Layered Coated Metal Mold for Wear and Adhesion Resistance
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Solution Overview
Problem
Conventional coated metal molds used in hot stamping processes for high tensile strength steel sheets, particularly those plated with aluminum or zinc, face issues with early mold life due to adhesion and insufficient wear, heat, and adhesion resistance, especially under heavy load conditions.
Innovation Solution
A coated metal mold design featuring a nitride A layer with a film thickness of 5 μm or more, alternately layered with chromium and vanadium nitrides, and a diamond-like carbon B layer with specific surface roughness characteristics, where the B layer is applied on top to enhance sliding characteristics and adhesion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional hard coating is applied to a metal mold for hot stamping plated steel sheets, then wear resistance is improved, but adhesion resistance deteriorates leading to early mold life termination
Solution Approach 1:
The coating is divided into multiple functional layers: a base coat layer providing wear resistance, an intermediate layer improving adhesion, and a top coat layer providing sliding characteristics. This segmentation allows each layer to optimize its specific function without compromising others, resolving the contradiction between wear resistance and adhesion resistance.
Solution Approach 2:
The coating uses composite material structure with different materials in each layer: hard ceramic materials in the base coat for wear resistance, metallic or transitional materials in the intermediate layer for adhesion, and low-friction materials in the top coat for sliding characteristics. This composite approach enables simultaneous achievement of wear resistance and adhesion resistance.
2Reliability
If the working plane surface roughness is reduced to improve sliding characteristics, then adhesion resistance is improved, but mold life under heavy load conditions deteriorates due to insufficient wear resistance
Solution Approach 1:
The coating is divided into multiple functional layers: a base coat layer providing wear resistance, an intermediate layer improving adhesion, and a top coat layer providing sliding characteristics. This segmentation allows each layer to optimize its specific function without compromising others, resolving the contradiction between wear resistance and adhesion resistance.
Solution Approach 2:
Different regions of the coating have different properties: the base coat layer has high hardness and wear resistance, the intermediate layer has high adhesion strength, and the top coat layer has low friction and smooth surface. This local quality differentiation allows the coating to simultaneously provide wear resistance and adhesion resistance in different locations.
3Duration of action of stationary object
If a thick nitride coating layer is applied to improve wear resistance and heat resistance, then durability is improved, but surface roughness increases reducing sliding characteristics and adhesion resistance
Solution Approach 1:
The coating is divided into multiple functional layers: a base coat layer providing wear resistance, an intermediate layer improving adhesion, and a top coat layer providing sliding characteristics. This segmentation allows each layer to optimize its specific function without compromising others, resolving the contradiction between wear resistance and adhesion resistance.
Solution Approach 2:
The coating uses composite material structure with different materials in each layer: hard ceramic materials in the base coat for wear resistance, metallic or transitional materials in the intermediate layer for adhesion, and low-friction materials in the top coat for sliding characteristics. This composite approach enables simultaneous achievement of wear resistance and adhesion resistance.
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 solution provides a coated metal mold with improved durability, extending mold life across cold to warm/hot usage ranges by enhancing wear resistance, heat resistance, and adhesion resistance, while preventing early galling and adhesion.
Implementation Method 1
coated metal molds in which the working plane is covered with a hard coating by physical vapor deposition (hereinafter, referred to as PVD method)
Implementation Method 2
a B layer formed from a diamond-like carbon coating
Data Source
AI summary
The purpose of the present invention is to provide a coated metal mold having superior durability and adhesion resistance over a usage range from cold to warm/hot; and a method for manufacturing the coated metal mold. The coated metal mold is characterized by having a hard coating on a surface, wherein the hard coating includes an A layer formed from a nitride and having a film thickness not smaller than 5 μm, and a B layer formed of a diamond-like carbon coating, the B layer is disposed closer to the outer surface side than the A layer, the surface of the B layer has an arithmetic mean roughness Ra≤0.2 μm, a maximum height Rz≤2.0 μm, and a skewness Rsk<0.