HiPIMS Coated Tap Drills Resolving Wear and Friction Trade-offs
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Solution Overview
Problem
Existing tap drill coatings, such as titanium nitride (TiN) and titanium carbonitride (TiCN), often require extensive re-grinding due to altered sliding and friction properties, leading to chip shape issues and increased costs, while alternative methods like cathodic arc evaporation result in unacceptable surface roughness and require costly post-treatments.
Innovation Solution
A High Power Impulse Magnetron Sputtering (HiPIMS) process is used to apply a hard material coating directly onto tap drills, achieving a compact, high-adhesion, low-surface-roughness layer system, specifically using nitrides, carbides, or oxides like AlCrN, which can be deposited without a bonding layer, and optionally combined with an amorphous carbon or DLC layer for improved sliding properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard material coating (TiN or TiCN) is applied by classic magnetron sputtering to improve wear resistance, then the coating provides hardness and protection, but the sliding and friction properties are altered detrimentally, requiring time-consuming and cost-intensive re-grinding
Solution Approach 1:
The patent applies HiPIMS (High Power Impulse Magnetron Sputtering) instead of classic magnetron sputtering, changing the deposition parameters to achieve a different coating structure. This process parameter change results in a coating that maintains hardness while preserving acceptable sliding and friction properties, eliminating the need for re-grinding
Solution Approach 2:
The patent uses a composite coating system consisting of multiple layers including AlCrN HiPIMS layers and optionally amorphous carbon or DLC layers. This composite structure combines the hardness of ceramic layers with the low friction properties of carbon-based layers, resolving the contradiction between hardness and sliding properties
2Strength
If cathodic arc evaporation is used to coat tap drills to achieve hard coating, then the coating provides hardness, but the surface roughness becomes unacceptable, requiring time-consuming and cost-intensive grinding
Solution Approach 1:
The patent replaces cathodic arc evaporation with HiPIMS technology, substituting one physical vapor deposition mechanism with another that offers better control over coating morphology. The HiPIMS process produces dense, fine-grained coatings with acceptable surface roughness, eliminating the need for post-coating grinding while maintaining hardness
3Duration of action of stationary object
If heat vapor deposition is used to coat tap drills with TiN or TiCN to avoid re-sharpening, then the coating maintains cutting edges, but the process requires great effort and is difficult to coat the required number of items economically
Solution Approach 1:
The patent changes the deposition process from heat vapor deposition to HiPIMS, which offers better process control and higher deposition rates. This parameter change enables economic coating of large numbers of items while maintaining the service life benefits through the use of hard AlCrN and carbon-based layers
4Strength
If a bonding layer is placed between the drill body and the coating to improve adhesion, then the coating adherence improves, but the device complexity and manufacturing steps increase
Solution Approach 1:
The patent changes the deposition process to HiPIMS, which provides such high adhesion that intermediate bonding layers become unnecessary. The high-energy ion bombardment during HiPIMS deposition creates strong mechanical and chemical bonding directly to the substrate, simplifying the layer structure while maintaining or improving adhesion
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 HiPIMS coating significantly extends the service life of tap drills by reducing wear and tear, eliminating the need for extensive re-grinding, and achieving comparable or superior cutting performance to plasma-assisted vacuum evaporation methods with reduced post-treatment costs and improved surface quality.
Implementation Method 1
A High Power Impulse Magnetron Sputtering (HiPIMS) process is used to apply a hard material coating directly onto tap drills
Implementation Method 2
high discharge current densities yield an increased degree of ionization of the sputtered material
Implementation Method 3
The corresponding ions are accelerated towards the substrate due to a negative has applied to the latter
Implementation Method 4
thanks to its good sliding properties, has the advantage of a lower friction on surfaces not corresponding to the cutting edges
Data Source
AI summary
The present invention relates to a method for coating a substrate, preferably a drill, wherein at least one first HiPIMS layer is applied by means of a HiPIMS process. Preferably, at least one second layer is applied to the first HiPIMS layer by means of a coating process that does not contain a HiPIMS process.