Efficiency design of mini factory for soy protein concentrate-based high protein biscuits

Choosing the right method for planning a mini-plant layout with the most efficient material handling is crucial to minimize its cost of production. This study aims to create the efficient layout design for soy concentrate-based high protein biscuit mini factory, as well as to evaluate the financial feasibility of the mini factory with the most efficient layout design. Layout generation methods used in this study were the Systematic Layout Planning and BLOCPLAN algorithm. The layout efficiency was evaluated through the calculation of rectilinear distance and material handling cost. The financial aspects on the feasibility study were evaluated through the calculation of rectilinear distance and material handling cost. The SLP method was able to generate the most efficient layout design with a material handling distance of 13.78 m and material handling cost of IDR 79,537 per month, while the BLOCPLAN algorithm was able to generate a layout design with a material handling distance of 15.56 m and material handling cost of IDR 89,397 per month. It could be concluded that the most efficient layout design for the high-protein biscuit mini factory was the one generated from the SLP method, which had the Net Present Value of IDR 14,619,251; Internal Rate of Return of 12.38%, and Payback Period of 4.42 years.


Introduction
The efficiency in facilities layout design of small-scale food factories seems to be overlooked by most manufacturers as it is commonly considered irrelevant to its cost of production.Facilities layout itself refers to the arrangement of every existing facility in the factory with the main purpose of delivering the smooth production process [1].The proper arrangement of facilities layout in a small-scale food factory allows a smooth flow of material handling despite the limited space available, which could result in reduction of the time, efforts and cost needed to optimize the food manufacturing processes.A study in small-scale tempeh industry suggested that improving the facilities layout efficiency could reduce the costs of material handling by 0.62% per month [2].Hence this reduction of material handling costs indicated the relevance of facilities layout efficiency to the cost of production even in a small-scale food factory.
There are several methods that can be applied for generating the efficient facilities layout.The Systematic Layout Planning (SLP) method, for instance, is widely used for both initial construction and improvement layout planning due to its capability in generating layout with the quickest material flow and the least amount of material handling [3].Using automated layout design programs like the 1230 (2023) 012158 IOP Publishing doi:10.1088/1755-1315/1230/1/012158 2 BLOCPLAN software for the same purpose is also suitable as its algorithm focuses on the layout efficiency, adjacency between the factory's facilities, and its material movement distance.
Recent studies suggested that rearranging facilities layout for the same factory with those two methods could result in the different material handling distances as well as the material handling costs [4,5].This implied that even with the same plant layout information provided, those two approaches might yield different layout efficiency.Therefore, choosing the best approach for generating the most efficient facilities layout appears to be one of the crucial factors in planning a small-scale food factory.
This study aims to create the most efficient layout design for a soy concentrate-based high-protein biscuits mini factory, and to evaluate its feasibility of the financial aspects.The manufacturing process of soy concentrate-based high-protein biscuit differs from the commercially made biscuits as it requires an additional pre-heating treatment.The flow of this biscuit manufacturing process needs to be taken into consideration when planning the facilities layout so that the optimum flow of materials and efficient production process can be acquired.Planning the facilities layout for the soy concentrate-based highprotein biscuit mini factory with the most suitable method is expected to increase the efficiency of material handling distances in order to obtain the minimum material handling costs.

P-Q-R-S-T data collection
The initial step in the facilities layout planning for the soy concentrate-based high-protein biscuit mini factory involved the P-Q-R-S-T (Product-Quantity-Routing-Services-Time) data collection.The P-Q-R-S-T data collection could be divided into three sections.The first section consisted the data collection of biscuit formulation and biscuit-making flow chart, which were then used as a reference in the biscuitmaking process for the following observation section.The observation section was then carried out on a biscuit-making process in the laboratory to obtain the data for mass and energy balance calculations, operation process chart (OPC), standard time, and product-quantity data sheet.The third section was conducted to decide the production capacity and operational hours assumptions, as well as the supporting services needed in the mini factory.

