is being operated and the base station.
- Saved data: In extremely remote or hazardous areas where there can be no wireless communication, videos and images are saved and analyzed later.
An additional advantage of these types of inspections is that the images and videos can be easily shared between technicians and other relevant team members, without having to be physically present at the inspection site. This collaboration can be extremely useful when solving complex problems or when there is a need to contact specialized experts.
Automated visual inspections (AVI) for mass production
Automated visual inspection (AVI) uses computer vision and artificial intelligence to perform visual inspections on products instead of quality inspectors. This technology aims to dramatically reduce the need for human intervention for inspection in large-scale automated factories.
Cognitive visual inspection solution from IBM (Image source)
Foxconn, one of the largest electronics manufacturers on the planet, is using AVI in their manufacturing facilities. We will use them as an example to briefly describe how this technology is supposed to work.
Suppose Foxconn is manufacturing motherboards for the latest iPhone. One ideal sample of the motherboard is made and inspected by a human visual inspector. Once it has been approved, this model is uploaded to the database and the algorithm can use it as a benchmark. Some examples of defective models are also uploaded to the server and used to teach algorithms how to recognize specific anomalies.
The rest of the motherboards will come out of the automated assembly line and pass under the camera systems for the AVI. Multiple images of the product are captured from various angles. The captured images are compared to the benchmark images stored using machine learning algorithms. Some of the factors compared could be:
- size and shape of different elements
- solder locations
- component locations
- missing components
- color anomalies
The product passes the inspection if it is sufficiently close to the benchmark.
At face value, this technology seems like a perfect solution. After all, the main idea behind automation is to leave routine and mundane tasks to machines so that employees can focus on creative problem-solving. It is a sound idea, but there are still many limitations that need to be addressed before it becomes a standard in the industrial space.
The limitations of automated solutions
There are two main impediments to the adoption of automation in visual inspection.
The first one are technological limitations. Though AI researchers have made great strides, the inspection algorithms are far from perfect. They need a lot of examples of good and defective products so they can learn how to detect different anomalies with enough success. Additionally, machines find it difficult to work with reflective surfaces. This would eliminate working with most metals found in a plant. Such minute differences cannot be captured by the algorithms yet, but humans can easily do that.
The second factor is cost. To implement an automated inspection system, there should be supplementary equipment like imaging machines, networking tools, computer hardware, etc. These hardware costs in addition to the software cost still make it cost-prohibitive for many organizations.
Over time, the quality and price of automated visual inspection systems should go down and we should see wider adoption.
How to standardize the visual inspection process
Standardizing any process makes it repeatable and verifiable. But a problem with the standardization of visual inspections is that a large part of the work is very subjective in nature and quite difficult to package as a checklist.
Standardization efforts in maintenance
Maintenance activities are often standardized through written standard operating procedures, safety guidelines (like LOTO), and maintenance checklists. Visual inspections, to some degree, can be tackled in the same way.
Since maintenance technicians should already know how to perform basic visual inspections, written guidelines can be created only for complex equipment where the proper inspection takes multiple steps to complete.
The process of standardization can look something like this:
- Record down all assets that are visually inspected regularly.
- Map the concerning areas to be checked.
- Note down the actions to be taken depending on the spotted deterioration sign.
- Create a flowchart based on the information above.
- Create a maintenance checklist for the cues that should be inspected.
- If possible, add the checklist and the flowchart to your CMMS system. If you have a mobile CMMS, technicians can quickly access that information on their smartphone and tablet, which can significantly speed up their workflow.
- Occasionally review and update those flowcharts and checklists.
An asset can have a million different issues but the goal of a direct visual inspection is to look for common signs of wear and tear.
Maintenance checklists should always be created by experienced technicians familiar with the inner workings of equipment at their facility. Usually, those will be the same people in charge of training new technicians. This is perfect, as new technicians will reap the most value out of these standardization efforts.
Standardization efforts for quality management
The key to standardizing visual inspections in quality management lies in the training process which should include:
- very clear guidelines on what is considered a defect
- what to do with a defective product
- when and how to use any special visual inspection tools
- who to contact for borderline cases (asking for a second opinion)
- how and where to note novel anomalies
- any other special guidelines that need to be followed on the plant floor
Even after that, there will be cases where the subjectivity of the process causes disputes. A small scratch on the product might be a deal-breaker for one inspector, while the other one would mark it as good to go. Some level of inconsistency is unavoidable but can be minimized through standardization.
