The Opportunity 

A contract aerospace manufacturer was supplying attachment brackets made from 17-4 stainless steel to a major aerospace company. They were being machined on a 40 taper horizontal machining center with 2 parts mounted to each tombstone. They were using a competitor’s end mill and the quality was okay, but tool life was short and the process was long. Cycle time was 1hour and 55 minutes per run. Our application specialist studied the operation and saw how the right tool and some toolpath tweaking could make a big difference. After a quick consultation, the customer authorized us to take the shot. 

GWS Action Plan

The customer was utilizing conventional milling strategies (slow speeds and feeds with heavy radial depths of cut) to machine the brackets. These parameters favored the competitor’s end mill. But this process was ultimately the cause for excessive cycle time and erratic tool life. To improve both, we shifted the customer to high speed machining processing, dramatically increasing speed and feeds while reducing radial step over. With the increased feed rates came the need for some toolpath reprogramming, which we were able to provide to the customer with the help of our in-house programming team. The new cutter path was programed in MasterCam using the Dynamic Milling option. With the proper toolpath and high speed running parameters, we could now apply the perfect tool for this application, a ¾ inch 7-flute Hurrimill end mill. Its heavy edge prep demands higher speeds to maximize performance, while variable helix geometry permit smooth and stable metal removal rates. 

The Results 

• Cycle time was reduced by 46 minutes (1 hour and 14 minutes for 2 parts)
• SFM increased from 250 to 550 with a 0.005″ chip load per tooth
• Tool life was improved from 4 to 12 parts per tool (3X tool life)
• Overall cost per part decreased 20%
• Part quality remained high & tool life became predictable (no more sudden failures)

The Bottom Line

Due to the relationship and level of trust with their application specialist, the customer was open to trying something new. They now have a higher level of production and efficiency at a considerable cost savings.