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Customized
NHD
▍Product Description
Most graphite crucibles on the market suffer from issues such as insufficient purity, poor thermal stability, susceptibility to cracking due to temperature differences, contamination from metal melt adhesion, and limited size options, which severely impact the purity of the final product and production efficiency. NHD flat-mouth graphite crucibles undergo strict quality control throughout the entire process, from raw material selection to production. We eliminate inferior clay-mixed raw materials and use high-density, high-purity graphite as the base material, which has an extremely low porosity. This eliminates issues such as impurity leaching and metal leakage at the source.
The product is manufactured using a one-piece molding process, eliminating any seams. The inner walls undergo precision polishing to achieve a smooth, dense surface. This allows molten metal to flow rapidly at high temperatures without sticking or leaving residues, significantly reducing material loss and ensuring more uniform and precise ingot formation. The proprietary flat-mouth design features a smooth, even opening that is compatible with matching sealed crucible lids. This effectively reduces metal oxidation during high-temperature melting while facilitating manual charging, pouring of molten metal, and cleaning and maintenance, significantly enhancing operational convenience.
Standard Flat Graphite Crucible
High Density Graphite Crucible
Multi-Size Graphite Crucible Set
Unlike traditional pointed-bottom or round-bottom crucibles, the flat-bottomed design provides a more stable heating surface and a larger opening, greatly facilitating charging and slag removal operations. Our graphite material has an extremely low ash content (typically <500 ppm), ensuring that no impurities are introduced into the molten metal at high temperatures above 1600°C.
▍Product Specifications
Parameter Items | Standard Specifications | Notes |
Product Material | High-purity synthetic graphite | No clay impurities, high purity |
Graphite Purity | 99.9%–99.99% (optional) | Customization available for ultra-high purity |
Product Density | ≥1.73 g/cm³ (customizable high-density options available: 1.78–1.90 g/cm³) | The higher the density, the better the strength and durability. |
Ash Content | ≤0.3% | Eliminate material contamination |
Temperature Range | Air environment: ≤600°C; vacuum/inert environment: ≤3000°C | Stable performance at high temperatures |
Coefficient of Thermal Expansion | Very low | Resistant to sudden temperature changes; less prone to cracking |
Surface Treatment | Mirror polish / Anti-corrosion coating (optional) | An antioxidant coating can extend the service life |
Structural Styles | Straight-sided with a flat bottom for stability | Compatible with a wide range of devices |
▍Why choose a flat-end design?
Comparison Items | Flat-Mouthed Graphite Crucible | Graphite crucible with spout |
Ease of loading | ⭐⭐⭐⭐⭐Large opening allows for direct feeding of chunked or sliced ingredients | ⭐⭐⭐Due to the size of the feed opening, large pieces of raw material must be pre-processed. |
Mixing Performance | ⭐⭐⭐⭐⭐The carbon rod/stirrer can be inserted vertically | ⭐⭐⭐Due to the angle of the mouth |
Sealed | ⭐⭐⭐⭐⭐The flat lid fits tightly, reducing oxidation | ⭐⭐⭐The mouthpiece does not seal completely |
Tipping control | ⭐⭐⭐Requires a tool for pouring | Precise pouring with a spout |
Applicable Scenarios | Batch melting, extended holding time, and processes requiring stirring | ⭐⭐⭐⭐⭐Continuous casting, small-batch precision molding |
Metal loss | Lower (steam loss is reduced by 15–20% when covered) | Relatively high |
Conclusion: Flat-mouthed graphite crucibles are better suited for smelting processes that require repeated charging, prolonged heat retention, and stirring to remove impurities. They are the preferred choice for gold and silver refining, alloy formulation, and laboratory research and development.
