Process Verification in Manufacturing: Trust, But Verify

process verification in manufacturing

In our previous post, we discussed the benefits automation equipment can have on business and on workers. One of the benefits of automation equipment and robots over humans is the machines’ ability to perform the same task continuously, consistently and reliably, without risk of injury and little risk of variation. However, this can only work if the machine is installed and programmed correctly, and regularly maintained. To optimize automation performance, it’s important to keep in mind a simple, but powerful maxim; “Trust, But Verify.”

“Trust, But Verify”

“Trust, But Verify” is a Russian proverb that first made its way into popular English during the Cold War and nuclear missile disarmament. It’s now used in many contexts, including automation. “Trust, But Verify” essentially looks at the process and the result; trust that the process works correctly, but verify that the result is correct.

This is especially important for optimizing automation performance, and ensuring that the process is working. While a person may perform an error a few times and then fix it themself, a machine will continue to perform the process incorrectly until the source of the problem is fixed. This means, without verification, a process may be incorrect for long periods of time. These errors can also multiply across the production line, turning a small problem into a dangerous product defect.

Process Verification in Manufacturing: Then and Now

Previously, a battery of tests was the best way to determine whether a process was running properly. Usually, this involved taking a sample and delivering it to a lab. The lab might test for values such as PH, humidity, temperature, fat content, protein content, sugar brix content, water content, weight, product hardness, elasticity, and manufacturing defects that might affect the visual appearance or the structural integrity of the product. This verification process was slow, with many potential pitfalls.

Now, many of these factors can be tested in real time on the factory floor, often with sensors or spot tests. There’s no need to halt the process while waiting for lab results, or recall product that turned out to test badly. However, this also means that a faulty sensor can cause product defects and incorrect processes to go unnoticed. Though it’s reasonable to trust that a quality sensor works, it’s necessary to verify this as well.

These process verification procedures can help to ensure that the information you’re receiving from sensors is accurate, and that automated machines are performing the process properly.

6 Verification Procedures to Optimize Automated Equipment

1. Calibration

Sensors, weighing instruments and other equipment must be regularly calibrated to maintain accuracy. This is one of the most important verification procedures to optimize automated equipment, and should not be left to chance. Otherwise, the machine’s accuracy is left to chance as well. Establish a clear calibration procedure for each instrument using the manufacturer’s instructions. Make sure workers know who should carry this procedure out, and when.

2. Redundancy

For procedures that must be very precise, or for processes that are prone to error, you can optimize automated equipment by using redundant sensors. While one sensor may fail, it’s unlikely that two would fail at the same time. Using two sensors can also help you see if one has become inaccurate.

3. Reduce Interference

Where possible, use instruments that are digitized locally to the sensor. Electromagnetic interference, vibration, or damage to wires can cause signal transmission errors across longer distances. If you’re transmitting analog values, be sure that you have a secure ground reference, and that the signal is properly spanned.

4. Use Reference Values

Reference values give you a baseline for what is accurate and correct. Without reference values, it’s difficult to know when your sensors and machines are working properly. Use test weights, optical references, voltage outputs and other measures to verify that the process is working properly.

5. Regular Maintenance

Regular maintenance is an essential process verification step to optimize automated equipment. The machines as well as the sensors should both be regularly maintained according to manufacturer’s recommendations. This includes cleaning procedures to prevent the build-up of dust and debris, visual inspections of wires and faceplates, replacing seals where necessary, and more. Some measurement devices, like hermetically sealed load cells, generally do not need maintenance as frequently as other, unsealed devices.

6. Visual Inspections

Establish visual standards and inspections so workers can spot a problem if it occurs. This might include visually inspecting the finished product, or inspecting the product as it moves through the process. Consider the product’s color, size, consistency, or other notable features. Be sure there is a procedure in place for reporting and fixing a problem if a worker detects it.

“Trust, But Verify” works on a fairly simple principle; you need to trust that your process works, but also make sure that it does. Using process verification procedures will not only help you optimize automated equipment, but also prevent problems, reduce costs and give you peace of mind.

The Myth of Chasing Cheap Labor

workplace safety regulations for grain and pet food 2018

Recent events shed a light on the potential downside to setting up manufacturing in other countries in order to cut labor costs, and the instability that can occur without established links in the labor force. More and more companies are looking at the long-term costs to these operations, rather than just the direct labor costs.  The following are some of the other factors to consider in going offshore for cheap labor.

The Consequences of Chasing Cheap Labor

Intellectual Property Loss

One large factor to consider is the potential loss of intellectual property.  This can include your product recipes as well as your manufacturing expertise.  It is of course possible to sign non-compete clauses and other agreements to help alleviate this concern, but we all know that getting an agreement that lasts forever is not going to happen. If an agreement is broken, good luck with the litigation in another country.  So in the long run you may be setting up a global competitor.

Loss of Control

Another factor to consider is the loss of control to your process and product.  In order to make sure that your product is being manufactured to specification, you will need a trusted employee on-site.  This may be a difficult position to fill. Employees from your home office with enough managerial experience are unlikely to want to uproot themselves. Employees with managerial experience in the destination country are likely already working for a competitor.

It will also be more difficult to control quality.  The ingredients that are required for your product may be more difficult to source locally, or you may have to pay shipping costs to get the ingredients shipped to your remote plant.  If the logistics are not set up just right, you run the risk of significant delays in manufacturing as you wait for materials.

