Conclusions

The throughput times of both sub-departments are very high, which indicates that improvement is needed. The throughput time of calculated jobs were for both the housing- and retail sub-

department higher than the non-calculated jobs, which is due to the larger amount of time that is needed to execute a calculated job.

The parts of the processes that cause the most throughput time are: job execution for calculated jobs, technically starting the job for the retail sub-department, and especially sending out invoices for all processes.

The execution of the job is in 14 of the 18 calculated jobs the most time-consuming part of the respective processes. The time spent idle in the execution due to other appointments or multiple visits is the main cause of the high throughput time, since the visits to the client are spread over too many days. This time spent idle is considered as waste, since no work on the job is done during that time. According to the Lean philosophy, waste must be eliminated. Sometimes, this waste is

inevitable due to a full schedule of the carpenter or the client.

Technically starting the job takes more than 10 days in 8 of 18 jobs from the retail sub-department, which is very wasteful. This is due to the agreed terms with company X, who are responsible for 90% of the jobs from the retail sub-department. These terms state that for a regular (non-emergency) job a response is needed within 30 days. So, when looking at these terms, 10 days is agreeable. However, for the throughput time to be lowered, the technical start of a job should be much earlier. Since every day that goes by without executing the job can be considered as waste. So, AKOR should strive to lower the days it takes to technically start a job.

Sending out invoices is the most time-consuming part of the respective process in 19 of all 36 selected jobs. It is a very time-consuming part of every researched process. This is, however, not needed. Since all details needed to send out an invoice are already booked, there is nothing to wait for with booking. The reason it takes so long now, according to the stakeholders, is that invoices are being printed and they all end up in a pile. And only when there is spare time or during a session once per month, invoices are being sent out. This means that these invoices are just lying around for the remainder of time, which is very wasteful, and this causes a large part of the high throughput time.

The reason why the invoices should go out as fast as possible is that the money to be collected by sending out the invoices is collected much later than is needed. So, by leaving the invoices on a pile, the amount of work-in-progress (WIP) adds up. If the invoices are being processed faster, the WIP is going to be lower, which gives AKOR the opportunity to use the money that is collected faster for other purposes. So, the working capital of AKOR will increase.

Goal values

The goal of this research is mainly to bring more structure and flow in the organisation. This way, the throughput time can be reduced, the efficiency can be improved and the working capital of AKOR will increase. To make this goal measurable, the desired throughput time is determined by the

stakeholders at AKOR. This throughput time is 5 days for the housing sub-department and 8 days for the retail sub-department. This throughput time is based on a regular job where no calculation is needed. It may take more time if calculation is required for a job. However, due to the

unpredictability of the number of visits and hours it takes to technically complete a calculated job, there is no goal value made for the calculated jobs.

This is a very ambitious goal, since, according to the data analysis, the throughput times of non- calculated jobs of the housing- and retail sub-department were respectively 29.03 days and 43.26 days in 2018. However, the goal is attainable, since the main cause of the high throughput times are the days that a job spends being idle. Ideally, technically starting the job can be done within a day and technically finishing non-calculated jobs can be done in the first visit in about 95% of the jobs. Only when the jobs require unusual materials that are not present in the inventory or the van, the job cannot be done on the first visit.

To book all details into the ERP system should not have to take long, since the cost of all regularly used materials are known and the hours worked are registered online by the carpenters of the housing sub-department. However, the hours worked are still registered on paper by the carpenters from the retail sub-department. All the other details, such as contact information and pictures, are also available from the moment the job is technically started, so booking all details needed should not take multiple days. The only reason for waiting to book all details is if not already known materials or materials from an unknown supplier are used to execute a job. Then, it is necessary to wait for the invoice from the supplier. However, according to the stakeholders at AKOR, this only happens in about 5% of all jobs.

Sending the invoices should not cause any idle time in theory, since all details that are needed for the invoice are already known and booked in the system. So, the only action that must be performed is checking the booked details and sending out the invoice to the client, which should not take a lot of time.

In conclusion, the goal values of respectively 5 and 8 days for the housing- and retail sub-department are attainable. However, it may take some time for the solution to be implemented and for the results to show.

3 Literature research

This chapter answers several research questions using literature. Section 3.1 answers the research question: “Which methodologies are suited for the research and what are the strengths and

weaknesses of these methodologies?”. This research question helps choosing the right optimisation methodology. Section 3.2 provides additional information about the chosen methodology. In Section 3.3, an answer is given to the following questions: “Which Lean tools are suited for the research?” and “Which assessment criteria will be used in choosing the right Lean tool(s) for creating possible solutions?”. Based on the answers to the last two research questions, the best-suited Lean tool is chosen in Chapter 4.