The traditional product development process at the prototype development stage is sequential. It includes product design, development of manufacturing process and supporting quality and testing activities, all carried out one after another. This situation assumes that there is no interaction among the major departments involved in product manufacturing during the initial development process. Often the need for engineering changes is discovered during planning or manufacturing or assembly. Design department in a typical sequential product development process finalizes the design without consulting the manufacturing, quality or purchase departments. Planning might feel it necessary to request design changes based on a number of reasons like the procurement or facility limitations. Changes in design may be called for when the manufacturing department is unable to meet design specifications or there are problems in assembly. These changes are however to be incorporated in design. The design documents are therefore sent back to the design department for incorporating the changes. The design/redesign path is shown in Fig. 2.4. The design documents are passed on back and forth to incorporate design changes as illustrated. This will lead to inevitable conflicts, each department sticking to their own decisions and may often require intervention of senior management to resolve conflicts or differences in opinion. Design changes will involve both material and time wastages. In such a situation, time taken to product development is usually more than what is anticipated and correspondingly the response to the market requirements will be slow compared to a competing company which can create an error free design at the first instance. In an age of reduced product life cycles as we witness today the time delay between market demand and introduction of product in the market has to be as short as possible. Sequential product development process, therefore, may not suit the present global scenario.
Even after the prototype development stage is over, the need for design change may arise during service. Such changes are usually few in number, but are very costly.
Thus in the traditional manufacturing, the design documents move sequentially through the various departments of the organization. The R & D group completes the design task and passes the data to planning, which in turn passes the information to manufacturing and so on. If any downstream department wants to introduce any change, the process has to backtrack and this often involves additional expenditure as well as inevitable delay in realizing the product.
Sequential Engineering is often called “across the wall” method. Figure 2.5 illustrates the insulated way each department may function in sequential approach. Each segment of the product development team (Design, Planning, Manufacturing etc.) completes its task in isolation and passes over the documents to the next segment. There is no interaction among the groups before the design is finalized. If a serious mistake in the product is detected during testing, the revision process has to start from design, resulting in materials wastage and loss of time. In the context of extensive outsourcing, there is also need for intensive consultation between vendors and manufacturers.