EPISODE 5: Game changer flat glass production logistics

Sarah: Hi and welcome back to Listen LiSEC, the podcast for everyone interested in glass processing! My name is Sarah Hummelsberger, I am a part of the LiSEC Marketing team, and with me in the podcast studio today is colleague Harald.

Harald: Hi everyone, nice to be here. I am Harald Miksch and I’m a product manager here at LiSEC.

Sarah: Nice to have you! Our podcast studio is located at our production site in Lower Austria. We are recording inside the Training Center, so there might be some machines moving in the background or operators being trained. But moving, specifically glass moving, already brings me to the topic of today’s podcast. You left me and our listeners last time with a cliff hanger: you claimed that Logistics is a game changer in flat glass processing. Today, you must tell me why that is.

Harald: Indeed! Logistics plays a large role in today’s global economy. Do you remember when the Evergiven got stuck in the Suez Canal? International supply chains got disrupted, delivery times went up, and it took ages for my coffee maker to arrive. The same is true for the logistics within an industrial company. Any disturbance of the material flow can bring the whole production to a grinding halt.

Sarah: So let’s get specific: What logistic systems are necessary to operate a flat glass production?

Harald: I’d categorize them into three distinct areas: Inbound logistics to get jumbo glass sheets into the warehouse, intralogistics to move materials through the production, and outbound logistics to move the final products to the customers.

Sarah: I think we already mentioned the special trucks transporting jumbo sheets from the glassworks to the factory. Can we take a closer look – what makes them different from regular trucks?

Harald: A regular truck transports goods on the truck bed. Those special trucks have a recess in the loading area instead, which accommodates a glass transport rack. The rack is not moved into the truck, the truck moves over the rack and lifts it into the loading area. Unloading works the same way. As you might expect, this only works when the glass is stacked vertically onto what’s called an L-rack or A-rack.

Sarah: This is the first time we mention types of racks today. Maybe that’s a good time to consider ways to store glass. Can you give us an overview?

Harald: Sure! It all depends on how you need to access the glass sheets. L-racks and A-racks both carry stacks of glass – L-racks only on one side, A-racks on both sides. These are easy to visualize – just think of the letter, that’s the profile of the rack. Then there are situations where you want to access every sheet of glass on the rack individually, regardless of the loading sequence – then you need harp carts, which offer a row of open slots. You can take out any glass pane at any given time.

Sarah: My guess is every type has a specific area of use.

Harald: Basically yes. In the glass warehouse jumbo sheets are loaded off the transport rack onto the warehouse racks, which are either L-racks or A racks – depending on how you can access them. Within the production you mainly use A-racks and harp-carts, and when it comes to the delivery, we’re back to A-racks. By the way, all of these store glass vertically. Only very few steps of the production happen with the glass sheets lying horizontally.

Sarah: Which steps are these?

Harald: Off the top of my head, mainly glass cutting, toughening and lamination.

Sarah: Interesting. Why is that?

Harald: Well, ideally, we would do all process steps vertically, because that would need the least amount of space, which is a scarce resource on the shopfloor. But wherever gravity works against us, we switch to horizontal processing.

Sarah: So we store jumbo sheets vertically, and for the next step, cutting, they need to be horizontal. How does that switch work?

Harald: You’re right, in the warehouse jumbo sheets are stored vertically. A feeding system, for example an overhead crane, picks up the topmost sheet and transports it vertically to a tilting table that then feeds it to the cutting table.

Sarah: I imagine after cutting the operator takes the glass panes off the table and stacks them on a rack, to be moved to the next machine.

Harald: Exactly, but this step is way more complicated than it seems. This is where logistics really comes into play. Logistics here means to have the right piece of glass at the right time in the right place. So the challenge is to place the glass panes in the right sequence on a rack that takes them to the right place.

Sarah: How does the operator know on which rack to place the glass, so it gets to the right machine?

