Abstract

Tool conditions are the essential factors in determining the geometric accuracy and the machined surface quality in the milling process. The different mechanisms of tool condition can be classified as tool wear, chipping, and built-up edge. The chipping, which is one of the decisive tool conditions when the brittle milling tools are used in milling, has not been well investigated by previous studies since the chipping is randomly occurs.

Therefore, the main objective of this study is to comprehensively investigate the generation and propagation of chipping in the milling process. To realize this objective, the carbide milling tools were used to dry cut 1020 low carbon steel with different combinations of cutting speed and chip load. Under each combination, the cutting tool was evaluated in terms of various tool conditions over a certain cutting distance until the milling tool failed.

The result showed that the chipping mainly occurred under the low spindle speed or high chip load per tooth since the cutting force was high. Once the chipping occurred on one flute, other flutes also had the chipping at the same position since the chipping occurred initially increased the chip load per tooth of the next flute. After the chipping was generated, it extended in the following milling process until the width of chipping met the failure criterion. It is found that most of the chipping extended and met the failure criterion in a short cutting distance. However, the chipping which propagated slowly shown three stages with different expansion rates before the end of tool life. Meanwhile, the flank wear was observed on the outline of chipping and was considered as a factor for the chipping propagation since the flank wear increases with the cutting force. The milling test was stopped at the end of tool life, and it was found that the tool life of all the milling tools was shorter than the tool life estimated by using the Taylor equation. However, the Taylor equation only considers the flank wear as a factor for the tool life, whereas, the chipping was dominated in this study.

Library of Congress Subject Headings

Milling cutters--Mechanical properties; Carbide cutting tools--Mechanical properties; Metals--Fracture; Mechanical wear

Publication Date

5-8-2019

Document Type

Thesis

Student Type

Graduate

Degree Name

Manufacturing and Mechanical Systems Integration (MS)

Department, Program, or Center

Manufacturing and Mechanical Engineering Technology (CET)

Advisor

Rui Liu

Advisor/Committee Member

Patricia Iglesias

Advisor/Committee Member

Alfonso Fuentes

Campus

RIT – Main Campus

Plan Codes

MMSI-MS

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