Language and Culture Gaps

The differences in language and culture can also play a role in product quality.  These differences can make it more difficult to train employees in good manufacturing practices and quality control.  Employees are eager to please and they may not want to admit that they do not understand instructions.  This same tendency also makes it difficult to get answers if there is bad news.  In some cultures, it is not proper to say ‘no’ to your boss.  Because of this, you may not know about a production problem until it results in late deliveries.

Employment Creep

Another problem that you can encounter in these manufacturing environments is a slow uptick in the number of employees that you have.  There is a natural tendency for employees to try to get family members hired at all levels of the business.  This can result in more workers than you actually need to do the work, or hiring workers that do not have the required skills. This can very quickly offset your potential labor savings.

Law and Policy Gaps

Navigating workplace safety regulations domestically can already present challenges. Navigating these laws and policies in other countries is even more difficult. Inspections, safety procedures, time off and many other rules and regulations may be governed by national or local organizations, and understanding how these groups work is essential to running a safe and successful workplace. In some areas, these rules may be an unwritten part of local culture, and finding the specifics can be a challenge.

Current Events

A number of events can create delays in production and shipping, both for raw materials and for finished good. Strikes, political unrest, weather events, and, as we’ve recently seen, widespread illness can all bring the production or shipping processes to a halt. While many of these events are beyond your control, familiarity with the local language, culture, news, laws and government can help you anticipate these events and plan accordingly.

 

Whether you are going to manufacture domestically or offshore, the solution to all of these problems is to refine the manufacturing process with a high degree of automation.  Regardless of what country that you are in, your competitors in that country will have the same fixed labor costs that you do.  The automation system will always allow you to get virtually instantaneous information on your process and will greatly simplify your quality control procedures and record keeping.  This type of system will also allow you to limit access to your intellectual property and make it easier to put procedures in place to keep it secure.  With automation, you can cut manufacturing costs domestically so you don’t have to go offshore and if you must go offshore, automation can help to address many of the problems that you could encounter.

8 Mixer Maintenance Tips to Extend the Life of Your Equipment

Ribbon blenders, paddle mixers and other types of mixers are integral to an ingredient system. With proper maintenance, these mixers can last for decades. Without proper maintenance, they may wear out prematurely. Setting aside time regularly to perform ingredient system mixer maintenance can save you thousands in the long run. Keep these mixer maintenance tips in mind to extend the life of your ribbon blender, paddle mixer or other mixers.

8 Mixer Maintenance Tips to Extend the Life of Your Equipment

1. Check Components for Lubrication

Regularly checking lubricant levels and ensuring that the moving parts in the mixer are properly lubricated can extend the life of your mixer for years. This is one of the most important general mixer and ribbon blender maintenance tips to keep in mind, and one that is easy to take care of. Some parts within the mixer, such as the drive components, make up a significant part of the mixer’s cost, so replacing these will be almost as expensive as buying a new mixer. Pay special attention to the lubrication around the drive, reducer, and shaft bearings especially. Set aside time once a month to check these levels.

2. Maintain the Seal

Mixer and agitator seals keep ingredients in the mixer, and also protect the movement of the shaft. If a seal is damaged, material will escape or the alignment of the shaft may shift. There are many different types of mixer seals, and the best mixer maintenance tips for each will depend on which your machine has.

  • Air-Purged Seal: Check the air pressure and air quality to make sure this air-tight seal is holding.
  • Stuffing Boxes: Check the packing material for wear or damage and tighten or replace the stuffing boxes where necessary.
  • Lip-seals: Check for leaks and damage regularly. If these mechanical seals wear out more frequently than normal, the seal material might be incompatible with the material being mixed, especially if you are working with corrosive or abrasive materials.
  • Single seals: Measure and adjust the spring compression to meet the manufacturer’s recommendations. Replace the seal faces if the wear is obvious or the seal isn’t holding.

3. Monitor the Drive System Tension

The drive system is one of the ribbon mixer’s and other mixer’s most valuable components. Keeping the reducer, belt, or chain-and-sprocket mechanism properly lubricated (see the first point, above) is one of the best ingredient system mixer maintenance tips to keep in mind. It is most important to regularly check the tensioning on the belt or chain. The the belt or chain slip if it is too loose and could cause damage to the sprocket or burn the belt. If the belt or chain are too tight, they will start to wear out bearings prematurely. Keep the tension within the manufacturer’s recommendations and check it monthly to be sure it is correct.

4. Check the Discharge Gate Operation

Over time, dust, dirt, powder, or foreign objects can get lodged in the discharge gate, causing it not to completely close. Check limit switches to make sure the gate is completely closed or open when the limit switch is used. Observe the discharge gate during operation to make sure it opens and closes properly. If the gate does not fully open, it can cause material to remain in the mixer. If the gate doesn’t fully close, material will leak out.

5. Protect the Mixer Tub

The body of the mixer is also an important part of proper ingredient system mixer maintenance. Whether you have a ribbon mixer, paddle mixer, or another type of mixer, the body of the machine can be damaged if the agitator is too close to the walls. Foreign objects, such as bits of metal or small rocks, can also damage the mixer as it operates.

