Palletizers, sometimes called “case pickers,” are machines specifically designed to load and unload pallets before and after shipping and during storage. More often than not, distribution and manufacturing plants use automated and robotic palletizers, rather than manual ones, for loading and unloading. Automatic and robotic palletizers have many qualities that elevate them above manual palletizers, such load stability, precision, operation speed and fewer associated worker injuries. In addition to taking away injury risk by repeatedly lifting, rotating and wrenching packages on their own, many varieties come equipped with QuickSTOP collision sensors and Smartscan work cell perimeter guards. These measures not only increase safety, but boost productivity. They may deal with a variety of products, or may be designed to work with only one, as is the case with drum palletizers, bottle palletizers and case palletizers. Some large-scale centers also use depallatizers to unload packages, as well as equipment accessories like pallet dispensers, which are devices that dispense or feed empty pallets to conveyors, and load transfer stations, which are systems set up to transfer loads from one pallet to another without disassembling.
Palletizers are divided into three main groups: the aforementioned robotic palletizers, low level palletizer and high level palletizers. Robotic palletizers, which are automatic or semi-automatic, usually stand between a pallet dispenser and a conveyor line that carries incoming products. The products are lifted and neatly organized onto a pallet by a hydraulic robotic arm, attached to suction cup arms or flat pincer arms. Robotic palletizers can handle both heavy and very fragile objects, and can be altered to accommodate different products, like pails, bags, cases and bottles. In cases like these, robotic palletizers may be renamed after the product they load and unload. So, you may also hear the above referred to pail palletizers, bag palletizers, case palletizers and bottle palletizers, respectively. Read More…
While robotic palletizers can only lift one item at a time, they are still much faster than their human counterparts, and they do not carry risks of fatigue or injury. Other robotic palletizers include articulated arm palletizers, selective compliant articulated robot arm (SCARA) palletizers and gantry palletizers. Featuring a jointed arm, articulated arm palletizers have a greater range of motion and flexibility for positioning than other robotic palletizers. Similarly, SCARA palletizers position products using a mast and cross arm. Gantry palletizers have capabilities that are enhanced by the addition of an I-beam or an overhead crane. Both low level and high level palletizers work with conveyors and a feed area that receives goods to be palletized. The difference between the two is that low level palletizers, also called floor-entry palletizers, load products from the ground level, while high level palletizers load products from above. In both cases, products and packages arrive on roller conveyors, where they are continuously transferred to and sorted on the pallets.
These palletizing processes may be automatic or semi-automatic, but either way, it is faster than the robotic palletizing process. Another group of palletizing systems are in-line palletizer systems, which are systems designed to stack complete layers of bags or cartons at one time. Row stripper palletizers, for example, are a type of in-line palletizer that organizes a row then pushes it to the side until another row forms. The palletizer will stack row on top of row like this until a pallet is complete. Another type of in-line palletizer is the vacuum-head unit. Vacuum head units grab and hold onto items not with pincers, but with air-powered suction cups.After pallets have been loaded, they may stay on-site, in which case they will be called “captive pallets,” or they may be taken elsewhere.
No matter the outcome, pallets must be moved by Mast-Equipped Automated Vehicles (AVGs). For safety reasons, an AVG operator must be highly trained. A thoughtfully selected, carefully installed and religiously maintained palletizer will bring productivity to new heights. It eliminates most human error, injury and disruption-fueled profit loss, while speeding up and streamlining the process in general. For example, a lower employee injury rate, in addition to being good for morale and reduced workplace health coverage costs like Worker’s Compensation, reduces the likelihood of fines from the United States Occupational Safety and Health Administration (OSHA). Though the purchase of a palletizer is a large initial investment, its many advantages compensate for the cost many times over.
What Affects the Speed of Palletizers?
Since the advent of the assembly line in manufacturing, the goal has been to make processes faster and more efficient. This also applies in packaging, and inventors have come with a myriad of palletizers to automate stacking and packaging, including conventional and robotic palletizers. Regardless of the type, palletizers can perform an array of tasks, ranging from metering products, orientation of the incoming load, putting loads in rows and in layers, and then transporting them forward.
In the manufacturing industry, palletizing systems have become necessary equipment. However, as there are a number of palletizers available on the market, choosing a palletizing system becomes a challenging and time consuming task. Many consumer help blogs and articles concentrate on a number of factors to consider, ranging from reliability, speed, packaging options, machine type, loading capacity and size. Although, the most important factor to consider is the speed, since it is what cuts the operation cost.
You may come across specifications saying speed, “up to 30 packages per minute” or something similar. This type of information is usually misdirecting, as there are a number of factors that decide the speed of a palletizer.
The product coming out of the manufacturing process in the palletizing industry is also called a case. The length of a case affects the speed a palletizer, as it influences how many cases can be put in a layer in a conventional palletizer. After every layer, the layer forming operation is interrupted, as the hoist moves and the layer is stripped. The interruption can take a toll on the speed of a palletizer. However, in new conventional palletizers, the steps, including layer forming operations, stripping, and hoisting, occur concurrently to help solve this issue. Although, these faster palletizers are expensive.
This problem is not inherent in robotic palletizers; however, the length of a case does affect speed in robotic design too, but for a different reason altogether. The time is lost in the movement of the arm; therefore, pattern in which cases will be layered is as important factor as the length of a case.
Product per Layer
In conventional palletizing machines, if fewer cases are put in a layer, the hoist movement slows down the speed of a palletizer. Similarly, if fewer layers are formed in a pallet, it also affects the speed, since the pallet has to be moved and an empty pallet has to replace the pallet. As an alternative to this problem, high-speed conventional palletizers are available.
The movement of cases in a conventional system relies on friction between the case and conveying system. The rule of thumb is the lighter a package, the probability that it will lead to jam increases. Even in robotic palletizers, weight influences the speed; however, the speed is hindered as the weight of the cases increases; robotic arms take more time to handle heavier cases when a vacuum cup is used to pick cases.
Therefore, to tell the speed of a palletizer, it is necessary that case length, cases per layer, cases per pallet and weight are determined beforehand, as they directly define he speed.