Practice for Developing a Deposition Step - P157

 

Practice for Developing a Deposition Step
Practice document
Document Type	Practice
Document Identifier	157
Themes	Materials deposition and consolidation management
Tags	Bagging Consumables Debulking Deposition Demoulding Development to production Factory cell Integrated product development Process step
Objective functions	Cost Maintain Rate Maintain Quality Maintain
MSTE workflow	Development
Prerequisites	Integrated Product Development Practice Practice for Developing a Process Step

Overview

This page provides guidance on taking the material deposition step from conceptualization to production. This includes conceptual screening and preliminary selection of tooling and equipment, then detailed finalization of the manufacturing (MSTE) system as a whole. The page is broken into three tabs that cover these activities. Conceptual screening covers initialization of tooling and equipment. Equipment selection involves identifying the type and if any specialty equipment is required for selected manufacturing method. Links to the Systems Catalogue provide a specific list of equipment and tooling to help guide these decisions. Preliminary selection involves maturing the material, shape, tooling and equipment and quantifying their parameters. This is done with consideration to foundational and systems level knowledge. Finally, detailed finalization covers the qualification process of ensuring that each component of the system functions as intended and part/material requirements are satisfied (i.e. outcomes are acceptable). Links to Systems Knowledge method documents are located here.

Introduction

The material deposition step is where the material system, ie. fibre and resin, is placed on the tool before being converted to the final product. This step builds up the thickness of the laminate and determines the final actualized fibre architecture of the part. This step is usually very labour intensive and can account for 40-60% of the cost of the part . The selection of tooling and equipment for this step is critical in determining the time it will take to make a part and also the amount of complexity that can be introduced to the part geometry. In general, a more automated process will only be able to give relatively simple geometries, whilst a process aimed more towards hand lay-up will be able to have more complex geometries.

Significance

The material deposition step is one of the first manufacturing steps for a part and will add the first major costs to the part in terms of material cost and labour costs. This step also plays a large role in determining the composite part's fibre orientation and fibre volume fraction, which are critical in determining the mechanical properties of the final part. Several manufacturing outcomes are directly related to material deposition and consolidation. This includes wrinkling, fibre waviness, Fibre volume fraction, Porosity (void content), residual stress and others. Further, material deposition rate can directly impact throughput. Choosing the correct manufacturing process and appropriate material deposition processing parameters are essential to a composite manufacturing system.

Practice

The following section follows the three process design gates of screening, selecting and finalizing. Each of the process design gates are discussed under the consideration of each of the MSTE topics. Each MSTE topic provides questions to consider for each design gate to further advance each topic from screen to finalize.

Screen

Select

Finalize

At this first process design gate the developer will narrow down the deposition process to best suit their application. By conducting a thorough screening process, they can identify potential issues and limitations early on, which can help to reduce costs, improve rates, and increase the likelihood of a successful final product.

Read more on the different types of predetermined material deposition steps in the Systems catalogue Material deposition.

Material

Material system is mostly defined at this point and will be furthered used to decide on the deposition method. At the screening stage there is a high level view of the processes and some important questions to look into.

• Is the reinforcement dry and going to need some form of wetting process? This may lead to selecting a wet lay up or some form of infusion process.
• Is the reinforcement pre-impregnated and will the deposition process be automatic?
• Is the system thermoplastic and require high temperatures for impregnation?

Shape

The part shape here will help to identify potential complications in the deposition process.

• Are there any deep areas that may be hard to reach?
• Is the part too large for someone to reach across?

Tooling

The tooling choices will depend on the decisions made previously about the type of deposition process and the shape of the part.

• If the shape of the part is very complex, will the tool have to be made in separate parts to be taken apart for demoulding?
• Does the resin system require heat to cure? If so the tooling must also be able to resist the temperatures.
• Should the tool account for the space required for a vacuum bag over the part as well?

Equipment

• Will there be a need for equipment to assist the operators in depositing material?
• Is there a need for in-situ cutting or forming of the material by the operators?

The selection design gate will allow the developer to select one process that will suit their application, then further move into selecting the supporting tooling and equipment for their process. Systems catalogue will have a section on types of equipment Equipment.

Material

The consideration for material at the selection design gate for a deposition step will be more focused on selecting a technique for depositing the material rather than choosing a material. At this stage of the development process, the material system should be mostly defined such that instead of selecting material, the developer will develop a sequence and technique. For example, if the deposition procedure is a wet layup, this step is an opportunity to decide the sequence of resin and reinforcement, or deciding if a pre-impregnating machine is needed as part of the equipment.

Shape

At the selection step, the role of the shape consideration will be to see the interplay between the shape of the tooling and the deposition method. If the shape is very complex, a more manual operation is needed to be able to ensure the material conforms to the complex shape, if the part geometry is simpler, a more automated approach may be considered. The shape of the part will also show the conformability of the material to the tool geometry and will at this stage begin to show the weaknesses of the material system selected.

Tooling

The selection of tooling at this step of the manufacturing process will mostly be focused on how the operators will interact with the tool. The tool needs to be constructed in such a way that the operators can perform the deposition step. On the other hand, if the deposition process is automatic or mostly automatic like a pultrusion step, the tooling decisions are not going to be affected to a large extent by this step.

The second half of the tooling selection process involve consumables. For a process that relies on vacuum bags, the use of consumables will be high because each part will use a disposable vacuum bag, breather, bag sealant etc. There are options to use re-useable silicone vacuum bags to reduce the amount of waste and reduce the time it takes to apply a bag to a part, where the downside will be increased cost. For processes that do not require vacuum bagging, like a Hot press, the consumables at this process step will be limited. Depending on the specific process, there may be a requirement for peel ply or release film, and most likely there will be a need for a release agent.

