Turbine & Compressor Disks

Turbine blades and compressor disks require complicated "root form" profiles in order to withstand the centrifugal forces present during operation.

These disk root forms are traditionally manufactured by broaching. The broaching process itself, once in production, is fast and efficient. That is, the actual cutting time — the time when the broach tool is engaged in the workpiece — is relatively quick. However, other aspects of the process make broaching a very expensive and time-consuming process. These factors include:

• The purchase price, maintenance cost, floor space requirements and long lead-time of broaching machines.
• The special concrete base and other infrastructure to support broaching machines.
• The purchase price, maintenance cost (resharpening & inventory) and long lead-time of broach tools.
• The time required to set up and change over broach machines for different part numbers.
• Manufacturers of turbine disks are very open to alternate methods to address the significant disadvantages of broaching.
• As shown in the diagram, a series of broach tools is used to complete the entire profile; starting with roughing broaches, then semi-finishing broaches, then finishing broaches. The broach tools are set end-to-end on the broach machine. In one stroke on the broach machine, the entire disk root profile is machined. The total length of broach tools can sometimes be well over 100" (2500mm).

Why The Huffman Approach Is Better