How to choose the right composite manufacturing method for your mechanical parts?

In recent years with the recent improvements to composite manufacturing technologies, composite mechanical parts have become more relevant. However, choosing the most suitable and economical manufacturing method for a composite part remained a challenge for companies and engineers. There are several factors such as part complexity, production rate, materials, capital cost etc. that need to be considered when choosing a composite manufacturing method.

The complexity of a part can help engineers determine the most suitable manufacturing method. For example, for cylindrical parts such as pipes, pressure vessels, and mechanical shafts filament winding is preferred because the cylindrical shape is easily achieved by filament winding. However, for pipes that have bends, bladder resin transfer molding (RTM) with pre-impregnated fabrics is preferred to prevent delamination.

For parts that have non-circular uniform cross-sections such as structural profiles, the pultrusion process is a cost-effective process that is suitable for mass production. Pultrusion offers a cost-effective solution for mechanical chassis. Pultrusion also utilizes uni-directional fibers which offer a significant strength and stiffness advantage for two-dimensional loads.

For parts that have complex surfaces, hand lay-up, vacuum infusion, and RTM processes are usually used. For complex composite parts, the two main parameters for deciding the right manufacturing method are the production rate and the capital cost. Hand lay-up and vacuum infusion processes have relative low capital cost but the production rate of the parts that are made using hand lay-up and vacuum infusion is comparatively low. Thus, if a production rate is desired, RTM is the correct manufacturing method.

The material choice can greatly affect the manufacturing process. Choosing the correct fiber can be quite important. Fiberglass is more cost-effective but does not have the high specific stiffness carbon fiber. Chopped fiber tows can be economical reinforcement for applications where lower strength requirements are present.

Moreover, the polymer matrix can affect the manufacturing method. Gel time, cure time, and viscosity of a resin matrix can change the manufacturing method and the production rate.

Composites have been becoming more relevant as they offer significant benefits such as weight reduction and corrosion resistance. Moreover, composite manufacturing is quite versatile in that a composite part can be manufactured via different manufacturing methods. Thus, it is important to know different manufacturing methods for composites to choose the most suitable manufacturing method for composite parts.

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