Sheeting Systems for Bread Products Thank you and good afternoon. Low stress dough sheeting is the process of taking dough in mass and forming a continuous dough sheet. (Slide 2) The goal of this is to do as little damage as possible to the gluten structure of the dough so that you can retain as much gas as possible. So once you form your continuous dough sheet, it will be cut and then formed into products. (Slide 3) Most people do not realize how versatile a sheeting line can be. You can have everything from pan bread to ciabatta, having a variety of shapes and sizes. Most people tend to think of sheeting lines as being for artisan bread dough only, which is their general use right now. (Slide 4) We will define artisan dough just to talk about it for a minute, as being very wet and sticky, very difficult to handle or shape by hand. It is generally a very high absorption dough, 60 to 90% water. It has a long bulk ferment time anywhere from 30 minutes to two hours. Some people even go and retard the dough and hold it up for 16 hours before processing it. So it is a very wet, sticky dough. It is difficult to handle, but a sheeting line does it very well. (Slide 5) Let us talk about the sheeting process first. It is all going to start with a low stress sheeting head. Generally there is a hopper above it where the dough is dumped from the mixer or dough trough mixing bowl or dough trough into the hopper. Oftentimes it is chunked into smaller pieces before it enters into the sheeting section. If you are using a grain dough or a stiffer dough, you are pulling the dough down with your top rollers down into the lower rollers or a wetter dough, you are also using those same rollers to tend to hold the dough back because it is very liquid and wants to flow out onto its By Jim Bruce own. But the goal is to bring the dough down through the rollers forming a thick, narrow dough sheet and bring it onto the conveyor bed. (Slide 6) Flour dusters are used throughout the processing method. You need flour put on the conveyor so the dough does not stick to the conveyor and on top of the dough so you can manage through the various rollers and reduction stations. (Slide 7) The first part of reducing the dough is usually a quick reducer. It is also called the satellite head or multi-roller in the industry. You have a central shaft with several small rollers around it. These rollers are going at a very high speed and I am sorry my animation for Jim Bruce is the Midwest Regional Sales Manager for Rademaker USA. Jim graduated with a degree from the University of Central Missouri. He is a 16-year veteran of the baking industry with the last ten years in the sheeting and laminating equipment side. Page 122
some reason does not work on some of the slides. You have several small rollers going very fast. The intent is to act like the small rollers would be a rolling pin going across the dough, very high speed. (Slide 8) You are going to make a big reduction step. Here it is saying 100 meters down to 10 millimeters with is a ten to one reduction step, although for bread you are generally not going to get nearly that kind of a reduction step. It is going to be more in the range of five to one. So if you come out of your sheeting head at 40 millimeters or an inch and a half, you are going to bring it down to about 8 mm after your quick reducer. You are sheeting against a bottom roller. You have the hard surface that you are sheeting against and again it comes down onto the conveyor bed for the next step. That next step is a cross roller. (Slide 9) When you look at a sheeting line, it is a linear function so all of your sheeting process is going in one direction. What we do at the cross-roller is two things. One, we are able to set the width of the dough sheet and we are able to put a little tension to the dough in this direction so that we are stretching the gluten. Instead of just always going in one direction, this is our chance to put a little tension or stress going in the opposite direction. The benefit of that is you tend to take some of that tension and put it out on the sides and get a more relaxed dough sheet. (Slide 10) The final part is the gauging station and we are not really making a big reduction step here, but what we are doing is we are making sure that the dough sheet is smooth and even across the entire sheet. This will give us better weight control and better product forming. A lot of bakers tell me that between the reduction steps they like to see about 1-2 meters of space, so between your sheeting head and your quick reducer and between your quick reducer and cross roller and so on, they like to see 1-2 meters because they feel the dough relaxes in-between those steps, that it tends to take some of the buckiness out of the dough. (Slide 11) Now that we have a dough sheet at a predetermined thickness and width, it is time to put it onto the make-up table. The first thing we are going to do at the make-up section is we are going to take off any of the excess flour dust that may still be on the dough sheet. This is done for a couple of reasons. The first is, if you are putting it into a refill package and you Sheeting Systems have flour that is not absorbed into the dough, a lot of consumers tend to think that that looks like a moldy product so it does not have a very good eye appeal. The next thing is if you are going to do a molded product say a baguette, the excess flour will cause you to have to work the dough harder to form your baguette and that just destroys all the work you have done up front by having a gentle process in the beginning. So we are able to take the flour dust off, take it to the side and you can do this both on the top of the dough sheet and the bottom of the dough sheet and remove all your