Size effect and minimum chip thickness in micromilling

Autor(es)

de Oliveira, Fernando Brandao ^[1] ; Rodrigues, Alessandro Roger ^[1] ; Coelho, Reginald Teixeira ^[1] ; de Souza, Adriano Fagali ^[2]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Engn Sch Sao Carlos, BR-13566590 Sao Carlos, SP - Brazil

^[2] Univ Fed Santa Catarina, BR-89 21800 Joinville, SC - Brazil

• Tipo de documento: Artigo Científico
• Fonte: INTERNATIONAL JOURNAL OF MACHINE TOOLS & MANUFACTURE; v. 89, p. 39-54, FEB 2015.
• Citações Web of Science: 63
• Assunto(s): Aço Cavacos

Resumo

This paper compares the size effect behaviour in micro- and macromilling by applying Analysis of Variance on the specific cutting force (k(c)) and relating it with the tool edge radius (r(e)), workpiece roughness (R-a), cutting force and chip formation when cutting slots in AISI 1045 steel. Size effect is observed in micromilling through hyper-proportional increase of the specific cutting force for feeds per tooth (f) lower than endmill edge radius, reaching levels of grinding process (similar to 70 GPa) when f congruent to r(e)/10. This particular milling condition does not produce chips. The minimum uncut chip thickness (h(min)) varied between 22% and 36% of the endmill edge radius. This range was determined by proposing a curve (k(c)/R-a versus f/r(e)) where specific cutting force becomes amplified (size effect) due to workpiece roughness association. In addition to the minimum uncut chip thickness, there is a cutting thickness between h(min) and r(e) that optimizes workpiece surface integrity and not only forms the chip completely. This thickness may be as important as h(min). Besides this, a relation between deformation mechanisms during chip formation and cutting force oscillations is proposed for micromilling and also related to tool tip radius (r(e)). This cutting force behaviour enables the determination of certain characteristic chip thicknesses including h(min). Finally, it is concluded that minimum uncut chip thickness varies practically from 1/4 to 1/3 of tool cutting edge, regardless of workpiece material, tool geometry, mechanical machining process and technique used for measuring or estimating h(min), i.e. numerical, analytical or experimental. (C) 2014 Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 04/13483-0 - Estudo da usinabilidade de materiais aplicando alta velocidade de corte: uma interação entre engenharia de microestrutura e de fabricação
• Beneficiário: Alessandro Roger Rodrigues
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores