Magnetic Keeper for Magnet Retention During Adhesive Curing
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Solution Overview
Problem
Magnetic properties of magnets are compromised when exposed to elevated temperatures, which can occur during the curing process of adhesives used in attaching magnets to portable computing device components, leading to partial or complete demagnetization.
Innovation Solution
The use of a magnetic shunt and keeper to contain magnetic field lines, allowing the adhesive to cure at elevated temperatures without affecting the magnet's magnetic properties, by attaching the magnet to a support structure with an adhesive, heating the assembly to a predetermined temperature, and then removing the keeper.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the adhesive is heated to elevated temperatures to cure within a predetermined time period, then the curing speed and productivity are improved, but the magnetic properties of the magnet deteriorate due to partial or total demagnetization
Solution Approach 1:
A magnetic keeper is introduced as an intermediary component between the magnet and the external environment. The keeper has high magnetic permeability and serves to contain the magnetic flux within the magnet-keeper assembly, preventing flux leakage. This allows the magnet to withstand elevated temperatures during adhesive curing without demagnetization, as the keeper stabilizes the magnetic circuit. After curing, the keeper is removed and the magnet retains its full magnetic properties.
2Loss of time
If the adhesive is heated to elevated temperatures to reduce curing time, then the manufacturing time is reduced, but the magnet becomes demagnetized losing its functional properties
Solution Approach 1:
The magnetic keeper is attached to the magnet before the heating process begins. This preliminary action prepares the magnetic circuit to withstand the upcoming thermal stress. The keeper is positioned to optimize flux containment, and then the entire assembly is heated to cure the adhesive. After curing completes, the keeper is removed. This sequence ensures the magnet never experiences demagnetization during the heating process.
3Strength
If the magnet is exposed to elevated temperatures during adhesive curing, then the adhesive bonding strength is improved, but the magnetic field strength of the magnet decreases
Solution Approach 1:
The magnetic keeper acts as a flux containment intermediary that allows thermal energy to pass through to cure the adhesive while simultaneously maintaining the magnetic circuit integrity. The keeper's high permeability creates a low-reluctance path for magnetic flux, preventing flux leakage even at elevated temperatures. This enables the adhesive to achieve full bonding strength through thermal curing while the magnet maintains its full magnetic field strength.
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
This method enables the adhesive to cure quickly at elevated temperatures while preserving the magnetic properties of the magnets, ensuring they remain functional and reducing the risk of demagnetization.
Implementation Method 1
placing a magnetic keeper on the magnet where the magnet fields from the magnet are substantially contained within the magnetic shunt and the magnetic keeper
Implementation Method 2
heating the magnet, the magnetic shunt and the adhesive to a predetermined temperature for a predetermined amount of time
Data Source
AI summary
A method and an apparatus for retaining magnetic properties of a magnet while undergoing manufacturing processes are presented. Ferrous materials with relatively good magnetic permeability are disposed adjacent to poles of magnet substantially containing magnetic field lines from the magnet within the ferrous materials. When the magnetic field lines are thereby substantially contained, the magnet can be exposed to elevated temperatures without losing magnetization strength. Adhesives, particularly adhesives that cure when exposed to elevated temperatures can be used with magnets configured to contain magnetic field lines without having the magnets lose magnetic strength.