The electrification of vehicles is taking the world by storm. Nearly every OEM has multiple all-electric models announced and some have even announced plans to end production of traditional fuel powered vehicles. This presents both challenges and opportunities for the companies involved in manufacturing these new vehicles:
1. Much of an electric drivetrain is completely new and different than an ICE (internal combustion engine) drivetrain
2. Battery energy storage makes up significantly more total value of a vehicle than any system on an ICE vehicle
3. Supply chains for EV’s are dominated by completely different and sometimes new companies as compared to ICE vehicles
4. Battery technologies are rapidly changing and are not likely to stabilize for many years
5. Battery cells and even modules are needed in much higher volumes than significant components of ICE vehicles, especially considering modules can be used across platforms no matter the vehicle size
6. Several unrelated processes are involved in battery module assembly:
- a. Laser welding
- b. Ultrasonic welding
- c. Riveting
- d. Adhesive tape component assembly
- e. Resistance welding
- f. Connector termination and assembly
- g. SMT electrical component assembly
Cells normally have dedicated high volume fully automated production lines but modules are more application specific and therefore a lot of discretion is used in production design. Equipment used in module production is normally performing standard processes and even though high-volume battery module production is new the process requirements have been around in industry for many years. For instance, a BMS circuit, no matter the substrate, uses quite standard surface mount technology or surface mount device assembly equipment used and refined for decades. Same holds true for almost all other processes involved in module manufacturing.
Production Decisions: Batch Vs. One-Piece Flow
One-piece flow is ideal, but the more processes that must be performed in any given assembly the less ideal this approach becomes. The primary motives promoting one-piece flow are (1) WIP reduction, and (2) lowering the risk of adding value to scrap. Both of these can be mitigated if there are other strong drivers to utilize batch flow. An example is when standard machines for a given process either don’t meet or greatly exceed the needed throughput. With one-piece flow in either case you end up with low equipment utilization. Another example is when a machine can be tooled to perform operations on two or more assemblies simultaneously while still meeting all requirements. The additional throughput is almost free.
There are two basic types of machine for a given job: (1) A standard machine that may get some custom tooling to perform a job; and (2) A completely custom machine designed and built for a specific job. There is a long list of reasons to favor standard machines. Here are some highlights:
1. Reusability—sometimes a machine can even be utilized to produce multiple products without changeover
2. Time investment in creating user requirement specifications from scratch
3. Benefits of machine refinement over time and application experience
4. Lower cost and availability of advanced business models like system as a service
5. More available service experts and more advanced service documentation
One-piece flow is almost always handled one of two ways: (1) by conveyor, or (2) by manual hand-off. Batch flow requires some planning from a material handling perspective to achieve success. The main consideration is the size and form factor of the typical assembly to be handled. Naturally a reasonable estimate of the largest potential assembly needs to be considered when wanting to build a flexible factory. Trays, cassettes, conveyors, index tables, shuttles, pallets, are all possible material handling options. Before choosing a method, an evaluation must be done based on all potential processes involved, and the capability of the best in class providers of equipment for each of the processes. It is often appropriate to model a few different methods before deciding and even run simulations with different inputs like ramping up and down capacities as well as what if scenarios like adding other stations or processes.
Given the size of the opportunity, EV battery manufacturing is set to be the most transformative industry in decades. Those who make the best decisions and build the most flexible factories are bound to reap the biggest rewards. Engaging the experts in each critical process, and better yet doing so during product design, will insure success.