Sacrificial Plastic Sections for Metal Insert Recycling
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Solution Overview
Problem
The integration of metal components in plastic parts, such as metal-threaded inserts, hinders mechanical recycling processes, making it economically unfeasible to recycle polycarbonate materials, especially in the electrical, electronic, and household appliance industries.
Innovation Solution
Designing plastic parts with a sacrificial section containing stress concentrators, such as patterns of openings or trenches around bosses, allows for the easy separation of metal inserts from the recyclable portion during recycling, maximizing the recyclable material's volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal-threaded inserts are integrated into plastic parts, then the part's structural strength and functionality are improved, but the recyclability of the plastic material deteriorates
Solution Approach 1:
The patent divides the plastic part into two distinct segments: a sacrificial section containing the metal insert and a recyclable section. This segmentation is achieved through design features such as recesses, reduced wall thickness, or separate molding processes that create a clear boundary between the insert-containing portion and the main recyclable body, enabling selective removal of the metal insert during recycling
Solution Approach 2:
The patent extracts the metal insert from the main recyclable plastic body by designing a sacrificial section that can be easily separated. The extractable insert portion contains all necessary structural functions while being detachable through mechanical means such as breaking at predetermined weak points, allowing the remaining plastic to be fully recycled
2Ease of manufacture
If a sacrificial section is designed to facilitate recycling, then the recyclability of the plastic material is improved, but the structural integrity of the part may deteriorate
Solution Approach 1:
The patent applies local quality by creating a sacrificial section with deliberately different structural properties compared to the main body. This section has reduced wall thickness, includes recesses, or contains stress concentrators that make it specifically suited for easy separation, while the rest of the part maintains full structural integrity and strength requirements
Solution Approach 2:
The patent introduces asymmetry in the wall thickness distribution or structural configuration, creating a distinct weak zone that is intentionally weaker than the rest of the part. This asymmetric design ensures that when force is applied during recycling, separation occurs predictably at the sacrificial section rather than compromising the main structural body
3Ease of manufacture
If metal components are removed from plastic parts, then the recyclability is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent performs preliminary action by incorporating design features for easy insert removal directly into the molding process. The sacrificial section is created during initial part fabrication through techniques such as insert molding with deliberate weak points, creating built-in separation features that require no additional manufacturing steps or specialized equipment during recycling
Data Source
AI summary
Provided is a formed plastic part comprising a sacrificial section; and a recyclable section, wherein the sacrificial section and the recyclable section are separated by at least one stress concentrator cut into the formed plastic part, and wherein the at least one stress concentrator is arranged in a pattern selected from the group consisting of a line, a groove, a triangle, a square, a rectangle, a pentagon, a hexagon, a heptagon, an octagon, a nonagon, a decagon, a rhombus, and a circle. Also provided is a process of recycling the formed plastic part, the process comprising: (a1) separating the sacrificial section from the recyclable section of the formed plastic part and discarding the sacrificial section; (a2) removing and discarding the at least one protrusion, if present, (b) mechanically shredding the recyclable section to obtain plastic fragments; (c) at least one of cleaning, sanitizing, and sorting the plastic fragments; (d) optionally, subjecting the plastic fragments to at least one of pyrolysis and chemolysis to obtain a monomer; (e) polymerizing the monomer to produce a recyclate polymer, and (f) optionally, pelletizing the recyclate polymer.