1. Immediate Response Measures (Damage Control):

   · Isolation of Problem Batch: Immediately stop the current process and isolate the rusted parts.

   · Enhanced Final Rinsing: Immediately use deionized water or ultrapure water with a resistivity of $\ge 1\text{M}\Omega\cdot\text{cm}$ for sufficient, multi-stage rinsing.

   · Upgrade Drying Process: For precision complex parts, vacuum drying or IPA vapor drying must be adopted to ensure absolutely no water residue.

   · Short-Term Anti-Rust: Apply a dehydrating anti-rust oil immediately after cleaning and drying for temporary protection before the root cause is found.

2. Long-Term Process Improvement (Cure):

   · Audit Cleaning Agents: Switch to neutral or weakly alkaline, chlorine-free, sulfur-free dedicated metal cleaning agents that are suitable for your material, and perform compatibility tests.

   · Optimize Rinsing Process: Establish a system of **"three or more stages of countercurrent rinsing"** and monitor the conductivity or resistivity of the final rinse water online as a quality indicator.

   · Upgrade Drying Equipment: Invest in a vacuum drying oven for high-demand parts.

   · Standardize Operation:

     · Prohibit the mixed cleaning of dissimilar metals.

     · Operators must wear clean gloves when handling dried workpieces.

     · Set reasonable ultrasonic power and time to avoid "over-cleaning."

   · Control Storage Environment: Store clean workpieces in a humidity-controlled (e.g., RH $<40\%$ ) and clean environment, or use anti-rust packaging.

To thoroughly resolve this issue, it is recommended to conduct a **"Process Validation Test"**: take several samples, strictly clean them according to the optimized new process (especially deionized water rinsing + vacuum drying), and compare the results with the original process. This is the most intuitive way to pinpoint the core problem area.

III. Main Causes of Sealing Leaks in Vacuum Chambers

Vacuum drying chamber sealing failure is a serious problem, leading to poor vacuum level achievement, prolonged drying time, increased energy consumption, and ultimately resulting in incomplete workpiece drying, water stains, or re-oxidation and rusting. This problem is usually the result of a combination of mechanical structure, sealing material, operation, and maintenance factors.

For systematic troubleshooting, you can follow an order from external to internal, and from simple to complex. The flowchart below summarizes the core troubleshooting logic and steps:

Main Causes and Detailed Checkpoints

According to the above process, the specific causes and inspection methods for each part are as follows:

1. Operation and Daily Maintenance Factors (Check First)

· Seal strip (ring) contamination or damage: This is the most common cause.

  · Phenomenon: Cleaning agent crystallization, particulate matter, or fibers attached to the seal strip.

  · Inspection: Clean the seal strip and contact surface with alcohol, check for cracks, flattened compression set, loss of elasticity, or local damage.

· Door closing incomplete/locking mechanism failure:

  · Phenomenon: The door appears closed but is not evenly pressing the seal strip.

  · Inspection: Check if the door hinge is loose, if the pneumatic/hydraulic locking device pressure is sufficient, and if the mechanical latches are worn or jammed.

· Chamber overload or improper loading:

  · Phenomenon: Workpieces or cleaning baskets are too high, hitting the drying rack or door, preventing the door from closing completely.

  · Inspection: Check the chamber space and loading height.

2. Key Component Aging and Wear

· Seal strip (ring) natural aging:

  · Material: Commonly used silicone rubber and fluororubber may harden, shrink, and lose elasticity due to long-term high temperature and chemical vapor exposure.

  · Judgment: If leakage persists after cleaning and the seal has been used for many years, replacing the seal strip should be the first step.

· Leakage at auxiliary sealing points such as viewing windows, sensor interfaces:

  · Checkpoints: Threaded interfaces of temperature sensors, vacuum degree sensors; the seal ring of the viewing window; stem seals of the inlet/outlet valves.

  · Method: Apply soapy water to these suspected points and observe if bubbles appear when drawing a vacuum.

3. Equipment Structural Failure (Requires Professional Handling)

· Chamber body or door deformation:

  · Cause: Equipment impact, long-term uneven heating, or material stress release.

  · Inspection: Use a straightedge to check the flatness of the door frame and door body, and whether the gap is uniform.

· Minor cracks in welds or chamber body:

  · Cause: Manufacturing defects or long-term stress corrosion.

  · Judgment: Such leaks are very small and difficult to find, usually requiring the manufacturer to use a helium mass spectrometer leak detector for precise location.

· Internal problems within the vacuum system:

  · Note: This is not a "sealing" problem, but symptoms are similar.

  · Inspection: Check if the vacuum pump oil is emulsified or insufficient; if the exhaust filter is blocked; and if the vacuum piping, solenoid valves, or bellows are damaged.

How to preliminarily judge the leakage source? Performing a simple test can help locate the problem:

1. Run Test: Close the drying chamber door, start the vacuum pump, and observe the vacuum gauge.

2. Phenomenon A: The vacuum level rises quickly but is difficult to improve further or slowly drops after reaching a certain value. This strongly indicates an external air leak; focus on checking all sealing interfaces.

3. Phenomenon B: The vacuum level does not rise at all or rises extremely slowly. This is more likely due to the vacuum pump itself failing, pump oil issues, or the main exhaust valve not being opened.

Summary and Action Recommendations

1. Immediate Action: First, thoroughly clean the door seal strip and contact surface, and standardize loading. This solves 80% of occasional sealing problems.

2. Systematic Check: Follow the flowchart sequence: check the locking mechanism, replace aging seal strips, and use soapy water to test auxiliary interfaces.

3. Seek Professional Support: If the above steps are ineffective, it is highly likely that the chamber body is deformed or an internal leak exists. At this point, you must contact the equipment manufacturer or professional maintenance personnel to use professional instruments (such as a helium mass spectrometer) for leak detection and repair. Do not attempt self-welding or cutting, as this may cause greater damage.

Reducing the operating cost of cleaning equipment is a systematic engineering task, especially when you already own precision cleaning equipment like vacuum and ultrasonic cleaners. The core idea is to shift from "single equipment energy saving" to "whole-process cost optimization," focusing on energy consumption, consumables, and equipment lifespan.