ORIGINAL ARTICLE Analysis of surface roughness and cutting force when turning AISI 1045 steel with grooved tools through Scott–Knott method Robson Bruno Dutra Pereira & Durval Uchôas Braga & Frederico Ozanan Nevez & Alex Sander Chaves da Silva Received: 4 March 2012 / Accepted: 10 June 2013 # Springer-Verlag London 2013 Abstract The chip breaker presents an important role in chip control on turning operation, as well as a significant influence on cutting force, surface integrity, wear, and tool life. In this exper- imental study, the grooved chip breaker, feed rate, and cutting velocity influence on cutting force and surface roughness of turning process of AISI 1045 steel were investigated through a complete factorial design and the Scott –Knott method. The multiple comparison method of Scott –Knott was used to iden- tify which combination of the factor levels was specifically different when a source of variation was statistically significant in ANOVA. This multiple comparison method was essential to choose an optimal combination between cutting conditions and chip breaker type assuring the lowest cutting force and surface roughness levels without ambiguity. The methodology proposed was effective at achieving process improvement. Keywords Chip breaker . Cutting force . Surface roughness . Factorial design . Scott–Knott method 1 Introduction According to Maity and Das [1], long chips curl around the tool and can pose serious hazards to the workpiece surface, the operator, and the machine–tool operations. To overcome this difficulty, a number of researchers have investigated the effective control of chip flow and breaking. Chip curl can be controlled by using an obstacle across the chip-flow direc- tion, commonly known as chip breaker or chip former. The chip breaker is defined as a modification of the rake face to control or break the chip, consisting of either an integral groove or an integral or attached obstruction [2]. It was investigated that the restricted contact length influ- ence the cutting process concluding that this narrow land decreases the cutting force and temperature, and therefore increases the tool life [3]. The geometrical parameters of grooved chip breaker on chip breaking performance were investigated [4]. The chip flow mechanism on chip breaker insert was studied reporting its influence on chip curling and breaking process [5]. Analytical models of chip flow, chip curling, and chip breaking with chip breaker inserts application were devel- oped under the concept of equivalent parameters [6, 7]. These models were studied and the chip breaker insert be- havior on machining force, surface roughness, and chip- breaking process was analyzed [8]. Semi-empirical models including cutting conditions, tool geometry, and work-piece materials properties based on chip flow and chip-curling mechanisms had been developed [9]. A force decomposition model counting the influential parameters on tool wear including cutting conditions, tool geo- metry, and grooved-chip breaker geometry was proposed [10]. It was presented as a newly developed equivalent tool-face (ET) model for predicting the most dominant tool failure modes in turning with complex grooved chip breaker inserts [11]. The ET model was extended to correlate chip curling when machining with progressive tool-wear mechanisms in grooved chip break- er tools [12]. The performance of commercial grooved chip breakers was evaluated using a neural network [13]. R. B. D. Pereira (*) Instituto Federal Tecnológico do Sudeste de Minas Gerais, Rua Monteiro de Castro, 550; Bairro: Barra, 36880-000 Muriaé, Minas Gerais, Brazil e-mail: robson.pereira@ifsudestemg.edu.br D. U. Braga : F. O. Nevez : A. S. C. da Silva Universidade Federal de São João del Rei, Praça Frei Orlando 170; Centro, São João del Rei 36307-352, Minas Gerais, Brazil Int J Adv Manuf Technol DOI 10.1007/s00170-013-5126-3