Senior Mechanical Design Engineer - Metal Structures

About Mainspring

Mainspring Energy manufactures and delivers fuel-flexible, low-emissions local power solutions that rapidly add new capacity and deliver reliable, affordable, and sustainable electric power. The company began commercial shipments of its Mainspring Linear Generators in 2020 and today has hundreds of megawatts in advanced development and field operations for leading Fortune 500 companies, data centers, and utilities. Mainspring also partners with global energy leaders including AEP, NextEra Energy Resources, Schneider Electric, and more.

The core values that ground our work, guide our decisions, and connect us together:

• Pragmatic Optimism
• Excellence without Ego
• Proactive Collaboration

Senior Mechanical Design Engineer - Metal Structures

Mainspring is looking for Senior Mechanical Design Engineers with a focus on designing sheet metal components and assemblies. In this role, you will be responsible for developing and improving designs, overcoming DFM challenges, managing vendors, procuring and testing parts, and ensuring high‑quality execution across all phases of product development. The ideal candidate will have a strong combination of technical expertise and the drive to solve complex problems in a collaborative environment.

Core Responsibilities

• Contribute to brainstorming and technical review sessions to develop solutions that improve performance, cost‑efficiency, and reliability of the Linear Generator.
• Take ownership of the design, analysis, testing, and optimization of structural systems, with attention to cost, safety, and reliability trade‑offs.
• Apply sheet metal and joint design knowledge to support development of complex assemblies with efficient manufacturing processes.
• Perform FEA analyses by breaking down complex loading conditions into solvable problems to inform design improvements.
• Conduct tolerance stack‑up analysis to support robust and manufacturable designs.
• Use CAD tools to create detailed drawings and 3D models, maintaining accuracy in design and documentation.
• Support procurement, fabrication, and testing of parts, contributing to hands‑on validation and iterative development.
• Collaborate closely with manufacturing, NPI, test, and reliability teams to ensure designs meet performance, manufacturability, and quality goals.
• Interface with vendors and suppliers to support quality manufacturing and timely delivery.
• Participate in DFMEA processes to help identify and mitigate potential failure modes.
• Manage tasks and priorities effectively, supporting delivery of key engineering milestones.

Qualifications

• Degree: BS or MS in Mechanical Engineering or a similar engineering field from an accredited institution. Experience and degree will determine the level, with the following minimum requirements: Senior: BS + 6 years or MS + 5 years
• Strong knowledge of sheet metal design, manufacturing processes, fastener selection, joint design, coatings, and assembly practices.
• Experience designing for durability under cyclic and thermal loading, with an awareness of vibration and acoustic challenges.
• Proven track record contributing to complex projects by helping define requirements, evaluating technical trade‑offs, identifying risks, and supporting key decisions to meet functional and performance goals.
• Detail‑oriented, with experience generating and reviewing drawings, bills of materials, tolerance stack‑ups, work instructions, and test documentation.
• Proficient in SolidWorks and PDM (or similar CAD version control systems), with experience using FEA and CFD tools such as SolidWorks Flow Simulation or Ansys.
• Familiarity with forming analysis tools to catch DFM challenges early is a plus.
• Comfortable working hands‑on with prototyping, testing, and failure analysis of structural components.
• Experience working cross functionally with manufacturing, supply chain, test and reliability teams.
• Self‑motivated and capable of delivering high‑quality design work in a fast‑paced environment. Experience across the full product development cycle—from concept through manufacturing support is valued.
• Enthusiastic about supporting and sharing knowledge with peers and junior engineers.
• Passion for creating innovative and cost‑effective solutions to enable the large‑scale deployment of zero‑carbon energy technologies.

$140,250 - $165,000 a year

This position is onsite at our Menlo Park HQ . The salary will be adjusted to reflect local market conditions based on employee location as well as the experience of the employee. Along with base salary, Mainspring offers pre‑IPO company equity through Restricted Stock Units (RSUs) + benefits.

Does your experience not meet all of our posted requirements? Studies have shown that some people are less likely to apply to positions unless they meet every listed requirement. At Mainspring, we are committed to building a diverse, inclusive, flexible, and collaborative environment, so if you want to help us transition the world to clean and affordable electricity, and don’t meet all posted requirements for a particular role, we’d still love to hear from you. Mainspring can sometimes be flexible enough to shift responsibilities for the right person, or otherwise identify open or upcoming roles that may better fit your professional background.

In more traditional words, Mainspring Energy, Inc is an Equal Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, or protected veteran status and will not be discriminated against on the basis of disability.

This compensation and benefits information is based on Mainspring Energy's estimate as of the date of publication and may be modified in the future. We generally do not negotiate on salary once we have made an offer. The level of pay within the range will depend on a variety of job‑related factors that may include location, relevant prior experience and/or education, or particular skills and expertise. New hires joining the company tend to be paid within the starting base pay range noted above, with opportunities to increase pay over time based on development of additional skills, competencies, and company‑specific knowledge.