From CAD to Clean Room: Why Composite Designs Must Consider Manufacturing

Composite materials are now everywhere in aerospace. Designers can create very efficient and lightweight structures, and on paper many of these designs look excellent. But between a CAD model and a finished composite component there is a long manufacturing journey, and that is where reality often steps in.

A typical composite component goes through several stages before it becomes a finished part. It usually starts with design, then composite laminate design, followed by tooling design (not to mention aerodynamic or stress analysis, which is a whole separate topic). After that the pattern for the tool is machined, the tool itself is manufactured, and only then does the actual part production begin — layup, curing, trimming and finishing.

What is sometimes overlooked is that many decisions made early in the design phase have a direct impact on what happens later on the shop floor.

I started working with composites in 2012, making relatively simple parts using wet layup before moving into more advanced processes such as infusion and prepregs. One of the first things you learn when you are actually producing parts is how much material can be wasted along the way. At that time I was running a small business, so material waste was always the first thing I looked at. Resources were limited and materials were expensive. You quickly realise that what looks efficient in CAD does not always translate into efficient manufacturing.

Material waste is one of the biggest examples of this gap.

When people look at a finished composite component, they usually see only the final weight of the part. What they don’t see is how much material was actually used during the manufacturing process to get there. In many cases a finished part may weigh only a few kilograms, but the amount of raw material used during cutting, layup and trimming can be several times higher.

There are many reasons for this. If we look at tooling, for example, composite moulds are often produced from tooling board patterns. These patterns are frequently single-use components. The tooling board must be machined, and depending on the design, a large percentage of that material can simply be cut away.

I have seen tooling block-ups where after machining nearly 70% of the tooling board ended up as waste. That becomes particularly painful when the part itself is large. Often this happens simply because material efficiency was not considered during the tooling design stage.

Moving away from tooling and looking at the part itself, geometry plays a major role in manufacturing efficiency. Complex shapes, tight radii and aggressive curvature might look perfectly acceptable in CAD, but they can create serious challenges during layup. Composite plies need to drape properly over the tool surface. If the geometry is too sharp or too complex, the fibres don’t always behave the way you expect. You start seeing wrinkles, bridging or areas where the material simply does not want to sit properly.

Once that happens, the theoretical laminate defined during analysis starts to drift away from what is actually achievable in practice.

When technicians encounter these situations, they adapt. Plies may need additional cuts, overlaps may increase, and sometimes extra material is added. All of this increases material consumption and makes the manufacturing process slower and more complicated.

Another issue is that many designers simply do not see how parts are actually built in the shop floor. There are many excellent engineers working on composite structures, but not all of them have spent time on the shop floor watching parts being laid up, vacuum bagged and cured. Without that exposure it is easy to design features that are technically possible but extremely difficult to manufacture or sometimes simply impossible.

Certain geometries may restrict technician access during layup or require extremely precise ply placement in tight corners. On a screen these details may look minor. On the shop floor they can turn into major challenges.

I remember one part my team worked on that had return flanges. To laminate it properly we spent days working with mirrors and head torches, essentially laying up material while looking at the reflection instead of the actual surface. Imagine trying to cut and position plies with a scalpel while watching your hands through a mirror, trying to create proper butt joints in a space you can barely reach.

This is the kind of reality that rarely shows up in a CAD model.

When designs reach the shop floor and these challenges appear, manufacturing teams usually find a way to make it work. Composite laminators are incredibly skilled at adapting processes and solving problems on the fly. But making it work often means extra process steps, longer production time, and sometimes redesigning parts after the first manufacturing attempts.

That is why early collaboration between design and manufacturing teams is so important in composite programmes. People who work with the materials every day — composite technicians, manufacturing engineers and tooling specialists — can often identify potential manufacturing issues immediately. Involving that experience early in the design process can save a significant amount of time, material and frustration.

At the end of the day, a good composite design is not only one that performs well in analysis. It is one that can also be manufactured efficiently in the real world.

Sometimes the difference between a smooth production process and a difficult one comes down to small design decisions made long before the first tool is ever built.

My advice to designers is simple: think about material waste, spend time on the shop floor, stay curious and ask questions. Understanding how parts are actually built will save countless hours later — and it will make life a lot easier for the technicians responsible for turning your designs into a real component.

Author : Leo A. , Former Orbex Structures Lamination Lead, AeroNexis Expert

Co-Author(Editing) : Kaan Deniz, PhD, Founder of AeroNexis