Over time, the shaft can shift, causing the mixer blades to move too close or too far away from the tub. This will not only damage the mixer, but it can introduce metal fragments into the mix, and disrupt the overall mixing operation. Remember that the mixer is designed to best meet the needs of your ingredients—if the mixer components are not in proper alignment, it will not mix properly. If you hear scraping sounds or the mixer is vibrating excessively, the shaft may be out of alignment and the blades are too close to the tub.

6. Clean Intervents

Intervents allow displaced air to escape as ingredients enter the mixer. These intervents can easily become clogged with dust. Clean them regularly to allow air to escape and your ingredients to enter the mixer easily. If the air can’t escape through intervents, dry materials can create clouds of dust as it escapes through other exits. Dust introduces risks of fire and explosion.

7. Inspect Electrical

Check electrical cords for breaks. As people and machines move around the facility, cords often get in the way. A broken electrical cord is a safety hazard, exposing workers to risk of shock and fire. Combine a damaged electrical cord with the previous issue—clogged intervents creating clouds of dust—and two seemingly minor problems can become a very serious problem, including a powder fire or explosion.

Using a damaged electrical cord can also damage the machine’s internal components. To make sure your ribbon blender or other mixer operates at the proper level, check the current consumed while it’s operating. If it’s consuming too much or too little, there may be damage somewhere in the electrical system or motor.

8. Check the Coefficient of Variation

One of the best ways to make sure your mixer is working property is to check the coefficient of variation (CV). Once a year, take a number of samples of your mix and send them to a lab to check the CV. This might seem like an overly-meticulous step, but it can help to prevent over- or under-mixing, and it can show if your mixer is not operating properly.

If your process changes, such as automating a hand-add step, you might also be able to speed up your mixing time to suit the new speed. Checking the CV will show if the new mixing time is adequate, or if other adjustments should be made.

These mixer maintenance steps may seem time-consuming all together, but setting aside a bit of time for these tasks will make maintenance much more manageable. Also, consider the time, money, and energy it takes to replace or repair a mixer that is not properly maintained. When comparing the two, setting aside maintenance time will always be faster, cheaper, and easier.

How to Customize Your Powder Feeder

questions to ask manufacturers

A powder feeder can improve your system efficiency by metering the right amount of materials from the ingredient source—such as a bulk bag or another container—into a mixer or another downstream process. Many ingredients can be challenging to work with, and knowing how to customize your powder feeder can prevent flow problems like clogging, flushing and inaccurate measurement.

How to Customize Your Powder Feeder

An experienced engineer can help you customize your powder feeder to prevent common problems that might affect your materials. However, your engineer must know some critical information about your system and ingredients to get started. As you consider customizing your powder feeder, the following information will be helpful. These don’t have to be exact, but more accuracy will mean better system customization.

  • Material properties: angle of repose, viscosity, fat content, moisture content
  • Volume: how much of the ingredient are you measuring in what time frame?
  • Accuracy: what is your margin of error?
  • Dimensions: what is the available horizontal and vertical space around the system?
  • Environment: are the temperature and humidity conditions stable, or will they change as the weather changes?

Type of Feeder

There are many ways to customize your powder feeder, and this starts with two different types of feeders. Each uses a different method for moving the materials through the feeder. The first, a vibratory feeder, uses vibration to move materials. A vibratory powder feeder can be effective for many ingredients, but it can also introduce noise and interference to the surrounding system. This can disrupt weight and volume measurements.

The second, an auger feeder, uses mechanical force from either a spring or a screw-shaped shaft. An auger feeder is highly versatile and preferable for most ingredients. There are many ways to customize this powder feeder further to perfectly suit the materials and the surrounding system.

The Feeder Core

You can customize powder feeders using augers with a spiral core or a shaft core. In a spiral auger, a spring inside the powder feeder creates the mechanical motion needed to move the material. In a shaft core, also called a screw auger, the flights around the core rotate and move the material. Either of these types of powder feeders can be effective. If your material is likely to bridge or clump, a screw auger can provide the additional movement needed to keep the material flowing.

Screw Auger Flighting

If you are using a screw auger powder feeder, you can customize the size, type and arrangement of the screw flights. The spacing between the flights, called the pitch, will partially determine how much material moves through the feeder. At full pitch, the spacing between the flights is equal to the diameter of the feeder. At half pitch, the spaces between the flights is half of the diameter of the feeder.

The screw auger flighting pitch will not only determine how much material moves through the feeder, but also the rate at which it moves. A full-pitch feeder will release a larger amount of material in slower intervals, while a half-pitch feeder will release a smaller amount of ingredients, but in faster intervals. This will change the overall flow of the ingredients through the system. Higher pitch will feed material in pulses, while lower pitch will create more continuous movement.

Variable Pitch

In a screw auger, it is important to alternate the pitch of the flights at the start of the feeder. If the flights are spaced and sized equally throughout, pressure will build up at one end of the feeder as it moves material. This requires the drive to work much harder than it needs to. Simply starting with half pitch and moving to full pitch will help to equalize the pressure across the screw auger. Conical-shaped flighting across the auger or variable pitch at the inlet will also solve this problem.

Diameter of Feeder and Auger Shaft

The feeder diameter is another obvious way to customize your powder feeder. Changing the feeder diameter will change how much material moves through it. When working with a screw auger, it is also important to consider the auger shaft. Widening the auger shaft will cause it to take up more space in the feeder, allowing less material to move through.

