Electric vehicles (EVs) require more efficient manufacturing to meet increased demands and use of robotics and servo motors can help. See table on battery types, information on cell housing types.
Learning Objectives
- Understand electric vehicle battery types and cell housing types.
- Review the EV battery manufacturing process where automated motion controls can help.
- Learn how robotics and servo motors can accelerate EV battery manufacturing to accelerate the processing, including depalletizing, uncasing, loading and unloading, applying adhesive, welding, storage and picking.
EVÂ battery manufacturing insights
- After reviewing electric vehicle battery types and cell housing types, review the manufacturing process where automated motion controls can help.
- Robotics and servo motors can be applied to steps of EV battery manufacturing to accelerate the processing, including depalletizing, uncasing, loading and unloading, applying adhesive, welding, storage and picking.
Electric vehicle (EV) manufacturing is on the rise, and this has created a high demand for EV batteries. With the demand for these batteries increasing, a need to efficiently automate the manufacturing process of these batteries is paramount to achieve the demand required to supply the EV market. AC servo motors and robotics will be important in automating the manufacturing of these batteries.
Many different types of EVs are creating demand for batteries. Although electric automobiles are what first comes to mind, there is also increasing demand for batteries to electrify aircraft, motorcycles, recreational vehicles, agricultural tractors and residential lawn equipment. All these vehicles and equipment are using batteries, however, there are various kinds of battery technology being used depending on requirements. Below are some of the different battery technologies being used along with pros and cons of each.
Lithium-ion batteries are most used in portable consumer electronics and are the most popular choice for EVs and plug-in hybrids. Lead-acid batteries have the lowest cost of the three battery types above, however, their low power density makes them an unappealing solution for EVs. NiMH batteries offer a high energy density and have proven to be very durable. They are commonly used in Hybrid Electric Vehicles (HEVs), however, their high cost, comparably higher heat generation and self-discharge limit their uses in EVs. With Lithium-Ion being the most popular battery choice for EVs, the demand for Lithium-Ion batteries is increasing rapidly. There is a need to ramp up production of Lithium-Ion batteries for EVs.
EV batteries have three types of cell housings
There are three cell housing types used for EV batteries.
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Cylindrical cells have a cylindrical shape as the name states. These cells can be stacked in large quantities to create a battery pack that may contain hundreds or thousands of cylindrical cells.
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Prismatic cells are rectangular in shape and can be very efficiently stacked within a work envelope. One prismatic cell may contain the same amount of energy as hundreds of cylindrical cells.
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Pouch-type cells vary in design greatly and use a metal bag that is flexible allowing them to fit into small or unique shaped spaces.
All three technologies are used today by various EV manufacturers. EVs, however, require many of these cells to be able to generate enough power for the vehicle. Integrating these cells into viable battery packs requires a significant amount of labor that can be automated to yield the throughput required for large scale production. Multiple steps in the manufacturing process create opportunities for use of ac servos and robotics to automate the assembly of these battery packs.
Depalletizing with robotics
Battery cells are most likely to be delivered to the EV manufacturer as groups of cells in boxes that are stacked on a pallet. The first step for these cells to be able to enter the manufacturing process will be for them to be removed from the pallet and placed into the manufacturing line. This process is called depalletizing. One of the most effective ways to automate this process is with the use of a depalletizing robot. A robot offers a good balance of repeatability and flexibility to properly remove cases from the pallet and place them onto the conveyor. Pallets often shift, flex, or compress during shipment so a combination of machine vision and a robot is usually required to properly solve this application.
Uncasing EV battery cells with robots
Once on the conveyor line, the battery cells need to be removed from the cases that they were shipped in. Depending on the complexity of the cases and cells this may be handled with a 6-axis robot and/or a gantry solution that uses AC servo motors.
Unload/load into battery holder with robotics
Similar to the uncasing process the battery cells need to be moved into the battery holder or pack. This will be the final container that will hold the groups of cells that represent a single battery pack. This process can also be solved with ac servos or a 6-axis robot. If the manufacturing line needs to handle various types of products a robot may be the best solution due to its flexibility to be repurposed for new products. If the line will be dedicated for a small amount of products, a gantry solution using ac servos and mechanical actuators may offer a better combination of throughput and cost of ownership.
Robotics adhesive dispenser
Adhesives may be used in multiple parts in the battery assembly process. This may include using adhesives to bond the battery cells together or to the pack, adhering the battery cells to the cooling plate, and applying a sealing adhesive to connect the top cover to the bottom tray of the pack. Many adhesives can be applied with a 3 axis XYZ gantry that is coordinated with a servo-driven dispenser. Depending on the complexity of the dispensing pattern the controller may be best programmed using G-code.
Wire bonding, laser welding with robotics
Once the battery cells are properly nested in a pack, the cells need to be connected to each other electrically. A common process to do this is called wire bonding. Wiring bonding offers a flexible solution to connecting all the batteries in the pack. An automatic wire bonder may use multiple ac servos to rapidly travers from cell to cell. Another process that may be used to connect the cells together is called laser welding. In this process a stamped bus bar template is placed on top of the battery cells. Next, a laser welder fuses the cells to the bus bars with controlled burst from a laser. AC servos are often used to move the laser welder across the battery cells.
Battery pack storage and picking
Completed battery packs need to be removed from the manufacturing line. For large production lines, these packs may enter an automatic storage and picking system. These systems, which are used to store, sort and pick the battery packs when needed may be best automated with the use of a large 6-axis robot and a seventh axis linear positioner that can allow the robot to traverse the system from end to end. The robot’s ability to reach multiple locations, articulate the battery packs and place them to the desired location makes it an ideal solution for this application.
EV manufacturing and EV battery manufacturing are creating a lot of new automation opportunities as automobile manufacturers retool their assembly process to support electric vehicles. Many applications are similar or slight variations of processes that are seen in other industries. Solutions using ac servos and robotics will continue to play an important role in automating the applications that this new industry is creating.
Jeff Willis, is director, motions sales, Yaskawa America Inc. Edited by Mark T. Hoske, content manager, Control Engineering, CFE Media and Technology, [email protected].
KEYWORDS: EV battery automation, motion control, robotics
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