Ferrite Injection Molding Binder Thickness Control

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Solution Overview

Problem

The existing powder injection molding methods experience fluctuations in flow characteristics and strength of molded articles due to inconsistent binder content relative to the base powder's specific surface area, leading to variations in sintered body characteristics.

Innovation Solution

The method involves calculating hypothetical binder thicknesses using specific formulas to ensure optimal binder coverage on ferrite particles, using a combination of first and second binders with different softening points to maintain particle distance and improve flow characteristics, strength, and sintered body density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If binder content is specified by weight percentage of base powder, then manufacturing process is simple, but flow characteristic fluctuates due to specific surface area variations

Engineering Contradiction:

Improvebinder content specificationVSAvoidflow characteristic consistency

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention changes the parameter basis for binder content specification from weight percentage of base powder to hypothetical thickness of binder layer. This parameter transformation directly addresses the problem by making the binder content independent of base powder specific surface area variations, thereby ensuring consistent flow characteristics while maintaining ease of manufacture through a clear calculation method.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If binder content is increased to ensure particle coverage, then particle aggregation is reduced, but molded article strength decreases due to excessive binder

Engineering Contradiction:

Improveparticle dispersion uniformityVSAvoidmolded article strength

Core Design Contradiction:

Stability of the object's compositionVSStrength

Solution Approach 1:

The invention transforms the binder content specification from weight-based to thickness-based parameters. By controlling the hypothetical thickness of the binder layer within a specific range (0.01-0.1 μm), the invention achieves optimal particle coverage that prevents aggregation while avoiding excessive binder content that would weaken the molded article. This parameter change enables precise control of binder distribution.

Inventive Principle:

Principle #35Parameter changes

3Strength

If binder content is decreased to improve molded article strength, then excess binder is reduced, but particle aggregation increases leading to poor flow characteristics

Engineering Contradiction:

Improvemolded article strengthVSAvoidflow characteristic consistency

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The invention changes the control parameter from binder weight to binder layer thickness. This transformation allows precise control of the binder amount to maintain optimal particle separation for good flow characteristics while using minimal binder to preserve molded article strength. The thickness parameter directly correlates with particle coverage efficiency.

Inventive Principle:

Principle #35Parameter changes

4Ease of manufacture

If binder content is adjusted based on base powder weight, then manufacturing is straightforward, but sintered body density fluctuates

Engineering Contradiction:

Improvebinder content controlVSAvoidsintered body density

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention transforms the binder content specification from weight-based to thickness-based parameters. By controlling the hypothetical thickness of the binder layer, the invention ensures consistent particle spacing and packing efficiency, which directly determines sintered body density. This parameter change maintains manufacturing straightforwardness through clear calculations while achieving precise density control.

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 approach reduces fluctuations in flow characteristics and enhances the strength and consistency of molded articles and sintered bodies by ensuring sufficient binder coverage and dispersion of ferrite particles, resulting in improved magnetic flux density and reduced density variations.

Implementation Method 1

particle surfaces of base powders are covered with binders to preserve a distance among particles

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

binders are prepared and compounded in base powder and then mixed with to be a mixture

Methodology Applied

Scientific EffectCoating: Coatings

Data Source

PatentUS8765860B2Injection molding composition and producing method thereof

Publication Date: 2014.07.01 TDK CORP

AI summary

An injection molding composition, having a small fluctuation characteristic and a better characteristic, is provided. The above composition is the injection molding composition comprising a ferrite powder which is a collection of ferrite particles, a first binder and a second binder. A weight and a specific surface area of the ferrite powders are represented by Wp and S, and a weight and a density of the first binder and the second binder is represented by Wb1, Wb2, and Db1, Db2. A hypothetical thickness Tb1 of the first binder is 2.0 to 15.0, and a hypothetical thickness Tb2 of the second binder is 16.5 to 32.0. In the composition, it is preferable that coated ferrite particles coating the outer circumference of the ferrite particles with the first binder and the second binder exist.Tb1 [nm]=(Wb1×103)/(Db1×Wp×S) formula (1)Tb2 [nm]=(Wb2×103)/(Db2×Wp×S) formula (2)