Lean Inventory Optimization and Repair Strategy of Mandrel Bars at VM Star

摘要

This paper is presenting the future works of a continuous improvement team formed at V&M Star. The CIT was formed in order to teach lean manufacturing principles and successfully implement an optimization strategy for mandrel bars. The mandrel bar is a perishable tool that acts as a guide when rolling a shell while also defining its internal diameter and pipe wall-thickness. The repetitive heating and cooling under extreme force loads adds to the complexity of a mandrel bar management strategy. Mandrel bars are highly susceptive to deformation during the rolling process which negatively impacts mandrel bar life. Including bar cycle time, which refers to the contact time a bar has with the steel during the rolling process. Another being related to mill set up in the multi stand pipe mill, which is dictated by each operator. All of these uncertainties inhibit housing excessive lot quantities of mandrel bars. Bars are purchased in large quantities due to high variability in tool life and long lead times after manufacture. All of these factors were considered by a steering committee which chose to form this CIT. The CIT's main objectives are: 1. Optimize a re-weld/turndown strategy; 2. Eliminate waste- Inventory, excessive transportation, work in process, defects related to material handling; 3. Better visually manage inventory by implementing 5-S; 4. Update standard work.