Introduction to Class 10,000 (ISO Class 7) Cleanrooms for Watchmaking

A Class 10,000 cleanroom (typically referring to ISO Class 7, equivalent to the US Federal Standard Class 10,000) is the most widely used and core production environment in modern watch manufacturing. It is not simply a "clean room," but a precision system integrating air purification, temperature and humidity control, electrostatic protection, and strict management protocols.

The following is a detailed professional introduction to Class 10,000 cleanrooms for watchmaking:

1. Core Definition and Standards

• Particle Control Standard: The core      indicator of a Class 10,000 cleanroom is controlling the number of      suspended particles in the air. The standard is: the number of particles      greater than or equal to 0.5 micrometers in diameter does not exceed      10,000 per cubic foot of air (hence Class 10,000). Converted      to the international standard ISO 14644-1, this means the number of      particles ≥ 0.5 micrometers per cubic meter of air does not exceed 352,000.
• Applicability: For watch      manufacturing, a Class 10,000 environment is sufficient to meet the      requirements of most processes, such as movement assembly, precision      machining, and hairspring installation. It represents the optimal choice      balancing cleanliness needs with construction and operating costs.

2. Main Functional Areas and Processes

A typical Class 10,000 watchmaking cleanroom is usually laid out according to the process flow, ensuring a gradient of control from coarser to finer steps:

1. Personnel and Material Purification Area:
• Changing Room / Air Shower: Before       entering the cleanroom, personnel must wear special anti-static cleanroom       garments (coveralls, masks, gloves) and pass through an air shower where       high-speed clean air blows off particles attached to the surface of the       clothing.
• Pass-Through Chamber: All       materials and tools must enter through pass-through chambers with       interlocking functions, undergoing cleaning or air flushing before entry,       preventing cross-contamination.
2. Core Production Area:
• Precision Movement Assembly Line:       This is the heart of the cleanroom. Workstations are often equipped with       local ISO Class 5 (Class 100) laminar flow units, providing a       higher level of localized clean protection within the Class 10,000       environment for the most precise operations like jeweling (oiling),       balance wheel installation, and escapement assembly.
• Component Machining and Cleaning:       Includes processes like mainplate decoration, gear deburring, and       temporary storage areas after cleaning. Strict control of dust generation       is necessary.
• Finished/Semi-finished Product Storage Area: Temporarily stores assembled or cleaned components in a       clean environment to prevent secondary contamination.
3. Inspection and Quality Control Area:
• Houses precision equipment such as timing machines, water       resistance testers, and vision measuring systems. This area has extremely       high requirements for vibration isolation. Often, the cleanroom       foundation requires independent damping treatment to prevent external       vibrations from affecting inspection accuracy.

3. Key Technical Parameters and Control Elements

• Airflow Organization: Typically      uses turbulent (non-unidirectional) flow with HEPA      filter supply from the ceiling + return air at the lower side. Clean      air is introduced from the ceiling, diluting and carrying away      contaminants from the work area, and is exhausted through return air vents      at the lower part of the side walls, creating a stable airflow path.
• Air Change Rate: To maintain Class      10,000 cleanliness, an air change rate of 60-90 times per hour is      typically required. This means the air inside the cleanroom is completely      or partially replaced every minute, ensuring continuous purification      effectiveness.
• Temperature and Humidity Control:
• Temperature: Strictly controlled       between 20°C and 22°C (±1°C). Temperature stability is       crucial for ensuring consistency in the thermal expansion/contraction of       movement parts and the stability of lubricant viscosity.
• Humidity: Relative humidity is       controlled between 40% and 55%. Excessive humidity can cause       metal parts to rust and quartz electronic components to leak current; too       low humidity can easily generate static electricity.

  
  

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