Facilities layout planning
The P-Q-R-S-T data that had been collected were then processed into the facilities layout planning phase to obtain 22 layout alternatives in total: 3 layouts generated from the Systematic Layout Planning (SLP) method, and 19 layouts generated from the BLOCPLAN method.

Systematic layout planning method.
Layout planning for the soy concentrate-based high-protein biscuit mini factory was firstly conducted by following the SLP pattern of procedures [6].The activity areas for the mini factory were listed in the first section.Relationships among the mini factory facilities (departments) from the Activity Relationship Chart as well as the From-to Chart were then combined into an Activity Relationship Diagram.The spaces required for each department were added into the Activity Relationship Diagram to form a Space Relationship Diagram.Three alternative layouts with the U, S, and L flow patterns were then created based on the Space Relationship Diagram.

BLOCPLAN method.
The facilities layout for the soy concentrate-based high-protein biscuit mini factory were also generated by the BLOCLAN algorithm in the BLOCPLAN90 software.The input data needed by the program were the number, name and area of the departments, activity relationship chart between the departments, and the L/W (length/width) ratio of the overall layout.A total of 19 layout alternatives were automatically generated by the BLOCPLAN algorithm.

Layout efficiency analysis
The efficiency of 19 layouts generated from the SLP and BLOCPLAN method were measured through the calculation of its material handling distances and material handling costs.The calculation of the material handling distances was carried out using the rectilinear distance method by connecting the coordinates of the centre points between production facilities through perpendicular lines.Material handling costs were determined based on the material handling distance multiplied by the material handling costs of the transportation equipment used as well as the frequency of material movements between production facilities [1].

Mann-Whitney U Test
The Mann-Whitney U test was performed to determine whether there was a difference in efficiency between the soy concentrate-based high-protein biscuit mini factory facilities layouts generated by the SLP method and BLOCPLAN method.A significance level of 0.05 was used in this Mann-Whitney U test.The conclusion of hypothesis testing was obtained by comparing the calculated U value of the sample with the Mann-Whitney U critical value [7].

Feasibility study of the financial aspects
The financial aspects on the feasibility study of the soy concentrate-based high-protein biscuit mini factory with the most efficient layout were evaluated through the following methods: Net Present Value (NPV), Internal Rate of Return (IRR), and Payback Period (PP) analysis.The analysis period used in the calculation of the NPV, IRR, and PP was 5 years, with the social discount rate assumptions of 7.5% per year.

Result and discussion
A total of 10 activity-areas (shown in Table 1) were set to be arranged in the layout planning of the soy concentrate-based high-protein biscuit mini factory.The activity-areas consisted of 2 sanitation facilities and 8 production departments which were identified based on the overall soy concentrate-based highprotein biscuit production process.The production departments also included the Department of Pre-Heating as an additional production facility that differentiated the soy concentrate-based high-protein biscuit manufacturing process from the commercial biscuit's in general.The facilities layout alternatives for the soy concentrate-based high-protein biscuit mini factory were established based on the space requirements shown in Table 2.An aisle requirement of 15% (3,7 m²) was added to enable the movement of materials and people between the activity-areas in the mini factory [6].The ratio of length to width of the 22 proposed layouts was set to be 6.1 to 5.6.

Material handling distances
Material handling (MH) distance could be defined as the distance travelled to move materials throughout the soy concentrate-based high-protein biscuit production process in the mini factory.The result of material handling distances calculation from the proposed soy concentrate-based high-protein biscuit mini factory layout is shown in Table 3.The result indicated that the total material handling distances of the layouts generated by the SLP method ranges from 13.78 -15.64 m while the layouts generated by the BLOCPLAN method ranges from 15.56 -26.66 m.The Mann-Whitney U test indicated that there was a significant difference between the material handling distance of the layouts generated by the SLP method and BLOCPLAN method (calculated U value < Mann-Whitney critical U value).The soy concentrate-based high-protein biscuit mini factory layout generated by the SLP method produced a lower material handling distance compared to the BLOCPLAN method (ΣR  < ΣR  ).Facilities layout with a lower material handling distance is more desirable as it could reduce the wastage of time as well as production costs in the factory [8].

