Razor Blade Coating for Low Cutting Force and Skin Safety
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Solution Overview
Problem
Existing razor blades face a challenge in balancing low cutting force, increased safety, and comfort, as sharper edges with reduced tip radii and profiles compromise strength and durability, leading to discomfort during shaving.
Innovation Solution
A razor blade design featuring a substrate with a coated edge, comprising a niobium adhesive layer, a DLC hard coating, a chromium overcoat, and a polytetrafluoroethylene lubricious layer, with a blade tip radius of 500 to 1500 angstroms and specific thickness profiles to maintain a low cutting force while ensuring safety and comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the blade tip radius is reduced to create a sharper edge, then the cutting force is reduced, but the strength and durability of the blade are compromised
Solution Approach 1:
The blade employs a composite structure with a stainless steel substrate providing strength and durability, overlaid with a diamond-like carbon (DLC) coating that enables ultra-sharp edge formation with tip radii of 0.5-1.5 micrometers. The DLC coating has superior mechanical properties including higher hardness and elastic modulus, allowing the blade to maintain both low cutting force and high strength simultaneously through material composition rather than geometry alone.
2Force
If the blade profile is thinned to reduce cutting force, then the blade becomes sharper, but safety and comfort are compromised due to increased skin engagement
Solution Approach 1:
The blade implements different tip radii at different locations along the cutting edge, with the apex having a radius of 0.5-1.5 micrometers for low cutting force, while the sides transition to larger radii. This gradient in local geometry allows the center to cut efficiently while the sides glide over skin without causing irritation or safety issues.
Solution Approach 2:
The invention changes the geometric parameters of the blade tip, specifically using tip radii in the range of 0.5-1.5 micrometers which is larger than conventional ultra-sharp blades but still provides low cutting force. This parameter optimization balances cutting performance with skin safety and comfort.
3Object-affected harmful factors
If the blade tip radius is increased to improve safety, then skin engagement is reduced, but cutting force increases
Solution Approach 1:
The DLC coating material enables the blade to achieve tip radii of 0.5-1.5 micrometers with significantly enhanced edge strength compared to uncoated steel. This material property allows larger tip radii to maintain low cutting force, breaking the traditional trade-off between safety and cutting performance.
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 design provides a blade with reduced irritation and increased comfort by minimizing skin engagement, allowing the skin to glide over the edge without nicking or scraping, while maintaining edge strength and reducing tug-and-pull associated with shaving.
Implementation Method 1
Hard coatings such as diamond, amorphous diamond, diamond-like carbon-(DLC) material, nitrides, carbides, oxides, or ceramics are often used to improve strength, corrosion resistance, and shaving ability
Implementation Method 2
Polytetrafluoroethylene (PTFE) can be used to provide friction reduction
Implementation Method 3
Layers of niobium or chromium containing materials can aid in improving the binding between the substrate, typically stainless steel, and hard carbon coatings, such as DLC
Data Source
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AI summary
A razor blade including a substrate with a coating joined to the substrate defining a coated blade. The coated blade including a cutting edge being defined by a blade tip having a tip radius of from 500 to 1500 angstroms. The coated blade having a thickness of between 0.3 and 0.5 micrometers measured at a distance of 0.25 micrometers from the blade tip, a thickness of between 0.4 and 0.65 micrometers measured at a distance of 0.5 micrometers from the blade tip, a thickness of between 0.61 and 0.71 micrometers measured at a distance of 1 micrometer from the blade tip, a thickness of between 0.96 and 1.16 micrometers measured at a distance of 2 micrometers from the blade tip, and a thickness of between 1.56 and 1.91 micrometers measured at a distance of 4 micrometers from the blade tip.