Equipment

After selecting the type of deposition process, a number of decisions are needed for selecting the equipment, especially if it is a labour intensive process. From deciding if scissors are needed to laser guides for ply placement.

• If there is allowance for in-situ ply alteration, what type of handheld equipment will be available to the operators?
• How will the ply placement be dictated, will there be a ply plan on the work instruction, or will there be a need for a laser projector?
• Is there some form of equipment required for the actual deposition of material, like a spray-up gun?
• Are rollers and squeegees needed?
• What kind of gloves and other PPE will the operators need?

Plies of glass fibre being rolled to saturate the fibre with resin in a prototype part.

At this process design gate, all the components of the process step are selected and possibly acquired in house. It is then time to discuss and discover the interactions of each of the four pillars and finalize a process that is effective. The effect of each of the material, shape, tooling and equipment on the material deposition step are discussed in detail in Materials deposition and consolidation management (MDCM). This section of the KPC also discusses the different System parameters - inputs and outcomes and System interactions that occur during processing and is important to consider when finalizing your material deposition step.

To finalize the process, prototype parts may need to be made or the deposition step needs to be trialed in order to quantify the interplay of all aspects of the system. An example may be that during a lay-up a certain ply or position of the ply is challenging to place and causes wrinkles. This may lead to the ply needing to be split into two halves or worst case to go back and make changes to the geometry of the part. Or, it is found that there is a section of the part that is starved for resin, which may lead to the sequence of resin and reinforcement placement changing or changing to a different type of roller for better resin distribution.

Production

Below is a list of best practice documents designed to assist with specific challenges that may appear during production and how to prevent them.

• Resin degassing describes the reasons for and best practices for removing entrapped air and volatiles from your resin before the deposition step.
• Practice for Applying Gel-Coat and When to Apply Reinforcement
• Preventing Void Formation During Material Deposition
• Knowing when to use edge dams and what type
• Preventing wrinkle formation during material deposition

Explore this area further

• Practice for Developing a Deposition Step - P157
  • Resin degassing - P166

Related pages

Page type	Links
Introduction to Composites Articles
Foundational Knowledge Articles
Foundational Knowledge Method Documents	How to measure gel time - M101 How to measure reinforcement content (and corresponding matrix content) - M109
Foundational Knowledge Worked Examples
Systems Knowledge Articles
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	Composite Production Part Drawing - P169 Consolidation of Thermoplastics - P170 Material Selection - P153 Practice for Developing a Consolidation Step - P158 Practice for Developing a Deposition Step - P157 Practice for Developing a Product - P111 Practice for Identifying Process Steps - P102 Process selection for production scale-up - P171 Selecting Functional Requirements - P152.0 Shape Development - P151.0 Vacuum Bagging - P168 Vacuum Bagging for Prepregs - P172 Vacuum Bagging for Vacuum Infusion - P173
Case Studies	Cost Comparison Study of a GFRP Leisure Boat Hull Manufacturing Method; Spray Up vs Resin Infusion - C115 Developing for Future Production Scale Up - C113 Lack of Requirements in Product Development - C104 Optimizing Cost vs Weight for Low Production Volume Parts - C112 Use of Right Sized Simulation to Aid Decision Making in Thermoplastic Composite Manufacturing Systems - C114
Perspectives Articles	CKN’s Approach to Developing Products with Composite Materials - A332 Composite materials engineering webinar session 5 - Manufacturing processes - Introduction - A124 Composite materials engineering webinar session 6 - Manufacturing processes - Prepreg processing - A125 Composite materials engineering webinar session 7 - Manufacturing processes - Liquid composite moulding - A126 Fabric Forming: how it affects design and processing, and how simulation can address this - A310 Fibre Architecture: Availability, pros and cons, and selection for my application - A309 Porosity in Composite Materials - Part I - A336 Porosity in Composite Materials - Part II - A337 Pultrusion of Thermoplastic Composites - A334

References

About	Help

In the context of knowledge in practice, knowledge refers to the systematic use of science based knowledge in composites manufacturing practice.

There is a distinction between experience based knowledge and science based knowledge:

• Experience based knowledge (‘know-how’) is an understanding of potential outcomes and their relationships that is founded on pragmatism and experience accumulated over time in individual programs, companies and in the industry more broadly.
• Science based knowledge (‘know-why’) is an understanding of potential outcomes and their relationships, based on the important processing physics, that is mature enough to be codified using the appropriate governing laws and constitutive equations.

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.

Fibre architecture refers to how the fibre is assembled.

Most common architectures:

• Unidirectional
• Chopped strand mat (CSM) and chopped fibre (chopper gun)
• Continuous filament mat (CFM)
• Woven fabric
• Non crimp fabric (NCF)
• Braided
• Prepreg

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.

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

Outcomes represent the range of response/sensitivity to factory system attributes. Those that fail to satisfy manufacturing requirements are known as defects. Examples of manufacturing outcomes include process parameter outcomes, material structure outcomes, and material performance outcomes.

A class of polymer, some common examples include polypropylene and polyethylene.

They soften and melt upon heating (i.e. potentially recyclable), high viscosity when melted, therefore difficult to saturate fibres. Usually needs a lot of pressure and heat to process.

Any manufacturing and/or decision making activity that occurs during any stage of the development design cycle (e.g. conceptual design to production).

In the context of Knowledge in Practice, practice refers to the systematic use of science based knowledge to reduce composites manufacturing risk, cost, and development time.