Influence of Non-Productive Operations on Product Quality

Abstract

Small batch production is mainly, due to the competitiveness of the market, oriented to achieve the required specifications with minimal manufacturing processes using standard cutting tools. Costume-made hydraulic valves are one of the unique cases of small batch production in combination with high tolerances requirements [1]. Honing represents the manufacturing process which enables achieving final geometric requirements for valve's cylinder bore and requires pre-processing on computer numerical control (CNC) machining centre with successive cutting processes drilling, milling and reaming. Specifications of the piston bore of the hydraulic valve housing prescribe cylindricity /○/ ≤ 12 µm and surface roughness Ra ≤ 1.6 µm after reaming and cylindricity /○/ ≤ 3 µm and surface roughness Ra ≤ 0.4 µm after honing.This paper deals with reaming process quality improvement. Experiment planning and process modelling were performed by design of experiments (DOE) methodology [2]. Measuring method for bore cylindricity was defined as suggested in [3] and [4] and surface topology with mean roughness parameter Ra [5]. Within the framework of an experimental investigation single and combined effects, as well as related reproducibility, of such parameters on bore geometry and surface finish were investigated.Factors that have been identified as key to achieve specifications (bolded factors in Fig. 1) have been studied within the experimental work. Authors in other reaming processes optimization studies investigated spindle speed n and feed rate f as numeric control factor [6] to [9]. In this study feed rate and spindle speed were recognized as the key productive operation factors as well.Studies The key non-productive operation factors that were analysed in this study were clamping device lack of rigidity and effect of surface cleanliness on measurements reproducibility. Clamping device weakness was minimized with focusing on only one (of three) clamping nest. Surface cleanliness impact was analysed with SEM analysis and was minimized with additional washing and degreasing. Influence of Non-Productive Operations on Product Quality

Effect of Vibrator Parameters and Physical Characteristics of Parts on Conveying Velocity

“…Analysis of variance (ANOVA) is a group of statistical models used to explore the differences between group means and the procedures related to them (such as "variation" among and between groups), developed by Fisher [31] and [32] to [35]. ANOVA is used to study the effect of the factors which affect the conveying velocity.…”