Dual-Solid Lubricant Screw Coating for Thermal Load Reduction

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Solution Overview

Problem

Existing coating agents for screws, particularly self-drilling and thread-forming screws, fail to provide sufficient drilling performance and handling efficiency, leading to high failure rates and increased manufacturing costs due to thermal loads and friction issues during metal construction assembly.

Innovation Solution

A coating agent comprising at least two different solid lubricants, including a thermoplastic and a wax, applied in a carrier liquid or as microgranules, which reduces friction and thermal loads by undergoing phase transformations, delaying the point of failure and improving screw performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If self-drilling screws are used to simplify the fastening process, then productivity is improved, but thermal stress and friction during drilling cause drill head deformation and screw failure

Engineering Contradiction:
Improvefastening process efficiencyVSAvoidscrew service life
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies a coating with solid lubricants that changes the friction parameters at the drill-bit and thread-contact surfaces. This reduces the thermal energy generated during drilling and thread formation, preventing plastic deformation of the drill head and extending screw service life while maintaining high productivity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful thermal stress and friction into beneficial reduced friction through solid lubricant coatings. The solid lubricants reduce the coefficient of friction at critical surfaces, transforming the harmful thermal effects into improved drilling performance and extended tool life

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If high-quality materials and sophisticated surface treatments are applied to cutting tools, then manufacturing precision and reliability are improved, but cost increases significantly

Engineering Contradiction:
Improvetool performanceVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of treating the entire screw with expensive coatings, the patent applies solid lubricant coatings specifically to the drill head and thread surfaces where friction and thermal stress are highest. This localized approach provides maximum performance benefit at minimal cost

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent uses cost-effective solid lubricant coatings that can be applied to standard screws, making high-performance fastening possible without requiring expensive specialty fasteners. The coating provides extended service life at a fraction of the cost of premium tools

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Temperature

If solid lubricant coatings are applied to reduce friction, then thermal stress is reduced, but the coating must withstand extreme thermal and mechanical conditions

Engineering Contradiction:
Improvethermal stress reductionVSAvoidcoating durability
Core Design Contradiction:
TemperatureVSStrength

Solution Approach 1:

The patent uses composite coating systems combining organic and inorganic solid lubricants. This composite approach provides both excellent friction reduction and high thermal stability, allowing the coating to withstand the extreme conditions of self-drilling while maintaining its lubricating properties

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent utilizes solid lubricants that maintain their lubricating properties across a wide temperature range, with some materials undergoing phase transitions that actually enhance their lubricating performance under the extreme thermal and mechanical conditions of self-drilling operations

Inventive Principle:
Principle #36Phase transitions

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 dual-solid lubricant coating significantly enhances drilling performance, reduces failure rates, and improves handling efficiency, with a notable reduction in failure rates from over 50% to below 10% in tests, and extends tool service life by postponing thermal overload.

Implementation Method 1

A coating agent comprising at least two different solid lubricants, including a thermoplastic and a wax, applied in a carrier liquid or as microgranules, which reduces friction and thermal loads by undergoing phase transformations

Methodology Applied
Scientific EffectPhase transformation: Phase Change

Implementation Method 2

These are sometimes referred to as lubricants because the reduced friction decreases the input of thermal energy into the material

Methodology Applied
Scientific EffectFriction reduction: Friction

Data Source

PatentEP3495431B1Coating agent for screws
Publication Date: 2021.07.21 SFS GROUP INTERNATIONAL AG

AI summary

A coating agent for fasteners, particularly self-drilling and self-tapping screws, serves to improve handling safety and reliability. The agent comprises at least two different solid lubricants, the first being a plastic or a wax, and the second being at least one other plastic. These solid lubricants are preferably present in a solution, for example, a water-based solution, an alcohol-based solution, or a solution containing another, particularly organic, solvent. The solid lubricants are preferably in the form of microgranules, which results in better distribution within the coating and thus improved availability of the solid lubricants during use. A method for coating such fasteners with this coating agent is also the subject of the present invention.