Porous Graphite Discs | Perforated Graphite Trays for Sintering Cemented Carbide | Custom CNC Precision Machining — Ningheda New Material

▍Product Description (In-Depth Technical Analysis)

Jiangxi Ningheda New Material Co., Ltd. specializes in the research, development, and precision manufacturing of isostatic graphite porous discs. Our graphite porous discs are made from high-purity, fine-grained isostatic graphite as the base material. Using a CNC multi-axis precision drilling process, we create a uniformly distributed array of ventilation holes, specifically designed for demanding applications such as cemented carbide powder sintering, tungsten powder metallurgy, and high-temperature processing of heat pipes.

Compared to traditional solid graphite plates, Ningheda’s porous discs feature an open area ratio of over 30%, which improves the penetration efficiency of protective atmospheres (hydrogen, nitrogen) by 40%. This effectively eliminates defects caused by localized over-sintering and under-sintering during the sintering process, increasing the workpiece yield to over 98%. The product can withstand temperatures of 1500°C for extended periods in an inert atmosphere, with a service life of 6–12 months under normal operating conditions, making it an ideal firing fixture for bell-type furnaces, pusher-type furnaces, vacuum resistance furnaces, and other equipment.

High-Density Perforated Disc

Center-Hole Sintering Disc

Micro-Pore Filter Disc

▍Materials Genomics: Why Choose Isostatic Graphite?

Ningheda porous discs are made from MSS80/MSS85/MSS90 three-grade isostatic graphite billets, which differ from ordinary molded graphite in the following ways:

Isotropic structure: Isostatic pressing (CIP) is performed under a uniform pressure of 200 MPa in all directions, resulting in no orientation defects within the material and a 60% reduction in edge chipping during drilling

Ultrafine-grained matrix: With an average particle size of 25 μm, this ensures the feasibility of precision machining for pore diameters ranging from 0.5 mm to 10 mm, with pore position accuracy of ±0.05 mm

High purity and low ash content: Fixed carbon content ≥99.9%; ash content can be purified to 30 ppm, eliminating surface contamination of workpieces caused by the volatilization of impurities during sintering

Whether used as a gas distributor in high-temperature environments or as a mechanical seal for oil-free lubrication, this porous disc delivers stable physical properties and an exceptionally long service life. We offer a variety of specifications, including MSS80 and MSS85, and can provide deep purification and precision machining according to customer requirements.

Notched Positioning Disc

Ultra-Fine Porous Plate

Star-Pattern Custom Disc

▍Product Advantages

Woven-Mesh Graphite Disc

Sparse-Hole Sintering Tray

Heavy-Duty Thick Disc

▍Product Features (Technical Specifications)

Physical Properties of the Base Material

Note: The ash content can be reduced to 30 ppm upon customer request; the above data are standard values, not guaranteed values. Actual values are subject to the factory test report.

Precision Drilled Disc

Six-Hole Heavy Plate

Nested Multi-Size Stack

▍Range of Custom Manufacturing Specifications

▍Use Cases

Carbide Sintering Application

Vacuum Brazing Furnace

Molten Metal Filtration

• Industry 1: Sintering of Cemented Carbide Powders

  Core Advantages: Uniform atmosphere penetration, precise positioning and support, single-piece trays capable of holding multiple layers of workpieces (separated by graphite positioning pins), resistance to thermal deformation, low contamination, and high purity

• Industry 2: Vacuum Brazing/Heat Treatment

  Core Advantages: High-temperature purification at 1800°C, thorough removal of volatile impurities, porous structure promoting uniform heat convection within the vacuum chamber, thermal shock resistance and long service life, custom-fit for specific furnace models

• Industry 3: Filtration and Impurity Removal from Molten Metals

  Core Advantages: 0.5–1 mm micropores form tortuous flow paths; slag retention rate ≥95%; thermal shock resistance; non-wetting surface for easy cleaning; no reaction with molten metals such as aluminum, copper, and magnesium; high flow rate with low resistance

▍Product Shipping Instructions

① Domestic Shipping: Finished graphite discs are wrapped in moisture-proof bubble wrap, and the outer packaging consists of a reinforced solid wood crate to prevent damage or chipped edges during transit. Standard-sized items in stock are shipped within 3–7 days, while custom products have a production lead time of 7–15 business days. We prioritize dedicated freight lines for logistics.

