Electrostatic Ceramic Mold Release Agent for Permanent Magnet Production
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Solution Overview
Problem
The production of permanent magnets from powder compacts faces challenges such as caking between the powder compact and the press mold during hot pressing, leading to defects and safety risks due to the use of flammable and hazardous carrier mediums for mold release agents, and the need for waiting times for drying, which slows down the process and can damage equipment.
Innovation Solution
The use of an electrically non-conductive ceramic mold release agent, such as boron nitride, applied electrostatically to prevent adhesion between the powder compact and the press mold, eliminating the need for hazardous carrier mediums and allowing immediate processing without waiting for drying, thus enhancing safety and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mold release agent is applied using a liquid carrier medium (e.g., alcohol or water), then the powder compact is coated to prevent caking, but the process requires waiting time for evaporation/drying and poses safety risks due to flammability and explosiveness
Solution Approach 1:
The patent extracts and eliminates the liquid carrier medium from the mold release agent formulation, using only dry powder form. This removal of the hazardous and time-consuming liquid component resolves the contradiction by preventing caking through dry powder application without requiring evaporation or drying time, thereby eliminating safety risks and process delays.
Solution Approach 2:
The patent employs a simple dry powder mold release agent that can be easily applied and does not require complex drying infrastructure. The dry powder formulation is designed for single-use application where the carrier medium would otherwise need to evaporate, replacing the need for energy-intensive drying processes and hazardous flammable liquids with a simple, safe, and efficient dry application method.
2Reliability
If a liquid carrier medium is used to apply the mold release agent, then the powder compact surface is coated, but the liquid may penetrate into the pores and hinder bonding of powder particles during pressing
Solution Approach 1:
The patent removes the liquid carrier medium entirely from the mold release agent system, using only dry powder form. This extraction prevents liquid penetration into the powder compact pores, thereby avoiding interference with the bonding process during hot pressing while still achieving effective caking prevention through the dry powder coating.
3Reliability
If alcohol is used as a carrier medium for the mold release agent, then the graphite powder is applied to the powder compact, but increased safety efforts and process complexity are required due to flammability and occupational safety regulations
Solution Approach 1:
The patent extracts and eliminates the flammable alcohol carrier medium from the mold release agent formulation, using only dry powder form. This removal eliminates all fire safety hazards and occupational safety concerns associated with alcohol handling, storage, and application, thereby simplifying the entire process while maintaining effective caking prevention.
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 faster and safer production of permanent magnets by preventing caking and surface cracking, allowing for higher production rates and maintaining the magnetic properties of the material, while reducing safety risks and equipment damage.
Implementation Method 1
a mold release agent which is electrically non-conductive and consists of a ceramic material or contains a ceramic material and which is electrostatically applied to the powder compact and/or the die
Implementation Method 2
water damages the magnetic powder and explosive hydrogen gas is also produced, which has to be extracted during the process
Implementation Method 3
The carrier medium then evaporates, leaving a thin layer of graphite on the surface of the powder compact
Implementation Method 4
in the case of alcohol, it would burn in the mold. The resulting temperatures can damage the pressing tool
Data Source
Figure 1
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Figure 4~5
AI summary
The invention relates to a method and apparatus for producing a permanent magnet (9) by hot pressing (4) a powder compact (2) made of mechanically pre-compressed magnetic powder (15) in a press mold (11). The powder compact (2) and/or the press mold (11) are/is coated with a release agent (12) before the hot pressing (4) in order to prevent adhesion of the powder compact (2) to the press mold (11). According to the invention, the release agent (12) is used, which is electrically non-conductive, made of or contains a ceramic material and is electrostatically applied to the powder compact (2) and/or the press mold (11). The use of conventional graphite suspended in isopropanol can thus be abandoned. This speeds up and simplifies the manufacturing process for there are no waiting times for the evaporation of the isopropanol and also no fire protection and work safety measures are required.