Fatigue Improvement by Sleeve Cold Working

The sleeve cold-working process for fastener holes is a process that uses a tapered mandrel in conjunction with a disposable, prelubricated split sleeve to compressively prestress a significant zone around a fastener hole. This compressive prestressing offsets the stress concentration of the hole itself to produce substantial improvements in structural fatigue performance of fastened joints. The sleeve method allows higher degrees of prestressing than are possible with other methods and does not require precision controls and skills germane to other fatigue-rated hole preparation/fastener systems.