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Robotic grippers for protein handling: Steak, poultry and sausages

Protein handling with SoftGrippers! A long article with several examples in sausage, chicken and burger meat handling!

Application

Since the pandemic hit the protein industry and the food processing industry in general, we have seen the trend of large manufacturers of consumer protein products that used a lot of labor turning to forward-looking solutions. Not only for hygienic reasons or to save on personnel, but also because labor was hard to find in this area, especially not in the quantities that companies like Tönnies need to function. The task of automating entire production lines went to integrators. That’s not to say that automated production lines for protein processing, meat preparation or sandwich making didn’t exist before; solutions for cutting and processing chicken were already on the market, but new developments in robotics, peripherals and end-of-arm tooling have made automation solutions more accessible at any size company in food manufacturing and even for niche applications. In this article, we discuss the technological advances in protein processing and highlight some of the applications we have done with our partners in the industry. All of this is to show you what to look for when developing an automated protein processing line.

Industrial standards in robotic protein processing: Food safety regulations

First, we need to talk about hygiene concepts in raw meat processing. The exact food safety guidelines vary from country to country, but one thing is undeniable: protein processing is a highly regulated area, and hygienic conditions are key to the operation of any plant. Food safety quality assurance will be with you every step of the way. Special attention is paid to hygienic design. Newer Delta robots designed for use in food environments are made entirely of stainless steel and can be cleaned with pressurized water and detergents without damaging the electronics. At the same time, the design ensures that no product parts get caught and create unsanitary spaces. Conveyor belts follow a slightly different logic. First of all, in food production, the belts are perforated and therefore easier to clean with pressurized water. The blue color is for safety, as the products are usually not blue, so the equipment can be easily distinguished from the goods. Other food contact components, such as our fingers, follow the same color logic. In addition, our SoftGripping product line follows a hygienic design with beveled surfaces, special seals and screws. This allows product residues and cleaning agents to roll off easily, leaving behind clean and hygienic surfaces.

For us as a gripper manufacturer, one thing became clear: Most automation systems inthe food industry with conveyors, industrial robots, cameras, automated packaging equipment and delivery stations differ slightly from application to application. They are often built first and the most important piece of the puzzle is only solved at the last moment: the robot gripper! The part that comes into contact with the food must simply be considered first. Food contact means that the shape of the gripper must be adapted to the product in question. A gripper that is optimized for the protein being handled means a more precise grip, less variation in picking and placement, and most importantly, less chance of handling errors! For this reason, we need to look at the typical challenges of handling protein and know what to look for, such as: Weight distribution, general shape, containers to pick up and put down. All with the aim of making the process as fast as possible and, above all, reliable!

safe industrial handling of sausages
Traditionally, we first test designs in-house or directly at our customers’ facilities using SoftActuators. These are end-of-arm tooling fingers that can form a variety of different gripper designs by placing them on sheet metal and aligning them to fit the object at hand. In this way, product variations can be tested, load balancing recorded via a high-speed camera, and initial design and assembly adjustments made using fingers, angles, spacers, and suction cups (only when possible, of course). At this stage, hygienic design is not important at all. All testing is done in an environment where the product will never touch the customer’s hand…. But eventually it will! So the knowledge gained from the preliminary tests must be transferred into a gripper base that is tailored to the task, has all the necessary functions and, most importantly, is hygienic! As you might imagine, this is just for your information: SoftGripping is about finding tailor-made solutions, but for general, widespread applications such as poultry, all kinds of sausage, fish and meat, there is a solution that has been tested with one of our previous projects. So feel free to contact us to see what solutions are available for your facility.
A long fingergripper for handling raw chicken

Alternatives to suction cups in pick&place of Protein

Suction cups are often used in high-speed automation. But in this case, with raw meat, marinade and breading, removing residues from pneumatic lines becomes a nightmare! Simple filtering, as with many other automation systems, is not enough. We’re not talking about dust or product residue here, but bacteria and liquid vapors created by the vacuum. In addition, the uneven surfaces and skin make gripping impossible. This is not the case with soft robot grippers. The pneumatic lines are not open to the environment and the process air does not come into contact with the product. The grippers still work with compressed air and vacuum. However, the compressed air ensures that the fingers wrap around the product, while the vacuum ensures a quick release of the gripper at the target position. This makes maintenance easy for production workers and keeps people responsible for quality control and food safety happy. If you need a cushioning effect for your product, we recommend using a spacer or suction cup to ensure the product stays in place throughout the gripping cycle, but in this type of scenario, activating suction cups for extra grip is something we do not recommend.
Gripping raw chicken filets pieces

Usage of soft grippers in Protein picking and packaging

There are many use cases in protein processing where robots can support humans or even take over the main role in the production process: Pick-and-place, pick-and-pack, sorting, product weight distribution and, of course, in processes where meat is cut and prepared before final packaging.

