Apprentice System Operator Jobs in California (NOW HIRING)

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 and technical excellence are decisive advantages - and we are building a team that can deliver real capability, not just concepts.

This is a rare opportunity to join at an early stage, where your work will directly shape critical systems, influence major technical decisions, and have immediate, real-world impact.

Machining Apprentice, Additive Manufacturing

The Machine Shop Apprentice supports daily machine shop operations by maintaining a clean, organized, and efficient work environment. This role assists machinists, programmers, and manufacturing personnel with machine maintenance, material preparation, secondary operations, and general shop support activities. The position also includes operation of support equipment such as 3D printers, waterjets, and saws.

Responsibilities

Shop Maintenance & Organization

• Maintain shop cleanliness and organization in accordance with 5S standards.
• Clean CNC machines, workstations, and common areas.
• Fill and monitor machine oils, coolant, and other consumables as directed.
• Empty chip bins and assist with routine housekeeping activities.
• Organize tools, fixtures, raw materials, and shop supplies.
• Support inventory management and material handling activities.

Production Support

• Assist machinists with machine setups and changeovers.
• Load and unload raw materials and finished parts.
• Deburr, clean, inspect, and package machined components.
• Transport materials, tools, and fixtures between departments.
• Assist with basic quality checks and documentation as directed.
• Support production activities to help meet delivery schedules.

Equipment Operation

• Operate and maintain 3D printers, including material loading, print setup, and part removal.
• Operate waterjet cutting equipment following established work instructions.
• Operate band saws and other cutting equipment to prepare raw materials.
• Perform basic preventive maintenance on assigned equipment.
• Report equipment issues, maintenance needs, or safety concerns promptly.

General Support

• Follow all company safety policies and procedures.
• Maintain a safe and organized work environment.
• Assist manufacturing, engineering, and machine shop personnel as needed.
• Participate in continuous improvement and efficiency initiatives.
• Perform other duties as assigned.

Basic Qualifications

• High school diploma or equivalent.
• Mechanical aptitude and willingness to learn manufacturing processes.
• Ability to use basic hand tools and measuring devices.
• Ability to follow written and verbal instructions.
• Strong attention to detail and organizational skills.
• Ability to lift up to 50 lbs and stand for extended periods.

Preferred Skills and Experience

• Previous experience in a machine shop or manufacturing environment.
• Experience operating saws, waterjets, CNC equipment, or 3D printers.
• Familiarity with shop safety practices and 5S principles.
• Forklift certification (or ability to obtain certification).

Benefits And Perks

• Employee Equity: Meaningful equity for all full-time employees - share value has increased 150x in three years
• Personal Time Off: Four (4) weeks of paid time off to unplug, reset, and come back sharp—velocity matters, burnout doesn't
• Company Paid Holidays: Ten (10) company paid holidays
• Medical: We offer plans at 100% employee covered and 80% of dependent coverage
• Dental & Vision: We cover 90% employees and 80% for dependents to ensure you and your family have access to quality preventive and ongoing care
• FSA/HSA: To support long-term health and financial resilience, we offer FSA and HSA options that allow employees to set aside pre-tax dollars for eligible medical and dependent care expenses
• Retirement: 401k plan offered to support long term financial growth along side high-impact, high-velocity work
• Paid Parental Leave: We support growing families with meaningful time to bond and recover. Birthing parents are eligible for up to 10 weeks of paid leave, while non-birthing parents may take up to 4 weeks of paid leave. This time can be used for pre-natal care, pregnancy, childbirth, and related medical needs—ensuring every parent has the support they need during this important life moment.8-weeks of paid parental leave for all parents. Additional paid pregnancy leave for CA employees
• Meals & Catering: Frequently catered lunches and team meals, plus company-covered meals when extra time or effort is required
• Snacks & Beverages: Fully stocked kitchen with unlimited snacks and drinks to keep you fueled throughout the day
• Performance & Fitness: $100 monthly fitness stipend to support peak performance and health, both inside and outside of work
• EV Charging: Onsite electric vehicle charging available for employees

Physical Demands

• Frequently stand, walk, bend, lift, and carry materials.
• Ability to safely lift and move materials up to 50 lbs.
• Work around machinery, cutting fluids, metal chips, and industrial equipment.
• Use appropriate personal protective equipment (PPE) at all times.

ITAR Requirements

To conform to U.S. Government export regulations, applicant must be a (i) U.S. citizen or national, (ii) U.S. lawful, permanent resident (aka green card holder), (iii) Refugee under 8 U.S.C. § 1157, or (iv) Asylee under 8 U.S.C. § 1158, or be eligible to obtain the required authorizations from the U.S. Department of State.

This position may require access to classified information or restricted U.S. Government sites, systems, or information, as determined by the Company and/or applicable U.S. Government requirements. If the position is so designated, your employment in the role may be contingent upon your ability to obtain and maintain the required U.S. Government security clearance or other government authorization, and to satisfy any citizenship or other eligibility requirements imposed by applicable law, regulation, executive order, or government contract requirements. You will be notified if and when such requirements apply. Failure to obtain or maintain any required clearance or authorization may result in reassignment, leave, or separation from employment, consistent with business needs and applicable law.

Affirmative Action/EEO Statement
Employment with Castelion is governed on the basis of competence and qualifications and will not be influenced in any manner by race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, sexual orientation, gender identity, marital status, mental or physical disability or any other legally protected status.

Other Duties
Please note this job description is not designed to cover or contain a comprehensive listing of activities, duties or responsibilities that are required of the employee for this job. Duties, responsibilities and activities may change at any time with or without notice.