Stiffner Strut

The stiffener strut forms the joint between the compressor case and the engine case. The main purpose of this part is to strengthen the rigidity of the engine.
This demonstrator is made of 17-4 PH stainless steel and we started from a block of 210 x 145 x 101 mm.
The market knows several ways of producing this part:

• Full machining
• Additive manufacturing
• Friction welding

For this demonstration we selected full machining for a simple reason that it is the most complicated kind of machining.
We machined this part on a Makino D500, one of our most successful 5-axis vertical machining centres. Its rigidity and spindle strength allow us to push hard in stainless-steel cutting applications.
The stiffener strut forms the joint between the compressor case and the engine case. The main purpose of this part is to strengthen the rigidity of the engine.
This demonstrator is made of 17-4 PH stainless steel and we started from a block of 210 x 145 x 101 mm.
The market knows several ways of producing this part:

• Full machining
• Additive manufacturing
• Friction welding

For this demonstration we selected full machining for a simple reason that it is the most complicated kind of machining.

We machined this part on a Makino D500, one of our most successful 5-axis vertical machining centres. Its rigidity and spindle strength allow us to push hard in stainless-steel cutting applications.

The main roughing during the second operation was performed with a 32 mm diameter porcupine cutter. But the important thing was, of course, the inner shape.

How could we cut all the way inside the narrow pocket and achieve excellent surface quality? To get this done we should normally use EDM processes or a very long extension of a tool and cut slowly. But then the performance would be very low.

So that is why we used a MONO CURVE MST toolholder for this process. The unique shape of this toolholder allows us to have a small diameter on the tip of the toolholder but a bigger diameter on the bottom. In this way rigidity is maximised to the greatest possible degree.

The 5-axis toolpath our engineers programmed and the smooth 5-axis movements of the D500 – mainly due to the twin DD motors on the A axis and the DD motor on the C axis – helped us achieve excellent quality even in such terrible conditions.