ch 7 supplement Flashcards
what does capacity have to do with?
activities and resources
capacity
the rate at which work (output) is withdrawn (produced) from the system (it is variable)
capacity (textbook definition)
the “throughput, or the number of units a facility can hold, receive, store or produce in a period of time
load
the volume of work (work in process) in the system (it is variable)
basic questions in capacity handling?
- what kind of capacity is needed?
- how much is needed?
- when is it needed?
capacity management
“function of establishing, measuring, monitoring and adjusting limits or levels of capacity in order to execute all manufacturing schedule…”
capacity management for medium to long term: purpose and techniques?
Purpose: to meet long term growth (or decline) in demand
techniques:
- additional equipment/machines (or selling equipment or machines 2. additional facilities (or closing facilities)
- improving/modifying capability
capacity management for short term; purpose and techniques?
purpose: to cope with short term fluctuations in demand (seasonal, randomness, etc.)
techniques: 1. overtime 2. extra shift 3. additional labor 4. temporary shutdown/layoff 5. subcontract 6. backorder 7 accumulate inventory
capacity measurement and evaluation: what to measure?
- design capacity
- effective capacity
- actual output
capacity measurement and evaluation: how to evaluate?
- utilization
2. efficiency
design capacity?
- theoretical, maximum output
- achievable only under ideal (perfect) condition
effective capacity?
maximum output achievable under practical, realistic conditions
will design capacity usually be more or less than effective capacity?
likely to be more!
what is the key factor in effective capacity?
unavoidable disruptions (problems) or normal/usual disruptions
possible causes of effective capacity (practical realistic conditions)
- schedule maintenance
- production planning
- product changeover
- tool change
- lack of demand
- age of machine, equipment
- types of inputs
actual output?
amount of output actually produced
likely to be less than effective capacity
Key factors that affect actually output?
avoidable disruptions (problems) or abnormal/unusual disruptions
possible causes in actual output?
- machine breakdown
- absenteeism
- poor planning
- input shortage
- quality problems
efficiency?
measures how closely a predetermined standard is acheived
=actual output/effective output
utilization?
measure how intensively a resource is being used
=actual output/design output
what does theory of constraints have to do with?
bottleneck operations
bottleneck?
- any resource whose capacity is less than the demand placed upon it
- it is the constraint that limits the throughput of the system
- can be a machine, person, tool, work center, department
non bottleneck?
- any resource whose capacity is greater than the demand placed upon it.
- contains idle capacity
capacity constrained resource?
-resource whose capacity is close to its capacity and could become a bottleneck if not scheduled properly
what is goldratt’s goal of a firm?
to make money
performance measurement: operational
throughput
the rate at which money is generated but the systme through sales
performance measurement: operational
inventory
all the money that the system has invested in purchasing things it intends to sell
performance measurement: operational
operating expenses
all the money that the system spends to turn inventory into throughput
productivity?
- all actions that bring a company closer to its goals
- traditional concept of productivity does not guarantee profitability
what issues must be addresses to improve productivity?
- has throughput increased?
- has inventor decreased?
- have operational expenses decreased?
Goldratt’s theory of constraints?
- Identify the system constraint
- Exploit the system constraint
- Subordinate everything else to the system constraint
- Elevate the system constraint
- Do not balance capacity, balance the flow
- Utilization of a non-bottleneck resource is not determined by its potential but by another constraint in the system.
- The capacity of a system depends on the capacity of the bottleneck.
- Increasing the capacity of a non-bottleneck facility does not improve the system throughput.
processing time at a station?
time needed to perform all the tasks at a station
bottleneck time?
time needed at the slowest station. that is, the longest station process time.
- also it is the time between two successive units coming off the line, therefore, it determines the system capacity.
throughput time
the minimum time needed to perform all the tasks at all the stations (with zero wait time)
Bottleneck in relation to the market demand?
a resource with the least capacity is called a bottleneck if its capacity is less than the market demand
Capacity constrained resource in relation to market demand?
a resource with the least capacity is called a ccr if its capacity is greater than the market demand
