Senior Mechanical Engineer

Company: i3 Product Development
Location: Sun Prairie
Posted on: April 1, 2026

Job Description:

i3 Product Development is a place for people who love to build, learn, and stay curious, especially when the problems are complex. We’re a high-performing team of designers, engineers, and problem solvers working together under one roof to turn ideas into real products. With 100 projects each year across medical, agriculture, consumer, industrial, health & wellness, and on- and off-road recreation industries, no two days are the same. You’ll take real ownership of your work, collaborate closely with teammates, and work directly with clients to help deliver solutions that truly delight. We value curiosity, trust, and people who take pride in delivering work that makes a meaningful impact. At i3, seniority is not defined solely by title. Senior Mechanical Engineers are trusted technical leaders who model strong engineering judgment, collaboration, and ownership. They help shape how we engineer as much as what we deliver. About the Role As a Senior Mechanical Engineer, you will take significant technical ownership of product development efforts from concept through production. This role is for an experienced engineer who understands how to navigate a wide range of product development scenarios and apply the appropriate level of rigor to each situation. You will regularly make and defend decisions such as: How manufacturing process selection should drive geometry, materials, and tolerances When fast, lightweight engineering is appropriate versus when deeper analysis and deliberation are required When tolerance analysis is required versus premature When FEA meaningfully reduces risk versus when rapid prototyping is the better learning tool Senior Mechanical Engineers remain hands-on while also serving as technical leaders. You may act as the final technical authority on a project, while still participating in peer review and cross-checking as part of i3’s collaborative culture. This role includes direct client ownership. On some projects, you will work alongside a Project Manager; on others, you may independently manage one- or two-discipline projects (Mechanical Engineering with adjacent disciplines such as Industrial Design or Electrical Engineering). What Senior Means at i3 At i3, Senior Mechanical Engineers are technical leaders and role models for our core values: Adapt & Learn, We Get It Done, Focus on Impact, Prioritize Partnerships, We Before Me, and Considerate Candor . Senior engineers are expected to: Demonstrate deep technical expertise while remaining open to feedback and peer review Set the tone for collaboration, engineering rigor, and professionalism on project teams Take ownership of project outcomes—not just assigned tasks Share knowledge openly and mentor engineers and designers through guidance, review, and example Build strong partnerships with clients, teammates, and manufacturing vendors Balance confidence with humility, knowing when to lead decisively and when to seek input This role is not a people manager, but it does require leadership through influence, technical excellence, and accountability. What You’ll Do Lead mechanical engineering efforts from early concept through production Apply sound engineering judgment to balance performance, risk, cost, schedule, and manufacturability Serve as a technical lead and, at times, final technical authority while participating in peer review and cross-checking Own client relationships and technical communication for assigned projects Perform and interpret engineering analyses, including: Structural FEA Tolerance stack-ups Basic thermal analysis and considerations Design and review parts and assemblies for multiple manufacturing processes, including: Machining Sheet metal fabrication and welding Injection molding Create, review, and approve engineering drawings (GD&T when appropriate) Review 3D CAD models for manufacturability, assembly, robustness, and risk Design and evaluate structures, joints, fasteners, bearings, and load paths Select materials based on performance requirements, environment, manufacturing process, and cost Work directly with manufacturing and tooling vendors to release designs and resolve issues Collaborate closely with Industrial Design, Electrical Engineering, and Prototype teams Mentor, coach, and guide other engineers and designers Remain hands-on—modeling, creating drawings, prototyping, testing, and working in the shop as needed Model i3’s core values through technical leadership, collaboration, and professional conduct What We’re Looking For Bachelor’s degree in Mechanical Engineering (or equivalent experience) 10 years of experience in mechanical product development Demonstrated experience taking products from concept through production Strong engineering judgment and ability to apply the appropriate level of rigor to different problems Proven experience with: FEA and understanding when it provides meaningful value Tolerance analysis and GD&T Design for manufacturing and assembly across multiple processes Extensive experience creating, reviewing, and checking engineering drawings High confidence using CAD tools, particularly SolidWorks Broad understanding of materials and material selection Experience designing mechanical systems including structures, fasteners, joints, and bearings Demonstrated ability to lead through influence, mentorship, and example Comfortable working in collaborative, cross-functional teams Clear, confident communicator comfortable in client-facing technical discussions Ability to manage multiple projects and shifting priorities Nice to Have Consulting or client-facing engineering experience Exposure to a wide range of industries or product types Hands-on prototyping, testing, and troubleshooting experience Understanding of basic thermodynamics Familiarity with electromechanical systems (motors, controllers, sensors) Experience leading technical scope across multiple disciplines Why i3 At i3, Mechanical Engineers work on real products with real impact. You won’t be siloed or stuck on the same problem year after year. Instead, you’ll collaborate with a tight-knit team, take ownership of your work, and see designs move quickly from idea to reality. We value curiosity, accountability, and people who care about both the details and the bigger picture. Benefits Health insurance with a $0 deductible and employee premiums as low as $9 per pay period Dental and vision coverage 401(k) with dollar-for-dollar match up to 6% Employee Stock Purchase Program Company-paid short- and long-term disability insurance Company-paid life insurance (2× annual salary) Flexible Spending Accounts (FSA) and Health Savings Accounts (HSA) Emergency Assistance Fund Charitable Match Program

Keywords: i3 Product Development, Buffalo Grove , Senior Mechanical Engineer, Engineering , Sun Prairie, Illinois