Material Handling Costs
The result of material handling costs calculation for the proposed biscuit mini factory layouts is shown in Table 4.The result indicated that the total material handling costs of the layout generated by the SLP method ranges from IDR 79,537 -90,843 per month while layouts generated by the BLOCPLAN method's ranges from IDR 89,397 -153,066 per month.Material handling costs itself could be defined as the costs incurred as a result of material movements between production facilities in the mini factory [1].The Mann-Whitney U test also indicated that there was a significant difference between the material handling costs of the layouts generated by the SLP method and BLOCPLAN method (calculated U value < Mann-Whitney critical U value).The soy concentrate-based high-protein biscuit mini factory layout generated by the SLP method produced a lower material handling cost compared to the BLOCPLAN method (ΣR  < ΣR  ).Layout with the minimum material handling costs are desirable for the soy concentrate-based high-protein biscuit mini factory as the minimum expenditure aspect was included as one of the efficiency aspects in material handling [9].

Selection of the most efficient facilities layout
Taken together, the result of the Mann-Whitney U test for the material handling distances and costs showed that the SLP method was able to generate facilities layout that was more efficient for the soy concentrate-based high-protein biscuit mini factory than the BLOCPLAN method.The proposed facilities layout from the SLP method which had the lowest material handling distances and costs was found in the "SLP-U" code (13.78 m and IDR 79,537).Therefore, the facilities layout with the code "SLP-U" was chosen as the most efficient layout to be applied in the soy concentrate-based high-protein biscuit mini factory.The facilities layout with the code "SLP-U" is shown in Figure 2.

Feasibility study of the financial aspects
It was assumed that the soy concentrate-based high-protein biscuit mini factory had a production capacity of 24,000 packs of biscuits in one year of production with the estimated net profit of IDR 36,135,526 per year.A summary of the financial feasibility analysis results is shown in Table 5 as follows.The results indicated that the soy concentrate-based high-protein biscuit mini factory was financially feasible as it had a positive NPV at the end of 5-year period (IDR 14,619,251 > 0), IRR greater than the social discount rate used in the calculation (12.38% > 7.5%), and payback period (4.42 years) less than 5 years.The positive NPV results indicated the extra wealth for the soy concentrate-based high-protein biscuit mini factory shareholders after 5-years period [10].The IRR of 12.38% indicated the highest interest rate that could be paid to return initial investment funds from cash inflows.The PP calculation results indicated that the cash flows of the soy concentrate-based high-protein biscuit mini factory would be able to recover the initial investment costs after 4.42 years [10].

Conclusion
The results of this study indicated that the proposed facilities layout for the soy concentrate-based highprotein biscuit generated by the SLP method had a lower material handling distances and costs than the one generated by the BLOCPLAN method.The facilities layout with the code "SLP-U" from the SLP method was chosen to be the most efficient facilities layout for the soy concentrate-based high-protein biscuit mini factory as it had a material handling distance of 13.78 m and material handling cost of IDR 79,537 per month.The financial aspects of the soy concentrate-based high-protein biscuit mini factory with the most efficient layout indicated the mini factory's feasibility as it had Net Present Value of IDR 14,619,251, Internal Rate of Return of 12.38%, and payback period of 4.42 years.

Figure 2 .
Figure 2. Facilities layout with the code "SLP-U"

Table 2 .
Space requirements for soy concentrate-based high-protein biscuit mini factory.

Table 3 .
material handling distances of the proposed layouts.

Table 4 .
Material handling costs of the proposed layouts.

Table 5 .
Summary of the financial feasibility analysis results