Design Guide for Advanced Ceramics

Engineering Success: Design for Manufacturability (DFM)

Ceramics are inherently brittle and undergo significant shrinkage during sintering. Unlike metals, they cannot be easily "bent" or "adjusted" post-production. At Shunda Ceramics, we help you optimize your designs to prevent cracking, reduce manufacturing costs, and ensure micron-level precision.

1. Wall Thickness & Uniformity

Uniform wall thickness is the most critical factor in preventing warpage and internal stress during sintering.

Avoid Abrupt Transitions: Gradual transitions between thick and thin sections reduce stress concentration.

Minimum Wall Thickness: For CIM (Injection Molding), we recommend a minimum of 0.5 mm. For dry pressing, 1.0 mm is ideal.

2. Radii & Fillets: Eliminate Sharp Corners

Sharp internal corners are prime sites for crack initiation.

Inside Radii: Always include a minimum radius of 0.15 mm – 0.5 mm on internal corners.

Outside Edges: Chamfering or radiusing outside edges prevents chipping during handling and assembly.

3. Hole Design & Spacing

Holes should be placed strategically to maintain structural integrity.

Hole-to-Edge Distance: Keep a distance of at least 1x the hole diameter from the edge.

Hole Spacing: Ensure a minimum of 2x the wall thickness between adjacent holes.

Avoid Blind Holes: Through-holes are easier and more cost-effective to manufacture than deep blind holes.

4. Threads & Fastening

Standard metal-style threads are difficult to machine in hard ceramics.

Coarse Threads: If threads are required, use the coarsest pitch possible.

Undercuts: Provide an undercut at the end of the thread to allow for tool exit.

Alternative: We often recommend using ceramic-to-metal assemblies (brazed metal inserts) for high-strength fastening.

5. Tolerances & Surface Finish

Precision costs time. Specify tight tolerances only where functionally necessary.

Feature	As-Sintered	Post-Machined
Linear Tolerance	±1% (Min ±0.1 mm)	±0.002 mm
Flatness	0.05 mm / 25 mm	0.001 mm
Surface Finish (Ra)	0.8 – 1.6 \μm	< 0.05 \μm (Mirror)

Summary Checklist for Engineers

Is the wall thickness as uniform as possible?

Have all sharp internal corners been radiused?

Are the tolerances realistic for as-sintered production?

Can the part be simplified for CIM or Dry Pressing?

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