When to use optical filtering in a machine vision application

Industrial image processing is essentially a requirement in modern manufacturing. Vision solutions can deliver visual quality control, identification and positioning. While vision systems have gotten easier to install and use, there isn’t a one-size-fits-all solution. Knowing how and when you should use optical filtering in a machine vision application is a vital part of making sure your system delivers everything you need.

So when should you use optical filtering in your machine vision applications? ALWAYS. Image filtering increases contrast, usable resolution, image quality and most importantly, it dramatically reduces ambient light interference, which is the number one reason a machine vision application doesn’t work as expected.

Different applications require different types of filtering. I’ve highlighted the most common.

Bandpass Filtering

Different light spectrums will enhance or de-emphasize certain aspects of the target you are inspecting. Therefore, the first thing you want to do is select the proper color/wavelength that will give you the best contrast for your application. For example, if you are using a red area light that transmits at 617nm (Figure 1), you will want to select a filter (Figure 3) to attach to the lens (Figure 2) that passes the frequency of the area light and filters out the rest of the color spectrum. This filter technique is called Bandpass filtering reference (Figure 4).

This allows only the light from the area light to pass through while all other light is filtered out. To further illustrate the kinds of effects that can be emphasized or de-emphasized we can look at the following images of the same product but with different filters.

Another example of Bandpass filtering can be seen in (Figure 9), which demonstrates the benefit of using a filter in an application to read the LOT code and best before sell date. A blue LED light source and a blue Bandpass filter make the information readable, whereas without the filter it isn’t.

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Figure 9

Narrow Bandpass Filtering

Narrow bandpass filtering, shown in (Figure 10), is mostly used for laser line dimensional measurement applications, referenced in (Figure 11). This technique creates more ambient light immunity than normal Bandpass filtering. It also decreases the bandwidth of the image and creates a kind of black on white effect which is the desired outcome you want for this application.

Shortpass Filtering

Another optical filtering technique is shortpass filtering, shown in (Figure 12), which is commonly used in color camera imaging because it filters out UV and IR light sources to give you a true color image.

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Figure 12

Longpass Filtering

Longpass filtering, referenced in (Figure 13), is often used in IR applications where you want to suppress the visible light spectrum.

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Figure 13

Neutral Density Filtering

Neutral density filtering is regularly used in LED inspection. Without filtering, light coming from the LEDs completely saturates the image making it difficult, if not impossible, to do a proper inspection. Deploying neutral density filtering acts like sunglasses for your camera. In short, it reduces the amount of full spectrum light the camera sees.

Polarization Filtering

Polarization filtering is best to use when you have surfaces that are highly reflective or shiny. Polarization filtering can be deployed to reduce glare on your target. You can clearly see the benefits of this in (Figure 14).

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Figure 14

How flexible inspection capabilities help meet customization needs and deliver operational excellence

As the automotive industry introduces more options to meet the growing complexities and demands of its customers (such as increased variety of trim options) it has rendered challenges to the automotive manufacturing industry.

Demands of the market filter directly back to the manufacturing floor of tier suppliers as they must find the means to fulfill the market requirements on a flexible industrial network, either new or existing. The success of their customers is dependent on the tier supplier chain delivering within a tight timeline. Whereby, if pressure is applied upon that ecosystem, it will mean a more difficult task to meet the JIT (just in time) supply requirements resulting in increased operating costs and potential penalties.

Meeting customer requirements creates operational challenges including lost production time due to product varieties and tool change time increases. Finding ways to simplify tool change and validate the correct components are placed in the correct assembly or module to optimize production is now an industry priority. In addition, tracking and traceability is playing a strong role in ensuring the correct manufacturing process has been followed and implemented.

How can manufacturing implement highly flexible inspection capabilities while allowing direct communication to the process control network and/or MES network that will allow the capability to change inspection characteristics on the fly for different product inspection on common tooling?

