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CNC Operator job description

A CNC Operator runs a computer controlled turning centre or lathe. They load the program and job, set tool offsets, run the first piece for approval, then machine parts in a cycle while checking dimensions and tool condition. The role reports to the Production Supervisor or Shift In-Charge. A good CNC operator keeps the machine cutting good parts within tolerance, catches tool wear before it makes scrap, and holds cycle time so the day's quantity is met.

DetailFor this role
DepartmentProduction
LevelEntry level
Reports toProduction Supervisor
Direct reportsNone
Experience1 to 4 years operating CNC turning machines

CNC Operator job description template

Copy this job description, replace the text in square brackets and post it on your careers page or a job portal.

Job title: CNC Operator

Department: Production

Reports to: Production Supervisor

Location: [City], [office, branch or site]

About the role

A CNC Operator runs a computer controlled turning centre or lathe. They load the program and job, set tool offsets, run the first piece for approval, then machine parts in a cycle while checking dimensions and tool condition. The role reports to the Production Supervisor or Shift In-Charge. A good CNC operator keeps the machine cutting good parts within tolerance, catches tool wear before it makes scrap, and holds cycle time so the day's quantity is met.

Key responsibilities

  • Load the correct program for the job, mount the workpiece, and set work and tool offsets before starting.
  • Run and measure the first piece, get it approved by quality, and only then start the production cycle.
  • Machine parts through the cycle while watching for chatter, tool wear and abnormal sound or chips.
  • Measure critical dimensions at the set frequency with a micrometer or vernier and adjust offsets as tools wear.
  • Change worn inserts and tools at the planned life and reset offsets so parts stay within tolerance.
  • Segregate any out-of-tolerance part, stop and inform the supervisor when a dimension drifts out.
  • Keep coolant level and concentration right and clear chips so the machine and job stay clean.
  • Record output, rejection and tool changes on the machine log through the shift.
  • Do daily machine checks on lube, hydraulics and guards, and report faults for maintenance.
  • Follow safe practice for chuck loading, door interlocks and swarf handling at all times.

Requirements

  • ITI in Machinist or Turner trade
  • Diploma in Mechanical Engineering is an advantage
  • CNC operating course from an institute
  • 1 to 4 years operating CNC turning machines

KRAs and KPIs for a CNC Operator

Key result areas for the appraisal form, each with a KPI you can measure every month or quarter.

Key result areaHow to measure it
Dimensional qualityMachined parts within drawing tolerance on at least 99 percent of pieces each month
First-pass yieldFirst-piece approvals cleared without a second setup on at least 95 percent of jobs
Cycle timeStandard cycle time held on every job so the daily quantity is met
Tool costInsert and tool consumption kept within the standard per thousand parts
Machine careDaily machine checks completed and faults reported before breakdown each shift
SafetyNo unsafe chuck, door or swarf incident recorded in the month

Skills and tools

CNC turning operationProgram loading and offsetsMicrometer and vernier useInsert selectionDrawing readingGD and T basicsCoolant managementAttention to detail

Tools used day to day: CNC turning centre, Fanuc or Siemens control, Micrometer and vernier, Bore and snap gauges, Insert tooling.

Reporting line and career path

Production SupervisorCNC Operator

Interview questions for a CNC Operator

  1. How do you set work and tool offsets on a CNC lathe for a new job?
  2. A dimension slowly drifts oversize through the shift. What is happening and what do you do?
  3. How do you decide when to change an insert before it starts making scrap?
  4. What safety checks do you make before you close the door and start a cycle?
  5. How do you read a drawing tolerance such as a diameter with an h7 fit?
  6. Tell me about a time you found the cause of repeated rejection on your machine.

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Frequently asked questions

What does a CNC operator do?

A CNC operator runs a computer controlled turning centre. They load the program and job, set tool and work offsets, run and get the first piece approved, then machine parts while checking dimensions and tool wear. They change worn inserts, hold the cycle time and set aside any part that falls outside the drawing tolerance.

What is the difference between a CNC operator and a CNC programmer?

A CNC operator runs the machine using an existing program and manages offsets, tooling and quality during the shift. A CNC programmer writes and edits the part program, plans the tool path and cutting parameters, and often sets up new jobs. Many operators move into programming after learning the machine well.

What qualifications do you need to be a CNC operator?

Most CNC operators hold an ITI in the machinist or turner trade, or a mechanical diploma, plus a CNC operating course. Employers look for the ability to read drawings, set offsets, measure with a micrometer and vernier, and understand tolerances. Hands-on experience on Fanuc or Siemens controls is a strong plus.