Fagor 8055 MC: Configuring a Fourth Rotary Axis Guide

Define the Required Rotary Motion

Start by deciding whether the machine needs a CNC-controlled fourth axis or an independently controlled indexing table. The distinction determines the hardware, PLC logic, programming method, and verification criteria.

A product sold as a fourth axis may function only as an indexer after installation if the CNC lacks the required axis module or integration. Confirm interpolation capability rather than relying on the product description.

Audit the Fagor 8055 MC Configuration

The evidence does not establish one hardware configuration for every Fagor 8055 MC. One retrofit assessment indicated that an added axis can sometimes be implemented without another CNC card or software option, but it still requires parameter and PLC changes. A separate installation could not provide interpolation because its fourth-axis module was absent.

1. Inspect the installed axis hardware and document whether the CNC has a usable fourth-axis interface or module.
2. Determine whether the existing CNC and drive interface is analog or digital; the rotary table and drive must match the available control architecture.
3. Check the CNC configuration for permission to define and interpolate an additional axis.
4. Review the PLC program for spare commands, outputs, completion inputs, interlocks, and alarm handling.
5. Have a Fagor-qualified integrator assess parameter and PLC changes before purchasing the rotary unit.

The visible presence of separate X, Y, and Z axis cards does not, by itself, prove whether expansion is possible. Resolve the installed hardware and enabled configuration directly on the machine.

Integrate an Independent Indexing Table

An indexing table with its own controller can be connected through a CNC output and a completion feedback input. Modify the PLC so an M function activates the request output. Hold CNC execution until the table returns its completion signal.

1. Program the required angle or indexing sequence in the table's independent controller.
2. Issue the assigned M function from the machining program.
3. Use the M-function logic to activate the table request output.
4. Prevent the CNC from continuing until the completion input confirms that the table has finished moving.
5. Resume machining only after the returned status satisfies the machine interlocks.

One reported installation initially proposed M80, but that identifier is installation-specific evidence, not a universal Fagor assignment. Select an available M function through the machine's PLC design. A suggested alternative was to force an output from the CNC program and loop until feedback arrived, but its feasibility was explicitly unverified; do not use it without confirming the supported CNC instructions and failure behavior.

Account for Programming and Simulation Limits

An independently controlled table requires separate CNC and table programs. The CNC program can request the move, but the CNC does not calculate the table trajectory as one of its own axes. Consequently, its graphical simulation cannot represent the complete coordinated machine motion.

Starting a table and a linear move near the same time does not establish interpolation. Verify that the CNC itself commands both positions in one coordinated motion block before classifying the installation as a true fourth axis. Otherwise, treat it as indexed positioning and prohibit cutting that depends on a controlled relationship between rotary and linear trajectories.

Add Automatic Workpiece Referencing

The Fagor 8055 MC evidence identifies a probing function for workpiece zero setting, but it does not establish a probe model, wiring arrangement, option status, or complete cycle sequence. The operator must first pre-position the probe near the center of the workpiece before running the documented probing operation.

1. Confirm that the required calibration or probing function is present in the installed control configuration.
2. Verify probe input operation and machine interlocks through the machine documentation and integrator.
3. Pre-position the probe at the required starting location near the workpiece center.
4. Run the supported probing operation for the required X, Y, and Z references.
5. Confirm the resulting work offsets against a known feature before machining.

Do not treat this operation as machine-axis reference return. It establishes workpiece references; the machine reference procedure serves a different purpose.

Commission and Verify the Retrofit

Test the installation without cutting before releasing it for production. For an interpolated axis, command a combined linear-and-rotary move and verify that both trajectories remain under CNC control. For an indexer, verify the request output, completion input, CNC wait state, final angle, and safe program resumption.

Interrupt or withhold the completion signal during commissioning and confirm that the CNC does not continue into the next machining move. Also verify that a table-controller fault cannot be mistaken for successful completion. Finally, repeat the probing cycle and independently check the resulting workpiece zero.

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