Dürr's EcoInCure paint shop oven employs a novel "inside-out" heating process with more-uniform temperatures ideal for mixed-material structures. (Dürr)
Dürr builds advanced paint shop for EV startup Byton
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China-based automotive startup Byton, fresh from beguiling attendees of the recent Los Angeles auto show and the subsequent CES at the start of 2019, confirmed it intends to begin manufacturing its M-byte battery-electric crossover at its assembly plant in Nanjing late this year. Standing behind its pledge to break new ground in many aspects of automotive development and manufacturing, Byton commissioned German automotive manufacturing specialist Dürr to outfit the Nanjing site with a state-of-the-art paint shop.
The payoff is big: Dürr said its full “ECO+” layout reduces the physical footprint of the paint shop area by 20%, as well as delivers throughput and cost reductions.
Byton—the brand name of China’s Future Mobility Corporation (FMC)—intends to initialize the Nanjing plant with a 150,000-vehicle annual output, which equates to roughly 30 vehicles per hour. Dürr’s new paint shop can handle the doubling of plant capacity Byton envisions.
Ideal for EVs
The central new feature of Dürr’s advanced paint shop for Byton is the EcoInCure oven, which Dürr said “is ideal for electric vehicles” because it provides more uniform drying of the painted vehicle body.
The EcoInCure system cleverly heats the body from the inside out, using a pair of high-velocity nozzles directing drying airflow through the windshield opening and another two nozzles forcing air through the engine compartment area. Dürr said the new oven concept is ideal for electric vehicles that typically seek to optimize overall vehicle weight with mixed-material structures, as EcoInCure “goes hand-in-hand with modified body concepts that use new materials or combine materials in new ways.
“Conventional ovens reach their limits when steel, aluminum and composite materials are used together, the company said in a release. But Dürr told Automotive Engineering that the new Eco InPure oven’s unprecedented uniformity for heating and cooling means the maximum temperature differential “is reduced by approximately 50%. This leads to a reduction in heat-up and cooling time or to a reduction of ‘tension’ for vehicles with mixed-material body structure.”
The EcoInPure oven design is largely what contributes to the claimed 20% reduction in the total area required for the paint shop—mainly because the oven transports bodies transversely, halving its required length, Dürr said, and also shortening the external conveyors. Also contributing is a central high-bay “warehouse” that saves the space typically needed for multiple intermediate buffers, bringing improved efficiency to material flow control. All this makes the paint-shop building smaller; a physically smaller building is mostly what creates a cost-saving compared to conventional layouts.
Meanwhile, shorter throughput times and higher-quality paint finish also come from the EcoInPure design.
“The reduced footprint of our ECO+ layout is the result of the use of our high-bay storage concept in combination with our EcoInCure ovens; this leads consequently to a reduced throughput time because it shortens the lengths of the external conveyor connections and reduces the number of elevators,” a Dürr source told Automotive Engineering.
And because of the heat-uniformity of the inside-out heating process, paint quality is enhanced because of reduced thermal stresses.
“Compared with conventional ovens, there is “a significant improvement in top-coat quality and process performance, because heating from the inside out reduces the risk of pinholing,” the company said in a release. “In addition, minimized flow velocities along the freshly-painted surfaces ensure a completely undisrupted top-coat appearance.”
To now, Dürr said, high bay storage and the EcoInCure oven design “have been used in several other projects, but not in combination.” The company has implemented gigh-bay storages in the latest BMW paint shops (BMW-Mexico, BBA-Tiexi, BBA-Dadong) and for several other customers, while EcoInCure ovens have been installed at the manufacturing facility of startup VinFast in Vietnam and for Skoda in the Czech Republic.
Better dipping and coating
Dürr’s scope of delivery for Byton’s Nanjing paint shop also includes the company’s RoDip rotational dip process for pretreatment and electrocoating, which at the Byton paint shop already is installed to accommodate a 60-units-per-hour line speed. And Dürr also handles the robotic and application technology for the sealing and painting processes.
For the Byton paint shop, Dürr also delivers an energy-efficient and failsafe electrocoating stage called EcoDC MACS. The technology employs modular anode control to create a voltage profile in the tank that moves with the vehicle body. Dürr also has installed its semi-automatic EcoDryX dry separation system, which separates the overspray in the paint booths for primer and top coat and requires no water or chemicals.
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