3D Printing Binder System for High-Strength Mold Removal

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Solution Overview

Problem

Existing 3D printing methods using gypsum, cement, and salt-bonded molding materials face issues such as low strength, poor gas permeability, difficulty in mold removal, and environmental concerns, making them unsuitable for series casting, especially in automotive applications.

Innovation Solution

A method involving a particulate material with a spray-dried alkali silicate solution, selectively activated by a water-based solution and dried, which provides improved bonding and strength, and can include additives like phyllosilicates and latent inorganic hardeners to enhance thermal resistance and reusability of unprinted material.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If gypsum-bonded molding materials are used for particle material solidification, then the material can be activated with aqueous solution and selectively hardens, but the plaster contains free water that causes problems during casting and the strength and temperature resistance are not high enough

Engineering Contradiction:
Improveease of mold productionVSAvoidmold strength
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent changes the binder material from gypsum to a combination of clay and resin, fundamentally altering the chemical composition and binding mechanism. This parameter change enables the mold material to achieve both high strength and temperature resistance while eliminating the free water problem inherent in gypsum-based systems

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite binder system combining clay and resin materials. The clay provides thermal stability and bonding capability, while the resin component enhances strength and temperature resistance. This composite approach resolves the contradiction between ease of manufacture and mechanical/thermal performance

Inventive Principle:
Principle #40Composite materials

2Strength

If cement-bonded molding materials are used, then higher strengths are developed when tempered, but the cast part can only be freed from the mold material with difficulty after casting and excess water leads to problems during watering

Engineering Contradiction:
Improvemold strengthVSAvoidease of mold removal
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The patent changes the binder chemistry from cement-based to a clay-resin system with controlled water content. This parameter change allows the mold to achieve high strength through the resin-clay bonding mechanism while maintaining ease of part removal by controlling the water-curing process and using release agents

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies release agents to the mold cavity before casting and controls the water content and curing process in advance. This preliminary action prevents excessive bonding between the cast part and mold material, enabling easy removal after casting without compromising mold strength

Inventive Principle:
Principle #10Preliminary action

3Productivity

If conventional particle materials are used in 3D printing, then the construction process can be performed layer by layer, but the unbound powder is strongly alkaline and not kind to the skin and creates unpleasant dust

Engineering Contradiction:
Improveconstruction speedVSAvoidskin irritation and dust
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the particle material composition from strongly alkaline cement-based materials to a clay-resin system with controlled pH and reduced dust generation. This parameter change maintains the layer-by-layer construction capability while eliminating skin irritation and unpleasant dust, making the process safer for operators

Inventive Principle:
Principle #35Parameter changes

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

This method achieves higher strength and improved thermal resistance, allows for easier mold removal, and reduces environmental impact, making it suitable for economic and environmentally friendly three-dimensional printing.

Implementation Method 1

selectively activated by a water-comprising solution

Methodology Applied
Scientific EffectHydration: Mineral Hydration

Implementation Method 2

a drying process

Methodology Applied
Scientific EffectEvaporation: Evaporation

Data Source

PatentEP2723697B1Method for the layerwise construction of models
Publication Date: 2018.05.16 VOXELJET AG

AI summary

A method is described here for the layerwise construction of models, wherein, in a building region, a particulate material is applied layerwise and selectively cured. These steps are repeated until a desired model is obtained. The material comprises in this case a particulate building material and a spray-dried alkali metal silicate solution. Selective activation of the curing proceeds using a water-comprising solution.