flour dust. (Slide 12) Now that we have a dough sheet, we are going to determine what kind of product it is going to be made into and at this time we are going to cut the dough sheet either into one strip or into multiple strips. Since the dough tends to be wet and sticky, we are using rotary knives as the diagram above to cut through that and the rotary knives are often driven so that instead of forcing the soft dough through the knives, we are driving the knives back through it and again not damaging the structure of that dough. But because the dough is wet and sticky it tends to want to grow back together as soon as it is cut, so a lot of times there will be a beveled plastic edge around the knife to pull the top of the dough sheet down over that cut wet edge and that way it inhibits the dough from sticking back together after the cutting process. An interesting thing is if you take let us say, for example, a ciabatta, and you have the exact same process throughout everything, that you seal the edge on one of them and do not seal it on the other, you let that edge be wet, then you will have a very different looking product. The product that you leave with the wet edge will have a more rustical or artisan type appearance. (Slide 13, 14) After we cut it into strips, we determine what size our strips are going to be and how many strips they are going to be. The next we have to do is we spread it. We want to spread immediately after the cutting. Again, this is to inhibit the dough from growing back together or sticking back together. We are going to spread it into lanes and the lanes are going to be set so that that will be our pattern that the product will go to onto the baking pan or the peel board later on. So we are determining our product size and we are also setting our pan pattern at this point. Page 123
(Slide 15,16) With any sheeted system you are going to have some side trim or side scrap and there are benefits to having this. The benefits are often when we are forming the dough sheet, you get somewhat of a ragged edge on it and so we are able to take the side trim off here, makes the edges very even and uniform so that your dough strips are the same width, but also if there is any tension still in the dough sheet that is not alleviated during the cross roller, we can simply cut it off here and take it off to the side of the line. It also gives us better weight control and you do not get the snapback or the shrinkage on the side if you have any tension. One thing that most bakers are transitioning from a more traditional method of producing bread to a sheeted method, this is the point that sticks with them. But just remember, your equipment vendor should be able to help you reformulate your process so that he can account for that scrap dough and take it back into the mixer and reintroduce. And common scrap percents are anywhere from 6 to 8%, 10% occasionally. (Slide 17) At this point we have our strips of dough either one or multiple lanes of dough and we are able to, if we need to, is to run it across a checkweigher. Especially with your very gassy dough, your artisan type dough, we work very hard to retain gas pockets in the dough and so the density may change from this point to this point just because of where you have gas pockets in the dough. What we have is a roller here that is underneath the belt. We are taking the dough across it. It is constantly weighing that dough sheet and feeding that information back to the PLC. From there the PLC then tells your guillotine where it should make a cutting stroke to get the weight that you have input. So in this case we have six rows, we were trying to do 80 gram pieces, we would have put in 480 grams as your target weight and once the checkweigher registered back, it would feed to the guillotine to make a stroke allowing for the time that it takes the dough to travel from here to here. The one issue with that is if you have six rows, it is taking an average of those six rows. Now you may have a larger gas bubble in this one and not so much here just because it is going to happen when you are doing general reduction steps that you are not able to predict where your gas pockets are, so this product may be light while this one may be heavy. If you are running a grain dough or a dough that is more consistent in density, you may not need a weighing module at all. It is something you should discuss with your equipment manufacturer and also do plenty of testing both with their line and with their weighing module to determine if this is something you want to do, But if you are taking products into the retail market, especially artisan-type products, then a checkweigher is usually a must. (Slide 18) The next step is we are going to cut our dough strips into a predetermined length and that is either done with the guillotine or it can be done with the rotary knife as well. I am sure you are pretty much familiar with the guillotine, but it is a straight up and down cutting motion that you could input the parameters or the length that you want your product cut. (Slide 19) Now we are into determining the product shape. From here we can mold it into baguettes or boules. We can put on toppings and seedings. We can let it pass through and go directly onto the peel board. Most of the products that are molded on a sheeting line are your baguette-type products, but we can also do round molded products as well. We will talk about the molded products first. You are going to cut your dough strips into rectangular or square pieces and then you are going to run those under a drag chain to coil them up and then under the molding board. The molding board can be static, it can be driven to go in the same direction as conveyor belt underneath or it can go in the opposite direction, depending on how much work you want to put into that dough, how much of the gas you want to take out of that product. (Slide 20) This is an example of the product coming out after molding. It is a baguette-type product. You can see the ends have been rounded by these side guides. The side guides also keep the dough from going out too far and making sure you have the correct length on the stick. Then we have a mat here that keeps the product straight as it comes out and it also helps to keep the distance between the products uniform. You can also do round products with the sheeting line. The beginning steps are the same. You are going to cut your dough into a rectangle or a square piece and you are going to advance the pieces into the molding head. Page 124
