Lecture two (2) Flashcards
Production process mapping
Developing a high-level map of a supply chain process
Useful to understand how material flows and where inventory is held
First step in analyzing the flow of material through a production process
Inventory measures
Total average value of inventory - The total investment in inventory at the firm
-Raw materials
-Work in process
-Finished goods
Inventory turn
An efficiency measure where the cost of goods sold is divided by the total average value of inventory
The amount of time that passes from the day an item is purchased by a company until its sold
Days-of-supply
A measure of the number of days of a supply of an item (the inverse of inventory turn scaled to days)
It measures how long inventory on hand will last. For example a manufacturer consumes 100 units a day of a certain component in manufacturing and has 800 units on hand. it has an eight day supply
Littles law
Additionally definitions for Inventory, Throughput and Flow time
The flow of items through a production process can be described using littles law
Inventory = Throughput rate x Flow time
Inventory: Materials held by the firm for future use
Throughput: Long term average rate that items are flowing through the process (the amount of a product or service that a company can produce and deliver to a client within a specified time period)
Flow time: time for a single unit to completely flow through the entire process (The full interval between the beginning and end of a particular process)
Workcenter layout (production process design)
Most common approach to developing this type of layout is to arrange workcenters in a way that optimizes the movement of materials
Optimal placement often means placing workcenters with high levels of interdepartmental traffic adjacent to each other
Sometimes is referred to as job shop and is focused on a particular type of operation
Competes on quality, speed of delivery, customization, innovation, not economies of scale
Project layout (production process design)
The product remains in a fixed location
Labor, material and equipment are moved to the product
A project layout may be developed by arranging materials according to their assembly priority
Manufacturing cell layout (production process design
A dedicated area where products that are similar in process requirements are produced
Cells are designed to performa aspecific set of processes
Dedicated to a limited range of products, typically at lower volumes
Manufacturing cell developments (Manufacturing cell layout)
- Group parts into families that follow a common sequence of steps
- Identify dominant flow patterns for each part family
- Machines and the associated processes are physically regrouped into cells
Assembly line (production system design)
Work processes are arranged according to the progressive steps by which the product is made
Area where an item is produces through a fixed sequence of workstations, designed to achieve a specific production rate
Like producing a car in a factory
Continuous process (production system design)
Similar to assembly line, follows a pre-determined sequence of steps, but flow is continuous
Usually highly automated structures
May constitute an “integrated” machine operating 24 hours a day
Production matrix
X - axis: Production volume (low -> high)
Y - axis: Product standardization (high standardization -> low standardization)
Bottom left would be inefficient (low volume but highly standardized)
Top right would be mass customization (highly customized but also high product volume)
Top left is project layout; highly customized and low volume
Workcenter is also top left less customized but slightly higher volume
Very big in the middle is manufacturing cell med. low. to med. high. on every aspect
To the right slightly overlapping is assembly line with med to high broduct volume but med to high standardization
And with high volume and high standardization at the bottom right is continuous process
Workstation cycle time
A uniform time interval in which a moving conveyor passes a series of workstations
Also the time between successive units coming off the line
Assembly-line balancing
Assigning all tasks to a series of workstations so that the required cycle time is met and idle time is minimized
Precedence relationship
The order in which tasks must be performed in an assembly process