Smart Vision Inspection Systems

Compact Smart Vision Inspection System technology has evolved a long way from the temperamental technologies of only a decade ago. Systems offered today have much more robust and simplistic intuitive software tools embedded directly in the Smart Vision inspection device. These effective programming cockpit tools allow ease of use to the end user at the plant providing the capability to execute fast reliable solutions with proven algorithm tools. Multi-network protocols such as EthernetIP, ProfiNet, TCP-IP-LAN (Gigabit Ethernet) and IO-LINK have now come to realization. Having multiple network capabilities delivers the opportunity of not just communicating the inspection result to the programmable logic controller (via process network) but also the ability to send image data independent of the process network via the Gigabit Ethernet network to the cloud or MES system. The ability to over-lay relevant information onto the image such as VIN, Lot Code, Date Code etc. is now achievable.  In addition, camera housings have become more industrially robust such as having aluminum housings with an ingress protection rating of IP67.

Industrial image processing is now a fixture within todays’ manufacturing process and is only growing. The technology can now bring your company a step closer to enabling IIOT by bringing issues to your attention before they create down time (predictive maintenance). They aid in reaching operational excellence as they uncover processing errors, reduce or eliminate scrap and provide meaningful feedback to allow corrective actions to be implemented.

Traceability in Manufacturing – More than just RFID and Barcode

Traceability is a term that is commonly used in most plants today. Whether it is being used to describe tracking received and shipped goods, tracking valuable assets down to their exact location, or tracking an item through production as it is being built, traceability is usually associated with only two technologies — RFID and/or barcode. While these two technologies are critical in establishing a framework for traceability within the plant, there are other technologies that can help tell the rest of the story.

Utilizing vision along with a data collection technology adds another dimension to traceability by providing physical evidence in the form of an image. While vision cameras have been widely used in manufacturing for a long time, most cameras operate outside of the traceability system. The vision system and tracking system often operate independently. While they both end up sending data to the same place, that data must be transported and processed separately which causes a major increase in network traffic.

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Current vision technology allows images to be “stamped” with the information from the barcode or RFID tag. The image becomes redundant traceability by providing visual proof that everything happened correctly in the build process. In addition, instead of sending image files over the network they are sent through a separate channel to a server that contains all the process data from the tag and has the images associated with it. This frees up the production network and provides visual proof that the finished product is what we wanted it to be.

Used separately, the three technologies mentioned above provide actionable data which allows manufacturers to make important decisions.  Used together, they tell a complete story and provide visual evidence of every step along the way. This allows manufacturers to make more informed decisions based on the whole story not just part of it.

What to Ask Before You Build an RFID System to Meet Your Traceability Needs

An industrial RFID system is a powerful solution for reliably and comprehensively documenting individual working steps in manufacturing environments. But an industrial RFID system that meets your application needs isn’t available off-the-shelf. To build the system you need, it is important to consider what problems you hope RFID will solve and what return on investments you hope to see.

RFID can deliver many benefits, including process visibility and providing data needed to better manage product quality. It can be used to improve safety, satisfaction and profit margins. It can even be used to help comply with regulatory standards or to manage product recalls. And RFID can be used in a wide range of applications from broad areas like supply management to inventory tracking to more specific applications. These improvements can improve time, cost or performance—though not typically all three.

It is essential to understand and document the goal and how improvements will be measured to in order to plan a RFID system (readers, antennas, tags, cables) to best meet those goals.

Other important questions to consider:

Will the system be centralized or de-centralized? Will the system be license plate only or contain process data on the tag?

How will the data on the tags be used?  Will the information be used to interface with a PLC, database or ERP? Will it be used to provide MES or logical functionality? Or to provide data to an HMI or web browser/cloud interface?

Will the system be required to comply with any international regulations or standards? If so, which ones: EPC Global, Class 1 Gen 2 (UHF only), ISO 15693, or 14443 (HF only)?

What environment does the system need to perform in? Will it be used indoor or outdoor? Will it be exposed to liquids (cleaning fluids, coolants, machine oils, caustics) or high or low temperatures?

Does the RFID system need to work with barcodes or any other human readable information?

What are the performance expectations for the components? What is the read/write range distance from head to tag? What is the station cycle timing? Is the tag metal-mounted? Does the tag need to be reused or be disposable? What communication bus is required?

With a clear set of objectives and goals, the mechanical and physical requirements discovered by answering the questions above, and guidance from an expert, a RFID system can be configured that meets your needs and delivers a strong return on investment.

