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GM Uses AM to Support Automotive Production

Adam Campbell
By Adam Campbell Additive Design & Manufacturing, Product Application Engineer, General Motors
Christine Bardsley
By Christine Bardsley Design Release Engineer, General Motors

As General Motors continues to evolve from a traditional legacy automaker to platform innovator, it is continually redefining the vehicle development process through new technology and innovative approaches to help accelerate the company towards its vision of a world with zero crashes, zero emissions, and zero congestion.

A series of HP Multi Jet Fusion 3D printers at a GKN Forecast 3D facility. (Provided by GKN Forecast 3D)

One of GM’s strategic investments to make the company more agile is in additive manufacturing. Opened in early 2020, the Additive Industrialization Center (AIC) is GM’s 15,000 ft2 dedicated to productionizing 3D printing technology and development work which enables 3D printed components to be used in production vehicles, assembly plants, and additional automotive applications.

GM uses the term ‘additive manufacturing’ to describe the entire ecosystem of a 3D printed part, supporting a holistic, integrated, enterprise approach to adopting accelerated product development and tooling. GM’s additive manufacturing function plays a key role in the agile development of parts for production and motorsports, eliminating expensive tooling costs, and even solving for unexpected challenges that arise in different stages of the vehicle development process.

A Challenge and an Opportunity

Not even a year after the opening of the AIC was announced, General Motors was preparing its manufacturing network for the production launch of model year 2022 full size SUV passenger vehicles when an engineering decision was made to implement a design change very late in the development process. The change required an additional part to be introduced on several of the company’s most popular full-size SUVs.

A 3D printed rear spoiler closeout seal, prior to undergoing the finishing process. (Provided by GKN Forecast 3D)

The additional part, a spoiler closeout seal added to the rear portion of each vehicle, would result in improved aerodynamics, and increase fuel efficiency for each of the final production vehicles.

The change was simple enough to accommodate under the proper circumstances and lead time, but design alterations this late in the development process are rare, and created a situation that required an extremely quick pivot from planned production operations. As a result, the GM team needed to quickly develop and manufacture the required parts at high volume in order to meet the originally scheduled production timeline.

From the onset of the required change, the team estimated it would take approximately twelve weeks to develop, produce, and install an injection molding tool to create the part with conventional manufacturing techniques—a timeline that would result in delayed customer deliveries of 30,000 vehicles.

A 3D printed rear spoiler closeout seal after undergoing the finishing process. (Provided by GKN Forecast 3D)

With the inclusion of the spoiler closeout seal being deemed necessary in order to proceed with production, and not having the means to produce the part itself, GM faced a potential supply chain gap which, if left unaddressed, could have resulted in a delay to the start of model year production—ultimately impacting the delivery of vehicles to dealerships and customers.

Solutions for the Alternative—AM

Requiring an alternative, GM quickly went to work evaluating potential solutions. For a stand-in solution to be considered viable, it would need to replicate the intended design as closely as possible while also enabling a more seamless changeover process once production parts became available, meaning the vehicle would not require a later customer replacement for the stand-in solution. Additionally, the replacement part would need to satisfy customer facing appearance quality requirements and meet environmental durability conditions.

As part of the exploration and validation process, GM initially evaluated the use of a readily available EPDM foam strip. Although this material was able to successfully meet the aerodynamic requirements of the desired part, the teams were having minimal success creating a potential stand-in which would be suitable for production from an appearance standpoint.

One of the inherent strengths of additive manufacturing is not only its ability to produce and replicate parts without the use of an existing mold, but the versatility to print with a variety of different materials.

A 3D printed rear spoiler closeout seal after undergoing the finishing process. (Provided by GKN Forecast 3D

With other proposed solutions falling short, GM’s additive manufacturing team recommended the use of HP’s Multi Jet Fusion 3D printing technology which uses applied ink to promote energy absorption from a fusing lamp. This results in the polymer powder sintering to the layer below until a 3D part is produced. By using this platform, the team was able to produce a 3D printed spoiler closeout seal which was comparable to its injection molded counterpart both aesthetically and functionally.

After creating a promising concept part, the team validated its functionality and design through wind tunnel testing to confirm that the proposed 3D printed solution could meet the desired aerodynamic performance. An appearance review with GM Engineering and Design executives ensured it met the necessary visual standards for inclusion on customer vehicles.

Although GM’s additive team had successfully identified a solution for the injection mold availability gap and obtained leadership sign-off, it still needed to navigate the challenge of achieving volume at the required scale.

A Collaborative Approach

In most cases, when a Multi Jet Fusion part has been 3D printed, the piece(s) go through a standard finishing process. In this case however, the parts needed to go through a vapor polishing process to provide a smooth, polished finish to support integration with the surrounding molded components and seals, as well as providing improved mechanical properties to the material itself.

Depending on the material and part geometry of the piece, this process usually takes 1-2 hours before the finished product can be removed from the digitally controlled processing chamber.

As the team was developing a process to polish these printed parts in high volume, they discovered a global material shortage of the required chemical vapor consumable—adding yet another layer of complexity to an already adverse situation.

With this polishing process a needed step in producing the part, the material shortage and long drying times would not allow for the necessary volume of 3D printed parts to be produced within the condensed timeline. It presented yet another production challenge.

Having a longstanding relationship with GKN Forecast 3D, a supplier of 3D printing, rapid machining, and quick-turn tooling solutions for high quality prototyping and production readiness parts, the team from GM solicited help in ramping up production of the approved 3D printed spoiler closeout seal part.

Taking into consideration all aspects of the production process, the teams were able to identify the optimal opportunity for reducing processing time to meet the increased demand and production timeline. Printing and vapor polishing the part were aspects of production that left little room for improvement, but the drying process had opportunity for change. GKN Forecast 3D was able to reduce the time to complete the production process by introducing and qualifying a way to speed up the drying time. And reaching out to GKN Forecast 3D’s network of suppliers allowed the team to procure the vapor polishing consumables to complete the finishing process.

In the span of only a few days, the new drying process was tested, validated, and implemented, reducing drying time by nearly 60 percent. This gain in production time essentially tripled the throughput of the finished parts.

By using an innovative approach, the teams were able to accelerate the production schedule and successfully create and polish the required 60,000 parts over the span of five weeks for use on approximately 30,000 full-size SUVs.

The resulting 3D printed parts were made available to a tier 2 production seal supplier for application of the adhesive required to bond the parts to the spoiler. The finished parts were then shipped to GM’s assembly facility in time to be successfully installed on the finished vehicles, avoiding costly impacts to production schedules.

Challenge Accepted, Solution Manufactured

GM’s additive manufacturing expertise and network of trusted suppliers resulted in the ability to quickly adjust to a myriad of challenges and ultimately deliver a viable solution on time, which may not have been available without the concerted and strategic investment the company has made in additive manufacturing.

In only three weeks’ time, the teams from General Motors, GKN Forecast3D, and other suppliers were able to leverage the Multi Jet Fusion platform to design, create, and implement a viable value stream for the rear spoiler seal. Through the innovative use of additive manufacturing, quick collaboration, and precise execution, the teams achieved an outcome which would not have been obtainable through traditional means of injection molded production.

Solving for this manufacturing challenge in a high-pressure situation not only resulted in direct financial benefits for GM and on time delivery for dealers and customers, but also demonstrated the significant value and versatility that additive manufacturing can provide.

Moving forward, the applications of additive manufacturing will continue to expand across the various domains at GM. As the company continues to introduce new technology, innovate, and accelerate product development cycles, the expanding use of additive manufacturing will play an even more significant role.

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