② International Export: Export orders are packed in fumigated solid wood crates or plywood export crates, accompanied by a packing list, commercial invoice, and factory material test report; we can coordinate with customers to arrange sea freight, air freight, or international express shipping; for customers in the EU, Southeast Asia, and Russia, we ensure smooth customs clearance with complete documentation.

▍FAQ

● Q1: What is the difference between your porous graphite discs and standard graphite sheets?

      A1: Standard graphite sheets are typically dense and are mainly used for electrical conductivity or thermal                            insulation. Our porous discs, on the other hand, have a controlled porosity of 11%–17%, which gives them                            breathability and oil-retention capabilities, making them ideal for specialized applications such as filtration, gas                distribution, or self-lubricating bearings.

● Q2: How should I choose between MSS80 and MSS85 graphite discs?

      A2: If you are working with laboratory samples, routine powder metallurgy sintering, or have a limited budget,                  MSS80 is the preferred choice; For high-volume cemented carbide production, applications with multiple stacked            discs, or situations requiring a long service life, we recommend the MSS85 (version with a bulk density of 1.90                      g/cm³); higher density results in better compressive and flexural strength, lower porosity, and a longer service life in        high-temperature environments.

● Q3: What is the maximum diameter available for porous graphite discs?

      A3: The maximum standard size is Φ600 mm; custom sizes up to Φ800 mm are available. For diameters exceeding            Φ600 mm, we recommend a sector-joined structure, where 2–4 sector-shaped blocks are joined to form a full circle.       This approach not only solves the molding challenges associated with large-diameter graphite billets but also                     facilitates transportation and on-site installation. The gap at the joints is controlled to within 0.2 mm, ensuring no             impact on sintering uniformity.

● Q4: Can you replicate a graphite disc based on a sample of my existing, used disc?

      A4: Yes. You can send the used disc to our factory, where our staff will precisely measure the hole diameter, hole                spacing, disc thickness, and center hole dimensions; we will then produce a 1:1 replica. Additionally, our engineers          can optimize the hole layout to address sintering defects in your existing product.

● Q5: Is a higher open area percentage always better? How do I choose the appropriate open area percentage?

     A5: Not necessarily. The open area percentage must be determined based on a combination of sintering                                  temperature, protective atmosphere flow rate, and workpiece loading density:

• Low-temperature sintering (≤1200°C) + high-flow atmosphere: A high open area percentage of 25–35% can be selected to enhance convective heat transfer

• High-temperature sintering (≥1500°C) + workpieces with significant self-weight: A low open area ratio of 15–22% is recommended to ensure the structural strength of the tray

• Molten metal filtration: 15–20% is sufficient; a higher ratio will reduce slag retention efficiency

Ningheda engineers can provide open area ratio simulation and calculation services based on your furnace parameters and process requirements.

● Q6: What is the typical service life of a graphite tray? How can it be extended?

      A6: Under normal operating conditions (hydrogen atmosphere, ≤1500°C, no mechanical impact), Ningheda’s                  standard trays have a service life of 6–12 months. Key measures to extend service life:

• Control the heating rate: ≤5°C/min to prevent microcrack propagation caused by thermal shock

• Atmosphere purity management: Hydrogen dew point ≤ -40°C to reduce oxidation caused by water vapor

• Rotate the tray regularly: Rotate 180° every 20 furnace cycles to ensure even wear

• Optional anti-oxidation coatings: SiC coating or resin impregnation can extend service life by 30–50%

If you are looking for MSS series porous graphite discs suitable for vacuum sintering furnaces or induction furnaces, please send us your drawings, the operating temperature inside the furnace, and workpiece layout conditions. Our technical team will recommend the most suitable graphite grade and disc perforation design based on your production conditions, and provide you with a detailed quote within 24 hours.

● Q7: As a first-time customer, can you provide free samples for testing?

      A7: Yes. Ningheda offers a free sample policy for first-time customers 

      (limited to standard specifications of Φ200 mm or smaller, single piece):

• The customer covers international shipping costs (collect on delivery)

• Samples come with a complete test report

• If the test is passed and an order is placed, the sample cost will be deducted from the first batch payment

• Custom-specification samples are charged at cost (material + processing fees), which will be fully refunded after the order is placed