Operations and Supply Chain Management The Core

MANUFACTURING PROCESSES chapter 6 185
Assembly line Area where an item is produced through a fixed sequence of workstations,
designed to achieve a specific production rate.
Continuous process A process that converts raw materials into finished product in one
contiguous process.
Product–process matrix A framework depicting when the different production process types
are typically used, depending on product volume and how standardized the product is.
LO6–4 Understand how to design and analyze an assembly line.
∙ The assembly-line design is centered on defining the work content of workstations that are
typically spaced along the line. This technique is called assembly-line balancing.
∙ The workstations need to be defined so that efficiency is maximized while meeting
maximum cycle times and precedence constraints.
Workstation cycle time The time between successive units coming off the end of an assembly
line.
Assembly-line balancing The problem of assigning tasks to a series of workstations so that the
required cycle time is met and idle time is minimized.
Precedence relationship The required order in which tasks must be performed in an assembly
process.
Production time per day
​C = ​ _______________________________ ​ [6.3]
Required output per day (in units)
Sum of task times (T)
​N​ t ​ = ​ ______________________ ​ [6.4]
Cycle time (C )
Sum of task times (T)
​Efficiency = ​ _____________________________________________________________ ​ [6.5]
Actual number of workstations (​N​ a ​ ) × Workstation cycle time (C) SOLVED PROBLEMS
LO6–2 SOLVED PROBLEM 1
Suppose we schedule shipments to our customers so that we expect each shipment to wait for two
days in finished goods inventory (in essence, we add two days to the expected ship date). We do
this to protect against system variability and ensure a high on-time delivery service. If we ship
approximately 2,000 units each day, how many units do we expect to have in finished goods inventory
by allowing this extra time? If the item is valued at $4.50 each, what is the expected value of
this inventory?
Solution
Using Little’s law, the expected finished goods inventory is
​Inventory = 2,000 units per day × 2 days = 4,000 units​
This would be valued at 4,000 units × $4.50 per unit = $18,000.