Material deposition management - A157

 

Material deposition management
Systems knowledge article
Document Type	Article
Document Identifier	157
Themes	Material deposition management
Tags	System theme
Prerequisites	Systems Knowledge

Overview

Material deposition management is concerned with knowing, understanding, and managing how the constituent materials of a composite part are placed onto the tooling, and onto each other. Completing the material deposition process steps and acheiving good quality outcomes in terms of fibre alignment (misorientation, wrinkling and waviness), voids and other factors are very important to the final quality of the part. These process steps can be extremely challenging and time consuming depending on the type of material deposition process steps carried out, the form of the material, and the curvature of the tooling. The combined effect of the material deposition process steps and the subsequent flow & consolidation and thermal transformation steps will determine local porosity, resin volume fraction leading to either resin rich or resin starved areas, and fiber misalignment.

Material deposition processes can be broadly separated into “infusion” processes where the fiber is positioned on the tool and then matrix is added, and “wet” or "prepreg" type processes where the fiber and matrix are combined before the mix is positioned on the tool.

A factory process flow. The process chosen should not be driven by historical process names often based on material depsoition process steps. Instead, it should be driven by the shape of the part and the material used for the part; these will define the equipment and tooling & consumables that are appropriate, thereby fully defining the MSTEP collection for each process step.

Additionally, by convention, the composites industry names and classifies manufacturing processes after one or more critical process steps in the manufacturing workflow (typically a material deposition step) or after the material form that is processed. Some examples of composites manufacturing processes historically named after material deposition process steps are:

• Vacuum assisted resin infusion (VARI)/vacuum assisted resin transfer moulding (VARTM)
• Resin transfer moulding (RTM)
• Spray-up
• Filament winding
• Tube rolling
• Automated fibre placement (AFP)/automated tape laying (ATL)

While these are common and sometimes useful names for discussing these manufacturing processes with others, it is important to remember that it is actually the part and material that determine which process steps must be performed and which equipment/tooling can be used to perform them. The layout of these process steps are what define the manufacturing workflow rather than a pre-defined manufacturing process. Recognizing this important fact and using it to guide the development of a manufacturing process will ensure that the most appropriate material deposition steps are utilized.

The content related to materials deposition manangement in the Knowledge in Practice Centre is currently quite limited as we are in the early stages of content creation and have focused on the theme of thermal management. We will be working on material deposition management next, and encourage you to check back in the future for more content in this theme.

Related pages

Page type	Links
Introduction to Composites Articles
Foundational Knowledge Articles
Foundational Knowledge Method Documents
Foundational Knowledge Worked Examples
Systems Knowledge Articles	Machining and assembly management (MAM) - A287 Materials deposition and consolidation management (MDCM) - A157 Quality/inspection management (QIM) - A288 Residual stress and dimensional control management (RSDM) - A165 Thermal and cure/crystallization management (TM) - A107
Systems Knowledge Method Documents
Systems Knowledge Worked Examples
Systems Catalogue Articles
Systems Catalogue Objects – Material
Systems Catalogue Objects – Shape
Systems Catalogue Objects – Tooling and consumables
Systems Catalogue Objects – Equipment
Practice Documents
Case Studies
Perspectives Articles

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The individual materials that combine to form the composite material. The constituent materials are separate and distinct on a macroscopic level.

Engineered materials (designed to have specific properties) made from two or more constituent materials with different physical or chemical properties. The constituents remain separate and distinct on a macroscopic level within the finished structure.

For polymer matrix composites (PMCs), resin refers to the matrix; the continuous material phase that binds the reinforcement together, maintains shape, and transfers load. Resins are divided into two main groups: thermosets and thermoplastics.

Volume fraction of either matrix or fibres with respect to total composite volume (matrix + fibre).

The continuous material phase that binds the reinforcement together, maintains shape, transfers load, protects the reinforcement from environment and damage, and provides the composite support in compression.

Desirable characteristics:

• Moisture/chemical resistance
• Low density
• Processability

Pre-impregnated (prepreg) material refers to fibre that is already combined with resin. It is the most common material form used in aerospace.

During prepreg production, (e.g. fibres are run through a resin bath), prepreg is heated and partially cured to B Stage (< 5 % degree of cure). Thermoset prepregs (e.g. epoxy prepreg) have to be kept in a freezer at around -20 °C. At room temperature, the epoxy starts to cure.

Vacuum assisted resin infusion (VARI) - also known as vacuum assisted resin transfer moulding (VARTM), vacuum infusion process (VIP) or often just resin infusion. VARI is a liquid composite moulding (LCM) closed mould process with a single side tool and vacuum bag where the resin is drawn through the preform using vacuum.

Vacuum assisted resin transfer moulding (VARTM) - also known as vacuum assisted resin infusion (VARI), vacuum infusion process (VIP) or often just resin infusion. VARTM is a liquid composite moulding (LCM) closed mould process with a single side tool and vacuum bag where the resin is drawn through the preform using vacuum.

Resin transfer moulding (RTM) involves loading a preform into a two (or more) piece, matched tool, closing it, and injecting resin under pressure (~15-100 psi, or ~1-7 bar).

Well suited to small to medium sized parts, limited to large sizes due to injection pressure loads and tool cost.

A key component of all composite manufacturing processes. Collectively, the four themes represent the time-temperature-pressure-vacuum history, which is traditionally used to define a manufacturing cycle.

The four processing themes are:

• Thermal management
• Material deposition management
• Flow and consolidation management
• Residual stress and dimensional control management

(Same as "Processing themes")

A central processing theme in the manufacturing cycle. It includes the steps primarily involved in moving material into the correct position on the tool or with combining fibre, resin and other constituents in-situ on tools.