Sheeting Systems The best way to describe this is it is like a Derby style molder where you have the cups come down over the dough pieces, they rub the corners of the piece and then they round and you can make either bigger or smaller revolutions and control the number of revolutions that you do with your rounder. It generally travels with the belt so it is rounding and then it comes back to pick up the next row or rows of product to mold. (Slide 21) This is typically done for smaller pieces of let us say less than a pound and if you are going to do round products more than a pound, it is typical in the industry to take those pieces off, run them through a conical rounder and then re-introduce them back on the line manually or automatically. (Slide 22) Seeding and topping is very common especially with artisan breads. You can do seeds, salt, dried herbs, a lot of different things, dried cheeses as well and there are different ways to do this. Here is an example of a molded product that has been seeded afterwards and it appears that they molded the product, ran it through a bath and then rolled the product through a bed of seeds so that it is encrusted all the way around the product. But you can also target spray or water mist onto the product and then drop the seeds on. The issue there is your seeds are going to be wet for those that do not adhere to the product. You have to take those off and dry them before reintroducing them back into the seeder or strewer. (Slide 23) Somewhat new in the industry is to do what we call roller moistening and that is instead of spraying the water, we are going to put water onto a roller and then either run the dough underneath that roller so just the top of the dough is wet, or run it over the roller so that we can put seeds in the bottom. The nice thing about this is any seeds that do not adhere to the product are not wet so they can be reclaimed and recycled immediately back to the strewer. There you see an example of some seeds on the bottom. The next step is we have now formed our products into either rectangular products like this or baguettes or whatever and we are going to load them onto a pan or a peel board. They may at this point also go straight into an oven or straight to a freezer. (Slide 24) At that point you would have two knife edge rollers come together so that you do not distort the product as they go over that transfer point. But here you can see the space that was set by the spreading belts. Here the space has been created by having a conveyor immediately after the guillotine so as they are cut, this belt is running slightly faster to give them space or create that separation. (Slide 25) A couple of different ways that you can put products onto a pan or board. Maybe the most common is a retracting belt where you allow the products to go to the end of the conveyor and you simply pull back and let the products drop into a pattern onto the pan or the board. You can also do that with a servo driven retractor where you are dropping one piece at a time across the board and then starting back at position one. Especially for molded products, it is typical that you will have a maligning gate or some way to make sure that the products are both straight and in a consistent distance between the products before they are retracted. A lot of companies also use a clamshell device where you take the products at the end, you drop them into the clamshell and then the clamshell places them onto the board. (Slide 27) Another method is to use an under-running conveyor. In this instance you would have your exit conveyor with the product. You would bring a conveyor underneath it with the board or the pan. They would be running at the same speed. Generally, the nose of your exit conveyor is tipped down so that there is minimal falling height between the board and the exit conveyor. (Slide 28) The products would simply merge onto the board and be kept at the predetermined distance that you had made by the guillotine, and then you get a slight jump to go from one board to the next so that you are back in the starting position for the subsequent board. I like this method because especially if you have small products or you have molded products, the retracting motion tends to make them maybe want to move or shift out of position or for a molded product to roll, but with this method it is a lot more gentle and you get a better pattern on the board. (Slide 29) Finally, let us talk a little bit about the controls. You can have analog controls where you basically set your belt speeds at the potentiometer and do your roller gap adjustments with a hand crank. You can also go do a PLC where all of this is inputted before the product is made. You can have a memory with 30 programs and that can control all of the belt speeds on the line. It can Page 125
