These problems have also affected a global manufacturer of air brake and train control systems. The manufacturer had a surge in production, and its in-house vacuum impregnation line could not meet the production demands. The impregnation system was in the company’s Mexicofacility. This facility cast, machines, impregnates, assembles, and tests the aluminum castings before shipping to its OEM customers.
An Ineffective Process Flow as just one of many Challenges
The manufacturer was using a batch impregnation system with a thermal-cure sealant. The system aggregated castings after machining and processed them in large batches. After processing, the castings moved to washing. After considerable research, the following challenges could be identified:
- Poor Recovery: The batch system’s historical average First Time Through (FTT) was 85 % recovery.
- Wash Contamination: The batch system lacked a centrifuge, which caused a significant amount of sealant to be dragged into the wash. The contaminated water affected the system’s ability to wash sealant from casting surfaces.
- Water Use: Due to this contamination, the manufacturer continuously replaced its wash water. Strict water regulations in Mexico forced the manufacturer to dispose of this water by collecting it in totes and sending it to a water treatment facility. The manufacturer used approximately 600 gallons of water per day.
- Ineffective Process Flow: The system was permanently positioned outside the flow of the production line, requiring the operators to move parts to and from the batch system. This increased overall production cycle time and increased the risk of handling damage.
The Solution: Integrating a Lean Vacuum Impregnation System
Based upon these requirements, a vacuum impregnation system could be a possible solution. For example the High Value Low Volume (HVLV) system from Godfrey & Wing that uses the Dry Vacuum and Pressure (DVP) process. DVP incorporates a fast, deep vacuum to evacuate air from a casting’s porosity. The system applies high pressure to allow the sealant to thoroughly penetrate deep in the casting walls.
After sealant penetration, the fixture is processed through a centrifuge to recover unused sealant. The sealant is returned to the sealant reservoir for use in subsequent cycles. Conserving unused sealant prior to the wash enables the wash water to remain pure. This allows the wash water to fully clean the part, eliminating the risk of contamination.
Custom-designed fixtures hold the castings in place. This maximizes the number of castings that can be processed per cycle, helps ensure sealant is flushed from blind holes, and protects critical machined features.
The HVLV’s ergonomics allow the operator to easily slide the fixture on the platform to each module, enabling faster processing than a batch system.
After just one month the manufacturer of air brake and train control systems achieved the following results:
- Scrap from porosity has been virtually eradicated with the HVLV delivering a FTT rate of over 99 %.
- The system’s centrifuge conserves excess sealant, and eliminates it from being dragged into the wash.
- The manufacturer has reduced water use by 40 %, and now uses 360 gallons per day.
- The system is integrated with leak testing. The fix on fail parts are delivered from leak testing via a conveyor belt, then delivered to the next operation via an outbound conveyor belt.
With the success of this new vacuum impregnation system, the company is projecting the capital expense recovery to be 12 months.