Pick and place

The first application that comes to mind is simply removing protein from the production line and placing it in boxes or trays for packaging. This step could be done after a line where the meat is cut. Here, the cutting of protein can be done either by factory workers or in an automated manner. What struck us here is that simply separating pieces of meat could save a lot of money on 3D vision and processing that would be required for the robot to pick individual pieces of meat. By the way, when we talk about pick-and-place applications, we’re talking about fast robots like Delta or Scara robots, and usually a production line with more than a few robots for a task.

Pick and package

Picking and packing protein could be similar to a pick and place application, but if pick and place is used to align pieces or transfer them from one conveyor to another, for example, pick and pack means having a tray, bag, or similar container in which to place chicken wings or sausages, for example. One application besides tray packing was to pack fried chicken wings in paper bags that were then dispensed and opened, another was to place sausages in fairly narrow containers. Be sure to investigate the space requirements for the grab-and-go operation. Some containers can be extremely narrow and the grippers should not be dipping deep inside to place the product. Instead, it’s a good idea to clear the gripper a few inches into the narrow package or even slightly above. Using a spacer between the gripper fingers will help with stability and alignment of protein goods, ensuring controlled release and placement in packing machines.

placing chicken breast into plastic crates

Sorting applications

Sorting isn’t just about making sure pieces are properly aligned for the next task or separating different cuts into multiple product streams. The simplest task we encountered was making sure the pieces were assembled into dishes of a certain weight. Protein, like pork cuts always varies in size and weight, but what the end customer sees is a packaged product of, say, 500 g! So the pieces of protein must weigh at least 500 g to ensure that the customer gets what he paid for. But the extra weight of the packaged goods is something that could have been distributed differently among the boxes. In this case, each piece of meat is weighed and given an ID. Pieces that meet the required packaging weight are put together by robotic fingers in the primary packaging process. This ensures efficient product distribution.

Protein gripper as part of an actuator

End-of-arm tooling is not just gripping alone. Often, grippers and other tools work together in a single application. Imagine automated cutting of meat with unevenly distributed weight, such as in automated poultry cutting and handling applications. Here, gripping the meat or the bones, or even where the gripper grips the chicken, makes a big difference in the end result. Using grippers that conform to the shape is the key to a good cut. Ask about custom solutions, our engineers are happy to work with you to implement custom tooling into the grippers.

Multistep product preparation

There are some tasks where meat meets other products, such as the preparation of sandwiches, burgers or whole meals. Preparing a burger in fast food restaurants requires a good and flexible grip. You probably know robots that prepare meals in a showcase? Such a case is discussed in our application examples below.

Primary packaging lines vs secondary packaging lines

Primary packaging differs significantly from secondary packaging. First of all, primary packaging lines have the unpleasant side effect of direct food contact between the product and the robot gripper. As we mentioned earlier, SoftGrippers are up to the task and perform well in this type of environment, provided cleaning cycles are in compliance. Secondary packaging is much less demanding on the equipment used, as direct food contact is often not required. For example, when vacuum-sealed packages are placed in cartons, there is no direct food contact. But in this case, the structure and feel of the object change and must be taken into account. This can make packaging more difficult because the places where the fingers will grip are not obvious, especially with raw products that tend to bend out of shape. But when packaging frozen meat, this makes it even easier to automate. Remember that SoftGripping fingers can also be used on frozen surfaces, as long as cycle times and the environment do not lead to complete icing.
picking chicken drumsticks for primary packaging

Robotic protein gripping with softgripping, what to look for?

To make a long story short: Soft finger gripping solutions are all about hygienic design and a good fit around the product. This means the right number of jaws, the right positioning of the robot fingers, angles that are important for a wide product size distribution, and of course the right robot flange, which can vary depending on the robot you want to use in your automation system.
Pneumatics are also important. We discussed that the air supply does not have to create contact, so look for a controller that is placed outside the body and pneumatic lines that run a relatively short distance from the gripper to make the gripping process as fast as possible. For us, it is important that you meet the pressure specifications for the robot’s fingers. The easiest way to do this is to use our pneumatic controller and set the pressure to the desired value. As long as you do not exceed the maximum pressure, everything is fine, but not every application requires the full pressure. This must be decided on a case by case basis. Too high a pressure could be too hard on the product, while a minimum pressure needs to be achieved to give the product a good grip. There is usually a pressure range to work with, depending on the spacers or other tools used.
hygienic design in sausage handling

Our Examples for robotic protein handling and protein packaging machines

We have discussed many rather general use cases and cannot present them all in a short article, but we can pick out a few examples that our engineers feel adequately represent the range of applications. Many of these applications relate to chicken parts as a prominent example, but tasks such as food chain attraction will also find their way onto this list (although right now this is 3 to 10 years away before it makes its way into every fast food chain you know).