How to Select the Best Lighting Techniques for Your Machine Vision Application

The key to deploying a robust machine vision application in a factory automation setting is ensuring that you create the necessary environment for a stable image.  The three areas you must focus on to ensure image stability are: lighting, lensing and material handling.  For this blog, I will focus on the seven main lighting techniques that are used in machine vision applications.

On-Axis Ring Lighting

On-axis ring lighting is the most common type of lighting because in many cases it is integrated on the camera and available as one part number. When using this type of lighting you almost always want to be a few degrees off perpendicular (Image 1A).  If you are perpendicular to the object you will get hot spots in the image (Image 1B), which is not desirable. When the camera with its ring light is tilted slightly off perpendicular you achieve the desired image (Image 1C).

Off-Axes Bright Field Lighting

Off-axes bright field lighting works by having a separate LED source mounted at about 15 degrees off perpendicular and having the camera mounted perpendicular to the surface (Image 2A). This lighting technique works best on mostly flat surfaces. The main surface or field will be bright, and the holes or indentations will be dark (Image 2B).

Dark Field Lighting

Dark field lighting is required to be very close to the part, usually within an inch. The mounting angle of the dark field LEDs needs to be at least 45 degrees or more to create the desired effect (Image 3A).  In short, it has the opposite effect of Bright Field lighting, meaning the surface or field is dark and the indentations or bumps will be much brighter (Image 3B).

Back Lighting

Back lighting works by having the camera pointed directly at the back light in a perpendicular mount.  The object you are inspecting is positioned in between the camera and the back light (Image 4A).  This lighting technique is the most robust that you can use because it creates a black target on a white background (Image 4B).

Diffused Dome Lighting

Diffused dome lighting, aka the salad bowl light, works by having a hole at the top of the salad bowl where the camera is mounted and the LEDs are mounted down at the rim of the salad bowl, pointing straight up which causes the light to reflect off of the curved surface of the salad bowl and it creates very uniform reflection (Image 5A).  Diffused dome lighting is used when the object you are inspecting is curved or non-uniform (Image 5B). After applying this lighting technique to an uneven surface or texture, hotspots and other sharp details are deemphasized, and it creates a sort of matte finish to the image (Image 5C).

Diffused On-Axis Lighting

Diffused on-axis lighting, or DOAL, works by having a LED light source pointed at a beam splitter and the reflected light is then parallel with the direction that the camera is mounted (Image 6A).  DOAL lighting should only be used on flat surfaces where you are trying to diminish very shiny parts of the surface to create a uniformed image.  Applications like DVD, CD, or silicon wafer inspection are some of the most common uses for this type of lighting.

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Image 6A

 

Structured Laser Line Lighting

Structured laser line lighting works by projecting a laser line onto a three-dimensional object (Image 7A), resulting in an image that gives you information on the height of the object.  Depending on the mounting angle of the camera and laser line transmitter, the resulting laser line shift will be larger or smaller as you change the angle of the devices (Image 7B).  When there is no object the laser line will be flat (Image 7C).

Real Life Applications 

The images below, (Image 8A) and (Image 8B) were used for an application that requires the pins of a connector to be counted. As you can see, the bright field lighting on the left does not produce a clear image but the dark field lighting on the right does.

This next example (Image 9A) and (Image 9B) was for an application that requires a bar code to be read through a cellophane wrapper.  The unclear image (Image 9A) was acquired by using an on-axis ring light, while the use of dome lighting (Image 9B) resulted in a clear, easy-to-read image of the bar code.

This example (Image 10A), (Image 10B) and (Image 10C) highlights different lighting techniques on the same object. In the (Image 10A) image, backlighting is being used to measure the smaller hole diameter.  In image (Image 10B) dome lighting is being used for inspecting the taper of the upper hole in reference to the lower hole.  In (Image 10C) dark field lighting is being used to do optical character recognition “OCR” on the object.  Each of these could be viewed as a positive or negative depending on what you are trying to accomplish.

