Parameters affecting quality in manual assembly of engines

In manufacturing, it is vital that operators and other production personnel have the right information at the right time and right place. But what happens if we overestimate the usability of information for supporting the personnel in their assembly tasks?When does information serve as a quality assurance tool, and when does it become a too large part of the workload, thus reducing the time for core workplace activities, and instead becoming a part of the personnel’s workload? This paper reports on work that has been conducted at a heavy diesel engine assembly plant with the aim of finding information usability parameters that can affect the personnel negatively or positively. The paper presents and describes an evaluation of an existing information system at the plant. The aim of the evaluation was to find out why the assembly personnel, despite the fact that they had “all the information they needed”, did not always assemble the product according to specification and thereby caused an engine reject that had to be re-assembled. The initial hypothesis was that there would be a strong correlation between the production volume and the number of rejects due to “Information Overload”. However, the study revealed that the personnel do not use the IT system in a way that causes information overload. Instead, the degree to which the IT system supports/triggers different forms of information seeking behaviour is thought to be one of the main factors influencing internal reject

An assembly line information system study

Assembly line information systems are designed to provide assembly workers with appropriate information that allows the assembly of the product in good time and good quality. In this context product quality might be defined relative to the number of internal rejects or products which need some kind of reworking before being in a deliverable condition. This paper describes a pilot study of a heavy diesel engine assembly line where considerable variety is presented to the assembly workers in the form of engines destined for trucks, buses, marine applications and stationary power generation each of which has to comply with a variety of national and international standards. Internal rejects might for example occur through the fitting of subassemblies that are unsuited to the eventual application, and although an extensive information system is currently in place the level of internal rejects is considered to be unsatisfactory. The objectives of the study were to understand how the assembly workers interact with information systems and the impact this has on product quality and productivity. A single line was studied for ten days during which 2600 engines were assembled. At four of the assembly stations the existing information system was changed to reduce the amount of information to be assimilated by the workers, the timing of its presentation and its location. The use of simple colour-coded cards and symbols resulted in the reduction of internal rejects by 40% on two of the assembly stations and to zero on the other two stations. It is believed that changing the information system has changed the workers' behaviour through a reduction in cognitive stress levels. The pilot study has provided useful insights into the basis for modifying information systems and a further study of the final assembly of heavy trucks is planned with an ultimate aim of determining a rationale for the design of information systems for use within the assembly of customised products

Ergonomics analysis in a virtual environment

Simulation can support the design of an ergonomic workplace by enabling early assessment of ergonomic conditions in a virtual environment. An important feature is the possibility to study alternative solutions or the effect of improvements from an ergonomics perspective. To be able to conduct an efficient and reliable evaluation in a virtual environment, an objective analysis method is essential. Such an analysis method should be integrated in the simulation software, and support a company's everyday ergonomics work process. In order to gain from existing ergonomics knowledge within a company, the possibility to implement such wisdom in the current simulation software becomes important. This paper presents an implementation work done with the purpose of integrating an established ergonomics work process into a virtual environment. It describes the benefits of an ergonomics work process where simulation and evaluation at early stages of a design process are key factors. The paper will also describe the integration process, i.e., the technical issues as well as the change in work methods

Attention, interpreting, decision-making and acting in manual assembly

In a modern manufacturing environment, data and information are a vital part of the manufacturing process and in particular for supporting the value adding activities. Modern manufacturing information systems allow fast distribution of, and access to, data and information. However, the technical improvements of manufacturing information systems do not always create the benefits that were expected from them. This paper discusses this problem in the context of manual assembly tasks. Attention, interpretation and decision-making are important drivers for how well the assembly tasks are performed - the acting. In other words, the acting is governed by how and when the attention of the assembly operator is caught, how easily the information can be interpreted, and to what extent the information is useful for decision making. The aim with the work is to find and present why data and information provided on the shop floor often fails to prevent quality problems; not seldom this data and information actually causes the problems. This paper focuses on one of the core issues related to assembly data and information, namely “active attention” and how this is triggered. If active information seeking behaviour is not present on the assembly shop floor, then the probability for a quality problem increases

Ergonomics analysis in a virtual environment

Simulation can support the design of an ergonomic workplace by enabling early assessment of ergonomic conditions in a virtual environment. An important feature is the possibility to study alternative solutions or the effect of improvements from an ergonomics perspective. To be able to conduct an efficient and reliable evaluation in a virtual environment an objective analysis method is essential. Such analysis method should be integrated in the simulation software, and support a company’s everyday ergonomics work process. In order to gain from existing ergonomics knowledge within a company, the possibility to implement such wisdom in the current simulation software becomes important. This paper presents an implementation work done with the purpose of integrating an established ergonomics work process into a virtual environment. It describes the benefits of an ergonomics work process where simulation and evaluation at early stages of a design process are key factors. The paper will also describe the integration process, i.e. the technical issues as well as the change in work methods

Future needs for cost calculation methods connected to ergonomics analysis and simulation

Simulation can support the design of an ergonomic workplace through early assessment of ergonomic conditions. An important feature is the possibility to study alternative solutions or the effect of further improvements in a virtual environment. This paper discusses a roadmap for linking economic information to ergonomics simulation. This can support a company in deciding to improve workstations that already fulfil the ergonomic standards

Towards dynamic ergonomics analysis of work sequences in virtual environments

Computer aided visualization and simulation enables early assessment of important design parameters of future products and production systems. Typically, humans affect the system performance, and in order to achieve the expected system efficiency ergonomics needs to be considered in the design process in addition to the more technical or logistical matters. Hence, there is a call for ergonomics to be a natural part of the product and production system design process, also at virtual stages. This paper portrays and discusses two cases where company-specific ergonomics guidelines were implemented into digital human modeling systems for performing static work analyses. Albeit useful, the approach of evaluating static postures gives a reduced picture of the actual situation since the work usually involves a series of movements and tasks. A recently commenced research project aims to enhance knowledge on how to estimate accumulated ergonomic load over time. This knowledge is eventually to be implemented in DHM tools to support objective ergonomics analysis of complete work sequences in virtualenvironments