Zirconia or alumina
- Hardness and wear resistance no plastic comes close to
- Stays stiff and insulating at temperatures that would melt any resin
- Brittle, so drops and point loads need care in the design
Process guide
Ceramic Injection Molding
CIM follows the same road as metal injection molding, from powder and binder to a sintered part. The difference is where it ends: a hard, brittle material that cannot bend to hide a flaw.
Same route, less forgiveness
Why ceramic molding is judged at the press
The furnace does not repair anything. It only reveals it.
The stages match MIM: feedstock, a molded green part, binder removal, then sintering to full hardness. A metal part can hide a small void or a weak knit line, because metal yields a little before it breaks. A fired ceramic has no such margin. Whatever went wrong in the mold tends to come out of the furnace as a crack.
So most of the engineering effort on a CIM part goes into the green state. Gate position, fill pattern, and how the part is picked off the core decide the yield long before anyone opens the furnace.
Materials
The ceramics that get injection molded
Two oxides cover most of the work.
| Material | Why it is chosen | Typical parts |
|---|---|---|
| Zirconia | Tough for a ceramic, polishes to a high gloss, tooth colored grades | Orthodontic brackets, fiber optic ferrules, watch cases, blades |
| Alumina | Very hard and electrically insulating, the workhorse among technical ceramics | Insulators, thread and wire guides, wear pads, sensor bodies |
| Translucent alumina | Lets light through after careful sintering | Lamp tubes, clear orthodontic brackets |
Defects
Molding faults that survive the furnace
Each of these can look harmless on a green part.
Knit lines where two flow fronts meet, which fire into weak seams
Voids and sink inside heavy sections, which open up during binder removal
Powder and binder separating near the gate, leaving a zone that shrinks differently
Ejection stress on a fragile green part, leaving microcracks that show only after firing
Uneven sections that trap binder and then crack or bloat in the kiln
Tooling and finishing
Hard powder in, hard part out
Ceramic wears the equipment on the way in and resists every tool on the way out.
- Ceramic powder scours screws, check rings, and gates, so they are hardened or coated and still treated as wear parts
- The gate goes into the heaviest section so it packs out fully before the thin areas freeze
- Green parts are often picked by robot, because hand handling leaves cracks nobody sees yet
- Anything the furnace cannot hold to size is diamond ground or lapped afterward, which is slow and costly, so drawings keep those features few
Alternative
Ceramic or high performance plastic
Ceramic is chosen for hardness and heat. When the job is really insulation or light wear, PEEK or PEI is often enough.
PEEK or PEI
- Tough under impact, so it survives drops that would chip a ceramic
- Molds on standard thermoplastic equipment with no powder wear or firing stage
- Wears faster and softens far sooner than ceramic under heat
FAQ
Questions about ceramic injection molding
How is CIM different from MIM?
The route is the same. The powder is ceramic instead of metal, it is fired at higher temperatures, and the finished part is brittle. That makes molding defects far more costly, and it makes finishing slower because only diamond tools cut it.
Why are ceramic parts ground after sintering?
Firing shrinks the part a lot, and tiny variations in that shrink limit how closely it holds size. Features that need better than that are ground or lapped with diamond afterward.
Where is ceramic injection molding used?
Orthodontic brackets, fiber optic ferrules, watch parts, insulators, textile thread guides, and small wear parts in pumps and valves. The common thread is a small, detailed part that needs hardness or heat resistance.
Does NetProto mold ceramics?
No. NetProto's production path is thermoplastic injection molding. This page is a reference for engineers deciding whether a part truly needs ceramic, and a PEEK or PEI version can be quoted from CAD.
Keep reading
Related guides
The metal version of the process and the plastics that take on ceramic jobs.
Metal injection molding
The shared powder and sintering route.
Metal injection moldingPEEK
Heat, wear, and chemical resistance in a plastic.
PEEKCarbon fiber PEEK
Stiffer and harder wearing than plain PEEK.
Carbon fiber PEEKPEI (Ultem)
Insulating and flame resistant.
PEI (Ultem)PEEK vs Ultem
Choosing between the two.
PEEK vs UltemMedical and dental
Molded plastic parts for devices and instruments.
Medical and dentalProcesses hub
Every molding process and secondary operation.
Processes hubNext step
Check whether a high performance plastic can take the job
Upload CAD with the temperature, wear, and electrical requirements. The review looks at PEEK, PEI, and filled grades on a standard injection mold. NetProto manufacturing is ISO 9001 certified.