Diamond Segment Graphite Mold | Ultra-Fine Grain High Purity Graphite Sintering Mold | NHD Carbon - Jiangxi Ningheda New Material Co., Ltd.

Detailed Product Description

What Are Sintered Graphite Molds for Diamond Tools?

Sintered graphite molds for diamond tools are indispensable core tooling in the diamond tool manufacturing process. In the hot-press sintering process, diamond powder and metal binders (such as cobalt powder, nickel powder, copper powder, etc.) are loaded into the cavities of a graphite mold. By applying an electric current to the graphite mold to generate heat, the mixture is subjected to a temperature of 1000±2°C and a forming pressure of 16–50 MPa. After maintaining the temperature and pressure for 15–30 minutes, the diamond particles and metal powders are densely sintered to form diamond cutting tips or tool blanks with high strength and high wear resistance.

The graphite mold plays a dual role in this process:

Heating element: Utilizing the high resistivity of graphite, it heats up rapidly when energized, providing a uniform heat source for sintering.

Forming support: It maintains the stability of the mold cavity’s shape under high temperature and pressure, ensuring the dimensional accuracy of the sintered part.

What Makes Ningheda Graphite Molds Unique

Compared with ordinary graphite molds on the market, Ningheda’s products have the following notable differences:

Key Product Advantages

1. Uniform thermal and electrical conductivity throughout the entire mold, ensuring consistent sintering quality: Graphite has an electrical conductivity 3 to 35 times greater than that of aluminum, and a thermal conductivity 3 to 5 times greater than that of ordinary steel. Ningheda graphite molds can transfer heat quickly and uniformly, ensuring even heating of the sintered material. This effectively prevents localized overheating or undercooling, shortens the sintering cycle by approximately 30%, and simultaneously improves the yield rate of finished products.

2. Ultra-low thermal deformation and exceptional thermal shock resistance: With an extremely low coefficient of thermal expansion, these molds can withstand frequent and drastic temperature fluctuations. Repeated sintering operations result in no deformation, cracking, or dimensional deviations, making them perfectly suited for non-vacuum high-temperature, high-pressure sintering conditions, with precision that remains unchanged even after long-term use.

3. Ultra-high-temperature resistance and enhanced high-temperature strength: Unlike ordinary molds, which suffer from high-temperature softening and strength degradation, this mold’s physical strength actually increases rather than decreases in high-temperature environments. With a maximum temperature resistance exceeding 3,000°C, it meets the demands of various high-intensity, long-duration sintering processes and adapts to complex production conditions.

4. Chemically Stable, Eliminating Finished Product Defects: With high-purity base material and extremely low impurity content, it exhibits strong chemical inertness. Under high-temperature, high-pressure conditions, it does not react with metal binders such as copper, iron, or cobalt, nor with diamond raw materials, thereby preventing issues such as mottling on the cutting edge surface, mold adhesion, and oxidation defects at their source.

5. Intrinsic self-lubricating properties ensure efficient, damage-free demolding: Graphite’s natural self-lubricating properties allow for smooth demolding after sintering, eliminating the need for additional demolding processes. This prevents scratching or bumping of the diamond cutting heads, ensuring the integrity of the finished product’s appearance and improving production turnaround efficiency.

6. Strong machinability and support for customization: The material is easy to precision-machine, grind, and drill. Molds can be customized with multi-cavity layouts, irregular shapes, and special dimensions based on customer requirements for cutting head sizes, layout needs, and equipment parameters, making them suitable for the production of all types of diamond cutting heads.

7. Longer service life, reducing production costs: With a dense structure, low porosity, and excellent oxidation resistance, these molds can be reused through sintering an average of 30–40 times—far exceeding ordinary graphite molds. This effectively reduces the frequency of mold replacement, significantly lowering customers’ costs for consumables and downtime.

Key Product Features

Use Cases

• Scenario 1: Sintering of Diamond Cutting Segments

  Application Description: Used for hot-press sintering of cutting segments for diamond circular saw blades, rip saws, multi-blade saws, and similar applications.

  Mold Features: Square or rectangular graphite molds with multiple holes; the hole arrangement is customized according to segment dimensions (e.g., 4×4, 5×5 arrays, etc.).

  Benefits:

☉ Sintering multiple segments in a single cycle, increasing production efficiency by 3 to 5 times

☉ High consistency in segment dimensions, resulting in minimal runout on the saw blade end face after welding

☉ Long mold life and low cost per sintering cycle

• Scenario 2: Sintering of Diamond Wire Saw Beads

  Application Description: Used for the forming and sintering of diamond wire saw beads, widely used in stone and mineral mining.

  Mold Features: Cylindrical graphite mold with a multi-hole design, used in conjunction with a mandrel.

  Benefits:

☉ High dimensional accuracy of the beads’ outer diameter and inner bore, ensuring smooth wire threading and assembly

☉ Uniform sintering density, improving the beads’ wear resistance by over 20%

☉ Supports high-volume continuous production to meet the demands of high-intensity mining operations

• Scenario 3: Sintering of Powder Metallurgy Parts

  Application Description: Used for the sintering of powder metallurgy products such as cemented carbide and ceramic-metal composites.

