Quality Control

Behind every filter is a manufacturing process that must be controlled and repeatable.
CMI operates modern production facilities with strict quality procedures to ensure stable and consistent performance.

Key Manufacturing Capabilities

• Precision fabrication and welding of filter housings and pressure vessels
• Automated production of filter bags
• Sintering and machining of metal filter media and components
• Custom fixtures, tooling and OEM production under customer brands

Documentation & Compliance

Depending on project requirements, we can support:

• ISO management systems
• PED related products
• Material certificates EN10204 3.1
• FDA compliant media options
• SGS test reports such as MOCA certificate
• ASME calculation report
• WPS and PQR

Quality Control Highlights

• Raw material inspection and traceability
• Dimensional checks and surface finishing inspection
• Bubble-point, micron rating and flow performance testing
• Pressure and safety testing according to agreed standards and customer drawings
• ISO-based quality management in accordance with ISO 9001

This combination of capability and control allows us to supply consistent products for critical industrial applications.

Quality Control for Filter Housings & Pressure Vessels

For filter housings and pressure vessels, CMI applies additional quality controls from incoming material to final inspection.

1. Incoming Material Inspection

• Each batch of stainless steel plates, pipes and fittings is checked using a spectrometer (PMI) to verify the actual chemical composition and confirm that the material is truly the specified stainless steel grade.
• Key component suppliers for flanges, forgings and castings are strictly evaluated and approved before use.

2. Process and Machining Control

• Critical parts such as tube sheets are machined again after welding to ensure flatness, hole position and sealing surfaces meet the requirements.
• Welding and fabrication steps follow defined procedures, with in-process checks to avoid dimensional deviation and misalignment.

3. Surface Treatment Control

• During shot blasting / sand blasting, the type and quality of the blasting media are controlled to achieve the required surface roughness and to avoid contamination of the stainless steel surface.

4. Hydrostatic (Pressure) Testing

• Each housing or vessel is hydrotested according to the approved drawing and specified test pressure.
• Test pressure is held for at least 30 minutes, and results are recorded for traceability.

5. Final Inspection and Packing

• Before shipment, a full final inspection is carried out, including dimensions, nozzle orientation, welding appearance, surface condition and accessories.
• Products are then packed in export-ready, seaworthy packaging, often with plywood cases and proper protection for nozzles and sealing surfaces, to ensure safe delivery to the customer.

Quality Control for Sintered Metal Filters

For sintered metal filters, we apply additional process and quality controls at each step.

1. Raw Material Control

• Material identification: Metal plates, tubes, elbows, cast parts and other components are verified using appropriate material identification methods to confirm grade and composition.
• Powder grading for porous metal products: For porous metal elements, we sort and classify metal powders into different grades using our own equipment instead of relying only on supplier grading. This helps ensure more stable pore size distribution.
• Loose density inspection: Loose density (weight per unit volume in a no-pressure condition) is measured to evaluate powder packing behavior. This parameter has a direct impact on pore size consistency. The inspection ensures that the expected pore size range can be achieved and kept stable from batch to batch.

2. Production Process Control

• Mold and tooling control: Dedicated molds and tooling are used for each type of filter element to maintain consistent geometry and dimensions.
• Welding control: Welder qualifications are kept up to date. In addition to standard metal welding, we use special welding equipment and procedures for porous metal parts to protect the structure and avoid pore blockage.
• In-process inspection of semi-finished products: Key dimensions of semi-finished parts are checked during intermediate steps. This ensures that only conforming parts move forward in production and reduces the risk of scrap at the final stage.
• Process records: Each critical step is recorded and traceable, so that in case of any quality issue, we can review the process history and identify the root cause.

3. Contamination Control

• Controlled working conditions: Workstations for porous filter elements are kept clean and organized, with appropriate supports and fixtures.
• Proper packaging of raw materials: Powders and other raw materials are stored in sealed and protected containers to avoid contamination and moisture.
• Vacuum sintering: Porous metal filters are sintered in vacuum furnaces to achieve stable pore structures and to minimize oxidation and contamination.
• Tooling materials: Molds and tooling for porous elements are mainly made of alloy materials suitable for repeated high-temperature service.

4. Final Inspection

• Permeability / air-flow test for standard filter elements: For standard non-porous filter elements, air-flow or ventilation tests are performed where applicable to confirm flow performance.
• Bubble-point test for sintered metal filters: All sintered metal filters are 100% bubble-point tested to verify pore size performance, integrity and consistency.

5. Packing & Shipping

• Export-ready packaging: Products are packed in seaworthy, export-grade packaging suitable for long-distance transportation.
• Plywood cases: Plywood boxes or crates are used where needed to protect filter housings, elements and accessories from mechanical damage during shipment.