The ideal diameter of the feeder and the auger shaft will both depend on the desired volume. If the material must be carefully metered with more accuracy, a smaller feeder diameter or a larger auger shaft will move smaller amounts of material more steadily. However, if you want to move material through the feeder quickly, a larger feeder diameter and a thinner shaft will be best.

The Drive

The drive on the powder feeder must be powerful enough to drive the screw or spring auger while delivering the right RPMs. The drive must also be accessible for maintenance or repairs. You can customize your powder feeder drive by changing the mounting position of the drive, the reducer, and the RPMs of the drive. This is another way to customize your powder feeder according to the material moving through it. Raising the RPMs will move material at a faster rate, and vice-versa.

There are many ways to customize your powder feeder to suit your materials and your overall process. This can seem complicated, however it also presents a number of different solutions if you encounter a problem with your particular ingredients or process. If your process repeatedly stalls at the feeder stage, or material moves too quickly or too slowly through the feeder, consider these customization options. Work with an experienced equipment manufacturer to ensure your powder feeder works with your materials, not against them.

How Capacitive Load Cells Work

hermetically sealed digital load cell

Capacitive load cells are relatively new to the weighing world, compared to strain gauge load cells, which have been used for decades to measure weight through piezoresistivity. Capacitive load cells use electric charge to measure weight. This, and other important differences, give capacitive load cells several advantages over traditional strain gauge load cells. Knowing how capacitive load cells work can help you choose the right one for the application.

How Capacitive Load Cells Work

As the name implies, capacitive load cells use capacitance to measure weight. This is essentially a small, stored electric charge. How this charge is created is what gives capacitive load cells their unique advantages.

The Capacitive Load Cell Construction

capacitive load cell diagramOn the outside, a capacitive load cell and a strain gauge load cell look the same. Either type of technology can be used in an S-beam, beam, pancake, button, or other types of load cells. However, the components inside are much different.

A capacitive load cell uses a series of capacitors to measure weight across the load cell. Inside each capacitor are two charged metal plates with a dielectric, uncharged material between them. This simple construction allows the capacitor to measure weight. A load placed on the capacitor pushes the plates closer together, creating a current at first and then a build up of energy between the two plates. The dielectric material between the plates stores this charge. This is then translated into voltage, which can be reinterpreted as weight.

How Capacitive Load Cells Work for Different Applications

A capacitive load cell can measure very small differences in weight for very fine measurements, as well as dramatic changes and heavy weights. The general principle and operation remains the same, while the construction of the plates, the dielectric material between them, and the distance between the plates can all change. All of these factors can change the sensitivity and capacity of the load cell, so the capacitive load cell can be constructed to meet the needs of the application.

Liquid Spray, Dust and Humidity

A capacitive load cell automatically produces measurements in voltage, where a strain gauge must be converted into voltage. This introduces an extra step and extra components that must be completely contained for the strain gauge load cell to be hermetically sealed. A capacitive load cell can be hermetically sealed more easily, since it doesn’t require extra connections or components. This not only means the capacitive load cell fits easily into applications around liquids, dust, or high humidity, but it also means the capacitive load cell will last longer and require less maintenance.

Vibrations and Electromagnetic Interference

A strain gauge requires a digital converter to turn its analog signal into a digital readout. A capacitive load cell automatically produces a digital output, so it doesn’t require a converter. This makes it less susceptible to interference, so it won’t be as affected by electrical noise that can be created by welding or the switching of large loads. Since the bending elements inside the load cell are heavier, then they are also less susceptible to damage due to vibration.

Capacitive load cells are relatively rugged compared to the delicate construction required for strain gauges. This means that they are less susceptible to damage due to overloading and side loading. This gives capacitive load cells a number of advantages in various applications, including those that might experience overload from heavy loads dropping a distance into the scale as well as small weights with delicate measurements. To find the right load cell for your weighing and batching system, work with engineering experts.

5 Considerations to Select a Ribbon Blender

batch mixing system ribbon mixer

The type and number of blenders you choose for your process will play an important role in how fast and how well your recipe is mixed. There are a number of different ways to customize your ribbon blender, and it can be difficult to choose the right model. Here’s a few factors that will help you choose the right ribbon blender for you ingredients and process.

5 Considerations to Customize and Select a Ribbon Blender

1. Size and Volume

Ribbon MixerThe volume and profile of the ribbon blender are the most important aspects to consider when selecting your ribbon blender. This will depend on the amount of material you are mixing, as well as the speed with which it must be mixed. In some cases, a very large blender might be suitable. In other cases, multiple smaller blenders can help you optimize the process. With multiple blenders, you can avoid a shut-down if something goes wrong, and you can also dramatically reduce the time needed to mix a batch.

The ribbon mixer should be filled to its swept volume to get the most efficient mix. The swept volume is the area occupied by the agitator. In order to get the best mix in the shortest amount of time the mixer profile is also important. The length of the mixer should not exceed 2.5 times the diameter of the agitator. Consider the length, width, height and volume of the vessel, as well as the agitator size, to customize your ribbon blender to the right size.

