Problem Solving Techniques Taught Through Validation of an Instantaneous Rigid Force Model

Abstract

Educating engineering students in the appropriate methods for analyzing and problem solving fundamental manufacturing processes is a challenge in undergraduate engineering education, given the increasingly limited room in the curriculum as well as the limited time and resources. Although junior and senior level laboratory courses have traditionally been used as a pedagogical platform for conveying this type of knowledge to undergraduate students, the broad range of manufacturing topics that can be covered along with the limited time within a laboratory course structure has sometimes limited the effectiveness of this approach. At the same time, some undergraduate students require a much deeper knowledge of certain manufacturing topics, practices or research techniques, especially those who may already be working in a manufacturing environment as part of a summer internship or part-time employment. The current work shows how modeling, actual machining tests and problem solving techniques were recently used to analyze a manufacturing process within a senior design project course. Specifically, an Instantaneous Rigid Force Model, originally put forward by Tlusty (1,2) was validated and used to assess cutting forces and the ability to detect tool defects during milling operations. Results from the tests showed that the model accurately predicts cutting forces during milling, but have some variation due to cutter vibration and deflection, which were not considered in the model. It was also confirmed that a defect as small as 0.050 inches by 0.025 inches was consistently detectable at multiple test conditions for a 0.5-inch diameter, 4-flute helical end mill. Based on the results, it is suggested that a force cutting model that includes the effect of cutter vibration be used in future work. The results presented demonstrate a level of knowledge in milling operations analysis beyond what can typically be taught in most undergraduate engineering laboratory courses.