A Divergent Approach to Vehicle Development and Production

Divergent Technologies has quietly developed everything from part-design software to the metal powders used to print components, and the adhesives to assemble them.

The hybrid-electric Czinger 21C features a V8 and electric-drive system generating a standard peak output of 1,250 hp (932 kW). This limited-production hypercar has an additively-manufactured structure. (Divergent Technologies)

Among the most intriguing vehicles on display at the 2022 Pebble Beach Concours D’ Elegance was a pair developed by an obscure brand, Czinger Vehicles, and its parent company, Divergent Technologies.

The chassis of the 21C, produced primarily with aluminum alloy components that are 3D printed then adhesive-bonded. (Divergent Technologies)

The 21C V Max and Hyper GT that impressed the concours audience showcase Divergent Technologies’ remarkable breadth of capabilities in design, engineering and production – a systems approach that is predicated on no specific designed tooling for components or assembly.

This has led to the Waterloo, Ontario, Canada-based company doing everything from developing its own topology-optimization software, called “Bi-directional Evolutionary Structural Optimization,” to working with 3D-printer company SLM Solutions to develop a high-throughput additive manufacturing system, to developing many of the metal powders that are used to build parts. It also has created a robot-based automated assembly system and formulates the adhesives that are used for bonding.

Full development

To get a sense of Divergent’s comprehensive development, SAE Media spoke with Mike Kenworthy, the company’s CTO.

“We spent a number of years engineering the joint architecture,” of the two show vehicles, he said, noting that about 350 parts per vehicle were created using additive manufacturing (AM, or 3D printing). The system being used is the SLM NXG XII 60. It employs 12 1,000-kW lasers to produce parts at a rate that is 10 to 20 times faster than most service bureaus using the latest four-laser systems, Kenworthy said.

Kevin Czinger, founder and CEO of the company bearing his name as well as of Divergent Technologies, worked with SLM personnel to develop the machine. “On average, depending on build density and packing, we are printing around a kilogram to a kilogram-and-a-half [of components] per hour,” he noted. The whole process is called the Divergent Adaptive Production System (DAPS).

Kenworthy explained that in developing the vehicle, the designers and engineers work to create components that are both light and strong. Due to the work envelope of the AM equipment (600 x 600 x 600 mm), to optimally partition the complete part – a rear frame, for example – requires a process that includes both artificial-intelligence software and human decision-making, he said.

Component design includes the design of mating surfaces and overall configuration so that they can be put together by the robotic assembly cell. There is no design-specific tooling used in the process.

Although production of the first Czinger vehicle, the 21C planned for launch in 2023, is limited to a total build of 80 units, Kenworthy said that the DAPS is predicated on higher volumes.

Adhesives are key

This thinking led to the development of the adhesives that are used as the primary joining method. (The vehicle uses a limited number of mechanical fasteners.) Two types of adhesive are employed: UV-cured and heat-cured. The UV-cured adhesive is particularly important: during assembly it acts as a tack weld that holds the primarily aluminum parts (made from AL alloys that Divergent developed to have specific characteristics, e.g., crash-energy management) together during build in the robotic cell.

Kenworthy said the company tested “literally hundreds of adhesives on the market” and determined that none of them would meet the requirement that would provide what he calls “automotive-relevant cycle times and rates.” The best UV-curing adhesive they found had a curing time of approximately 40 sec.

The adhesive Divergent developed cures in about 3 sec. and, Kenworthy explained, is capable of dealing with the temperatures used when the primary structural adhesive is cured. He said that organizationally Divergent, which has some 180 employees, has people working in four divisions, Structures, Software, Additive Manufacturing, and Automation. He further noted that these engineers and scientists are responsible for what is now more than 500 patent filings.

Additive by the kilo

While most automotive OEMs currently are using AM for trim pieces, assembly jigs or small numbers of production parts, Kenworthy says Divergent is working toward hundreds of thousands of vehicle structure programs. In addition to Czinger, Divergent operates as a Tier One supplier. It currently has “around 20 active programs” with major OEMs, Kenworthy explained. He noted that Aston Martin’s DBR22 concept, introduced at Pebble Beach, features a 3D-printed aluminum subframe by his company. This involved being involved in the design, engineering and validation of the components, he said, as well as their manufacturing and assembly.

The Czinger Hyper GT is a four-place vehicle that will be structurally based on AM. Because of the adaptability of the Divergent production system, the equipment used to produce the 2-seat 21C can efficiently produce the Hyper GT because no design-specific tooling is involved. (Divergent Technologies)

“Our perspective on additive manufacturing and its trajectory for deployment in is clearly different than the vast majority of folks doing it in automotive,” he asserted. “The types of programs we’re performing today are focused on frame structures and suspension components.” He says there can be as much as 100 kg (220.5 lb.) of AM-printed mass on a given vehicle (i.e., front and rear frame and suspension).

While the company initially is focused on working with higher-end luxury vehicles, he says that as the technology becomes better understood, it will move down-segment.

Electric vehicles? “There is a massive opportunity for additive manufacturing,” he answered. “We can leverage it to reduce weight and improve the performance of those structures.”

The high cost of tooling

Kenworthy said that one of the issues that currently restrains changes in conventional automotive manufacturing is its capital intensity. He notes, for example, that even when companies discover that products released in the market aren’t doing as well as envisioned, changes often are limited due to the high cost of tooling.

“We have developed an agile system. We want product lifecycles that look more like consumer electronics than the five-year automotive development programs,” Kenworthy said.

He also pointed out that the company is concerned with the entire product lifecycle: manufacturing, use, and end-of-life. “These are fundamental problems that the automotive industry is wrestling with and doesn’t have great answers to. I think additive manufacturing and our system provides those answers,” Kenworthy said.