Lean and Six Sigma Metrics/ Introduction to Measure Flashcards
Pull System
Customer Requirements > On Demand > Adaptation
upsteam
Push System
Expected demand > mass manufacturing > economies of scale
downstream
Measure Process
- Determine which data to capture
- Develop a data collection plan for the process and collect data
- Establish baseline performance
- Compare to customer results to determine the shortfall
Mean based Measurement vs Variance Based Measurement
Customers feel variance
Look at distribution graphs on the 4th slides and youll get what am saying
Common causes(Noise) of variation
- present in every process and is produced by the process itself
- it can be mitigated but requires a fundamental change in the process
Special causes (signals) of variation
exists in most operations/processes
- caused by unique distubances or a series of them
- can be removed/lessened by basic process control and monitoring
If only common causes of variation are present…
the output of a process forms a probably and stable distribution over time
if special cause of variation are present…
the output of a process is not stable over time
Data Collection Plan
Decide what data to collect
- develop operational definitions
- determine the sampling plan
- collecting data
Collecting data
determine which metrics
-identify continuous variable avoid discrete as continuous conveys more info
continuous data traits
CONTINUOUS - inference can be made with few data points
- Smaller samples there less expensice
- High sensitivity
- Variety of analysis options that can off insight into the sources of variation
Discrete data traits
More Data points required
- larger samples
- low sensitivity
- limited options for analysis
Operational Definition of Measurement
Unless you are measuring everything, an operational definition must be set to ensure consistancy
Lean metrics
value added/non value added
throughput yield
work in process
takt time
six sigma
defects per million opportunities
sigma quality level
Throughput yield
number of acceptable units at the end of the end of a process divided by the number of starting units excluding scrap and rework
TPY= no parts right first time/ total no of parts
WIP work in process
refers to all materials and partly finished products that are at various stages of the production process
Lead time
amount of work in process/average completion rate
takt time
time which reflects the rate at which customers buy one unit. helps define how fast work must go to keep up with demand
DPMO calculation
U= units CTQ = critical to quality D = Defect O = Opportunity
Total opportunities (TOP) = Ux0 Defect per unit (DPU) DPU = D/U Defects per unit opportunity (DPO) DPO =DPU/O DPMO = DPO*10^6
