The aerospace manufacturing industry is becoming increasingly competitive every day. There is a huge demand for creating safer and more efficient airliners. The design and manufacturing of aircraft are vital phases to reach the ultimate goal of an acceptable and superior product.
When manufacturing and assembling an aircraft, there are certain aspects that must be met:
- Structural integrity
- Operational efficiency
- Maintainability
- Tooling
- Market viability
- Further development capability
Designing the Aircraft Structure
It is imperative to design the aircraft structure with precision and care. Many factors including metal fatigue, environmental stresses, and corrosion have to be taken into account. To help reduce these factors, aluminum is used as the choice metal for producing the skins of the aircraft.
The aluminum is riveted and bolted together, as these fastening joints provide structural dampening, which reduces oscillations and vibrations. Each bolt and rivet is precisely compressed to accomplish the stress carry capability. Specialized aircraft tooling is used during this phase and the rest of the manufacturing process. One of the most well-known tools is aircraft assembly fixtures.
Aircraft Assembly Fixtures
Fixtures are specialized tools that are used to hold components in position while the required fasteners are bolted and welding is done. Also known as tack fasteners or tack welds, fixtures are installed onto the aircraft by drilling through precisely located drill bushings. Fixtures are required to be extremely rigid and accurate for construction.
Fixture Construction
There are a variety of metals that can be used to design and construct aircraft tooling fixtures. Depending on the section of the aircraft, and layers of sheet metal for that section, fixtures can be constructed using materials such as magnesium, resin, plastics, as well as composite materials. For thicker and boarder aircraft sections, cast iron and stainless steel plates are used for fixture construction. Machined fixtures can either be welded or bolted together. As a supporting tool, the main objectives of fixtures are to provide accuracy when assembling individual components, interchangeability, and reduce the overall construction costs.
The accuracy of fixtures always has to be higher that the accuracy of the machined part. The tolerances of fixture dimensions have to be higher as this will ensure interchangeability of components. There is no set standard for fixture dimensions. A number of examples have been recommended by engineering experts, any one of which can be used. That is why engineers use analysis, calculations, as well as logic and practical judgment to create the right kind of tolerance dimensions.
Advantages of Fixtures
- Accuracy and Interchangeability: By locating the work and accurately supporting the component, one fixture can be used for producing different parts within the same specified limits.
- Reduces Human Error: As fixtures are manufactured under precise tolerances and dimensions, there is very little chance of human error taking place.
- Simplifies Operations: Fixtures can be used to simplify otherwise complicated operations. This gives aircraft manufacturers the opportunity to hire medium skilled laborers to work on the product, and thus finish the work quickly.
- Faster Repetitive Production: Clients often ask manufacturers for multiple products, creating a large product order. This can be a painful task for the engineers and workers. With fixtures, engineers can simply reuse the specified dimensions and tolerances from the previous manufacturing process, saving costs, design and assembly time.
There are many benefits that come with using fixtures in aircraft manufacturing. They can provide accuracy in construction, reduce the work pressure on employees, save time and costs, add to the overall process improvement of aircraft assembly.