2. The Ribbon or Agitator Type

A ribbon mixer successfully mixes materials by agitating them with a corkscrew-like metal blade. The outer helix of the ribbon moves product in one direction, while the inner helix of the ribbon moves the material in the opposite direction. This movement of material from one end to the other provides a fast but gentle mixing action. If more shear is needed to change the ingredients’ characteristics, then the mixer can be run at a higher speed or other devices can be added to the mixer, such as high-speed choppers. Some types of materials may work better with a mixer that uses paddles for the agitators instead of ribbons. This can be true of ingredients that have a high liquid content or those that are sensitive to shear. Selecting the right ribbon or agitator type is important for customizing the right ribbon mixer, or another type of mixer. The type of agitator you will need will depend on your ingredients, as well as the mixing time and mixer profile.

The following factors can help you determine what type of agitator to use:

  • Shear: If you are working with dense or viscous materials, your agitator may need a higher degree of shear. The speed of the agitator and the tolerances between the mixer body and agitator can increase the amount of energy that goes into the mix. Generally, more shear will require more horsepower.
  • Friability: Contrastingly, if your materials might easily break as they’re being mixed, you might use a gentler agitator, such as a paddle mixer. Mixing at a lower speed will also help this process, which we’ll discuss later in the post.
  • Single or double ribbons: Using mixers with two sets of agitators will decrease the overall mix time required for the process.  These mixers use ribbons, paddles, or sometimes a combination of the two. Using double agitators will also increase the horsepower required.

3. Mixer Construction Materials and Finish

Ribbon mixers are made from both mild and stainless steel. The materials of construction will depend upon the ingredients that are being mixed and the how those ingredients are going to be used. For example, in the case of food-grade ingredients, the mixer should be stainless steel with special finishes so that it can be easily cleaned and sanitized. If the ingredients are corrosive, then stainless steel would also be a good choice, since mild steel would be dissolved by the ingredients over time. However, your materials or process may require other materials or finishes. If your materials are not susceptible to foodborne illnesses, these finishes might not be necessary.

Quite often, the exterior of the mixer or non-contact areas of the mixer can be made from mild steel and painted. The interior of the mixer is usually not painted, since it could contaminate the ingredients being mixed. A mixer can also be lined with a material to enhance it’s performance. This is typically seen when a material is abrasive and would prematurely wear out the interior parts. Or, if you are working with corrosive materials, another finish may be required. Your ribbon mixer can be customized with a range of materials, finishes and paint to suit your facility.

The following are popular materials and finishes in ribbon mixers:

  • Various weld finishes from standard welds to sanitary
  • Industrial enamel paint or epoxy paint
  • Stainless steel food grade
  • Abrasion resistant linings such as ceramic and UHMW plastic

4. Horsepower

Most ribbon mixers operate at around 20 RPMs, though mixers with dual agitators or wider ribbons will require more power. A general rule of thumb for medium-density material in a single-agitator ribbon blender is 10hp per ton of material being mixed. To select a mixer that is both effective and efficient, use a motor with the appropriate horsepower. The supplier of the mixer can help with motor sizing and type. Selecting a motor that is too powerful can mean adding extra expenses, but underestimating the motor power can mean that the mixer cannot be started under load.

5. Discharge Gate

How your ingredients exit the mixer is also important when customizing your ribbon blender. The cycle time and downstream processes will partly determine which ribbon blender is best. Some processes may require complete, immediate discharge. In this case, a full-length drop bottom discharge gate would be ideal. Other processes may require gradual discharge or a tighter seal, and a slide-gate may be better in these cases.

The most common types of discharge gates for your ribbon mixer are:

  • Drop bottom: A drop bottom discharge gate will fully release materials in the mixer immediately. Though these gates work quickly, getting a tight seal can be difficult, especially when working with fine powders. This quick discharge can cause dust to escape into the air, so proper venting of the mixer is needed.
  • Pneumatic Slide Gate: A slide gate will allow a set amount of material to escape, which can be helpful for measuring, batching, or bagging processes following mixing. These will also have a tight seal to prevent powder from escaping.
  • Multiple Slide Gates: If you are looking for a faster discharge rate as well as a tight seal, you can use multiple gates to speed up the process, while still preventing powders from escaping.

Choosing the right ribbon blender and customizing features to suit your process and materials means getting the perfect mix. With consistency and accuracy built into your process, you can eliminate many concerns and problems both upstream and downstream. Work with a supplier who can help you customize these features to suit your process and provide testing to ensure you have the right fit. If you’re interested in ribbon mixers, APEC has horizontal ribbon mixers suitable for nearly every application.

How to Use Automation for FSMA Compliance in Food Processing

automation for FMSA compliance

The Food Safety and Modernization Act has set a higher standard for reducing contamination in food and dangers to consumers. Automation has helped to improve FSMA compliance by increasing accuracy and consistency in food processing. Automation allows you to streamline processes and remove human error to make FSMA compliance simpler and more accurate. With some set-up from the start, you can take advantage of time- and cost-savings for years down the road.

Advantages of Automation for FSMA Compliance

Simplifying FSMA compliance with automation means utilizing the right integration and implementation. To get the most out of these benefits, it is important to allow your machinery and programs to communicate properly, so they do not become isolated in operational silos. When this information is transferrable across the organization, from shipping and receiving to processing to supply chain management and more, it becomes more useful to every person in the department. Each of these procedures is made simpler and more efficient through automation. Automation offers the following advantages at each step in the process

  • Accuracy: Automation eliminates the need for a staff person to check a box, pull a lever, or record an amount. While these staff are still essential for ensuring that the equipment is working properly and the process is running smoothly, the automation system frees them from tedious or unnecessarily time-consuming tasks.
  • Speed: By programming your automation equipment to run tasks in succession, you eliminate downtime and pauses in between. One process goes into the next without the need to perform extra checks or mark a chart.
  • Consistency: Consistent operations as well as a consistent recipe are an essential part of FSMA compliance. By making the process systematic, automation improves consistency at every step.

