Black Hawk Drive Shaft Drilling NCDMM Project No. 07-0133-04

PROBLEM / OBJECTIVE
Sikorsky Aircraft, located in Stratford, CT, has developed a new composite drive shaft for the UH- 60 Black Hawk helicopter. This drive shaft is composed of an inner titanium liner, an IM7 carbon fiber tube, and an outer titanium end fitting. It is necessary to machine holes in the drive shaft in order to join the components together by way of mechanical fasteners (rivets). The complexity of the material and geometry of these components represent a unique machining challenge for Sikorsky. For these reasons, Sikorsky Aircraft has requested that the National Center for Defense Manufacturing and Machining (NCDMM) develop a cost effective process to machine the fastener holes. Sikorsky requested that the NCDMM establish a single tool solution to reduce costs and eliminate the use of multiple tools.

ACCOMPLISHMENTS / PAYOFF

Process Improvement
Sikorsky provided a sample of the IM7 carbon fiber material to be used in construction of the new driveshaft. The NCDMM procured titanium bar stock and machined an inner and outer sleeve in order to create a mock driveshaft for testing purposes.

The NCDMM developed a Design of Experiments (DoE) in order to determine optimal tooling and machining parameters for creating the fastener holes. Three different tool geometries with various substrates and coatings were acquired from three different tool vendors and, subsequently, evaluated at a range of cutting parameters to determine an optimal machining solution. Hole size, burr height, and hole micro-finish were measured and recorded.

Testing began by evaluating the three different tools at a range of parameters in order to define ideal cutting conditions for each specific tool. Once these parameters were identified, a series of holes were drilled with each tool. Each hole on the test piece
was identified by; tool, cutting conditions, and hole number. Hole size, entrance burr height, and hole micro-finish were measured and recorded for each hole. This data was evaluated and a recommendation on a cutting tool and machining parameters were presented to Sikorsky.

Implementation and Technology Transfer
The following process and tool recommendations were made to Sikorsky:
- Champion cutting tool should be used to perform one shot drilling of the new drive shaft
- Implement the process at the selected Sikorsky supplier

Expected Benefits
- Capable process for drilling holes to specification with one tool
- Increased productivity over drilling and reaming
- Reduced cost compared to drilling and reaming


TIME LINE / MILESTONE
Start Date: April 07
End Date: July 07

PROJECT FUNDING
NCDMM: $30K

PARTICIPANTS
AMAMCO Tool
Diamond Tool Coating, LLC
Haas Automation, Inc.
Karadon Corporation
Kennametal Inc.
Precorp Inc.

For additional information concerning this project, contact the NCDMM at www.ncdmm.org