Flying high with diamond hones

END USER: Sikorsky Aircraft Corp., (800) 946-4337, www.sikorsky.com.
CHALLENGE: Efficiently remove scale from the bearing surface of a high-volume, 9310 alloy steel part.
SOLUTION: A custom diamond honing tool.
SOLUTION PROVIDER: Brush Research Manufacturing Co. Inc., (323) 261-2193, www.brushresearch.com.

Sometimes, the most experienced technicians and skilled toolmakers must turn to outside specialists when solving critical service problems. Such was the case when Sikorsky Aircraft Corp. had a problem cleaning the scale off of a carburized bearing surface in a 4.5mm (0.18 “) bore on a high-volume outsourced part, preventing the Stratford, Conn.-headquartered company from proceeding with production of its helicopters.

Sikorsky attempted to remove this scale with a carbide reamer and a diamond lap, according to Tony Lawrence, tooling services manager for Sikorsky Product Center Core Services. However, the long cycle times for those tools made them impractical for the large quantity of bores that needed rework.

Courtesy of Sikorsky Aircraft

Sikorsky Aircraft designs and builds helicopters for commercial, industrial and military use.

He explained that the part is made of 9310 alloy steel with a hardness of about 66 HRC, and, therefore, requires a tool with suitable hardness to properly remove the scale. Previously, Lawrence’s group successfully used diamond Flex-Hones from Brush Research Manufacturing Co. Inc. in a limited set of applications and decided to try the tool in this high-volume job.

The ball-style tool is characterized by a shaft with small, abrasive globules permanently mounted to flexible filaments. According to the toolmaker, the tool can be mounted in an electric hand drill motor, which is how Sikorsky needed to apply it, or in a machine tool chuck for resurfacing hard metals, ceramics and other challenging materials. The tool can impart surface finishes as fine as 0.1µm Ra.

For Sikorsky’s application, Brush Research constructed the special flexible hone with 170/200 diamond grit. The 0.18 “-dia. tool has an overall length of 6 ” and a 2 “-long brush section.

Courtesy of Brush Research Manufacturing