The Complete Guide to CNC
Ballscrew Overhauls & Recommissioning
In high-precision manufacturing, positioning accuracy is everything. Whether producing Tier-1 aerospace parts or high-volume automotive components, your CNC machinery relies entirely on mechanical integrity to maintain sub-micron tolerances.
When positioning errors, poor surface finishes, or axis backlash begin to creep into your production, the primary culprit is often a worn or damaged ballscrew assembly.
Many machine shop managers assume a failing axis requires a costly, brand-new replacement part with long lead times. However, a complete bench overhaul and precision recommissioning can return your existing assembly to original OEM specifications at a fraction of the cost and downtime.
Here is an inside look at how the Alt CNC engineering team takes a ballscrew from initial tear-down back to factory-fresh recommissioning.
1. On-Bench Teardown & Inspection
A reliable overhaul begins with rigorous diagnostics before any reassembly takes place. Once the ballscrew and drive assembly are removed from the machine tool and transferred to the bench, our engineers begin a complete teardown.
Dismantling & Visual Checks - The assembly is systematically disassembled, separating the ballnut, support housings, drive ends, and journals. We conduct a detailed visual inspection across the entire screw thread and recirculating raceways to detect pitting, scoring, or thermal wear.
Deep Chemical Cleaning - Contaminated grease, micro-swarf, and debris build up inside the ballnut over thousands of operating hours. All internal parts undergo thorough chemical degreasing and deep cleaning to ensure an ultra-clean environment for precision measurement.
2. Micrometer Measurement & Precision Re-Balling
Eliminating axis backlash requires micro-level adjustments to the ballnut assembly.
Measuring Tolerances - Using micrometer gauge equipment, each individual recirculating bearing ball is measured to quantify mechanical wear.
Backlash Calculation & Re-Balling - We calculate the exact ball sizes required to eliminate axial play while maintaining smooth rolling resistance. The ballnut is loaded with fresh, precision-sorted bearing balls to restore correct preload.
Documentation - Every measured tolerance, pre-load reading, and replaced component is logged in a formal inspection report, providing a clear record of compliance back to OEM standards.
3. Support Housing & Bearing Preparation
Restoring the ballscrew thread is only half the battle; the support bearings carrying the dynamic load must be equally precise.
Super-Precision Bearings - We replace worn support bearings with new, high-grade angular contact bearing sets (such as Koyo matched units).
Correct Greasing & Sealing - Bearings are packed with exact grease volumes specified for high-speed CNC applications to prevent thermal expansion issues, before being fitted into wiped-down support housings.
4. Machine Refitting & Geometric Alignment
Once the bench overhaul is complete, the ballscrew is ready for refitting back into the machine tool structure. Mechanical alignment during this phase is vital to prevent premature wear and binding across full travel.
Manual Placement & Drive Mounting - The assembly is manually fitted into the machine bed. The drive ends, belt pulleys, and drive motors are carefully remounted.
Clocking & DTI Verification - Using a magnetic dial test indicator (DTI), the table and axis assembly are clocked up against the machine’s precision linear guideways. This ensures runout alignment, parallelism, and squareness across the full stroke of the axis.
Eliminate Downtime & Restore OEM Accuracy
Allowing a worn ballscrew to run unchecked leads to catastrophic axis failure, spindle damage, and scrapped components. By opting for a dedicated overhaul, you protect your machine’s baseline calibration while avoiding the delays of international parts sourcing.
Whether you are experiencing backlash on a 5-axis machining centre or need scheduled preventative maintenance across your fleet, Alt CNC delivers certified engineering expertise to keep your production running. Get in touch today!