How to Use Automation for FSMA Compliance

Electronic Record-Keeping

Accurate record-keeping is an essential part of FSMA compliance. If your facility undergoes inspection or audit, your records will show your due diligence. Automation can make record-keeping faster and more accurate by taking measurements and recording them as they happen. Automation can also improve the accuracy and consistency of the records, when using the right set-up and the right precautions.

Consider the following for automated record-keeping:

  • Ingredients: Automatically record the type of ingredient you are working with, the bin or silo storing it, its origins and the supplier.
  • Weights: Automated weighing systems record how much of the ingredient was used in the recipe the moment it is distributed.
  • Lot numbers: Electronically recording lot numbers facilitates a smooth track and trace system.
  • Dates: Delivery dates, use dates, shipping dates, and expiration dates will all help you to maintain a FIFO system and improve your track and trace process.

Measuring

Weighing and measuring systems are one of the best ways to simplify FSMA compliance with automation. Automated weighing systems improve accuracy, speed, and consistency in multiple ways. With the right weighing and batching system, you can distribute exact amounts of any ingredient and you can be sure that the material is going to and from the right place. This eliminates the need for any manual operation, and also eliminates inconsistencies that may arise from manually filling bins, selecting ingredients, and recording these selections. As the automation system automatically releases and weighs materials into the recipe, it also records the amount, so there is no risk of inaccuracy between measurement and recording.

Packaging and Labeling

The right packaging and labeling are key parts of FSMA compliance and general food safety, regardless of the product. A fully integrated automation system can automatically label products with all of the information acquired through the process, such as the ingredients, lot numbers, expiration dates, and more.

Effective recall procedures are an essential part of HACCP assessment and FSMA compliance, and proper labeling plays an essential role in this. While it is impossible to test for and prevent every possible contaminant, accurate lot tracking and recall operations allow producers to stop damage from contamination. With lot information tracked automatically, start to finish, from raw ingredient receiving to shipping the finished product, all of this information is accurate and placed on the package.

Testing

Though it is impossible to test for every possible contaminant, it is possible to test for and prevent the spread of the most common contaminants. For food processing facilities this includes a number of foodborne illness pathogens such as salmonella, listeria or E. Coli, among others. For grain and livestock feed processors, it might include grade and quality testing or testing for the presence of aflatoxins or vomitoxins. Automation is not feasible for every test or every operation, but testing processes can be simplified by automation in some situations. Automating this process ensures that the test is conducted properly and at regularly required intervals.

In addition to improving accuracy, consistency, and speed, automation for FSMA compliance also provides other advantages. Workers are freed from repetitive and unengaging tasks that inevitably produce errors. By keeping detailed records automatically, the business reduces liability and protects its reputation. Finally, automation also reduces product and material losses, saves time, and ultimately reduces cost.

Hermetically Sealed Load Cells Explained

hermetically sealed digital load cell

Though they’re often used in highly durable scales and heavy equipment, load cells themselves are somewhat delicate, and can easily be damaged by surrounding elements. This is what makes hermetic sealing so important. Hermetically sealed load cells are air- and water-tight, protecting the delicate measurement components inside from damage. In this blog post, we’ll explain further what hermetically sealed load cells are, why they’re important, and how you can ensure that your load cells are sealed properly.

Hermetically Sealed Load Cells Explained

What is a Hermetically Sealed Load Cell?

A hermetically sealed load cell is an air- and water-tight weighing instrument. The load cell is contained by a welded seal around the gauge, which prevents dust, moisture and other materials from disrupting it. The connecting cable also uses a welded header to maintain the seal.

Hermetic sealing is slightly different for a capacitive load cell compared to a strain gauge load cell, which we will explain later in the blog post, however the principal of completely sealing the weighing elements remains the same.

Are Hermetically Sealed Load Cells Necessary?

strain gauge load cell
A simple diagram of a strain gauge load cell

Load cells, including both strain gauge load cells and capacitive load cells, can be disrupted by changes in conductivity. This means that any conductive element can contaminate the load cell, and disrupt the measurement, or cause the cell to stop working all together. The load cell may be exposed to many different conductive materials, the most common being simply water. The inner workings of the load cell are very delicate, and can be damaged by water from washing down equipment, contact with other liquids used in the process, or even changes in humidity.

Other conductive materials such as metallic dust or salt can also disrupt the load cell. Finally, corrosive chemicals and vapors can erode the exterior and damage the load cell. Hermetically sealed load cells made from laser-welded stainless steel offer the best protection from all of these threats.

If you are washing your equipment, or it is exposed to salt, metallic dust, notable changes in humidity, corrosive chemicals or chemical vapors, hermetically sealed load cells are necessary. The load cell will last longer, and it won’t need to be recalibrated or replaced as often as a non-sealed cell. The additional cost of hermetic sealing will be lower than the costs associated of repeated maintenance and replacement of a non-sealed cell. A non-sealed cell is also at much greater risk of sudden failure, which can cause expensive downtime.

