Side Mount (SMTC) - Double Arm - How it Works and Troubleshooting Guide

How it Works

The cambox [1] controls the double arm [2] movement with a motor and a cam. One rotation of the cam moves the double arm through the entire tool change cycle. The cam is driven by a DC motor [3] or by a servo motor.

A cambox that has a DC motor uses (3) proximity sensors to determine the position of the double arm throughout the tool change cycle: clamp/umclamp, origin, and motor stop.

A cambox that has a servo motor uses an origin proximity sensor as a reference home position and motor encoder counts to determine the position of the double arm throughout the tool change cycle.

  1. Double arm: Moves tools to the carousel and the spindle.
  2. Slide: Pushes against the tool to hold it in place during double arm movement.
  3. Return spring: Pushes the slide against the tool.
  4. Shim washers: Shims adjust the slide for proper grip. If the slide is adjusted too tightly against the tool, it may not lock during rotation.
  5. Adjuster rod: Locks the slide in place during a tool change.
  6. Jam nut: This nut tightens against the slide to prevent the adjuster rod from rotating loose.
  7. Plunger: Locks the adjuster rod during arm motion. The adjuster rod and slide cannot move when the plunger is in the extended position.

Symptom Possible Cause Corrective Action Section

Alarm 622 TOOL CHANGER ARM FAULT

Alarm 2066 TOOL CHANGER HOME POSITION FAULT

The tool changer arm is not at the origin position when the machine is powered on, or it was not recovered correctly. Do a tool change recovery. 1
One or more of the proximity sensors on the cambox are defective. Rotate the arm in recovery mode and test the sensors. 2
Alarm 627 ATC ARM MOTION TIMEOUT One or more of the proximity sensors on the cambox are defective. Rotate the arm in recovery mode and test the sensors. 2
The cambox drive belt is worn or damaged. Inspect the belt. 5
Alarm 628 ATC ARM POSITIONING ERROR The double arm's travel was obstructed.

Check the tool changer alignment.

Move the obstructions or set a safe tool change position.

4
The spindle orientation is incorrect. Find the cause of the spindle orientation error. 3
The cambox is defective. Test the cambox. 8
Tools fall out of the spindle side during a tool change. The toolholders or pull studs are incorrect. Check for correct tool specifications. 6
The tool is too heavy. Check for correct tool weight specifications.
The arm and plunger are worn. The double arm cannot correctly engage with the tool. Replace the worn parts in the double arm. 7
The spindle orientation is incorrect. Find the cause of the spindle orientation error. 3
The double arm is bent. Find the cause of the double arm bending. Straighten or replace the double arm. 4
Tools fall out of the arm during rotation. The arm and plunger are worn. The double arm cannot correctly engage with the tool. Replace the worn parts in the double arm. 7
Tools fall out of carousel tool pockets. The pocket spring or plungers are worn or damaged. Refer to SMTC - Carousel and Pocket Troubleshooting Guide N/A

Section 1

Symptoms: Alarm 622 TOOL CHANGER ARM FAULT. Alarm 2066 TOOL CHANGER HOME POSITION FAULT.

Possible Cause: The tool changer arm is not at the origin position when the machine is powered on, or it was not recovered correctly.

Corrective Action:

Check the arm at Arm at Origin bit in Recovery.

Recover the tool changer.

Refer to Video - Tool Changer Recovery - Side Mount Tool Changer (SMTC)

Refer to VMC, HMC - Side-Mount Tool Changer - Manual Recovery

Section 2

Symptoms: Alarm 622 TOOL CHANGER ARM FAULT. Alarm 2066 TOOL CHANGER HOME POSITION FAULT. Alarm 627 ATC ARM MOTION TIMEOUT. 628 ATC ARM POSITIONING ERROR.

Possible Cause: One or more of the proximity sensors on the cambox are defective.

Corrective Action:

Remove the carousel number plate to get access to the sensors [1]. Go into the manual tool recovery and push ATC FWD to move the arm through a complete cycle. Make sure the LED on the sensor and the diagnostic bit state change at the correct stage of the tool change cycle. See the chart below.

If the sensors fail to change state, go to diy.haascnc.com to troubleshoot and replace the proximity sensors.

