Razor Blade Substrate Tip and Coating Tip Distance Optimization

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Solution Overview

Problem

Existing razor blades face a trade-off between durability and cutting force, where making the substrate thinner to reduce cutting force compromises durability, and increasing the coating layer thickness to enhance durability increases the cutting force.

Innovation Solution

The razor blade features a substrate with a substrate tip and a coating layer with a coating tip, where the coating layer's thickness at specific points relative to the substrate tip is optimized to ensure a distance between the substrate tip and the coating tip that ranges from 1.5 to 3, enhancing durability while maintaining a low cutting force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If the substrate is made thinner to reduce cutting force, then the shaving experience is improved, but the durability of the razor blade decreases

Engineering Contradiction:
Improvecutting forceVSAvoiddurability
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The patent applies composite materials by combining the substrate with a coating layer having different material properties. The coating layer is specifically designed with higher hardness and wear resistance than the substrate, creating a composite structure where each layer performs its specialized function - the thin substrate provides low cutting force while the coating layer provides durability protection.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by making the coating layer thickness non-uniform across the blade surface. The coating layer is thicker at the cutting edge region where durability is most critical, and thinner toward the rear. This localized variation optimizes the balance between durability at the cutting point and overall flexibility of the blade.

Inventive Principle:
Principle #3Local quality

2Reliability

If the coating layer thickness is increased to enhance durability, then the durability is improved, but the thickness of the entire razor blade increases which increases the cutting force

Engineering Contradiction:
ImprovedurabilityVSAvoidcutting force
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The patent applies local quality by varying the coating layer thickness across different regions of the blade. The coating layer is designed to be thickest at the cutting edge where durability is most needed, and gradually thinner toward the rear of the blade. This localized thickness variation ensures durability enhancement at the critical cutting zone while minimizing the overall thickness increase that would affect cutting force.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent applies dimensionality change by transitioning from a uniform two-dimensional coating to a three-dimensional varied thickness profile. The coating layer thickness is optimized as a function of position along the blade length, creating a gradient structure that provides enhanced durability where needed while maintaining low cutting force through reduced thickness in non-critical areas.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP4556181A1Razor blade
Publication Date: 2025.05.21 DORCO CO LTD
  • EP4556181A1 patent drawingFigure 1
  • EP4556181A1 patent drawingFigure 2
  • EP4556181A1 patent drawingFigure 3A

AI summary

According to one embodiment of the present disclosure, there is provided a razor blade comprising: a substrate having a substrate tip formed on an end portion; and a coating layer laminated on the substrate and having a coating tip formed on an end portion, characterized in that: the substrate comprises a pair of substrate facets extending from the substrate tip, a value obtained by dividing a distance between the substrate tip and the coating tip by a thickness of the coating layer at a point SD1 ranges from 1.5 to 3.