Applying the Goken Way of Product Development for Optimizing Windshield Defrost Duct Design for an Automotive OEM

Applying the Goken Way of Product Development for Optimizing Windshield Defrost Duct Design for an Automotive OEM

Goken’s client, an Automotive OEM was designing and developing a defrost duct that helps to defrost the large surface area of the windshield. The current 3D printed design made by the OEM met regulatory standards, however it could not be mass manufactured as the construction of the airflow path and its geometrical shape made tooling non-feasible. As a result, the client requested Goken’s engineering team to come up with alternative designs that could be mass produced.


The new design needed to meet stringent requirements including manufacturability, FMVSS standards, and defrost performance.

This project involved tasks such as defining the master sections, introducing new parts and assembly processes, conducting tolerance/stack-up analysis, and consolidating two parts into one integrated defrost panel. The key requirement was to ensure that the injection molding process was feasible, while meeting FMVSS defrost regulations. The deliverables expected were defrost design in 3D, 2D drawings with GD&T annotations, DFA, DFM, and tool feasibility reports. The design project had a tight deadline of 240 hours.


Goken assigned a team of exterior engineer and project lead to address the issue and deliver designs to meet the client expectations. The team also supported the client's engineers in part development, tool manufacturing, and supplier interaction.

We established a structured approach consisting of phases such as Input Study, Concept Development, Parametric Modeling, Design Optimization, and Review to fulfill all client requirements within the designated timeframe and ensure zero design errors.

The Input Study phase commenced with analyzing existing RPT Designs and conducting a HOMOLOGATION study to identify issues, supported by an analysis of engineering documents. In the Concept Development phase, we assessed the feasibility of the master section for tooling and developed sections with identical duct internal air path surfaces and outlet positions relative to the RPT design. Additionally, we devised RPS datum and mounting schemes, established a new defrost installation process and sequence, defined duct molding processes for mass production, generated Bills of Materials (BOM), and conducted regulatory checks.

The Parametric Modelling stage involved designing part geometries, developing locating and mounting features, addressing gap and flush issues, and selecting and designing child parts and fasteners. During the Design Optimization phase, we explored alternative material possibilities and assessed the feasibility of alternative molding processes. Multiple designs were prepared and analyzed with respect to various manufacturing processes (such as injection molding, blow molding, and plastic joinery processes) to identify suitable designs and molding processes.

Subsequent adjustments were made to optimize thickness, weight, and child parts based on client feedback. Tolerance/Stack-up analysis and CFD simulations were conducted to ensure compliance with FMVSS defrost regulations and performance standards. We then finalized 2D drawings, verified GD&T product feasibility, and provided DFA & DFM Tool feasibility reports and BOM reports, ensuring the completion of the task with zero rework and design errors.

Unique solution

While developing design the team realized that even though 3D printed part achieved performance, it was not manufacturable due to few undercuts. The challenge was to achieve performance while still being able to mass produce with injection molding process. The existing Defrost outlet & air flow internal surface area also needed to be kept the same to avoid any performance issues and conflicts with FMVSS standards. Hence multiple designs iterations were conducted due to limitation and constraints of different molding process like Blow molding, Forming, injection molding etc.

We developed multiple design iteration and created a process involving check points such as design as per FMVSS standards, its manufacturability, supplier tooling feasibility, CAE/CFD performance (Defrost efficiency), design for assembly, optimizing the number of parts, weight, and cost.

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  • Our finalized design successfully enhanced Defrost performance, surpassing the client's target of 45%.
  • Additionally, the design streamlined assembly processes, resulting in a 31% reduction in process complexity and a significant reduction in weight.
  • Cost savings of approximately 20% were achieved, alongside a notable decrease in assembly cycle time from 9 minutes to just 4 minutes.
  • Remarkably, the design was completed within 75% of the allocated time, demonstrating efficient project management and execution.