Chicken drumsticks

Let’s start with one of the most well-known applications in automated protein processing: picking up and placing chicken legs. At first glance it seems simple, but for conventional grippers the asymmetry and chicken skin would cause many problems. Gripping around the meat is important here to maintain balance. A slight tendency to grip near the center mass can help with stabilization. Most importantly, pressure on the fingers must be adjusted to ensure the chicken skin stays in place during the pick-and-place cycle. What makes the task easier compared to other cuts of protein is the bone inside the leg, where the gripper can hold the piece of protein well.

chicken drumstick gripper

Recommended gripper setup for robotic chicken drumstick handling

Due to the uneven weight distribution of the chicken leg and the iregular product shape, we recommend a longer, parallel gripper, in some cases with frontal fingers for stabilization. Size and weight distribution are not a problem, but skin movement is a challenge for process standardization. Therefore, we recommend more than 4 fingers to maximize surface contact with a low air pressure of 0.7 bar on the fingers themselves. Optimally, a gripper that is just wide enough to grip the chicken drumstick without touching and moving the skin when the robot arm is lowered to start the gripping process. It is best to lower the robot arm as low as possible so that the fingers can grip the underside of the chicken leg.

Automated handling of filets and tenderloins

We have chosen the chicken breast fillet as a good example of meat cuts to be processed automatically. Of course, the results may vary depending on the tenderness of the protein and the shape of the cut and thus the weight distribution in the piece. These are important parameters when switching from chicken to beef or pork. In the present case, rather large pieces with a good height are handled so that a human or robotic hand can easily pick them up. Flatter and wider pieces, on the other hand, are more difficult to handle. Here, up to a certain size, it can be useful to press the pieces against a spacer instead of letting them slide into the gripper fingers. In addition to the size of the pieces and the cooling condition, you should also take a close look at the marinade used.

Recommended gripper setup for handling filets

For long pieces of tenderloin, we recommend a parallel gripper with fingers distributed to fit your largest piece of tenderloin. In our example, an 8-finger parallel gripper was used with the fingers evenly spaced to minimize sagging. A slight 10° angle between the fingers allowed for gripping a wider range of fillets. In this way, a natural variation from 30 mm to 130 mm wide fillets could be handled at high speed. A pressure of ~0.8 bar was sufficient to provide a good grip on 400 g pieces with a minimum height of 40 mm. Slightly lower pressure was required for thinner pieces to minimize curl. A slight angle in the finger position also means that the space required is less than if the fingers have to be splayed when gripping and releasing.

Robotic meatball handling

The video shows a case study with meatballs made from raw dough. The behavior is usually similar, with only a slight shift toward the size of the ground meat in question. Too much pressure and they crumble. Too little pressure? They don’t grip well anymore. Trying out the right conditions was a good test for our grippers and a good step forward for our partners.

Recommended robotic setup for meatball handling

Meatballs come in different varieties: with pure meat, with a high proportion of dough, or in some cases even with rice as the base. In our video example, we have chosen a dough ball to simulate the meatball so that you can get an idea of what the process looks like. In this case, a centric gripper with 0.6 bar pressure and 6 fingers is good for sizes 50 mm or larger in diameter. For smaller sizes, a centric SoftGripper with 4 fingers is best. According to our findings, weight does not matter, but rather the structure of the meatball. Remember that handling dough and meatballs is easier when the product in question is still frozen or has a cooling temperature of about 6 °C. Then the meatballs and dough balls are firm and the gripping process is easier to automate. Lower temperatures are common in food packing and especially in meat packaging solutions.

Sausage primary packaging machines

Long, but rather light sausages need a gentile grip and fixation at at least two points to of contact to prevent twisting and to make sure the packing equipment places them straight lines for lower space requirements in plastic packaging.

The perfect gripper for handling sausages

Our findings show that a parallel 4 finger gripper is enough to handle sausages of several lengths. 0.7 bar of pressure ensure a good grip while a spacer can be used to enhance process stability. As for the grippers angle, 0° is a good choice since product variety is not present and pick and package solutions profit from precision in placing sausages into the package.

Cobot burger preparation

This is perhaps the most prominent example of automation on social media: a robot preparing an entire meal. Be it a fast food meal or something more sophisticated. In this case, the gripper must be able to handle several types of completely different products: from a bun to meat to a rather oddly shaped lettuce leaf and back to the bun. That’s a lot of variety to take into account. This leads to three possible approaches:
burger making robot picking bun

Recommended automated setup for preparing burgers

In our setup, we chose a 4-finger SoftGripper with a wide-angle gripper. In a cobot setup, it is not the speed that is crucial, but the ability to handle all objects with a single flexible gripper. By using a variable pneumatic controller, an individual pressure setting can be made for each item. While buns and patties require higher pressure, the same pressure would cause lettuce to crumble. Therefore, a light touch is sufficient to pick up the lettuce and place it on the bun.

Contact

We are happy to get in touch with you! Let’s have a quick talk and find out how to automate your application. Our engineers will validate your application and provide you with test material in form of videos pictures and whitepapers:

About the Author

sergey_stepanyuk

Sergey Stepanyuk

"It's getting harder and harder to find employees to sort protein in cold, sterile workrooms. It's time to get comfortable with robotic protein processing."

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