JIT/Lean: Production Smoothing (heijunka), Kanban, and misc. issues:
a. Toyota Georgetown (a.k.a. Toyota Motor Manufacturing, Kentucky or simply TMMK) has two mixed model production lines each producing over two eight-hour shifts per day (with 480 minutes of working time per shift per production line), for five days per week. The models produced at TMMK include Camry (C), Avalon (A), and Venza (V). Suppose the weekly demand rates for Camry, Avalon, and Venza models are 7200 C, 600 A, and 1200 V, respectively. If the same mixed-model JIT scheduling (and TAKT time) is used in both production lines, calculate the TAKT time, in seconds, of the assembly line. How many units of each model will be produced before the production cycle is repeated? For one such production cycle, determine a satisfactory JIT production sequence of models.
b. Suppose one TMMK production line makes Camry (C) and Avalon (A), while the second TMMK line makes Camry (C) and Venza (V), with both lines operating for the same duration per day. Assuming both lines use the same TAKT time as in part II. a above, for each line, determine how many units of each model will be produced before the production cycle is repeated and specify a satisfactory JIT production sequence of models. Suppose there are two types of Camrys, CG and CH, representing gas-engine only and hybrid, respectively. About 1/6th (16.667%) of the Camrys are hybrid (CH), the rest are CG. Both lines produce CH and CG vehicles in a mixed-model mode. How does the presence of the two Camry models, affect the above JIT production sequences? [Specify the JIT production sequence for each line.]
c. Why are a relatively constant volume and stable mix essential to kanban & TPS?
d. Consider a Component X, one unit of which is used in every 5th Venza (e.g., X could be a Panoramic glass roof). The average lead-time (= wait time in queue + production time) for one container of Component X is one week. The container size for X is 20 units; so each time Component X’s kanban authorizes production 20 units of X are produced. A 16% minimum safety stock is desired to compensate for uncertainties; this means that the desired target inventory is at least 1.16 times the work-in-process inventory level computed using only the average data provided above (without uncertainties). Estimate the number of kanban cards required for Component X.