It will be a while until technology becomes a suitable substitute for human eyes and judgment. And it will take that much more until the same technology becomes accessible to small and medium-sized operations.
Until then, this simple activity will continue to be a crucial part of asset management and quality control, performed by trained personnel.
As always, if you have any questions, feel free to start a discussion in the comments below. If you’re interested in learning more about equipment maintenance and reliability, check out the latest articles on the Limble blog.
Bryan Christiansen CEO & Founder Limble
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Visual inspection are one of the oldest and most trusted ways to evaluate the condition of an asset as part of the overall maintenance process. The goal of a visual inspection is to find anything that might be wrong with the asset which could require maintenance.What is visual inspection process? ›
In its simplest form, visual inspection is the process of examining a component or piece of equipment using one's naked eye to look for flaws. Optical aids such as illuminators, mirrors, borescopes, etc. can be used to enhance one's capability of visually inspecting equipment.What are the benefits of inspections? ›
- listen to the concerns of workers and supervisors.
- gain further understanding of jobs and tasks.
- identify existing and potential hazards.
- determine underlying causes of hazards.
- recommend corrective action.
A well-achieved visual inspection provides a reduction in the amount of repairs to the weld, leading to greater production of the other non-destructive tests and therefore decreasing the cost of production.How effective is visual inspection? ›
Is visual inspection effective? Overall, the visual inspection method on its own cannot produce the same quality results as other nondestructive testing (NDT) methods. For one, it cannot detect certain minute flaws regardless of how keen an eye or how much experience an analyst has.What is the purpose of using visuals? ›
Visual supports aid and enhance communication. They provide children and adults with speech, language and communication needs (SLCN) with an alternative mode of communication. Visuals can help to provide structure and routine, improve understanding, avoid frustration and offer opportunities to interact with others.What are the three purpose of inspection? ›
Inspection helps: 1) the product disposition decision-making process; 2) in collecting data in an orderly fashion for actions; and 3) satisfy regulatory and procedural requirements.What are the 4 benefits of inspection checklist? ›
- Minimize project delays and unproductivity.
- Lower maintenance costs.
- Reduce recurring problems.
- Prevent the use of unsafe assets, thus reducing employee injury.
- Discourage the improper or abusive use of assets.
- Help determine ideal maintenance schedules.
- Presentation visuals grab an audience's attention—and keep it. ...
- Presentation visuals make complex ideas easier to understand. ...
- Presentation visuals build emotional bridges with the audience. ...
- Presentation visuals help audiences retain information.
Visual methods enhance the richness of data by discovering additional layers of meaning, adding validity and depth, and creating knowledge. They add to traditional methods by capturing more detail and a different kind of data than verbal and written methods.
- Apply the 80-20 principle.
- Have a clear baseline of what's good and what's not good.
- Process spot checks.
- Redesign the process when needed.
- Training and certification process.
Visual inspections in quality control
In its original form, visual inspection is used to observe the surface of an object and look for cracks, scratches, misalignments, corrosion, and other physical defects.
These are the inspector's visual acuity, the work-place lighting conditions, the time available for inspection and the provision of feedback or knowledge of results to the inspector.What tools are used in visual inspection? ›
- Digital cameras. Digital cameras vary greatly in terms of quality and cost, so it's important to know exactly how precise you need your images to be. ...
- Borescopes. ...
- Video and digital microscopes. ...
- Videoscopes. ...
Visual aids help teachers establish, explain, connect, and associate ideas and concepts to make the process of learning more interesting, enjoyable, and effective. Some of the benefits visual aids provide for teaching and learning include: Helping inspire students to study more effectively.For what reasons is visuals important in teaching? ›
Teachers value the support that visuals lend to classroom instruction because they encourage students to make associations between pieces of information, soak up chunks of course content quickly, and function as a memory aid.Why is visual impact important? ›
Almost since the first moving picture the use of visual effects has gone hand in hand with cinematic storytelling. They can enhance a scene, help build something which does not exist, cover up a mistake and so much more. Basically, they help a filmmaker tell a story the way they want to.What is the method of inspection? ›
Some common. methods are visual, microscopy, liquid or dye penetrant inspection, mag- netic particle inspection, eddy current testing, x-ray or radiographic test- ing, and ultrasonic testing. This chapter provides an overview of the in- spection methods that will be covered in the remainder of this book.What are the five 5 types of inspection? ›
- Sample Checking.
