Senior Mechanical Engineer, Machine Design

Stealth Co•San Diego, CA

2d•Onsite

About The Position

We are seeking a Senior Mechanical Engineer, Machine Design to own the design of precision mechanical systems, thermal control hardware, and fluid control hardware. This role involves performing detailed analysis, validation, prototyping, and documentation to ensure the performance, reliability, and manufacturability of our products. You will collaborate with cross-functional teams and support the transition from prototype to production.

Requirements

B.S. or M.S. in Mechanical Engineering or related field
5–8+ years of experience in precision machine design, thermal systems, and/or fluid handling hardware
Strong foundation in tolerance analysis and error budgeting
Experience performing thermal and fluid flow calculations
Proficiency in 3D CAD (e.g. SolidWorks)
Hands-on experience building and testing hardware
Analytical thinker who quantifies performance limits and tradeoffs
Strong mechanical fundamentals with systems-level intuition
Comfortable owning subsystems end-to-end
Hands-on builder who enjoys working in the lab
Clear communicator across electrical, firmware, fluidics, and systems teams

Nice To Haves

Experience in bioinstrumentation, medical devices, diagnostics, or scientific equipment
Experience designing closed-loop temperature-controlled systems
Experience with microfluidic or low-volume reagent handling systems
Familiarity with FEA tools for structural and thermal analysis
Experience selecting materials for chemical compatibility
Experience supporting early-stage production builds

Responsibilities

Own the design of precision mechanical systems including frames, motion elements, fixtures, and actuation mechanisms
Perform tolerance stack-ups and define GD&T for precision assemblies
Develop and manage mechanical error budgets (alignment, motion accuracy)
Analyze stiffness, deflection, vibration, and fatigue using analytical methods and FEA
Design mechanisms that balance performance, cost, manufacturability, and reliability
Design thermal control systems including heaters, heat exchangers, insulation, cold plates, airflow systems, and structural thermal paths
Translate temperature stability and uniformity requirements into hardware specifications
Perform thermal modeling and first-principles heat transfer calculations (conduction, convection, radiation)
Develop and maintain thermal error budgets (drift, gradients, response time)
Collaborate with electrical and firmware engineers on sensor placement and control strategy integration
Design fluid handling assemblies including manifolds, tubing routing, fittings, valves, pumps, and reservoirs
Perform flow calculations (pressure drop, flow rate, Reynolds number)
Support material selection for chemical compatibility and biocompatibility
Integrate fluidic subsystems with thermal and mechanical assemblies
Develop leak testing and validation strategies
Build structured analytical models to predict mechanical, thermal, and fluidic performance
Maintain subsystem-level error budgets (mechanical, thermal stability, flow accuracy)
Design and execute validation testing for temperature stability, fluid accuracy, drift, and mechanical robustness
Perform structured root cause analysis when performance targets are not met
Support DFMEA and risk assessment activities
Assemble and debug mechanical, thermal, and fluidic prototypes
Instrument systems for temperature, flow, and mechanical performance measurement
Iterate quickly based on test results and integration feedback
Support alpha and beta system builds
Create detailed mechanical drawings with proper GD&T
Participate in DFM/DFA reviews
Work with vendors on machined, sheet metal, molded, and fluidic components
Support transition from prototype to low-volume production