Tec de Monterrey, 2023

The client, SMTC (Surface Mount Technology Centre), a Canadian electronics manufacturing company, faced production delays in assembling high-amperage multi-contact connectors. Process analysis identified two bottlenecks: Screw insertion & tightening (~2:07 min), and Welding (~3:37 min). The team focused on improving the screwdriving stage, since reducing its time would also ease the welding bottleneck and increase overall throughput.

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In order to keep the progress going smoothly and keep track of the project, a SMART objective was defined in the early stages: Design a functional prototype of a screwdriver with an automatic screw dispenser to reduce screwdriving process time by at least 30% by June 2023.

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In the concept generation and analysis stage, we generated multiple concepts using brainstorming, SCAMPER, brainwriting, and morphological matrices. initially, we were going for Concept 6, but it proved to be overdesigned and costly, reason why we switched to Concept 7, which became the basis for the final prototype.

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We divided the final product into 3 main parts/segments: the screw dispenser, the fixturing system, and the positioning system. Starting with the screw dispenser, we analysed multiple designs (market available and principle-based from other mechanical systems) and the geometric constraints from the screws to choose the system to power the dispenser, this being a mechanical piston design (custom to the screws and overall product), being cost-effective and compact. The fixturing system was a custom Delrin fixture to hold SMTC’s product securely while minimizing human error, designed for press-fit assembly, enabling quick positioning without metal contact to reduce electromagnetic fluxes that could potentially damage SMTC's product. And for the positioning system, it was decided to do an Orthogonal rail setup allowing vertical motion of screwdriver and dispenser, horizontal movement along two axes, and fully built from steel rails and guides, validated for stiffness and load bearing.

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Such system required validation to ensure proper functionality during usage and safety to both the operator and the product, for which an FEA analysis was made. It was roughly calculated that the system requires to withstand a 20kgf load and required to have a minimum of 1.5 in the safety factor, for which such parameters and calculations were placed as inputs in the FEA simulation. The simulation revealed that the system (mainly the rail, made from ASTM A36 steel) has a maximum deflection of 0.31–1.72 mm, which is within acceptable values.

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A manufacturing and optimization plan was also made in order to reduce parts and improve functionality. From the DFMA analysis: Baseline efficiency: 31.2%, after design adjustments: 32.2–35.5% (improved but not ideal). RP (Reduction of Parts) analysis suggested combining the screwdriver housing with the dispenser body to cut unnecessary components. We also generated manufacturing drawings, material selection, and assembly instructions.

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A TPM (Total Productive Maintenance) plan was also developed during this project, which mentioned/included standard operation procedures, daily inspection and cleaning protocols, and startup checklists to prevent downtime. As part of the improvement plan, we proposed future automation upgrades with Arduino-based controls and digital monitoring. 

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The prototype achieved the goal of reducing screwdriving time, addressing SMTC’s production bottleneck. Such improvements directly impacted ergonomics, operator efficiency, and throughput. And although DFMA scores showed room for further simplification, the design proved economically viable (~$240/unit) and practical for industrial deployment.

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Please find attached below the relevant documents to this project. (Note: most, if not all documents, are in Spanish)