Manufacturing Engineer – Advanced Composite Machining

Why Castelion, Why Now Castelion is moving incredibly fast to develop and deliver advanced defense systems at a time when execution matters more than ever. We believe focus, ownership, and excellence are decisive advantages - and we're building a world-class team to turn bold ideas into real capability. This is a rare opportunity to join at an early stage, where you'll have significant ownership, collaborate with exceptional teammates, and make a direct, measurable impact on our mission and the future of the company - regardless of your function. Manufacturing Engineer – Advanced Composite Machining About the Role We are seeking an experienced, hands-on CNC Machinist / Manufacturing Engineer specializing in 5-axis machining and advanced composite materials. This role combines advanced CAM programming, machine setup and operation, tooling strategy, and manufacturing process development. The ideal candidate will have extensive experience programming and operating 5-axis CNC machines using Siemens NX CAM and/or Mastercam, with direct experience machining advanced materials such as carbon-carbon, phenolic composites, and carbon-silicon carbide (C/SiC). A major focus of this position is cutting tool selection and optimization. The successful candidate will understand how tool geometry, substrate, coating, cutting-edge preparation, toolpath strategy, feeds, speeds, and tool engagement affect machining quality, tool life, cycle time, and overall process capability. This individual will help develop robust machining processes for complex components, working closely with engineering, quality, and manufacturing teams to transition R&D hardware into repeatable production. Key Responsibilities • 5-Axis CNC Programming & Machining • Develop, program, simulate, and prove out complex 5-axis CNC machining operations. • Create advanced CAM toolpaths using Siemens NX CAM and/or Mastercam. • Optimize toolpaths for material removal, surface finish, dimensional accuracy, cycle time, and machine utilization. • Generate, verify, and maintain CNC programs, post-processed code, setup sheets, and machining documentation. • Set up and operate 5-axis CNC machines, including workholding, tooling, probing, and process verification. • Troubleshoot toolpath, machining, vibration, surface quality, and dimensional issues. • Apply appropriate strategies for complex geometries, thin sections, intricate features, and close-tolerance components. • Cutting Tool Selection & Optimization — Primary Focus • Select and validate cutting tools specifically suited to carbon-carbon, phenolic, C/SiC, and other advanced composite materials. • Evaluate tool geometry, cutting-edge design, substrate, coatings, abrasive-wear resistance, and tool construction. • Determine appropriate feeds, speeds, chip loads, stepovers, stepdowns, and tool engagement strategies for each material and operation. • Evaluate diamond tooling, PCD tooling, carbide tooling, and other specialized cutting tools as appropriate to the material and application. • Develop tooling strategies that minimize fiber pullout, delamination, edge breakout, chipping, thermal damage, and dimensional instability. • Establish tool-life expectations, wear limits, replacement criteria, and tooling performance standards. • Conduct tooling trials and document results to compare tool life, surface finish, dimensional accuracy, cycle time, and cost per part. • Work directly with cutting tool suppliers to evaluate new tooling technologies, conduct trials, and resolve machining challenges. • Standardize tooling selections and cutting parameters to improve process repeatability and reduce unnecessary tooling costs. • Build a structured tooling database containing tool specifications, approved applications, cutting parameters, performance data, and lessons learned. • Advanced Composite Machining • Machine carbon-carbon, phenolic, and carbon-silicon carbide components using appropriate material-specific machining strategies. • Develop processes for abrasive, brittle, and fiber-reinforced materials with unique cutting and failure characteristics. • Identify and mitigate defects associated with edge chipping, fiber damage, breakout, surface finish, and dimensional variation. • Develop suitable workholding, fixturing, support, and datum strategies for composite components. • Establish appropriate dust extraction, housekeeping, material handling, and exposure controls for composite machining operations. • Support prototype development and transition proven processes into repeatable production. • Manufacturing Engineering & Process Development • Develop manufacturing plans, setup sheets, tooling lists, work instructions, and standard operating procedures. • Collaborate with design engineering to provide design-for-manufacturability feedback. • Support first-article inspections, process validation, root-cause investigations, and corrective actions. • Develop repeatable machining processes that improve throughput, reduce scrap, and support production scaling. • Establish standard machining methods, programming practices, and tooling strategies across the machine shop. • Use data-driven continuous improvement to improve OEE, reduce cycle time, and increase first-pass yield. Required Qualifications • Extensive hands-on experience with 5-axis CNC milling. • Demonstrated CAM programming experience using Siemens NX CAM and/or Mastercam. • Direct experience machining advanced composites, preferably carbon-carbon, phenolic, or C/SiC. • Strong expertise in cutting tool selection, cutting parameters, and machining process optimization. • Proven ability to develop and troubleshoot complex machining operations independently. • Strong understanding of engineering drawings, GD&T, CAD models, and dimensional inspection. • Experience with workholding, fixturing, CNC setup, program prove-out, and process validation. • Strong analytical and problem-solving skills, with the ability to use machining data to improve performance. • Commitment to safe machining practices, particularly around composite dust and material-specific hazards. Preferred Qualifications • Experience with both Siemens NX CAM and Mastercam. • Experience with diamond, PCD, carbide, or other specialized tooling for abrasive and brittle materials. • Experience machining aerospace, defense, propulsion, thermal protection, or high-performance composite components. • Experience developing tool-life studies, tooling cost models, and standardized cutting parameter libraries. • Experience with CNC post-processors, simulation, collision avoidance, and complex 5-axis verification. • Experience taking parts from R&D prototypes through process qualification and production release. What Success Looks Like • Establish validated tooling strategies for each composite material and machining application. • Improve tool life, surface quality, dimensional consistency, and machining productivity. • Reduce scrap, rework, tool failures, and unplanned machine downtime. • Establish standardized NX CAM/Mastercam programming methods and tooling documentation. • Develop repeatable, scalable machining processes for advanced composite components. • Build a data-driven approach to tooling selection based on demonstrated machining performance rather than trial and error. Ideal Candidate The ideal candidate is a technical expert who can move seamlessly between CAM programming, cutting tool selection, machine operation, and manufacturing engineering. They understand that successful composite machining depends on the complete process: the material, cutting tool, toolpath, workholding, machine capability, and process controls. They should be comfortable working hands-on in an R&D environment, running tooling trials, solving difficult machining problems, and developing documented processes that other machinists and programmers can reliably execute. Castelion offers a generous be