- Pre-Production Inspections (PPI)
- During Production Inspection (DPI)
- Pre-Shipment Inspection (PSI)
- Piece by Piece Inspection (or Sorting Inspection)
- Metal Detection.
A basic car check-up is the most fundamental, periodical inspection of your car, which includes engine oil and filter change. The check-up covers a range of components responsible for the safety of the driver and the passengers, such as the braking, fuel, cooling and air-conditioning systems.
In quality control, there are 4 types of quality inspections, namely: pre-production inspection, during production inspection, pre-shipment inspection, and container loading/unloading inspections. Each of these types of inspection has its own purpose.What are steps in the inspection process? ›
The stages in the inspections process are: Planning, Overview meeting, Preparation, Inspection meeting, Rework and Follow-up. The Preparation, Inspection meeting and Rework stages might be iterated. Planning: The inspection is planned by the moderator.What is the role of inspection? ›
To make sure a system is producing as expected, control of the process is needed. The best processes have little variation from the standard expected. In fact, if variation were completely eliminated, there would be no need for inspection because there would be no defects.What are the types of inspection when they can be useful? ›
There are three primary types of quality inspections: pre-production, in-line, and final. There are a variety of details that must be inspected and approved during each phase in order to detect and correct quality problems.Who can best benefit from visual support? ›
- Fragile X syndrome.
- Attention Deficit Disorders.
- Nonverbal Learning Disabilities.
- Learning Disability.
- Hearing Impairment.
- Down Syndrome.
- Emotional Impairment.
Because visuals are easy to understand, an effective visual workplace can improve safety by reinforcing training and eliminate wasted downtime that had previously been spent searching, asking or waiting for information.What are the benefits of using visual imagery strategy? ›
Why use visual imagery? Generating an image while reading requires that the reader be actively engaged with the text. Creating mental images while reading can improve comprehension.What are the best ways to use visuals effectively? ›
- Keep it simple. Your slides should complement your verbal message, not detract from it by unnecessary visual clutter. ...
- Limit bullet points and text. ...
- Use high-quality graphics. ...
- Use appropriate charts. ...
- Choose your fonts well. ...
- Spend time in the slide sorter.
Visual communication is a way to communicate ideas graphically in ways that are efficient and help to convey more meaning. It's a critical element of any content marketing strategy. This is because visuals can help to evoke emotions in your audience, provide stronger examples for your message and so much more.What is the use of visual inspection in NDT? ›
Visual Inspection (VT)
Visual Testing (VT) is based on the inspection for flaws that are visible to the naked eye and is the most commonly used NDT method across all industries. It allows for a feasible and fast control of quality at every step of the fabrication or maintenance process.
Construction site inspections are critical to ensuring that quality and safety procedures are followed correctly from the start. Construction projects involve co-ordinating multiple project team members, materials and equipment, which may expose contractors to many potential risks and hazards.Why is visual inspection of a parenteral solution important? ›
Visual inspection ranks as an essential operation in parenteral drug production to ensure the safety of the drug product in its container, such as a vial or syringe.How important is the visual inspection for forensic investigation? ›
Visual Inspection: The purpose of this inspection is just to determine the type of evidence, its condition, and relevant information to conduct the examination. This is often done in the initial evidence seizure.What are the main objectives of inspection? ›
The main objective of inspection is to meet customer requirements, wants, and needs. The objective is to prevent defective product flowing down the successive operations and prevent loss to the company. Many characteristics cannot be inspected at the final stage of production.What is the purpose of inspection form? ›
Inspection reports are one of the most important maintenance documents. They indicate whether an item, a place, or material is in proper condition, whether it is safe, and whether any regulations are broken. There are different types of inspection reports depending on the subject inspected.What are the factors affecting visual inspection? ›
These are the inspector's visual acuity, the work-place lighting conditions, the time available for inspection and the provision of feedback or knowledge of results to the inspector.What is visual inspection in quality control? ›
Visual inspection is a non-destructive testing technique that helps identify issues with assets or manufactured goods. While modern inspection techniques like vibration analysis continue to evolve, visual inspection remains one of the most cost-effective quality control methods of condition-based maintenance.