Fixed tools now cut about 2 mm short after the collision, but that does not prove the spindle cartridge moved inward by 2 mm. Treat the change as a machine-geometry failure until spindle position, runout, clamping, tool-change alignment, and pallet alignment have all been measured.
Reject the quick fixes first
| Quick fix | Why it fails | Use instead |
|---|---|---|
| Edit every tool length by about 2 mm | This hides a common shift without identifying whether it came from the spindle, head, table, foundation, tool interface, or coordinate references. The correction can also become dangerous when the damaged component moves again. | Record the offset error, then measure spindle and machine geometry from stable references. |
| Replace the spindle immediately | A length change alone does not prove bearing or cartridge failure. In this case, the spindle test and tool change later ran correctly while pallet exchange remained impossible. | Separate spindle-condition tests from full-machine geometry checks. |
| Run straight to maximum spindle speed | A damaged bearing, loose tool, or displaced component can deteriorate during a high-speed test. Temperature alone also cannot clear the rest of the machine. | Inspect at rest, rotate by hand, measure runout, and stage the speed test under the machine builder's procedure. |
| Clear alarms and restart production | Control readiness does not verify mechanical alignment. A pallet changer may remain displaced even when spindle rotation and tool exchange work. | Prove every affected mechanical function independently. |
| Force or jog a misaligned pallet into position | The changer can bind, drop the pallet, or transfer collision load into another component. | Stop the exchange and measure the base and transfer alignment. |
Get it running only after the measurements show what remains serviceable. Fix the geometry properly before releasing normal production.
Separate the symptom from the cause
The reported symptom is an approximately 2 mm change in the effective length of fixed tools after a severe negative-Z collision. That observation identifies a common axial relationship change; it does not locate the movement. The spindle cartridge may have shifted, sacrificial crush elements may have absorbed load, the head or machine base may have moved, or a reference used for setting the tools may have changed.
| Observed symptom | Likely area to inspect | Deciding check |
|---|---|---|
| All fixed tools show nearly the same axial error | Spindle-to-table geometry, head position, reference surface, or common tool-setting reference | Measure a qualified spindle reference against a stable machine reference; do not infer physical spindle movement from tool offsets alone. |
| Roughness or rattling while rotating the spindle by hand | Spindle bearings or internal components | Stop powered testing and request a spindle inspection. |
| Runout at a test arbor | Tool interface, arbor, spindle taper, bearings, or cartridge alignment | Clean the interfaces, repeat with a known test arbor, and compare indicator readings at defined positions. |
| Spindle does not return after a controlled lateral deflection check | Mechanical looseness, displacement, or bearing damage | Stop; record the displacement and call official service. |
| Temperature continues climbing during a controlled run | Bearing damage, lubrication, cooling, or preload problem | Stop the spindle and trend temperature against time rather than relying on one reading. |
| Tool change fails or the mechanism is pulled out of alignment | Spindle clamping position or tool-changer alignment | Check exchange position and mechanical alignment without forcing the cycle. |
| Spindle and tool change pass, but pallets will not enter straight | Machine base, pallet changer, or transfer geometry | Measure base level and pallet-transfer alignment. |
Lock down the machine before testing
Preserve the collision state before anybody edits offsets or reference values. Save alarms and diagnostic information, note the active tool and program position, and record the approximately 2 mm discrepancy. Photograph witness marks and document which axis and components made contact.
- Remove the workpiece, broken tooling, and loose debris only when the machine can be accessed safely.
- Inspect the spindle nose, taper, toolholder, table, fixtures, pallet interfaces, covers, and changer mechanisms for contact marks or displacement.
- Check whether the spindle can be turned by hand under the machine builder's safe maintenance method. Stop if it binds, feels rough, or rattles.
- Do not command an automatic tool or pallet exchange until the exchange paths and alignment have been inspected.
- Do not compensate the 2 mm error in production offsets. Keep the measurement as diagnostic evidence.
Stop here if the spindle binds, the tool cannot be released safely, a pallet is unsupported, or any structural component is visibly displaced. Those conditions require mechanical recovery procedures, not control edits.
Measure the spindle before running it hard
Use a clean, known test arbor and a dial indicator. Dirt or damage at the taper can imitate spindle runout, so clean both mating surfaces and inspect them before recording values. The allowable runout must come from the DMC 60 T service specification or the test-arbor procedure; no universal acceptance value can be assigned from the collision report.
- Mount the test arbor using the normal clamping system.
- Place the indicator at a defined position near the spindle and mark that position in the record.
- Rotate the spindle slowly by hand and record total indicated variation.
