What is the preferred method for enlarging a hole to final size in composite material?

The preferred method for enlarging a hole to its final size in composite materials is to use a reamer. Reaming is particularly effective for this purpose because it provides precise control over the final dimensions of the hole. This is crucial in composite material applications where maintaining tight tolerances is essential to ensure the integrity and performance of the assembly.

A reamer is designed to produce a smooth finish and a uniform hole size, reducing the likelihood of damage to the composite layers, which can be more fragile than metal materials. It also minimizes the risk of delamination or fraying that can occur when using tools like drills that might generate excessive heat or vibration during the cutting process.

In contrast, other methods listed are less suitable for various reasons. Drilling, while common for creating initial holes, may not achieve the precision required for final sizing in composites. Using a saw would create too rough of an edge and could compromise the structure's integrity, while a file may not be efficient for enlarging holes to specific sizes and could lead to inconsistencies in the hole diameter. Therefore, reaming stands out as the optimal choice for ensuring the quality and performance of composite assemblies.