Sintered Bearing Surface Opening Control

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Solution Overview

Problem

Sintered bearings with large surface openings due to melting of Sn powder suffer from defective lubrication and dynamic pressure issues, leading to performance deterioration, especially in fluid dynamic bearing devices, and existing solutions like shot blasting increase manufacturing costs.

Innovation Solution

The sintered bearing is produced with a maximum surface opening diameter of 25 μm or less through the use of binder metal powder with a small particle diameter, ensuring uniform dispersion and preventing segregation, thereby reducing surface openings without additional costly treatments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If Sn powder is segregated in the mixed powder, then the mixing process is simple, but large holes are formed on the bearing surface

Engineering Contradiction:

Improvemixing process simplicityVSAvoidsurface opening size

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The Sn powder is pre-sorted into two particle size fractions before mixing with the bearing material. This preliminary classification ensures proper distribution without requiring complex segregation prevention during mixing, maintaining manufacturing simplicity while achieving precise surface quality.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If hole-sealing treatment such as shot blasting is applied, then surface openings are eliminated preventing lubricant infiltration, but manufacturing cost increases sharply

Engineering Contradiction:

Improvelubrication stabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The sintered bearing itself provides the hole-sealing function through its internal structure. By controlling the particle size distribution of Sn powder, the bearing naturally forms a surface with minimal openings, eliminating the need for additional shot blasting or rotary sizing treatments.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Instead of using expensive post-processing treatments, the patent uses a cost-effective particle size control approach during manufacturing. The dual-fraction Sn powder system achieves surface sealing as a byproduct of the sintering process itself, avoiding additional manufacturing steps.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 effectively prevents defective lubrication and dynamic pressure issues, maintaining bearing performance while avoiding the cost increase associated with hole-sealing treatments.

Implementation Method 1

Sn powder having a relatively low melting point is hardened after being molten at the time of sintering

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

when the binder metal powder having a small particle diameter is used, the binder powder becomes easier to uniformly disperse in the mixed powder

Methodology Applied

Scientific EffectDispersion: Dispersion (of waves)

Implementation Method 3

the lubricating fluid with which it is impregnated oozes out to a sliding portion between the bearing and the shaft to form a lubricating film

Methodology Applied

Scientific EffectLubrication: Lubrication

Data Source

PatentUS9316253B2Sintered bearing

Publication Date: 2016.04.19 NTN CORP

AI summary

A maximum diameter (d) of each of surface openings formed in a bearing surface through melting of Sn metal powder as a binder is set within a range of 0 μm<d≦̸25 μm. In order to attain the range, binder metal powder having a maximum particle diameter of 25 μm or less is used.