Dimitris Mourtzis et al. / Procedia CIRP 79 (2019) 574–579
577
warehouse operators’ guidance to the position of the product is developed. The application allows the operator to have constant connection with the database of the available stock, record product entries or exits, while also being able to ask for navigation instructions inside the warehouse. The application targets mobile devices, so as to be easy to use in the warehouse, offering increased mobility and enabling access from everywhere to the available stock. The application hosts a user-friendly interface, which aims to be used by warehouse operators and/or warehouse vehicles drivers. The application offers three functionalities: monitor available stock, manage product (un-)loading and navigation. To visualize current stock, a top-down depiction of the warehouse is used. The operator may select one storing department and see what is stored there. Additionally, a list option is also available. To (un-)load products, QR codes are placed on each pallet of products but also on all the storage shelves, so that the operator may easily scan the QR codes and update the inventory management database for product input and output. Finally, to facilitate the retrieval of products, Augmented Reality navigation instructions are available. The operator provides the product that needs to be retrieved and the application navigates him to it.
Regarding all the above results for twelve scenarios, the one with 95% Service level, 18% storage cost and 1 month production cycle seems to fulfil industry’s expectations. The main decision making criteria are highlighted in bold.
Table 1. Results for 1 months, 18% storage cost and 95% Service level
Proposed solution
Criterion
Unit
Safety Inventory Average Inventory Inventory Cost Warehouse Size Production Quantity (per month)
Parcels Parcels
30185 55010
Euro/ Year
179449
M 2
1802
44983
Parcels
After selecting the optimum scenario, the CAD of the warehouse layout is created, considering some basic criteria:
a) First-In-First-Out must be served as often as possible so as to limit the possibility for the products to VSRLO FROXPQV unless we have access from both sides). b) The existing space must be used as efficiently as possible. c) There are two types of pallets: the dimensions of each is either 1,40m*1,40m*0,15m or 1,2m*0,8m*0,15m. d) Integer number of columns and rows must be used for each code. e) Stack support must be secured at all times. That means that single columns must not have more than 2 pallets. f) Warehouse surface must be as small as possible. The layout has been based in real dimensions taken from the existing warehouse storage area and are used for placing inside these limits the existing and the new warehouse layout. The main disadvantage of the existing layout, which is presented in Figure 2, is that bulky storage areas are created for each product, which prevents from FIFO serving and make products reachability a tough issue. Another disadvantage that makes current layout has is that products are not supported so well. The proposed layout indicates a new way to store the products (Figure 3). This scenario allows FIFO to be served to a greater extend and offers a better reachability for most of products due to the fact that smaller spaces are created. Moreover, following this layout warehouse achieves higher structural support of the piles and increased functionality.
4
Case Study and results
This methodology has been applied to a papermaking industry in order to give a solution to warehouse design problem. Targeted industry has to cope with a very high inventory cost which stems from the bad warehouse design and management systems that is currently applied. The developed methodology has been adapted on the warehouse of final products, in close collaboration with experts from the papermaking industry production line. There are four basic categories of final products which are taken into consideration: 1) kitchen paper 2) rough toilet paper 3) 3-plies toilet paper and 4) 4-plies toilet paper. The demand profile for each product is generated based on actual 8 months demand, as given by the industry. The main targets were to minimize the storage costs while keeping a high service level of about 95% and 98%. Adjusting the proposed methodology to the industrial use case needs, we assumed that the cost of production stems only from the cost of machines’ set up. All the methodology has been based on Fixed Order Quantity System with no-constant demand and order time. 4.1 Warehouse Design Twelve scenarios have been run for 53 final products following real industrial specifications. The scenarios come from the combinations of the possible storage levels (95 or 98%), the storage costs (16, 18 or 20%) and the production cycle duration (1 or 2 months). The selection is based on two basic criteria:
x Minimum inventory cost (first priority) x Minimum warehouse size (second priority)
Fig. 2. Existing warehouse layout.
Made with FlippingBook Digital Publishing Software