Value Stream Map

Before value streams are identified and visualised with a value stream map, the process areas are defined. In Lean Thinking a process area is not a cluster of related practices that share the same goals that are considered important for making improvement in the area. This definition of process area is not used in Lean Thinking can be interpreted very broad when it is applied on a manufacturing system. For instance, the whole fillet line is sharing the same goals, but waste is hardly identifiable if this process area is not split into pieces. Therefore a special designed method to identify process areas was introducted to by P. Womack. First, try to identify between which processes clear

intermediate products are located. Second, identify between which processes a significant new level of skill is required.

In Chapter 1 and 3 the scope of the research discusses how and why it is narrowed down to one product family: fillets. This limits the scope to the fillet department. However, the preceding process bird supply, primary process and secondary process until fillet lines are also visualized in the VSM to make it more comprehensive and understandable. The same matters for packaging and shipping that are somewhat out of the scope due to the time limit.

In addition to the process areas stated above, the following areas are identified (see gray areas in Figure 5.1): the Breast cap cutter & placer, where the broiler is cut by a breast cap cutter module and fed to the fillet lines with the help of an employee. Next there is the Filleting system & manual harvesting, where the breast cap enters the filleting system to be deskinned and to receive cuts and which is then harvested for fillets (or sometimes whole breasts). Then, the breast caps enter the Tenderloin system & manual harvesting where the harvested tenderloins are also batched in trays and weighted (excluded from Figure 5.1 since it is comparable to Filleting system & manual

harvesting). The trays with tenderloins are transported to the packaging department while the fillets enter the process area of Trimming & deboning. Here, all the fillets are trimmed and scanned on quality. After that, fillets can either go to batching to be batched into trays, crates or sacks, or they are transported to Portionning to be portionned into other products like schitzels and medaillons. Portionned products are batched after being portionned.

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Figure 5.1 process structure fillet department. Gray areas are the identifieid process areas.

The value stream map (VSM) consist of information flows, material flows and a lead time ladder (Rother & Shook, 1999). See Chapter 3 for more information on VSM. The information flow is created with the help of the flowcharts from Planning and Control (Section 2.2) and the material flow is created with the process structures (Section 2.1).

In creating the VSM, some important decisions are made. First of all, the lead time ladder is not considered very important, since the production speed of the lines are variable. Thus, the lead time is dependent on the speed of the lines. In addition to this, the lead times for products in the fillet lines are also dependent on the allocated capacity (including available labor) and capacity utilization. The sequence of activities within the process areas are worked out and timed. In example, how long it takes for an employee to move a crate with rejected products from the end of a process to the beginning, and how long it takes to make the pieces re-enter the system. If forms of muda are observed, they are valued. For instance, if on a frequent basis unnecessary inventory is observed, then the average storage time of a product is recorded and estimated. Also, mudas like motion and transport are valued with, in example, time or distance.

Another important decision is made to consider the retail customer as the only customer for the manufacturing system and thereby excluding the industry customers. In Chapter 2, the focus on retail customers is discussed. The manufacturing system is adjusted on Scheduling and Control level with the goal to prioritize the satisfacation of retail customers. Industry orders are fulfilled with products that could not or were not able to be processed for retail orders, for instance the products with poor quality and by-products. Rejected products are commonly processed for industry orders. For some processes the reject rate has a threshold. Therefore the reject rate could be considered as some form of yield loss, since most of the rejected products were supposed to be processed for retail orders but are now fulfilling industry orders. Industry orders are simply the side-effect of retail orders.

Nonetheless, the manufacturing system tries to perform as well as possible on industry orders too. Figure 5.2 on the next page visualizes the basis of the Value Stream Map for the current situation. Due the limited available information the VSM covers the Cycle time (C/T) that is interpreted as the lead time of a product, Yield loss, Capacity utilization (C/U), Uptime, Waiting time (WT) and defects for the process areas that are studied. In the future, other information can be collected for process areas to identify their current performance. Examples are change over times, set up times, scheduled changes, corrent information (% of the job instructions being accurate/corret and how many times there is asked for clarification), Inventory, etc.

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