S9-10 Capacity management and design of work system Flashcards
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
