Associate Manufacturing Engineer

Mainspring Energy
Mainspring Energy

Software Engineering

Menlo Park, CA, USA

USD 115k-136k / year + Equity

Posted on Mar 13, 2026

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

Job Overview

    We are seeking an innovative and highly motivated recent Mechanical Engineering graduate to support the design, development, and implementation of assembly tooling, material handling systems, and scalable production processes for a groundbreaking large electromechanical machine.

    In this role, you will participate in translating product designs into manufacturable, assemblies at scale. You will work closely with Senior Manufacturing engineers to drive DFM/DFX initiatives, process error-proofing, and tooling robustness, ensuring efficiency, repeatability, and quality across our production lines.

    The ideal candidate will have a basic understanding in tooling and fixture design. Be able to use SolidWorks to generate 3D mechanical assemblies. Additionally in this role you will support process testing and contributing to Engineering Change documentation.

    Join our team if you are ready to bring your enthusiasm and fresh ideas to the forefront of manufacturing technology, contributing to the success of our linear generator startup.

What you'll do

    Design and Development:

  • Contribute to the design of high-precision fixtures, tools, and equipment for electromechanical assembly and testing.
  • Work with material handling solutions, overhead lift assist systems, and custom conveyors
  • Conduct tests, produce test reports to enable the implementation of precision joining technologies like Torque+Angle control Nutrunners..
  • Learn to evaluate tooling and process equipment to ensure that they meet defined quality and performance standards.
  • Vendor and Project Support:

  • Work with senior engineers on project execution, from concept through installation and commissioning.
  • Learn to collaborate with cross-functional teams, including R&D, operations, and procurement, to align manufacturing solutions with product requirements.
  • Be introduced to layout planning for future factory design initiatives and collect and document product and process requirements to feed equipment and tooling design and also define the process readiness for automation introduction.

What you'll bring

  • Bachelor’s or Master’s degree in Mechanical Engineering, Manufacturing Engineering, or a related field.
  • Proficiency in CAD software (e.g., SolidWorks, CATIA, or AutoCAD) for tooling and fixture design.
  • Strong analytical and problem-solving skills.
  • Finite Element Analysis (FEA) capability is a plus.
  • Willing and able to travel internationally up to 15%

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.

86000 - 98000 USD 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 the base salary, Mainspring offers pre-IPO stock options + benefits.