Short Flat Graphite Crucible
Polished Graphite Crucible
Matte Finish Graphite Crucible
▍Customizable in all specifications, with a minimum order quantity of one piece
Custom Projects | Notes |
Dimensions | Inner diameter: 20 mm–300 mm; height: 30 mm–500 mm (customizable to any specifications) |
Wall Thickness Design | Optimize wall thickness (typically 8–25 mm) based on the type of metal and melting temperature |
Capacity marking | Laser-engraved weight markings (e.g., “1 kg Au,” “5 kg Ag”) |
Matching graphite cover | Flat lid or grooved lid available, designed to fit the crucible opening precisely |
Special Treatment | Inner surface polished; outer surface coated with an anti-oxidation treatment |
▍Application Scenarios and Their Advantages
Precious Metal Jewelry Casting Industry：Suitable for the smelting, ingot casting, and jewelry processing of precious metals such as gold, silver, and platinum. Thanks to its high purity and low impurity content, it fully preserves the purity of precious metals. The non-stick inner surface minimizes waste of valuable raw materials, and the flat-bottomed design facilitates manual handling, making it an essential consumable for jewelry manufacturers and custom jewelry workshops.
Laboratory Research and Testing：Designed for high-temperature chemical analysis, ash content testing, sample fusion, and sintering experiments on new materials in universities, research institutes, and testing laboratories. It offers excellent chemical stability, does not contaminate experimental samples, provides precise experimental data, and its resistance to temperature fluctuations makes it well-suited for intermittent laboratory operations.
Small-scale precision casting：Ideal for precision melting and molding of small hardware castings and alloy components, this process offers high mold accuracy and excellent melt fluidity, effectively reducing defects such as porosity and imperfections in castings and improving the yield rate of precision castings.
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▍FAQ
Q1: What is the biggest advantage of flat-mouthed graphite crucibles compared to standard crucibles?
A:Compared to ceramic, quartz, and clay crucibles, this flat-mouthed high-purity graphite crucible conducts heat faster, heats more evenly, and offers excellent thermal shock resistance, making it less prone to cracking under temperature fluctuations; they offer greater chemical stability, resisting acids, alkalis, and metal corrosion without contaminating the melted material; the flat-mouth design allows for easier operation, broader application scenarios, and a longer service life, making them far more cost-effective than traditional crucibles.
Q2: Will your flat-mouth graphite crucibles oxidize at high temperatures?
A: All graphite will oxidize slowly in air at temperatures exceeding 500°C. We offer two solutions: 1) We provide high-density material, which oxidizes more slowly than standard crucibles; 2) We can customize an anti-oxidation coating to form a protective layer on the surface. Additionally, the flat-mouth design facilitates a tight seal with the furnace lid, reducing oxygen flow.
Q3: How do I select the appropriate size of graphite crucible?
A:You can choose a model based on the weight and volume of the material to be melted in a single batch, as well as the dimensions of your melting equipment. As a general rule, we recommend that the amount melted in a single batch does not exceed two-thirds of the crucible’s capacity to prevent high-temperature molten material from overflowing. For small-scale experiments and jewelry melting, choose small-capacity models; for industrial batch smelting, opt for large-capacity custom models. Alternatively, provide your equipment specifications, and our professional team will assist with one-on-one selection.
Q4: Does the crucible need to be cooled immediately after use?
A: Never place a hot crucible directly on a cold metal surface or wet ground, as this can cause severe thermal shock and result in the crucible shattering. Use crucible tongs to remove it and place it on a dry graphite pad, refractory brick, or ceramic plate to allow it to cool naturally to room temperature.
Q5: Can the same crucible be used to melt different metals?
A:We do not recommend mixing metals. Melting different metals can leave trace impurities, which may cause cross-contamination and affect the purity of the final product. We recommend using a dedicated crucible for each type of metal to ensure melting quality and the accuracy of experimental and production data.
+86-795-4605783 
sales@nhdcarbon.com 
No. 966 of Tiangong South Avenue, High-tech Industrial Park, Fengxin County, Yichun City, Jiangxi Province, China.