Thermoplastic Pellet Adhesive Layer for 3D Print Warpage Control

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Solution Overview

Problem

In 3D printing, the initial layer of thermoplastic material often warps due to differential shrinkage relative to the foundation layer, leading to distortion and stress, and existing solutions like heated platens are costly and inefficient.

Innovation Solution

A method involving a removable surface with adhesive material and thermoplastic pellets on a CNC machine worktable, where the pellets are bonded with polyvinyl acetate glue, allowing the thermoplastic material to fuse and absorb movement, reducing warpage without complex equipment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the initial layer is securely bonded to a foundation sheet, then the layer is held in fixed position, but the structure becomes distorted due to warpage as the deposited layer shrinks

Engineering Contradiction:

Improvebonding strengthVSAvoidshape accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent introduces an intermediary layer consisting of thermoplastic pellets embedded in adhesive material between the foundation sheet and the deposited thermoplastic layer. This intermediary layer acts as a buffer that allows controlled movement and shrinkage accommodation, preventing direct rigid bonding that causes warpage while maintaining sufficient holding strength.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the physical state and properties of the bonding interface by using pellets embedded in adhesive rather than solid continuous bonding. The adhesive material's viscosity and bonding characteristics are controlled to provide initial holding strength while allowing subsequent dimensional changes during cooling and curing processes.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If a heated platen is used to prevent solid bonding, then flexibility is provided to compensate for shrinkage, but substantial financial burden is incurred

Engineering Contradiction:

Improvewarpage controlVSAvoidequipment cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces expensive, complex heated platen equipment with a simple, inexpensive adhesive layer and thermoplastic pellets that can be easily applied and discarded after use. This achieves the same warpage control function at minimal cost without requiring specialized heating equipment.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent substitutes the mechanical/thermal system of heated platens with a chemical bonding system using adhesive materials. The adhesive provides the necessary flexibility and shrinkage compensation through its bonding characteristics rather than through thermal control mechanisms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If the initial layer is deposited onto a heated platen, then flexibility is provided, but sufficient bonding is lacking resulting in subsequent movement

Engineering Contradiction:

ImproveflexibilityVSAvoidbonding strength

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent creates a composite bonding interface combining thermoplastic pellets embedded in adhesive material. This composite structure provides both flexibility (from the adhesive matrix) and bonding strength (from the embedded pellets that mechanically interlock with the deposited layer), resolving the contradiction between flexibility and bonding strength.

Inventive Principle:

Principle #40Composite materials

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 securely fixes the first layer while allowing flexibility to compensate for shrinkage, minimizing warping and eliminating the need for expensive heated platens, thus producing stable and accurate 3D printed components.

Implementation Method 1

applying an adhesive material to the removable surface; depositing a plurality of pellets into the adhesive material

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

depositing a flowable material on at least some of the plurality of pellets; the flowable material, while generally hot and pliable, may be deposited upon a substrate

Methodology Applied

Scientific EffectThermal fusion: Melting

Implementation Method 3

the newly deposited material cools, and correspondingly shrinks

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentEP3439855B1Methods of securing an initial layer during additive manufacturing of thermoplastic material

Publication Date: 2020.05.06 THERMWOOD CORP

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AI summary

In one embodiment, an additive manufacturing method including the steps of positioning a removable surface on a worktable; applying an adhesive material to the removable surface; depositing a plurality of pellets into the adhesive material, wherein at least a portion of each pellet of the plurality of pellets remains exposed; depositing a first plurality of layers of a flowable material on at least some of the plurality of pellets; and depositing a second plurality of layers of the flowable material on the first plurality of layers.