Global Manufacturer of Marine Propulsion Systems

The company wanted an automated or semi-automated solution for turning of drive shafts on their 4-Stroke Outboard 200-275HP engines. The solution needed to handle parts between 24” and 37” in length and turning through a friction weld between 4140 and stainless steel. The process would need to hold length and diameter tolerances, as well as the friction weld turn diameter to 1.33Cpk or better, with a cycle time inside 60 seconds and a 30-minute part to part change over.

Assessment
The solution requirements were challenging. Of particular concern was holding the overall length of the part to a .010 tolerance while handling the part in an automated method and turning through a significant friction weld with varying depth and hardness. The process would need to be repeatable to .002” tolerance with a 1.33 Cpk.

Solution
Ellison Machinery and Robotics recommended a 2-axis Okuma Heritage ESL8II lathe with box way design and 10HP spindle to handle rigidity requirements through the friction weld cut. A Maranco Flexsys LE-51 loader/unloader was used to automate the drive shaft process. Ellison engineers collaborated with the equipment manufacturer to design a custom method for locating the part to accommodate for the fact that the shafts were dimensioned from the back side of the part opposite the face being machined.

End Result
The process is capable of producing drive shafts in less than one minute each, and holding the OAL to a 1.33 Cpk statistical window for both the OAL and the friction weld turn diameter. In addition, adequate tool life has been achieved despite turning through friction welds with inconsistent depth and hardness. The semi-automated nature of the process allows for unattended operations with the exception of unloading the part tray and the periodic changing of inserts.