Graphite bolts are non-metallic fasteners made from high-purity graphite. Compared with conventional metal bolts, they offer more stable performance in environments involving high temperatures, corrosive media, or where electrical or thermal conductivity is required.
We specialize in the development and manufacturing of graphite bolts. Our main product range includes:
- Graphite threaded rods
- Graphite nuts
- Graphite screws
- Custom-shaped graphite fasteners (available upon request with drawings)
High-Purity Graphite Material
The performance of graphite bolts depends largely on the quality of the raw material. We use high-purity graphite with the following characteristics:
- Low ash content: Impurity levels are kept low, reducing the risk of outgassing or unwanted reactions at high temperatures.
- Uniform microstructure: The material has low porosity and consistent density, which helps achieve stable mechanical properties after machining.
- Thermal stability: In non-oxidizing or vacuum atmospheres, the material can withstand temperatures above 2200°C without significant deformation over extended periods.
Machining Accuracy and Dimensional Tolerances
Graphite is a brittle material and requires careful machining. Our approach includes:
- Equipment and process: CNC lathes, thread grinders, and other dedicated machines are used with cutting parameters suitable for graphite to minimize edge chipping, cracking, and other defects.
- Tolerance control: Thread tolerances can be supplied according to common standards such as GB/T, DIN, or ANSI (e.g., 6g, 6H). Non-standard dimensions are machined to customer-provided tolerances.
- Inspection: Finished bolts are checked using thread gauges, calipers, optical comparators, and other measuring tools to ensure that key dimensions remain within the agreed tolerance range.
Through these steps, we aim to achieve a reasonable fit between graphite bolts and mating nuts or threaded holes, helping to avoid assembly issues caused by excessive tightness or looseness.
Quality Consistency
From raw material to finished product, we follow a routine quality control process:
- Incoming material inspection: Each batch of high-purity graphite is tested for bulk density, compressive strength, electrical resistivity, and other parameters to verify that it meets internal specifications.
- In-process control: Semi-finished parts are sampled and measured at regular intervals during production to detect and correct any dimensional drift.
- Final inspection: Finished graphite bolts are inspected for visual appearance, thread go/no-go fit, and critical dimensions before being approved for shipment.
While we do not claim “zero defects,” our ongoing process controls help keep batch-to-batch variation within a relatively narrow range, meeting users’ basic expectations for consistency.
Key Characteristics (Summary)
| Property | Description |
|---|---|
| High temperature resistance | Can be used above 2200°C in non-oxidizing or vacuum atmospheres without notable deformation |
| Corrosion resistance | Good chemical stability against most acids, alkalis, and salt solutions |
| Thermal & electrical conductivity | Suitable for applications requiring heat transfer or static charge dissipation |
| Low density | Significantly lighter than steel or stainless steel, helping reduce overall equipment weight |
| Self-lubricating | Low friction during threading and assembly, which helps reduce wear; service life can be comparable to or longer than that of metal bolts in many cases |
Typical Applications
- Metallurgy: Fastening and connections in high-temperature furnaces, aluminum electrolysis cells, graphitization furnaces, and similar equipment
- Chemical industry: Reactors, heat exchangers, pickling tanks, pipe flanges, and other corrosive environments
- Photovoltaics & semiconductors: Single-crystal silicon furnaces, multi-crystal silicon casting furnaces, PECVD equipment, and other high-temperature vacuum systems
- Other demanding conditions: Aerospace test equipment, specialized nuclear components, high-temperature molds, etc.
Installation and Handling Notes
Graphite bolts are brittle. Please observe the following during installation:
- Avoid dropping, impact, or heavy hammering, which can cause cracks or fracture.
- A torque wrench is recommended to control tightening force; do not overtighten.
- Using flat washers or spring washers can help distribute load more evenly.
- In oxidizing atmospheres (e.g., ordinary air), the recommended continuous service temperature is below 400°C. For higher temperatures, vacuum or inert gas protection is required.
Custom and Non-Standard Machining
We can produce non-standard graphite bolts and other custom graphite fasteners based on customer drawings or samples, including:
- Graphite threaded rods of various diameters and lengths
- Matching graphite nuts (standard or non-standard thread pitches)
- Graphite countersunk screws, socket head screws, etc.
- Special graphite connectors with steps or custom head shapes
Custom products are also made from high-purity graphite and machined to agreed tolerances with corresponding inspection procedures.
