Graphite Shim and Adjusting Spacer for Furnace and Fixture Alignment
Product Overview
Our graphite shims and adjusting spacers are thin, precision-ground graphite sheets and blocks used to align, level, and adjust the position of graphite hot-zone components, furnace loads, and fixtures during vacuum furnace assembly and maintenance. Available in thicknesses from 0.1 mm to 10 mm, these shims fill small gaps, level uneven surfaces, and compensate for thermal expansion differences without introducing metal contamination. At Jincheng Graphite, we precision-grind graphite shim stock to tight thickness tolerances and cut them to custom rectangular, square, or washer shapes for specific furnace alignment requirements.
Proper alignment of vacuum furnace hot zones is critical for temperature uniformity and heater life. Over time, insulation panels sag, hearth plates wear, and support posts settle, requiring shims to restore flatness and parallelism. At Jincheng Graphite, we supply precision-ground graphite shim sheets and custom-cut spacers that furnace maintenance teams use to re-level hearths, center heating elements, and adjust fixture heights. Each shim is flat, dimensionally accurate, and chemically clean for vacuum service.
Key Features
- Precision thickness tolerance - ground to ±0.02 mm thickness accuracy
- Flat and parallel - both faces surface-ground for even load distribution
- Wide thickness range - 0.1 mm foil shims to 10 mm solid spacers
- Custom shapes - rectangular, square, round, or washer-style cutouts
- High temperature stable - no deformation at furnace operating temperatures
- Non-contaminating - clean vacuum performance without metal outgassing
- Easy to trim - graphite cuts easily to fit on-site during furnace maintenance
- Corrosion resistant - stable in vacuum, inert, and reducing atmospheres
Technical Specifications
| Parameter | Value |
|---|---|
| Material | Fine-grain isostatic / molded graphite |
| Bulk Density | 1.75 - 1.85 g/cm³ |
| Available Thicknesses | 0.1, 0.2, 0.5, 1, 2, 3, 5, 10 mm |
| Thickness Tolerance | ±0.02 mm (ground shims) |
| Flatness | < 0.02 mm per 100 mm |
| Parallelism | < 0.03 mm per 100 mm |
| Max Sheet Size | 300 × 300 mm |
| Shape Options | Rectangle, square, round, ring, custom |
| Max Temperature | 2200°C (vacuum/inert) |
| Surface Finish | Ra 0.8 µm (ground both sides) |
| Dimensional Tolerance | ±0.1 mm (cut to size) |
| Lead Time | 5-10 business days |
Applications
- Vacuum furnace re-leveling - shim hearth plates and insulation after maintenance
- Heater alignment - adjust heating element position for uniform temperature
- Fixture height adjustment - set exact load height in batch furnaces
- Support post shimming - compensate for post settlement and wear
- Thermal expansion compensation - allow controlled movement during heating cycles
- Laboratory fixture setup - precision shims for custom research furnace builds
Why Choose Jincheng Graphite?
- Precision grinding - both faces ground for accurate shim thickness
- Stock thicknesses - common shim sizes available for immediate shipment
- Custom cut shapes - cut to your exact rectangular or circular dimensions
- Fine-grain material - dense graphite that does not shed particles
- Fast delivery - standard shim sheets ship within 3-5 business days
- Bulk supply - shim kits for furnace maintenance departments
- Cost effective - affordable shim stock for routine furnace maintenance
- Quality inspection - each shim batch checked for thickness and flatness
FAQ
Q: How do I select the right shim thickness?
A: Use a feeler gauge or dial indicator to measure the gap that needs filling, then select the nearest standard shim thickness. If the gap is between standard sizes, stack multiple thinner shims rather than forcing an over-thick shim. We supply shim assortments in 0.1, 0.2, 0.5, 1, and 2 mm thicknesses for maintenance kits.
Q: Can graphite shims be reused?
A: Yes. Graphite shims can be removed during furnace maintenance and reinstalled if they remain flat and undamaged. Inspect shims for warping, cracking, or thickness changes before reuse. Thin foil shims (0.1-0.2 mm) are typically replaced each maintenance cycle.
Q: Do you supply shims with pre-cut bolt holes?
A: Yes. We can drill mounting holes, slots, or notches in shims to match specific furnace anchor patterns. Send us a drawing or specify the hole pattern, and we will deliver ready-to-install shims.
Q: What is the thinnest shim you can make?
A: We can supply graphite shims as thin as 0.1 mm in sheet form. Below 0.1 mm, graphite becomes fragile and is typically only available as flexible graphite foil rather than solid machined shim stock.
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