University of Twente Student Theses
Optimal relationship between the use of labour, number of running machines and type of product : Modeling labour allocation over the number of running machines and type of product.
Baan, Frank (2012) Optimal relationship between the use of labour, number of running machines and type of product : Modeling labour allocation over the number of running machines and type of product.

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Abstract:  Due to confidential information this paper is cut on results and findings. This version of the paper is a short version of the actual paper. In this summary the whole paper is described in short and some conclusions are given which are not confidential. Introduction: TenCate Geosynthetics Europe at Nijverdal assigned me to conduct research on declining yield figures at the weaving mill. One of the expected causes is that there is uncertainty regarding the number of weavers to schedule in relation to the given number of machines running and the desired output. For my research I used articles that looked to the allocation of labour at a given number of machines running. Reading these articles I found that the problem that I want to investigate, is known as the ‘Machine interference problem’ or ‘Machine repairmen problem’. The authors Stecke & Aronson (1985) and of Hague & Armstrong (2007) give a summary for this problem and a list of authors that have researched this problem. The machine interference problem is described in short: Take a simple system with N (number) machines and R (number) operators. A machine operates for a period of time until it stops. Then it needs repair by the operator or repairman. When there are more machines than operators, the chance arises that a machine stops but the operator or operators are all busy. This is called the interference of the machine and causes the machine to be idle, which leads to decreased productivity. This also applies to the situation at the TenCate weaving mill where a weaver has to operate a given number of machines. These machines will sometimes break down and this results in interference of the machine. Based on the literature and the actual problem at TenCate I came up with the assignment to construct a model where variables like type of machine, type of yarn and type of personnel are input and the outcome is how to plan the workload at the weaving mill. From the problem statement I have come with the following problem statement: To develop a model to allocate labour over a given number of machines running, taking into account the quality of the yarn. Research: The problem statement will be dealt with answering several research questions. Through the conclusions derived from the answers to the research questions I have come up with a model that gives a few outcome possibilities on how to allocate labour over the given number of machines running, taking into account the quality of the yarn. The problem is influenced by three main variables:  Personnel.  Machines.  yarn. These variables are the key objects of my research. In the research that is conducted I examined these variables on how the output is influenced by each of the variables. By working with the weavers of TenCate alongside of the machines I have experienced the problem myself. For my research and model this was very important to do. By experiencing the problem in reality I was able to adjust the model more to the situation at the weaving mill of TenCate. For engineering of the model I have used the literature on machine interference problems. The literature used describes the aspects of the machine 5 interference problem and how to build a machine interference model with several parameters. The information used is a mix of empirical articles and information from TenCate. In my research I have use this information to get four parameters that gives the input for the model. These parameters are:  Breakdown frequency per product per shift.  Service time per machine type per shift.  Repair time per machine type per shift.  Walk time per machine type per shift. The measuring of data which is done by collecting the individual breakdowns per product per shift and the individual times per machine per shift. Several times I went to the weaving mill to measure the service, repair and walk time of the weavers. These individual measurements I put in a database from where I distracted the averages. The validation of these averages can be tested by using the Poisson or Erlang distribution. These distributions give a probability distribution for the found averages. Conclusions and recommendations: With the results of my research I subsequently answered the research questions which is used to build a model for TenCate to allocate the plan the correct number of weavers per shift per route of machines for a given objective. The model uses the input parameters to calculate the output produced per shift by one weaver per hour. Based on the output produced per hour for one weaver the model calculates the outcomes for the following objectives:  Desired output for the next week.  Maximum output for the next week.  Maximum profit for the next week.  Maximum weaver occupation for the next week. For each of these objectives an overview is given per machine type per shift from which the management can decide what number of weavers they need to achieve an objective. Unfortunately the model is not perfect and needs some improvements for more accurate results. The model is based on certain assumptions which in reality are not applicable. One omission which has a huge impact is the assumption that when a weaver services the machine he also prevents any upcoming breakdown. This assumption ignores the fact that machines will break down randomly based on their break down rate and that not every breakdown is prevented. Further research is needed to deal with the fact that breakdowns occur randomly. Therefore I give TenCate the recommendation to investigate the model further by a candidate with more expertise in mathematical modeling and optimizationAnother recommendation of a list of recommendations is to split the model between an experienced and an inexperienced weavers. At last I have also do interesting analyses at TenCate where results are coming forward that are of interest in the study on the output yield at the weaving mill. Enjoy the reading of this paper. 
Item Type:  Essay (Master) 
Clients:  TenCate Geosynthetics 
Faculty:  BMS: Behavioural, Management and Social Sciences 
Subject:  85 business administration, organizational science 
Programme:  Business Administration MSc (60644) 
Link to this item:  http://purl.utwente.nl/essays/61965 
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