- Move the indicator to a second defined position farther along the arbor. Repeat the measurement to separate angular error from local interface error.
- Unclamp, rotate, and reclamp the arbor if the service procedure permits. A changing high point points toward the arbor or interface; a repeatable high point tied to spindle rotation directs attention toward the spindle.
- Check axial position from a qualified spindle reference to a stable machine reference. Compare that result with the common tool-length change.
- Apply only the controlled lateral check specified by the builder, then verify that the spindle returns to its original indicator position. Do not pry on the spindle nose.
If sacrificial crush sleeves or similar energy-absorbing elements are fitted, inspect them through the manufacturer procedure. Their presence was suggested as one possible explanation, but the machine configuration must be checked before planning replacement.
Stage the spindle run and trend temperature
Run the spindle only after the static inspection and runout checks pass. Use a correctly retained tool or approved balance tool, close the enclosure, and increase speed in controlled stages. Listen for new vibration or bearing noise at every stage and stop on any abrupt change.
The cited field check used maximum speed for about 10 min and watched spindle temperature. One installation reportedly stabilized around 35 to 37 degrees C; that is a historical observation, not a DMC 60 T acceptance limit. Judge this machine against its normal baseline and the manufacturer's permitted temperature and rate-of-rise values. An uncontrolled rise matters more than a single temperature reading.
On a TNC-equipped DMG machine, the temperature was displayed as S-Temp. The affected DMC 60 T used a MillPlus control, so that TNC screen path did not apply. For the reported MillPlus interface, open the Controll surface where the tool table is located, select Install, activate temperature compensation, then display machining status in automatic operation to view temperature. Treat this path as interface-specific; if those selections are absent, use the machine documentation or official service rather than changing unrelated installation settings.
Test tool and pallet exchange separately
A successful spindle run does not clear the automatic handling systems. A collision can move the machine structure or changer while leaving spindle rotation apparently normal.
- Verify spindle orientation, tool-release action, clamping, and exchange position using the maintenance procedure.
- Observe a controlled tool-change test at reduced operating risk. Stop if the spindle clamping mechanism lifts, pulls, or misaligns the tool changer.
- Inspect pallet rails, locating features, lift points, transfer components, and the machine base before requesting pallet movement.
- Command only the permitted maintenance movement. Stop immediately if the pallet approaches at an angle or requires abnormal force.
- Measure machine level, base alignment, and pallet-transfer geometry with suitable metrology equipment.
In the reported case, the spindle test and tool change passed, but no pallet could be exchanged. Inspection found the machine base displaced enough that pallets no longer entered straight. That result changes the repair scope from a spindle-only investigation to a complete geometry and pallet-system recovery.
Verify geometry before releasing production
Request a complete geometry inspection after a collision that produces an approximately 2 mm common tool-length change or visible base displacement. The inspection must cover the spindle axis, table or pallet references, relevant axis relationships, tool-change position, and pallet-transfer alignment. Use the machine builder's tolerances rather than shop-selected numbers.
- Complete the mechanical repair and restore the machine base and changer alignment.
- Repeat spindle runout and axial-reference measurements with the same setup used before repair.
- Repeat the staged temperature test and compare the full temperature trend.
- Cycle the tool changer through all required positions without a cutting tool or workpiece exposed to collision risk.
- Cycle the pallet system under the approved recovery procedure and verify smooth entry, seating, clamping, and release.
- Run a geometry test and document results against the manufacturer's limits.
- Cut or probe a controlled verification feature before restoring the original tool offsets and production program.
Pass each subsystem on measured results. A good test in one area cannot cancel a failure in another.
FAQ
What happens if I correct every tool by 2 mm and keep running?
The offsets can hide displaced geometry while the spindle, base, tool changer, or pallet system remains damaged. Preserve the common 2 mm error for diagnosis and release production only after geometry and handling checks pass.
What happens if spindle temperature reaches 35 to 37 degrees C?
That range was reported after about 10 minutes at maximum speed on one installation, not as a DMC 60 T limit. Compare the rate of rise and stabilized value with this machine's baseline and official limits; stop if temperature continues climbing or noise and vibration increase.
What happens if the spindle test passes but pallets bind?
Keep the machine out of production and inspect the base and pallet-transfer geometry. The documented case passed spindle and tool-change tests but still required service because the displaced base prevented straight pallet entry.
Stop testing and contact official manufacturer service when the spindle binds, runout or position exceeds the specified tolerance, temperature rises without stabilizing, the tool changer is pulled out of alignment, or a pallet will not enter straight. Request a documented geometry inspection and repair plan; do not force an exchange or mask the condition with offsets.