Measuring the assembly quality from the operator mistake view: a case study

Abstract

PurposeThe purpose of this paper is to focus on the assembly quality of copier products, specifically, concentrating on the prediction of the operator‐induced assembly defect.Design/methodology/approachBased on the Shibata model, the design‐based assembly complexity is redesigned. And the Sony Standard Time is replaced by the Fuji Xerox Standard Time in the calculation of the process‐based assembly complexity. Furthermore, different correlation functions are attempted and comparatively studied in the regression analysis. Thereby, a new defect rate prediction model is proposed and validated with three copier assembly cases.FindingsThe new proposed model is much more accurate and stable in the human‐induced assembly defect prediction in copier production.Practical implicationsThe proposed model can be used to ensure the assembly quality by removing potential defects at the structure and process design stages. Meanwhile, with this model, the interactions between the engineers and designers can be more effective.Originality/valueThis paper presents a novel assembly defect rate prediction model for copier assembly quality management.

Research on assembly quality adaptive control system for complex mechanical products assembly process under uncertainty

“…Assembly quality optimization Liu et al [6] Assembly cost-tolerance model Cheng and Tsai [7] Cost-tolerance model Xiaoqing et al [8] Assembly process model, activity control model and quality data model Huang et al [9] Tolerance optimal allocation model by introducing the reliability index Assembly performance prediction Su et al [11,12] A novel defect-rate prediction model Liu et al [13] Maximum compatible constraint model Zhang et al [14] Relationship model with grey system theory based on determining reliability control points Xu et al [15] Predictive performances using the neural network time series models Hong et al [16] Generic mathematical model and state space model to predict and control the variation Hu et al [17] Assembly precision prediction for spacecraft Du et al [18] A stream of variation methodology developed and applied…”

“…Improper design, defective part, variance in assembly system, and operator error are the main causes of assembly defects [11]. Su et al [11,12] presented a novel defect-rate prediction model that is derived from the study of the design-based assembly complexity factor and the process-based assembly complexity factor, which are defined according to the structure and production characteristics of the product.…”

“…Su et al [11,12] presented a novel defect-rate prediction model that is derived from the study of the design-based assembly complexity factor and the process-based assembly complexity factor, which are defined according to the structure and production characteristics of the product. Considering that the dimension and geometric tolerance consists of three classes, namely deterministic constraint, micro-degree constraint, and release constraint, Liu et al [13] proposed a uniform model called maximum compatible constraint model to solve the problem of precision predicting for complicated product.…”

Hierarchies of adaptable learning during product development

“…1) Process-based Complexity Factor: The process-based complexity factor is derived from a time standard defined for a set of assembly tasks. Initially proposed by [14] and utilized by [15], [16], [17] and [18] the process complexity factor (Cf P ) shows satisfactory correlation with defect rates and is defined as:…”

“…where T M : the total manual assembly time, N a : the number of assembly operations and t 0 : a constant that represents a threshold minimum assembly time for the simplest assembly operation. The Westinghouse method was used by Shibata to estimate the total assembly time for the entire product (T M ) [19], while in [18] instead of using the Sony Standard Time (SST) method the Fuji-Xerox Standard Time was utilized. 2) Design-based Complexity Factor: Despite the various frameworks evaluating the simplicity and the manufacturability of a design the correlation between complexity and defective output is rarely considered in the literature.…”