control the roller gaps; it can control the flour dusters, the amount of flour dust that you are putting on, so it makes it very quick and easy to go from product 1 to product 5. It is basically the tough of a button and changing out some tooling parts, but you can get very rapid changeover times. Also, when you are operating with a touch thing or a PLC, you generally have one person operating a line and that line can be anywhere from 1000 pounds per hour up to 12,000 pounds per hour, all managed by one operator. (Slide 30-40) The benefits of having a sheeting line is the flexibility, the ability to run a wide variety of doughs, create a lot of different shapes and sizes, high throughput, flexibility in developing new products, a high degree of automation and quick and easy product changeovers. (Slide 41) Now, I would like to open it up for questions if there are any. GEORGE POULOS: Bartlett, IL. How long generally are those lines? JIM BRUCE: You can have a line that is 40 feet long or you can have a line that is 120 feet long. It all depends how many products you want to make on it. If you add a check-layer and some different components, minimum I would say is probably 40 feet, but you can get up 100 feet or more. GEORGE POULOS: Is there a way to run those in nonlinear? JIM BRUCE: It depends on the dough. Generally if you are running a very soft dough, you do not want to make a 90-degree turn with those. I have seen instances where they stack, where you have the first sheeting part on an overhead and then you bring the dough sheet down on the make-up, so there are interesting ways to do that. Most of the lines you will see are all linear. Thank you. GEORGE POULOS: How did you do the round rolls? The round rolls. JIM BRUCE: That is the part that is like a Derby-style rounder so we have a square piece of dough that we have cut both with our strip cutters and with our guillotine and we have a cup that comes over that and this makes a circular motion. It pulls the dough inside and forms it into a round piece. GEORGE POULOS: There is no scrap with that? JIM BRUCE: Your scrap would come earlier. Like I said, you are always going to have a little bit of side trim just to get back...just to get your dough edges even and to get a little bit of that tension out of the dough. GEORGE POULOS: You did not mention tension control or anything like that. What percentages of your lines have automatic tension control? Do all of them have it now? JIM BRUCE: Different companies have different ways of doing that. You have either a mechanical or a photo eye that tells you when the dough is maybe coming too fast through one of your sheeting sections or too slow. If it is coming too slow, you may get some pulling of the dough sheet too fast and you are going to get overfeeding, but, yes, that is pretty common on lines. DON KINDSTRAND: Don Kindstrand, Naperville. I have a question in relation to feet per minute: how fast can the lines run? JIM BRUCE: It is kind of product-dependent. If you are running more of a flat bread or just a cut product, your speeds can be, really whatever you want. Typically I would say you are not...these are not really high-speed lines in terms of running feet per minute. You could get up to let us say 60 feet per minute, but that is very atypical. Generally these lines are running more at like 10 feet a minute. The focus is really on maintaining the integrity of the dough structure so...but you can run lines faster. It is product dependent and I am sorry, but I am going to say that a lot. It is just the way it is. DON KINDSTRAND: Would you have a line that is more diversified that would run like pizza crust as well as bread and rolls or are they product specific? JIM BRUCE: No, you could do a pizza crust on a bread line as well. The flexibility is there to do just about any product, any yeast product on a line like that. Page 126
Sheeting Systems DON KINDSTRAND: Jim, just to be clear, scrap. How is that handled, all manual or can that be automated? JIM BRUCE: It can be manual or it can be automated. You can take it off to the side and put it in a bin and weighed manually or it can be taken back to the mixer, to a load cell where it is weighed and then released into the mixer. It is all money however you want to do it. Money upfront or money behind, however you want to do it. DON KINDSTRAND: Can you do die cutting? JIM BRUCE: Yes, you can do die cutting. So you could cut out different shapes: triangles, hexagons, a lot of different shapes as well. DON KINDSTRAND: Jim, the cross roller. Like how much can you stretch the dough crosswise? You talked about reduction ratios on the gauge rollers. Is there a rule of thumb by how much you can stretch the dough sideways? JIM BRUCE: Well, what I have seen is it is generally you can get about 40% maximum, so if you have a dough sheet that is 600 millimeters wide before it goes through the cross roller you may get that out another 40% wider before you really start doing damage to the dough. There are also companies with what they call spiral cross rollers or cross relaxers. So instead of working across the top of the dough, if you are going to run softer doughs, you have a typical roller on top and then you have a profiled roller underneath that tends to work the dough from the middle to the ends. It is kind of like a baker taking a piece of dough and doing this with his hands to get it spread out. That is another method, but again the increase is about 40%. Another thing I wanted to add to that is when you cross roll you have some down line issues you have to pay attention to in regards to shrinkage. You start with a narrow sheet and try to work it out too far the closer you get to a width issue, the more you are working with. You are not trying to control the shrinkage of the cut now in all directions. PAT WILKENS: Very good. Jim, thank you very much. JIM BRUCE: Thank you Page 127
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