SENSOR Origin Rotation Tool Pick - Up Down / Rotation 180 / Up Tool Exchange Arm Backup (Reverse) Origin
Clamp/unclamp Amber/0 Amber/0 Off / 1 Amber/0 Off / 1 Amber/0 Amber/0
Origin Off / 1 Red / 0 Red / 0 Red / 0 Red / 0 Red / 0 Off / 1
Motor stop Off / 1 Red / 0 Off / 1 Red / 0 Off / 1 Red / 0 Off / 1

Section 3

Symptoms: Tools fall out of the spindle side during a tool change. Alarm 627 ATC ARM MOTION TIMEOUT.

Possible Cause: The spindle orientation is incorrect.

Corrective Action:

Find the cause of the spindle orientation error.

Make sure spindle drive and encoder belts have the correct tension. Make sure the spindle motor pulley [1] and encoder pulley [2] are not worn.

Refer to VMC - Side-Mount Tool Changer - Spindle Orientation Offset - Parameter 257.

Section 4

Symptoms: Alarm 628 ATC ARM POSITIONING ERROR. Tools fall out of the spindle side during a tool change.

Possible Cause: The double arm's travel was obstructed. The double arm is bent.

Corrective Action:

Use a straightedge to find out if the arm is bent. If the arm is bent, these are some of the possible causes:

1: The tool release piston (TRP) sensor(s) are not adjusted correctly.

If the TRP sensors are not adjusted correctly, a tool can get stuck in the spindle taper, or the drawbar might not release a tool. Damage to the double arm can occur. Adjust the tool release piston switches correctly. Refer to VMC - 20/30/40-Taper- TRP - Proximity Sensor - Adjustment.

2: The arm crashed into a rotary or a fixture during a tool change.

Refer to your operator's manual to set the tool change offset, or alias an M06 command, to move the spindle to a safe height. Move the obstacle on the table to a safe distance away before the tool change. If you install a rotary or trunnion unit, mount it as far to the right as your setup will allow. This gives you more room for safe tool changes.

Go to Episode 21 - How to Command a Safe Tool Change Position to Avoid Fixtures and Rotaries for more information.

3: A failed cambox position sensor may cause the machine to think the arm is at the home position. The Z Axis comes down and bends the arm. Refer to Section 2 in this document.

Go to parts.haascnc.com to find the correct double arm for your machine. Follow the replacement instructions that ship with the assembly.

Section 5

Symptoms: 628 ATC ARM POSITIONING ERROR.

Possible Cause: The cambox drive belt is worn or damaged.

Corrective Action:

Inspect the belt for damage and replace it if necessary. Refer to VMC Side-Mount Tool Changer - Cambox Motor Replacement for how to replace the cambox belt.

Section 6

Symptoms: Tools fall out of the spindle side during a tool change. Tools fall out of the pocket during a tool change

Possible Cause: The toolholder or pull studs are incorrect. The tool is too heavy.

Corrective Action:

Refer to these documents for the correct pull stud and tool weight specifications:

If you have a heavy tool, install the Pocket Dampening Service Kit (P/N 93-0254). This kit dampens the air to the pocket up/down cylinder to slow down the pocket.

Section 7

Symptoms: Tools fall out of the spindle side during a tool change. Tools fall out of the arm during rotation.

Possible Cause: The arm and the plunger are worn. The double arm cannot correctly engage with the tool.

Corrective Action:

Inspect the plunger and adjuster assembly. Refer to Side-Mount Tool Changer - Double Arm - Plunger and Adjuster Assembly - Inspection

Refer to Video - Side Mount Tool Changer (SMTC) Double Arm Maintenance for more information on how to maintain the double arm.

Section 8

Symptoms: Alarm 628 ATC ARM POSITIONING ERROR.

Possible Cause: The cambox is defective.

Corrective Action:

Remove the motor and cycle the cambox by hand. There should not be any binding in the arm. There should be less than 1/4" (6 mm) of lost motion in the rotation or lift of the arm.

Be aware: Many service and repair procedures should be done only by authorized personnel. The service technicians at your Haas Factory Outlet (HFO) have the training, experience, and are certified to do these tasks safely and correctly. You should not do machine repair or service procedures unless you are qualified and knowledgeable about the processes.

Danger: Some service procedures can be dangerous or life-threatening. DO NOT attempt a procedure that you do not completely understand. Contact your Haas Factory Outlet (HFO) and schedule a service technician visit if you have any doubts about doing a procedure.

Feedback