Harald: This information is precalculated by a production planning system and displayed either on a printout or on monitors on the shopfloor. Once the glass is taken off the table, it is only identifiable by its position on the rack. Therefore, at this point, many productions put labels on the glass or laser in a barcode to keep it identifiable throughout the entire process. Loading and unloading unto racks may happen multiple times to a glass pane until it becomes a finished product ready for delivery.

Sarah: That’s quite a lot of manual steps, potentially heavy lifting, prone to mistakes or accidents… ?

Harald: Well, there are possibilities to automize! On the one hand, loading and unloading can be handled by robots. Humans get tired or distracted, while robots are great at repeating the same task in the same way over and over without getting bored or hurting their back.

Sarah: So you’ve automized brawn, what about brains?

Harald: There’s a technology that allows you to unlock a potential in the production that racks on their own can hardly ever reach. The solution is a buffer system that can store a certain amount of glass panes and reorganize them according to the next step. It can even react to changing priorities and bring forward panes needed more urgently, for example in case a glass breaks and needs to be remade. In principle a buffer is a big harp cart that is being loaded and unloaded automatically.

Sarah: So could we say that the buffer is the brains of the production?

Harald: In a way, yes! But at the same time, it is also the heart. Because the buffer coordinates the flow of the material and acts as the pacemaker for the entire production. It routes the glass from the warehouse to the cutting table, to various processing steps to the final A-rack, where the finished product waits for delivery.

Sarah: I have a feeling there’s logistics involved yet again.

Harald: You’d be right! The main goal of delivery logistics is to get the goods to the customer on time. Pretty straightforward until secondary goals come into play: You want your trucks to take the most efficient route, and you want to use the least number of trucks, but you don’t have infinite loading capacity on your trucks. And to make things even more complicated, you don’t only have to deliver full racks, but collect empty ones as well. This takes either a very experienced dispatch planner, or a very sophisticated software that supports the entire delivery process.

Sarah: I am beginning to see why you keep calling logistics a game changer. It seems if you’re able to improve on logistics, this can have a huge impact on the entire production. Can you give us a glimpse of the logistics of tomorrow? Where are we headed?

Harald: Let me think about that. I see major developments taking place in three areas: the warehouse, the production and the outbound logistics.

Sarah: So what’s new in the warehouse?

Harald: A major challenge in the warehouse is the speed with which stock plates can be transported to the cutting table. The issue compounds when your warehouse feeds multiple cutting tables. To shorten the distances whole racks are transported over to the cutting table and unloaded continuously by a shuttle. The racks only need to be changed when a different glass type is required. This makes the most sense if the cutting optimisation extends over multiple stock sheets. You get the most out of this solution if you combine it with a compactor storage system, which is structured almost like an accordion. This means it compacts the racks to the least amount of space and expands only at the slot where you need to remove the next L-rack.

Sarah: That solution sounds quite ingenious. What about the production?

Harald: In the production the main focus is removing manual glass handling, like loading and unloading, with robots, and rack handling with automated guided vehicles. When it comes to robots, the challenge lies in serving more than one machine and more than one rack at the same time. To allow for multiple racks they are put on carousels, making them rotatable. This way, racks can be switched out once empty without interrupting the process. Meanwhile, the racks are towed through the production by self-driving vehicles.

Sarah: That sounds quite futuristic, almost like a lights-out-production. Last, what about outbound logistics?

Harald: Well, I said outbound logistics, but it’s actually more than that – the whole production planning is determined by outbound logistics. Right now, many productions follow the push principle. The goal is to produce as much as possible on a single day with the machines at hand. This leads to overproduction on a single day and a large amount of finished goods standing around waiting for shipment. The new approach follows the pull principle: daily production is determined by the exact that need to be ready for delivery on the next day. That reduces the finished goods warehouse and frees up space in the production for more better use.

Sounds like logistics can really give you an edge. Which lead us seamlessly to the topic of our next podcast: Edge seaming. Among other types of edge processing. For today, thanks so much for your insights.

Harald: Thanks for having me.