S9-10 Capacity management and design of work system Flashcards
(10 cards)
Describe the relationship between design capacity, effective capacity and actual output. What are the two ratios associated to these concepts?
Design capacity -> Effective capacity -> Actual output
Gap between design capacity and effective capacity: planned and controlled
Gap between effective capacity and actual output: unplanned and uncontrolled
Efficiency = Actual output / effective capacity
Utilization = Actual output / design capacity
What are the determining factors of capacity?
- Time for transforming inputs into outputs
- Amount of resources (human, machines, or space)
- Potential stoppages or slowdowns
- Hours worked
- Range of product and batch sizes
- Transformation process
- Learning curve effect
What is the learning curve effect? How do you compute it?
Relatively permanent change in behaviour due to repetition and rewards (we will accomplish a task faster the second time than the first)
Learning curve:
T1
T2 = T1 x p
T4 = T2 x p
etc. (bonds of 2)
What are the objectives of the design of work system? What is the main principle to remember?
Objective: Eliminate any useless operation and develop the most efficient, fastest, and safest method to execute a task, in order to increase productivity:
- Eliminate unnecessary movement
- Combine activities
- Reduce fatigue
- Improve facility layouts
- Improve the design of machinery and tools used
Principle: Increase productivity by working more efficiently.
What is cycle time? How do you compute it?
Interval of time between the exit of two consecutive units at a stage, or at the end of a process.
Cycle time = Standard time / # of resources assigned to the task
What is the rate? How do you compute it?
Number of units produced per unit of time, generally in hours.
Rate = 60min / cycle time
What is the difference between a sequential process and a parallel process?
Sequential process: Process where a work is divided in a series of specific tasks. Employees are assigned to specific parts of the process. team>
Parallel process: Process where each employee realizes all tasks, independently for the others.
Ex.: employee 1 does task a.b.c, employee 2 does task a.b.c, etc. individual>
What is the production rate of a process? How do you compute it?
Number of units produced during one unit time (ex.: 1 hour) by the process.
In a sequential process: The rate of the process is the rate of the bottleneck.
In a parallel process: The rate of the process is equal to the sum of rates of each working station (performing all the tasks) of the process.
Calculation methodology:
1. Sum of ST for each workstation
2. Unit rate = 60min / sum of ST
3. Total rate = #employee x unit rate
How do you compute the utilization rate of a workstation?
In a sequential process:
Utilization rate of the workstation of a stage = production rate of the bottleneck / production rate of this stage
or
cycle time of the stage/cycle time of the bottleneck
What is the utilization rate of a worker? How do you compute it?
When a part of an operation is done by a machine, the utilization rate of a worker is the proportion of time worked by the employee vs the total ST of the operation.
(Total standard time - Machine time) / Total standard time
