Audi developing modular assembly principle as successor to production line; Győr testing for 2018 e-tron electric motor production
Audi is developing a new modular assembly principle intended as the enabler of the post-production line assembly era. Modular assembly—intended to address the need for growing complexity and flexibility in production—breaks up the traditional fixed-rhythm production line into individual process steps.
In the latest issue of Audi Encounter, Fabian Rusitschka, managing partner of Ingolstadt-based startup arculus GmbH, Audi’s partner in developing this concept, noted that while the current A3/Q2 production line has around 160 process steps, modular assembly turns that into roughly 200 spatially distinct stations manned by one or two people. The processes each have different timing, and are flexible. Audi anticipates modular assembly will deliver productivity benefits of at least 20%. While development of the principle is ongoing, Audi has begun to use modular assembly in developing the production process for the electric motor for the 2018 e-tron SUV (C-BEV) (earlier post).
According to arculus, modular assembly offers a number of systemic benefits:
Every working station is an independent module. These can have a predetermined buffer, and even their own small supermarket for materials and components. Modules can go on- and off-line whenever needed, without affecting others; line dependency is no longer a restriction.
Each product makes its own process line, making a new decision of where to go next after every working station. This decision is made based on the Assembly Priority Chart (APC): a tree of dependency relations between all needed processes to complete a specific product.
Products must be as free to move as possible. Each one of them is carried across the shop floor on top of an automated guided vehicle (AGV), taking them only where needed and with the lowest waiting time, thus boosting efficiency. (For Audi, these are the driverless transport systems (DTS), which began testing at Ingolstadt in 2015. Earlier post. A central computer controls the DTS activity, albeit flexibly. If a DTS approaches a station that is still occupied, it is diverted to another open station.)
Modularity enables extreme flexibility and efficiency: ramp-ups for new models, implementation of new technologies, accommodating process failures.
At its Győr engine plant in Hungary, Audi is developing a possible future production process for the electric drive motor to be used in the 2018 C-BEV. (Győr is also the Audi Technology Center for Electric Drives.) In designing the process, the team is testing various production technologies and is configuring all the steps as they would be used in a future production scenario, according to Lórant Székely, Project Manager Production.
The Győr team is currently combining a conventional production line process for the production of the stator with final motor assembly being handled by the new principle of modular assembly, using both automatic as well as highly flexible manual stations, according to Dr. Jari Hyvönen, Head of Production Planning Electric Motors from Ingolstadt.
Although the original concept was to use conventional sequential assembly, that approach had a number of disadvantages, including a sub-optimal line rate; underutilization of the 29 stations; a larger space requirement; and longer routes to the parts supermarket.
The Győr team then opted to try modular assembly—the first implementation of with the Group. Modular assembly uses 19 island stations, some of which are used several times within the build process. DTS units carry the motors and their parts to the stations.
A Production Control System (PCS) determines the order in which the motors are built and generates a parts issue program. It distributes driving orders to the DTS and manages their routes.