Assisted Production Tasks: Robots, PLCs, and Drives

Assisted Production Tasks: Robots, PLCs, and Drives

During your externship placement you will move from the lab to a live production environment. Your role is to support the site technician — not to work independently — and every task you perform must be authorized by your supervisor before you begin. This lesson prepares you to carry out the three main categories of assigned production-support tasks: robot preventive maintenance (PM), PLC and HMI fault monitoring, and drive setup support. It also reminds you of the safety obligations that apply on any industrial site.

Safety First: Lockout/Tagout and Electrical Hazards

Before touching any machine, confirm which energy-control procedure applies. OSHA 29 CFR 1910.147 (Control of Hazardous Energy) requires that all potentially hazardous energy sources — electrical, pneumatic, hydraulic, gravitational — be isolated, locked, and tagged before any servicing or maintenance activity. You must have your own lock and tag; never rely on someone else's lock to protect you.

For electrical work, NFPA 70E requires you to determine the arc-flash and shock boundaries before approaching exposed conductors. Wear the PPE specified on the site's arc-flash label (at minimum, safety glasses; often a face shield, arc-rated clothing, and insulating gloves for energized-work tasks). Before declaring a circuit de-energized, use a properly rated meter to verify the absence of voltage — test the meter on a known live source first, test the circuit, then test the meter again.

For robot cells, ANSI/RIA R15.06 / ISO 10218 defines safeguarding requirements. Confirm that safety-fence interlocks and light curtains are functional before any cell operation resumes after maintenance. Never defeat or bypass a safety device, even temporarily, without explicit written authorization from the site safety officer.

Machine guarding rules under OSHA 1910.212 also apply: pinch points, rotating shafts, and nip points on conveyors must be guarded whenever the machine is running.

Robot Preventive Maintenance Tasks

Scheduled PM keeps industrial robots reliable and safe. When assisting with FANUC or equivalent robot PM, your responsibilities typically include:

Joint lubrication check. Consult the robot manufacturer's maintenance schedule (found in the controller or a paper log) to confirm whether grease replenishment is due based on operating hours. Record the date of the last service and the current hour count from the controller. Do not add lubricant unless specifically instructed — using the wrong grease type or quantity can damage seals.

Teach-pendant battery backup. The FANUC controller stores programs and system parameters in battery-backed memory. Check the controller alarm log and the pendant display for any low-battery warning. Record the battery installation date from the maintenance log. A dead battery can cause loss of all stored programs, so this check is critical and maps directly to the FCR-T1/T2 curriculum area of program backup.

Safety fence interlock verification. With the site technician supervising and the cell in a safe state, test each gate switch and light curtain: open the gate and confirm the robot enters a safe stop; close the gate and confirm the run-enable signal returns. Record each test result (pass/fail) in your field log. This links to ANSI/RIA R15.06 safeguarding requirements.

I/O and frame notes. Review the program structure with the technician — note which user frame and tool frame are active, and confirm that the I/O signals for the gripper or end-of-arm tool respond correctly during a dry-cycle jog. These topics are core FCR-T curriculum areas.

PLC and HMI Fault Monitoring

In a live facility you will use the site's PLC software or HMI to observe real-time production data. When monitoring I/O in ladder logic (the most common IEC 61131-3 language on manufacturing floors), energized contacts appear highlighted and coils show their true ON/OFF state. To trace a fault:

1. Open the maintenance or alarm log and note the fault code, time stamp, and affected device.

2. Navigate to the rung that controls that device. Look for contacts that should be closed but are open, or coils that are unexpectedly de-energized.

3. Cross-reference the I/O address with the site's wiring diagram to identify the physical sensor or switch involved.

4. Report your finding to the technician before any corrective action is taken.

Record the IEC 61131-3 language observed, the fault code, and the corrective action the technician took. Common corrective actions include clearing a jammed sensor, resetting an overload relay, or correcting a wire connection — each of which must follow the appropriate LOTO procedure.

Drive Setup and Motor Speed Calculations

When a cell changeover involves a VFD or servo drive, you may be asked to record motor nameplate data and verify that the drive parameters match the motor's specifications. Key nameplate values include rated voltage, full-load amps, horsepower or kW, rated RPM, and the number of poles.

From the nameplate pole count and the supply frequency, calculate synchronous speed:

Ns = 120 × f / P

where f is supply frequency in Hz and P is the number of poles. An induction motor always runs slightly below synchronous speed; the difference is slip. Confirm that the speed shown on the HMI is close to (but less than) the calculated Ns at full load — a large deviation may indicate a load or parameter problem. Log the nameplate data, your calculation, and the HMI reading in your field log.

Field Log Requirements

Every task must be logged on the same day it occurs. Each entry must include: date and hours worked, a description of the task, the equipment involved (make, model, tag number if available), the safety steps you followed (LOTO applied, PPE worn, interlocks verified), and a credential-mapping note identifying which FANUC CERT, PMMI, or Siemens SMSCP domain the task relates to. Your school coordinator reviews entries bi-weekly, and your site supervisor completes a midpoint evaluation between weeks 8 and 10 of the placement. A passing result requires a satisfactory or better rating on all evaluated domains.