RFID: Using Actionable Data to Make Critical Decisions

While RFID technology has been in use since the 1950s, wide-spread implementation has come in waves over the years. Beginning with military applications where it was used to identify friend or foe aircraft, to inventory control in the retail industry, and now to the manufacturing space where it is being used to manage work in process, track assets, control inventory, and aid with automatic replenishment.

The bottom line is RFID is critical in the manufacturing process. Why? Because, fundamentally, it provides actionable data that is used to make critical decisions. If your organization has not yet subscribed to RFID technology then it is getting ready to. This doesn’t mean just in the shipping and receiving area.  Wide-spread adoption is happening on the production line, in the tool room, on dies, molds, machine tools, on AGV’s, on pallets, and so much more.

Not an RFID expert? It’s ok. Start with a quick overview.

Learn about the fundamentals of a passive RFID system here.

In the past, controls engineers, quality assurance managers, and maintenance supervisors were early adopters because RFID played a critical role in giving them the data they needed. Thanks to global manufacturing initiatives like Smart Factory, Industry 4.0, the Industrial Internet of things (IIOT) and a plethora of other manufacturing buzz words, CEOs, CFOs, and COOs are driving RFID concepts today. So, while the “hands-on” members of the plant started the revolution, the guys in the corner offices quickly recognized the power of RFID and accelerated the adoption of the technology.

While there is a frenzy in the market, it is important to keep a few things in mind when exploring how RFID can benefit your organization:

  • Choose your RFID partner based on their core competency in addressing manufacturing applications
  • Make sure they have decades of experience manufacturing and implementing RFID
  • Have them clearly explain their “chain of support” from local resources to experts at the HQ.
  • Find a partner who can clearly define the benefits of RFID in your specific process (ROI)
  • Partner with a company that innovates the way their customers automate

Smart choices deliver leaner processes in Packaging, Food and Beverage industry

In all industries, there is a need for more flexible and individualized production as well as increased transparency and documentable processes. Overall equipment efficiency, zero downtime and the demand for shorter production runs have created the need for smart machines and ultimately the smart factory. Now more than ever, this is important in the Packaging, Food and Beverage (PFB) industry to ensure that the products and processes are clean, safe and efficient.

Take a look at how the Smart Factory can be implemented in Packaging, Food, and Beverage industries.

Updating Controls Architecture

  • Eliminates analog wiring and reduces costs by 15% to 20%
  • Simplifies troubleshooting
  • Enables visibility down to the sensor/device
  • Simplifies retrofits
  • Reduces terminations
  • Eliminates manual configuration of devices and sensors

Automating Guided Format Change and Change Parts

  • Eliminates changeover errors
  • Reduces planned downtime to perform change over
  • Reduces product waste from start-up after a change over
  • Consistent positioning every time
  • Ensures proper change parts are swapped out

Predictive Maintenance through IO-Link

  • Enhances diagnostics
  • Reduces unplanned downtime
  • Provides condition monitoring
  • Provides more accurate data
  • Reduces equipment slows and stops
  • Reduces product waste

Traceability

  • Delivers accurate data and reduced errors
  • Tracks raw materials and finished goods
  • Date and lot code accuracy for potential product recall
  • Allows robust tags to be embedded in totes, pallets, containers, and fixtures
  • Increases security with access control

Why is all of this important?

Converting a manufacturing process to a smart process will improve many aspects and cure pains that may have been encountered in the past. In the PFB industry, downtime can be very costly due to raw material having a short expiration date before it must be discarded. Therefore, overall equipment efficiency (OEE) is an integral part of any process within PFB. Simply put, OEE is the percentage of manufacturing time that is truly productive. Implementing improved controls architecture, automating change over processes, using networking devices that feature predictive maintenance, and incorporating RFID technology for traceability greatly improve OEE and reduce time spent troubleshooting to find a solution to a reoccurring problem.

Through IO-Link technology and smart devices connected to IO-Link, time spent searching for the root of a problem is greatly reduced thanks to continuous diagnostics and predictive maintenance. IO-Link systems alert operators to sensor malfunctions and when preventative maintenance is required.

Unlike preventative maintenance, which only captures 18% of machine failures and is based on a schedule, predictive maintenance relies on data to provide operators and controls personnel critical information on times when they may need to do maintenance in the future. This results in planned downtime which can be strategically scheduled around production runs, as opposed to unplanned downtime that comes with no warning and could disrupt a production run.

