ROOT CAUSE ANALYSIS KERUSAKAN SISTEM PENGEREMAN SPINDEL MESIN FRAIS AJAX MODEL N2A MKV MENGGUNAKAN METODE 5 WHY

Abstract

The spindle braking system is one of the most important components in a milling machine because it stops spindle rotation immediately after machining. Failure of the braking system reduces operational safety, decreases machining efficiency, and accelerates component wear. This study aims to identify the root cause of spindle braking system failure in an Ajax Model N°2A M^KV milling machine using the Root Cause Analysis (RCA) method with the 5 Why approach. Data were collected through direct observation, machine manual review, electrical testing using a multimeter, and systematic root cause analysis. The results indicate that the braking system failed due to a short circuit in the electromagnetic motor coil, causing excessive current in the AC-to-DC braking circuit. Consequently, the bridge rectifier diode and fuse repeatedly failed. The root cause was identified as coil deterioration caused by prolonged service life. The 5 Why method effectively identified the root cause and provided a basis for corrective actions and preventive maintenance to improve machine reliability.