Pressure-Cast Ceramic Bodies With Impermeable Dry-Release Mold Surfaces

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Solution Overview

Problem

Traditional ceramic casting methods face issues with significant drying times and surface tackiness due to liquid penetration through porous molds, leading to cracks and breakage, and are limited by mold taper requirements.

Innovation Solution

A pressure casting method using an impermeable mold cavity surface and a porous substrate with small pore size to inhibit liquid penetration, allowing for a 'dry release' process that ejects ceramic bodies without re-introducing liquid, ensuring smooth and non-tacky surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If pressure casting is used with porous molds to enable rapid ejection, then productivity is improved, but the cast body surface becomes tacky and prone to cracks

Engineering Contradiction:

Improveejection speedVSAvoidsurface quality

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The mold is segmented into two distinct functional zones: an impermeable cavity surface that contacts the ceramic slurry and prevents liquid penetration, and a porous exterior structure that enables rapid water removal and ejection. This segmentation allows each zone to perform its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different parts of the mold have different permeability properties tailored to their specific functions. The cavity surface is made impermeable to prevent surface defects, while the exterior porous structure facilitates rapid water removal. This local differentiation of material properties resolves the contradiction between rapid ejection and surface quality.

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If traditional porous molds are used for casting, then liquid removal is improved, but significant drying time is required

Engineering Contradiction:

Improveliquid removal efficiencyVSAvoiddrying time

Core Design Contradiction:

Quantity of substanceVSLoss of time

Solution Approach 1:

The harmful function of liquid penetration into the mold structure is extracted and eliminated by using an impermeable cavity surface. Meanwhile, the useful function of water removal is enhanced by applying external pressure to force water through the porous exterior structure, enabling rapid ejection without traditional drying time.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Pressure is applied during the casting process to force water through the porous mold structure, accelerating the water removal process. This hydraulic approach replaces the slow passive drying process with an active pressure-driven water removal mechanism.

Inventive Principle:

Principle #29Pneumatics and hydraulics

3Ease of operation

If mold taper is used to facilitate removal, then ease of operation is improved, but the shape of the cast ceramic body is limited

Engineering Contradiction:

Improvemold removal easeVSAvoidshape flexibility

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

Water removal and ceramic body formation are performed as preliminary actions while the ceramic body is still within the mold cavity. By the time ejection is needed, the ceramic body has already shrunk and consolidated, naturally facilitating removal without requiring taper geometry.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The mechanical taper system is replaced with a pressure-driven ejection system. Pressure is applied to force water through the porous structure, and the ceramic body is ejected through the cavity opening without requiring mechanical clearance or taper, enabling complex shapes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The method significantly reduces casting time and eliminates surface defects, enabling rapid ejection of ceramic parts with minimal shrinkage and improved structural integrity, suitable for producing ceramic mill blocks and dental restorations.

Implementation Method 1

a porous mold surrounded by an enclosure... water that enters the porous structure of the mold is forced back through the porous structure

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Implementation Method 2

removing liquid from the slurry under pressure via the porous casting substrate

Methodology Applied

Scientific EffectPressure-driven flow: Pressure Gradient

Implementation Method 3

A mold is described that has an impermeable cavity surface providing a 'dry release' of the cast object... Impermeable cavity surfaces resist penetration of the liquid component of a ceramic slurry under casting pressure

Methodology Applied

Scientific EffectImpermeability:

Implementation Method 4

dispensing a ceramic slurry into a mold cavity under pressure... removing liquid from the slurry under pressure... ejecting the resulting ceramic body from the mold opening by application of pressure

Methodology Applied

Scientific EffectPressure: Pressure Increase

Data Source

PatentUS20250262798A1Pressure casting of submicron ceramic particles and methods of ejection

Publication Date: 2025.08.21 JAMES R GLIDEWELL DENTAL CERAMICS

AI summary

Methods and apparatus are provided for pressure casting ceramic bodies. Methods and apparatus are provided for rapid ejection of cast ceramic bodies from a mold. A mold is described that has an impermeable cavity surface to provide dry release of the cast body. Ceramic bodies produced by the methods and apparatus have smooth, non-tacky surfaces after ejection from the mold