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Reducing the time it takes to change over a machine to a different packaging size allows the process to finish the batch quicker than if a manual change over was used, which in turn means a shorter production blog 2.20 2run for that line. Automated change over allows the process to be exact every time and eliminates the risk of operator error due to more accurate positioning.

 

 

blog 2.20 3Traceability using RFID can be a very important part of the smart PFB factory. Utilizing RFID throughout the process —tracking of raw materials, finished goods, and totes leaving the facility — can greatly increase the efficiency and throughput of the process. RFID can even be applied to change part detection to identify if the correct equipment is being swapped in or out during change over.

Adding smart solutions to a PFB production line improves efficiency, increases output, minimizes downtime and saves money.

For more information on the Smart Factory check out this blog post: The Need for Data and System Interoperability in Smart Manufacturing For a deeper dive into format change check out this blog post: Flexibility Through Automated Format Changes on Packaging Machines

 

 

Traceability of production material with RFID

As we progress toward a more automated factory, the need to more efficiently manage what happens prior to the production process has become apparent. Tracking of raw material and production components from the dock door to the warehouse is quickly evolving from a best guess estimate to real-time inventory levels driven by production. Essentially, we are moving from a practice of holding just-in-case inventory to Just-in-Time (JIT) inventory. The JIT concept helps to optimize the amount of in-house inventory based on production. In addition, the entire supply chain benefits because the levels of raw goods inventory upstream can be managed more efficiently and forecasted with more accuracy.

RFID and barcode technology have played a critical role in the actual production process for decades, but its benefits are currently being leveraged in other areas of the plant as well. Whether its tracking every item or every pallet that comes into the receiving dock, ID traceability provides visibility where it did not exist before.

Traceability of production material 

Upon receiving a pallet with raw material, the 2D matrix code on the shipping label is read by a barcode scanner. The relevant data needed for the further traceability process is transferred onto the stack of trays which contain UHF carriers. The number of carriers is saved together with the traceability data in a database. This process takes place at one single station and the data is updated immediately to represent the inventory level.

Transmission of incoming goods data on the transponder

Automated review of loaded pallets

Based on the material number, the system contains a standard load for the number of trays on the pallet. An automatic screening takes place to determine if all transponders on the pallet are registered. In case of a difference between the registered data and the expected data, an error message pops up to indicate the need for manual intervention. This process allows for proactive management of inventory to prevent false inventory levels or goods that cannot be accounted for.

Key Features of a traceability solution:

  • Corresponds to the global ISO standard
  • Suitable for attachment to major control systems via bus interfaces and higher level IT systems
  • Variety of accessories available for easy integration into different applications

To learn more about RFID technology, visit www.balluff.com.

Five things to consider before selecting an RFID system

So, you have reached a point where you believe RFID is going to be the best solution. Now what? One of the most critical phases of a RFID project is deciding which product is going to address the application. While the planning stage can be highly conceptual, the hardware selection is truly a close-up inspection. This is where the rubber meets the road.

Here are the top five things, in no specific order, to consider after you have determined RFID is the appropriate technology for your application:

  1. Throughput

How much and how fast? How much data will be written to the tag and how much data will be read from the tag at each read point? Will the tag be moving during the read/write or will it stop in front of the antenna? Some RFID systems are capable of handling a large amount of data, while others are designed to read only small amounts of data. It is also important to consider if your data requirements will change in the near future.

  1. Read/Write Range

What is the required distance from the antenna to the tag? Will the tag be presented to the antenna at the same distance every time? Multiple frequency ranges can limit some systems to a few millimeters, while others are capable of communicating up to six or seven meters.

  1. Form factor

How much space do you have to mount both the reader and the tag? If space is limited, you can choose a system in which the antenna and the processor are combined in one housing. As for the tags, they can be as small as a grain of rice or as large as a license plate. The key is to make sure the equipment will not interfere with your process.

