Fanuc Parameter 1860 [ CERTIFIED × 2024 ]

Mastering Motion: Understanding FANUC Parameter 1860

When working with FANUC CNC machines, few things are as frustrating as a machine that refuses to reach its commanded speed, or worse, throws an alarm during a rapid move. Often, the culprit isn't a mechanical failure or a broken servo motor—it's a parameter setting deep within the control.

Today, we are taking a close look at FANUC Parameter 1860.

Whether you are a service engineer, a maintenance technician, or a CNC machinist looking to understand your machine better, this post explains what this parameter does, why it matters, and how to troubleshoot issues related to it. fanuc parameter 1860

9. Safety and Best Practices

• Never set 1860 to zero – The axis will not move during reference return.
• Document original values before changing. Back up parameters via RS-232 or memory card.
• Test without tools or workpieces first. An unexpected fast homing could crash a tool into a fixture.
• Use a consistent procedure when tuning—environmental temperature affects limit switch repeatability, which interacts with 1860.
• If the machine has multiple reference positions (e.g., G30 2nd reference), Parameter 1860 applies only to G28 (1st reference). Separate parameters (1861, 1862) control other reference return speeds.

3. Servo Alarms

This is the most common reason technicians look up this parameter. If the acceleration is too aggressive for the load on the axis, the servo motor may not be able to keep up with the commanded position. This frequently results in Servo Alarm 410 (Excess Error in Stop) or Servo Alarm 411 (Excess Error in Moving).

Part 6: Common Alerts and Troubleshooting Related to 1860

Step 5 — Set and Validate

Write the final 1860. Power cycle the CNC (some controls require restart). Re-home and verify repeatability. Never set 1860 to zero – The axis

Warning: Do not exceed the maximum allowable feedrate of the axis motor/drive. Check motor torque curves. High 1860 on a heavy axis may cause following error (alarm PS0410).

8.1 Alpha i Series (Most common today)

• Parameter 1860 is active only when using the serial interface (Fanuc serial spindle bus).
• Supported on software version 9040 or higher.

Prerequisites

• Machine is powered on, emergency stop released.
• Know axis rapid speed (Parameter 1420) and maximum feedrate (1430).
• Know dog length (typically 20-50 mm for linear axes).

Part 9: Best Practices from the Field – A Maintenance Engineer’s Guide

1. Document Everything: Keep a log of original 1860, date of change, and observed behavior. Copy parameters to a memory card before tuning. Listen and Feel: After each M19

2. One Change at a Time: Never adjust 1860 and 1861 (time constant) simultaneously. Change gain first, settle time second.

3. Listen and Feel: After each M19, place your hand on the spindle nose. A “snappy” but silent lock is ideal. A slow, mushy lock indicates low gain. A high-pitched whine indicates excessive gain.

4. Temperature Compensation: On machines with high spindle duty cycles, re-check orientation behavior after the spindle reaches thermal steady-state (2-3 hours of cutting). You may need a slightly higher 1860 when hot due to decreased magnetic flux.

5. Backup SRAM Memory: Parameter 1860 is stored in the CNC’s non-volatile SRAM. If the battery backup fails, you will lose it. Always keep a printed or digital backup of all parameters.

Mastering Fanuc Parameter 1860: The Complete Guide to Spindle Orientation and Positioning