Composite Production Part Drawing - P169

 

Composite Production Part Drawing
Practice document
Document Type	Practice
Document Identifier	169
Themes	Quality/inspection management
Tags	Development to production Inspection Part parameters Shape Shape parameters Integrated product development
Objective functions	Cost Maintain Rate Maintain Quality Increase
MSTE workflow	Development

Overview

Engineering drawings are required to communicate all the information necessary to manufacture a component or assembly. In the past, before 3D modelling software was commonplace, engineering drawings were the only form of communication for describing a part or assembly so that it could be manufactured as intended. Important information provided on drawings includes material type, dimensions, and tolerances. Today, CAD files are often used to support drawings and can reduce the need for rigorous dimensioning. However, engineering drawings are still typically used to convey all of the key information needed to manufacture a part.

Scope

The purpose of this document is to provide instruction on creating composite production part engineering drawings. This will include background information on the purpose and requirements of engineering drawings in general, with emphasis on the additional information that is required for composite parts.

Aspects of part drawing

Drawings for composite components are unique in that they are designed to achieve properties for a certain purpose, and the material is in essence designed and built specifically for that component. Therefore, lay-up schedule, ply orientation, identification of tool side, fibre content and other composite related information must also be included.

Dimensioning

Because composite components are fabricated using tools, major geometry is already captured by the tool itself and does not necessarily require rigorous dimensioning. Overall dimensions should still typically be included for reference purposes. However, important dimensions to capture, which may not be included in the CAD geometry are trim, holes, cut-outs, locations of inserts, tapping plates and other finishing details.

Layup Schedule

The layup schedule provides instruction on building the material that will make-up the composite part. The clearest way to communicate the layup schedule is in a table form that indicates at a minimum, ply number, material, and angle. When specifying ply orientation, a reference axis should be provided to indicate which direction has been assumed as 0 degrees on a particular layup/part. Additional information may include thickness, amount of resin required, and layup regions among other items. Information regarding tool side, manufacturing method, gel coat, etc. can be included in a separate note block or in the layup table as deemed appropriate.

Example of Layup Table/Schedule

Materials

If the composite component is designed with materials specific to a particular supplier, the product trade names should be used and the supplier identified in the notes. If cores, infusion media, or other intermediary materials are specified in the layup schedule, these should be included in either the table or notes as deemed appropriate. If generic materials are required, the fibre type should be defined as glass, carbon, or other, and fabric type and weight should be provided. Alternatively, if appropriate, minimum mechanical and/or thermal properties may be provided to guide material selection.

Manufacturing Method

Manufacturing method should be indicated on the drawing, with any additional information required to clarify or control the process. A particular manufacturing method may be interpreted or performed slightly differently from one fabricator to another. In many cases, this may not be critical, but for parts where a specific design requirement is highly process dependent, this must be noted. The drawing should control the manufacturing process where necessary, but allow freedom for the fabricator where feasible. For example, if a part must have a certain glass transition temperature, this is achieved with resin choice and cure cycle. In this case, a note could be included on the drawing prescribing a specific cure cycle or referencing another document that does so. Another option is to specify the required glass transition temperature, leaving the fabricator the freedom to achieve this as they see fit. Alternatively, the drawing may reference a process specification document that outlines the process requirements in detail. As another example, for a prepreg layup with many plies, intermediate consolidation at every X number of plies may be suggested to ensure desired thickness and fibre content is met.

Notes

Examples of critical pieces of information that should be provided in the notes block are provided below:

• Tool side ply
• Manufacturing method
• Fibre content by weight or volume if it is critical to part performance
• Brief description of materials to support information in layup table
• Trim details/requirements
• Joint/splicing/overlap details if critical
• Alternative allowable materials if available
• Reference to CAD geometry if applicable

An example note block is provided in the figure below.

Example of notes block

Example Drawing

Example of production part drawing

Conclusion and Further Information

This article has provided the basic guidelines for creating an engineering drawing for a composite part. It is intended to supplement references on engineering drawings in general. There are a number of references available that provide extensive detail and instruction regarding standard drawing practices, including dimensioning style, annotation style, and other information.

Related pages

Page type	Links
Introduction to Composites Articles
Foundational Knowledge Articles
Foundational Knowledge Method Documents
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 Material Selection - P153 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
Case Studies	Developing for Future Production Scale Up - C113 Lack of Requirements in Product Development - C104 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

About	Help

The use of multiphysics models to predict the outcome of real-world scenarios. May be analytical (closed form, "hand calculations") or computational (implementation on computers is required due to the large number of calculations involved. e.g. finite element method, finite difference method)

Most often in composite materials engineering, modelling refers to either:

• Process modelling (predicting manufacturing outcomes, or the inverse problem of predicting manufacturing parameters to achieve a desired outcome), or
• Performance modelling (predicting the stiffness/strength/suitability of a structure, or the inverse problem of the material properties and dimensional requirements to achieve a desired stiffness/strength/suitability of a structure)

(same as "Simulation")

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.

The glass transition temperature (T_g) is the temperature region where the polymer transitions from a hard, glassy material to a soft, rubbery material. It is one of the most important properties of any amorphous polymer.

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.