Multi-Layer Syringe Overmolding for Integrated Luer Thread Tips

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing co-injection molding technologies struggle to integrate a male threaded connection part, such as a Luer thread tip, with a multi-layered syringe body due to challenges in forming a consistent multi-layer structure, leading to increased manufacturing complexity, cycle time, and cost, as well as potential particulate generation.

Innovation Solution

A syringe design with a multi-layered structure formed by co-injection molding, where the main body and threaded connection part are overmolded in a single mold using different materials, integrating a threaded connection part made of a plastic material by injection molding, with a core layer providing a gas and moisture barrier.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If co-injection molding is used to form a multi-layered syringe body, then gas and moisture barrier function is improved, but integrating a threaded connection part becomes difficult due to inconsistent multi-layer structure formation

Engineering Contradiction:

Improvegas and moisture barrier functionVSAvoidintegration of threaded connection part

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The syringe is divided into two separate components: a multi-layered syringe body formed by co-injection molding and a separate threaded connection part (Luer tip) formed by injection molding. This segmentation allows each part to be optimized independently - the multi-layered structure provides barrier function while the separate threaded part avoids the multi-layer formation challenges.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The threaded connection part is positioned to surround and nest over the nozzle of the syringe body. The Luer tip is designed to fit over the distal end of the multi-layered barrel, creating a nested configuration where the connection part envelops the nozzle without requiring multi-layer co-molding.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Adaptability or versatility

If the threaded connection part is separately molded and attached to the syringe body, then manufacturing flexibility is improved, but manufacturing complexity and cycle time increase

Engineering Contradiction:

Improvemanufacturing flexibilityVSAvoidmanufacturing process complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The manufacturing process merges the formation of the multi-layered syringe body and the threaded connection part into a single co-injection molding operation. The threaded connection part is formed in the same mold cavity as the multi-layered body, eliminating separate molding and assembly steps despite the different material requirements.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The threaded connection part is pre-formed by injection molding with appropriate bonding surfaces prepared in advance. The multi-layered syringe body is also pre-formed by co-injection molding, and both components are prepared with suitable surfaces for overmolding bonding, allowing rapid final assembly.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If separate molding and attachment steps are used for the threaded connection part, then manufacturing adaptability is improved, but particulate generation occurs during bonding

Engineering Contradiction:

Improvemanufacturing adaptabilityVSAvoidparticulate generation

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The mechanical bonding process (ultrasonic welding or glue welding) is replaced with a thermal overmolding process. The threaded connection part is overmolded directly onto the syringe body using heat and pressure in the injection molding process, eliminating the mechanical bonding steps that generate particulates and ensuring a cleaner, more controlled joint.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 reduces manufacturing complexity, cycle time, and eliminates particulate generation, thereby improving the efficiency and cost-effectiveness of producing syringes with integrated threaded connections.

Implementation Method 1

The core layer is made of the second material, e.g. ethylene-vinyl alcohol copolymer (EVOH), that provides the barrier function

Methodology Applied

Scientific EffectBarrier function:

Implementation Method 2

the main body and the threaded connection part are overmolded one to the other

Methodology Applied

Scientific EffectOvermolding:

Data Source

PatentUS20250345525A1Multi-layered syringe with a threaded connection part and method of manufacturing same

Publication Date: 2025.11.13 PFIZER INC

AI summary

The invention relates to a syringe comprising an elongated main body having a nozzle formed at a distal end thereof and a threaded connection part at least partially surrounding the nozzle. The main body is made by co-injection molding from at least two different materials and the threaded connection part is made of a plastic material by injection molding, with the main body and the threaded connection part being overmolded one to the other. The invention also relates to a method of manufacturing such a syringe.