Hermetically Sealed Load Cell Technology: Strain Gauge vs Capacitance

a strain gauge
A closer look at the delicate strain gauge

In a strain gauge load cell, the strain gauges themselves are comprised of arrangements of thin, conductive metal and an insulated backing, which are very delicate. The fine interconnecting wires and electrical circuits measuring resistance are also very fragile. These components depend on electrical conductance to work, so any conductive material can contaminate the load cell and disrupt the measurement. This includes water and moisture in the air, as well as conductive dust. If the load cell is not hermetically sealed, water, dust, and even changes in humidity can damage it. The external output must also be directly connected to the load cell, so this connection area must also be hermetically sealed. This is the most common area where a hermetic seal might fail.

capacitive load cell diagram
A simple example of how a capacitive load cell works.

A capacitive load cell uses capacitance instead of conductance to measure the load. In a capacitive load cell, a change in charge between two metal places and a dielectric material in between measures the load. These elements can also be disrupted by conductive materials. The capacitive load cell, however, can be more easily self-contained, since it does not require complex circuits, namely a Wheatstone bridge, to measure resistance. A capacitive load cell also uses a coaxial cable for an external output, which is separated from the hermetically sealed load cell itself. This means seal around the external output does not endanger the hermetic seal of the load cell. A coaxial cable connection is also less prone to connection interruption and damage. For these reasons, hermetically sealed capacitive load cells offer more advantages in many risky environments.

Learn more about digital capacitive load cells » 

How to Detect an Low-Quality Hermetic Seal

As previously discussed, the best type of hermetically sealed load cell is made from laser welded stainless steel. Some believe that a stainless steel load cell is adequately sealed and protected by itself, but only hermetic sealing will completely protect the load cell.

For strain gauge load cells, the output should also have a welded cable header. In some cases, the cable may be sealed using foam, adhesive, or epoxy. While these may provide adequate protection for a time, they will eventually break down and expose the load cell to dust and moisture. A welded cable header and seal will not break down prematurely and it will prevent dust and moisture from building up in cracks or pockets.

Hermetically sealed load cells are requirements in many facilities, and advantageous in most others. There are many different types of load cells that can be hermetically sealed, including many different designs, configurations, weights and tolerances. With a high-quality hermetically sealed load cell included in your weighing system, you can extend the life of your machine and reduce maintenance and risks. Download the brochure to learn more about hermetic load cells.

8 Advantages of Capacitive Digital Load Cells

In our previous post, we discussed problems engineers and scale dealers often face when working with traditional strain gauge scales and load cells, and solutions that can improve accuracy and durability. In many cases, utilizing capacitive digital load cells can help to avoid problems posed by the strain gauge. In this post, we’ll explore the capacitive digital load cell, how it works, and advantages it provides to scale dealers and their customers.

How Do Capacitive Digital Load Cells Work?

While strain gauge load cells use resistance to change voltage and therefore measure weight, capacitive load cells use changes in capacitance. Inside a capacitive digital load cell, two plates with opposing charges stand a small distance apart. When a load is applied, it forces the plates closer together. As this happens, current moves between the negatively- and positively-charged plates in an effort to establish equilibrium. A charge is then stored between the plates, creating capacitance. This then produces voltage output which can be transferred to a reading on a digital scale.

Capacitive digital load cells are simpler to construct than strain gauge load cells, and this simple design makes them less susceptible to many of the issues that often disrupt strain gauge load cells. Other advantages also make capacitive digital load cells easier to use, and more affordable to manufacture.

8 Advantages of Capacitive Digital Load Cells

1. Fewer Start-Up Costs

Capacitive digital load cells are already calibrated at the factory, and do not need to be recalibrated when they are installed. To install in the field the engineer or operator must only zero off the dead load of the system and check for binding.

2. More Sensitive

For strain gauge load cells, detecting small changes and measuring small loads means utilizing very small changes in resistance. This requires the load cell to be more sensitive, which also makes it more susceptible to damage and requiring more frequent recalibration. Thanks to their simple design and versatile materials, capacitive digital load cells retain their durability even at high sensitivity. Since a smaller amount of movement can be easily sensed with a capacitive cell, then the metal can be thicker and able to withstand more load, with the same amount of sensitivity. This makes the cell less susceptible to overload.

3. Simple Maintenance

The delicate cables and wires that interconnect strain gauge load cells are not required with capacitive digital load cells. This means field wiring of small connections in difficult arrangements is a thing of the past. The only cables needed are communication and power transfer cables, which can be replaced in the field without the need for recalibration.

4. Versatility

Capacitive sensors can be built from a wide variety of materials, and in many different shapes and sizes. They are also suitable for very large and very small loads, with many levels of accuracy. This makes it easy to design and manufacture a capacitive digital load cell for any application. Digital capacitive load cells may be designed in beam, compression buck, tension or single point configurations, as well as specialty configurations like on-board weighing, tensioning, force measurement and more.

5. Less Noise

Capacitive load cell output is completely digital. Since it does not use DC signals in milliVolts, which are easily disrupted by ambient noise, the signal is less susceptible to interference. This also means there is no need for an analog to digital converter to convert the signal to a digital format.

6. More Affordable

Reducing the noise levels, eliminating the need for an analog to digital converter, and utilizing a wider range of materials with a simpler design allows manufacturers to produce capacitive digital load cells that are more affordable, when comparing feature for feature.