  Benefits:

☉ Rapid and uniform heat transfer, shortening the sintering cycle

☉ Product density can reach over 98% of the theoretical value

☉ Surface roughness optimized to Ra 1.6 μm

Product Shipping

Packaging Methods

Shipping Methods

Sea Freight: FOB Tianjin Port/Shanghai Port; suitable for large-volume orders

Air Freight: Suitable for urgent small-volume orders; delivery within 3–7 days

Land Freight: Domestic customers can arrange dedicated truck transport or logistics delivery

Express Delivery: Samples or small items can be shipped via DHL, FedEx, or UPS international express

Delivery Timeframe

Ningheda Custom Manufacturing Process

Step 1: Requirements Discussion—The customer provides drawings of diamond tools, sintering process parameters (temperature, pressure, time), or sample molds.

Step 2: Solution Design—Ningheda’s technical team analyzes the requirements, designs the mold structure, selects materials, and provides 3D design drawings for the customer’s approval.

Step 3: Material Preparation—Based on the design plan, suitable graphite raw materials are selected, and the blanks are cut and pretreated.

Step 4: CNC Precision Machining: High-precision CNC machining centers are used with diamond-coated cutting tools to perform roughing, semi-finishing, and finishing operations, strictly controlling dimensional tolerances within ±0.03–0.08 mm.

Step 5: Surface Treatment: Depending on requirements, polishing, anti-oxidation coating, or impregnation treatments are applied to enhance the mold’s surface quality and service life.

Step 6: Quality Inspection: Comprehensive dimensional inspections are conducted using equipment such as coordinate measuring machines (CMMs) and surface roughness meters to ensure that every product meets the requirements specified in the drawings.

Step 7: Assembly and Packaging: Multi-component molds undergo trial assembly to verify fitting accuracy. Afterward, they are cleaned, protected, and packaged for shipment from the Jiangxi factory to destinations worldwide.

Why Choose Jiangxi Ningheda New Material?

FAQ

Q1: What is the maximum temperature this graphite mold can withstand? Is it suitable for the sintering process of diamond cutting tips?

A1: The product has a maximum temperature resistance of over 3,000°C, with no loss of strength at high temperatures. It is fully compatible with the standard hot-press sintering process for diamond cutting tips—which operates at approximately 1,000°C and high pressures of 16–50 MPa—and is a specialized mold designed for the sintering of diamond tools.

Q2: Will the mold stick during use, causing defects on the cutting tip surface?

A2: No. The product is made from 99.9% high-purity, low-ash graphite, which is chemically stable and does not react with metal powders or diamond raw materials at high temperatures. Combined with its natural self-lubricating properties, demolding is smooth, with no sticking, no scarring, and no impurity adhesion, ensuring the appearance and quality of the finished cutting tips.

Q3: What is the approximate service life of a graphite mold? Can it be reused?

A3: This mold features a dense structure and excellent resistance to oxidation and thermal shock. Under standard atmospheric sintering conditions, it can be reused 30–40 times; its service life can be further extended in a vacuum sintering environment, significantly reducing consumable replacement costs compared to ordinary graphite molds.

Q4: Can the mold be customized to fit my cutting head dimensions?

A4: We support full-range customization. Based on the customer’s cutting head length, thickness, and specifications, we can customize the overall mold dimensions, number of cavities, arrangement (three rows—top, middle, and bottom—or double-layer arrangement), and special-shaped structures. We can also machine the mold precisely according to drawings or samples.

Q5: Why do cutting heads sintered using this mold have higher precision and more consistent quality?

A5: The mold’s base material has uniform electrical resistivity and balanced thermal and electrical conductivity, ensuring consistent temperatures throughout the sintering process. This eliminates issues such as uneven hardness in the cutting heads and porous formation. Additionally, the ultra-low coefficient of thermal expansion ensures no deformation at high temperatures. Combined with precision CNC machining processes, this precisely locks in the cutting head dimensions, resulting in exceptional consistency in the finished products.

Q6: How can I tell when a graphite mold needs to be replaced?

A6: We recommend replacing the mold when the following signs appear: ① Sintered cutting heads are out of tolerance (larger or smaller than specified), indicating that the mold cavity has worn out; ② Visible pits or deposits appear on the cutting head surface, indicating that the mold’s working surface has been damaged or oxidized; ③ Abnormal fluctuations in the sintering current or temperature curve, which may indicate a change in the mold’s electrical resistance. Regularly inspecting the mold’s appearance and measuring key dimensions are effective ways to manage mold lifespan.

Q7: What is your minimum order quantity (MOQ)? Can you provide samples?

A7: We understand that customer needs vary widely, so our minimum order quantity is very flexible and depends on the size and complexity of the mold. We strongly encourage customers to conduct sample testing or small-batch trials before placing bulk orders to verify our quality and compatibility. Please feel free to contact us at any time to discuss your specific requirements.