  1. Communication Protocol

How will the RFID processor “talk” to the control system? This is critical in a mixed control environment where multiple brands of PLCs or servers are present. What communication protocol do your controls engineers prefer — Ethernet/IP, Profinet, CC-Link, TCP/IP, etc?

  1. Environment

Where will the equipment actually be mounted? Does anything stand in the way of getting a clear read? Are there metal beams, tanks of liquid, or even operators walking in between the tag and antenna? This is probably the most critical of all the considerations because constant interference will block the antenna from reading or writing to the tag. While RFID technology has come a long way in recent years, metal and liquid can still affect the RF waves.

Keep these five things in mind and your RFID implementation will go a lot smoother!

To learn more about RFID solutions visit www.balluff.com.

The Evolution of RFID in Metalworking

RFID – A key technology in modern production

It’s not just IIoT that has focused attention on RFID as a central component of automation. As a key technology, radio frequency identification has been long established in production. The inductive operating principle guarantees ruggedness and resistance to environmental stress factors. This makes the system highly reliable in function and operation. With unlimited read/write cycles and real-time communication, RFID has become indispensable. The beginnings for the industrial use of RFID go far back. RFID was first successfully used on machine tools in the mid-1980’s. Since the usage of RFID tags on cutting tool holders has been internationally standardized (ISO 7388 for SK shanks, ISO12164 for HSK shanks), there has been strong growth of RFID usage in cutting tool management.

Cutting tool in tool taper with RFID chip

Track-and-trace of workpieces

Modern manufacturing with a wide bandwidth of batch sizes and ever compressed production times demands maximum transparency. This is the only way to meet the high requirements for flexibility and quality, and to minimize costs. Not only do the tools need to be optimally managed, but also the finished parts and materials used must be unambiguously recognized and assigned.

Workpiece tracking with RFID on pallet system

RFID frequencies LF and HF – both RFID worlds come together

In terms of data transmission for cutting tool identification, established systems have settled on LF (Low Frequency), as this band has proven to be especially robust and reliable in metal surroundings. Data is read with LF at a frequency of 455 kHz and written at 70 kHz.

When it comes to intralogistics and tracking of workpieces, HF (High Frequency) has become the standard in recent years. This is because HF systems with a working frequency of 13.56 MHz offer greater traverse speeds and a more generous read/write distance.

As a result, RFID processor units have been introduced that offer frequency-independent application. By using two different read-/write heads (one for tool identification and one for track-and-trace of workpieces) that each interface to a single processor unit, the communication to the control system is achieved in an economical manner.

RFID processor for both tool identification and workpiece tracking

New Hybrid Read-Write Head

Industrial equipment is designed for a working life of 20 years or even more. Therefore, in production you often find machines which were designed in the last century next to new machines that were installed when the production capacity was enlarged. In such a brown field factory you have the coexistence of proven technology and modern innovative equipment. For the topic of industrial RFID, it means that both low frequency and high frequency RFID tags are used. To use both the existing infrastructure and to introduce modern and innovative equipment, RFID read/write heads have been recently developed with LF and HF technology in one housing. It does not matter whether a LF RFID tag or a HF RFID tag approaches the RFID head. The system will automatically detect whether the tag uses LF or HF technology and will start to communicate in the right frequency.

This hybrid read-write head adds flexibility to the machine tools and tool setters as you can use the entire inventory of your cutting tools and tool holders.

RFID Tool ID tag ready for the Cloud

The classical concept of data storage in Tool ID is a decentralized data storage, which means that all relevant data (tool dimensions, tool usage time, machining data, etc.) of a tool/tool holder is stored on the RFID tag which is mounted on the single tool holder. The reliability and availability of this concept data has been proven for more than 25 years now.

With the Internet of Things IIOT, the concept of cloud computing is trendy. All — tool setter, machine tool and tool stock systems — are connected to the cloud and exchange data. In this case only an identifier is needed to move and receive the data to and from the cloud. For this type of data management Tool ID tags with the standard (DIN 69873) size diameter 10 x 4,5 mm are available now in a cost effective version with a 32 Byte memory.

Evergreen – more modern than ever: RFID Tool ID in Metalworking

Learn more about the Evolution of RFID in Metalworking from true experts at www.balluff.com  or at  Balluff events worldwide