Heat-Embedded Threaded Sleeve for Stronger FDM Screw Joints
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Solution Overview
Problem
Existing solutions for assembling threaded sleeves in components manufactured by FDM processes lack sufficient strength and stability, often resulting in weakened screw connections due to the anisotropic nature of FDM materials and the risk of filament separation when using self-tapping screws or threaded sleeves.
Innovation Solution
A threaded sleeve with a groove along its longitudinal axis and a self-tapping thread on the outwardly facing surface, combined with a metric thread on the inwardly facing surface, is used with heat input to melt and embed the FDM material, creating a strong and reusable connection by allowing the filament to adhere to the thread geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If self-tapping screws or threaded sleeves are screwed into FDM components, then assembly is achieved, but the screw connection strength is insufficient due to filament separation and material anisotropy
Solution Approach 1:
The patent changes the temperature parameter during assembly, heating the FDM component to its melting point range (200-300°C) to transform the material state from solid to semi-molten, enabling the threaded sleeve to be pressed in and fuse with the surrounding material, thereby achieving strong connections that overcome the weakness of cold-screwing into anisotropic FDM structures
Solution Approach 2:
The patent utilizes the phase transition of the FDM material from solid to semi-molten state through heating, allowing the threaded sleeve to be inserted and the material to fuse around it. This phase change enables the material to flow and bond with the threaded sleeve, creating a strong, integrated connection that prevents filament separation and overcomes the anisotropy issue
2Productivity
If self-tapping screws are used for assembly, then quick and inexpensive assembly is achieved, but the plastic melts on contact surfaces and desired preload force cannot be applied
Solution Approach 1:
The patent controls the temperature parameter to reach the melting point range (200-300°C) but prevents excessive heating that would cause burning or degradation. This controlled temperature parameter allows the material to become sufficiently soft for easy insertion and strong bonding, while maintaining integrity and avoiding the harmful effect of overheating that melts contact surfaces
Solution Approach 2:
The patent applies preliminary heating to the FDM component before inserting the threaded sleeve. This preliminary action softens the material in advance, allowing the threaded sleeve to be pressed in easily without generating excessive friction heat during insertion that would melt the contact surfaces, thereby achieving both quick assembly and preventing harmful overheating
3Reliability
If threaded sleeves are inserted by heat embedding, then reusable connection is achieved, but the insertion process is complex requiring mandrel heating and defined pressure
Solution Approach 1:
The patent designs the threaded sleeve with a conical leading end that combines multiple functions: it acts as a guide for alignment, a press-fit tool for insertion, and a mixing element that stirs the semi-molten material during insertion. This multi-functional design simplifies the insertion process by eliminating the need for separate mandrels and complex heating/pressing equipment, while still achieving reusable connections
Solution Approach 2:
The threaded sleeve's conical leading end enables self-guided insertion into the heated FDM component. The cone shape naturally aligns with the hole and guides the sleeve in during pressing, eliminating the need for external alignment tools or mandrels. The sleeve essentially prepares its own insertion path through the softened material
4Adaptability or versatility
If FDM components are designed with printed metric nuts, then screw connection is achieved, but the connections lack sufficient strength and cannot be incorporated after production
Solution Approach 1:
The patent applies preliminary heating to the FDM component to soften the material before inserting the threaded sleeve. This preliminary action creates a receptive state in the material that allows easy insertion and strong bonding, enabling post-production modification with sufficient connection strength that printed nuts cannot achieve
Solution Approach 2:
The patent utilizes the phase transition of FDM material to semi-molten state during insertion, allowing the threaded sleeve to fuse with the surrounding material. This creates a strong, integrated connection that is mechanically superior to printed nuts, while still enabling post-production modification capability
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 approach significantly increases the strength and stability of screw connections in FDM components by ensuring the filament adheres to the thread, preventing loosening and enhancing the overall firmness of the bond, while avoiding the need to cut threads into the material.
Implementation Method 1
assembling with heat input in a component manufactured by FDM process
Implementation Method 2
melt and embed the FDM material, creating a strong and reusable connection
Implementation Method 3
allowing the filament to adhere to the thread geometry
Data Source
AI summary
A threaded sleeve for assembling with heat input in a component manufactured by FDM process is provided. The threaded sleeve includes a groove along its longitudinal axis. Further, the outwardly facing surface of the threaded sleeve includes a self-tapping thread which is divided into two sections along the threaded sleeve's longitudinal axis. The first section includes a constant pitch diameter and the second area comprises a pitch diameter decreasing along its longitudinal axis. The inwardly facing surface of the threaded sleeve comprises a metric thread. Furthermore, a kit, a system and a method for assembling with heat input the above-mentioned threaded sleeve in a component manufactured by FDM process is provided.