7. Durable and Hygienic

Many capacitance digital load cells are ATEX certified for hazard zones 1, 2, 21 and 22. These load cells can also be hermetically sealed (rated at least IP 68 and some at IP67) without significant additional expense, unlike the strain gauge load cell, which can be difficult to completely seal. This makes it suitable for hygienic applications such as food and pharmaceuticals.

8. Additional Features

The reduction in noise, simpler design, and digital output makes it easy to augment the capacitive digital load cell with additional features. Ethernet IP, EtherCAT, Profibus DP, ProfiNet, DeviceNet, Serial outputs and analog outputs are all available in neat compact packages.

Capacitive digital load cells are replacing strain gauge load cells in a number of applications. If your strain gauge load cells are making processes more difficult or less efficient, or if you’re looking for a competitive advantage as a scale dealer, consider the digital alternative. Learn more about capacitive load cells and talk to an expert to find the right load cell for your application.

5 Strain Gauge Scale Problems and Solutions

Load cells are essential devices used in many processing systems, though we seldom think about them. Only when the load cell malfunctions and the scale is inaccurate do we think about the workings behind the measurement. When it comes to measuring ingredients, from fine pharmaceutical powders to silos full of grain, understanding how strain gauge scales and traditional load cells work, and common strain gauge scale problems, can help prevent inaccuracies.

How do Strain Gauge Scales and Traditional Load Cells Work?

Strain gauge scales use traditional load cells, also called resistive load cells or strain gauge load cells, to measure weight. Strain gauge load cells operate on the principle of piezoresistivity. When voltage is applied to the strain gauge within the strain gauge scale, and then a weight is applied, the strain gauge senses changes in piezoresistivity, and this creates a change in voltage output. For this to work, several strain gauge sensing elements are often used throughout the load cell, and these are connected with wires. For the sensing elements and the strain gauge scale to be accurate, the wires must be able to transmit small changes in voltage, so the wires can be very delicate.

A strain gauge scale relies on mechanical forces to change piezoresistivity and voltage output. When a load is applied, the conductive material within the strain gauge is deformed, causing changes in resistance, and therefore changes in voltage output. This can introduce a number of challenges to both large and small loads. If your scale is repeatedly inaccurate, and you have determined that other aspects of the system are not to blame, look for the following issues with the load cell.

5 Traditional Strain Gauge Scale Problems and Solutions

Low-Quality Manufacturing or Construction

Small mechanical changes within the strain gauge are responsible for changes in voltage, which creates the reading on the scale. If flaws in the strain gauge’s construction prevent the material inside from moving properly, the reading will not be correct. For this reason, the process to manufacture an accurate strain gauge-based load cell is delicate. If this isn’t done correctly, the load cell won’t deliver adequate readings. This can be particularly problematic when working with discount scale dealers, who rely on fast manufacturing and testing. Working with a reputable scale dealer with references can help you to avoid load cells with faulty construction.

Temperature Changes

Temperature changes effects the conductivity of metals, which will change the output of the strain gauge. Once the load cells are built, they need to be tested at different temperatures in order to ascertain their drift with temperature. When the traditional strain gauge is needed to measure particularly small amounts, temperature changes can be especially problematic. Thermistors installed prior to the final test and calibration stage will reduce the temperature effect.

Wrong Type of Load Cell

There are many types of load cells using traditional, strain gauge technology, and certain types are better suited to certain applications. Capacitive load cells, which use changes in capacitance instead of resistivity, can also be used in many different applications. Finding the right load cell for your application can make significant differences in accuracy, longevity and efficiency.

  • S-Beam Load Cell: Instead of a load sitting on top of the load cell, an S-Beam load cell hooks the load on one side and uses the pulling force to measure the load.
  • Beam Type Load Cell: The beam type load cell uses compression to measure weight, and it is often used in tank weighing and platform scales.
  • Single Point Load Cell: The single point load cell works similarly to the beam load cell, except it is ideal for loads that are not centered.
  • Button Load Cell: The button load cell also uses compression, but measures load applied axially.
  • Pancake Load Cell: These load cells are used for high-capacity loads up to 500 tons, such as silo weighing or structural loads.
  • Capacitive Load Cell: Since capacitive load cells operate on a different principle, they are not as affected by noise and interference as strain gauges, and they can be more sensitive with less need for delicate manufacturing. Capacitive load cells are highly effective for a variety of applications, and are also available in all of the above configurations.

Exceeded Sensitivity

Smaller, more precise strain gauge load cells are much more delicate than their larger counterparts. The nature of strain gauge technology requires that the strain gauge be much smaller, and its components more delicate, to be more accurate. This makes the strain gauge and the load cell much more susceptible to disruption from physical impacts, electromagnetic interference, dust, temperature changes, and other issues. More frequent calibration of traditional load cells can help them to maintain their accuracy. Capacitive load cells can also be used in lieu of strain gauges for these applications.

Improperly Sealed

If your traditional load cell must operate around water, dust, or other debris, it must be hermetically sealed. For traditional strain gauge load cells, hermetic sealing raises the price significantly, and some scale dealers may cut corners in this area. If your traditional strain gauge is significantly cheaper than other comparable models, it might not be properly sealed.

Careful attention to detail and working with a reputable scale dealer can help traditional scale gauges to maintain accuracy. Utilizing the right load cell designs, as well as newer technology like capacitive load cells, can also help to solve many common load cell problems.