Used Charmilles: How to ensure accuracy?

Author:JL           Date:2025-11-21

A Systematic Approach to Ensuring the Accuracy of Used Charmilles

Ensuring the accuracy of used charmilles is a comprehensive, systematic project encompassing everything from procurement evaluation to routine maintenance. It's not merely about verifying a static indicator, but about continuously guaranteeing the overall performance and stability of the machine tool. The following are the core steps in ensuring its accuracy:

First, precise inspection and verification before procurement are the cornerstone.

Before investing in used charmilles, a professional accuracy certification that goes beyond visual inspection is essential. This requires experienced engineers using specialized tools:

Geometric Accuracy Inspection: Using precision levels, right-angle rulers, and laser interferometers, the flatness of the machine tool's worktable, the straightness of the X/Y/Z axes, and the perpendicularity between axes are inspected. This forms the foundation for all motion accuracy; any deviation will directly affect the machined workpiece.

Motion Accuracy and Positioning Accuracy Inspection: Positioning accuracy and repeatability of each axis are measured using a laser interferometer to ensure the machine tool accurately reaches the commanded position. This is the lifeline for machining complex contours using wire EDM.

Actual machining test cuts: The most direct verification method is to machine a standard test piece, such as cutting a test block with sharp corners, rounded edges, and vertical surfaces. Then, a coordinate measuring machine (CMM) is used to precisely measure the dimensions, contours, and surface roughness of the test piece. This comprehensively verifies the coordinated performance of the machine tool's mechanical, electrical, and control systems under real loads.

Secondly, comprehensive and in-depth preventative maintenance is essential.

Precision requires continuous maintenance, the core of which lies in meticulous attention to key systems:

Mechanical transmission system maintenance: Regularly check and adjust the clearance and preload of the lead screw and guide rails to ensure no backlash or appropriate preload. Strictly adhere to lubrication requirements for the guide rails and lead screws to prevent wear-induced precision loss.

Fluid system maintenance: This is paramount to ensuring the machining accuracy and surface quality of Charmilles machine tools. The water tank must be cleaned regularly, the filter element replaced, and the condition of the deionized water resin strictly monitored to ensure the resistivity of the dielectric fluid remains within the optimal range. Impure machining fluids or those with substandard conductivity can cause abnormal discharge and uneven electrode wire wear, directly leading to dimensional inaccuracies and surface defects.

Guide and Conductor Block Management: Wear on the guide nozzle directly affects the positioning accuracy and perpendicularity of the electrode wire, while worn conductor blocks can cause wire breakage and unstable energy transmission. These critical wear parts must be inspected regularly and replaced promptly.

Third, professional refurbishment and calibration are key improvements.

For machine tools with long service lives, necessary professional intervention is an effective means of restoring accuracy:

Accuracy Repair (Scraping): When basic components such as guideways show wear, manual scraping by professional technicians is the only reliable method to restore their original geometric accuracy.

System Parameters and Servo Debugging: Optimization and calibration of servo gain and circuit parameters by engineers familiar with Charmilles systems can significantly improve the machine tool's dynamic response performance and machining stability.

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