S + 8: Process Thinking and Operations Performance Flashcards
Process
Central role of all management functions
Main quality of a process
Should run well regardless of the people in charge
Process componants (5)
Evenets Tasks Decisions Inputs (5M's) Outpouts - Products / services
Typical process characteristics (4 V’s)
Volume
Variety - Amount of flexibility built into the process to meet fluctuations in demand
Visibility - The extent to which customers have sight of the operations process
Variations - Changes in demand patterns over a pre-defined time period (icecream sales)
Types of operating processes (5)
1) One-off - Low volume, high variety. Specialised skil set (spacecraft launch)
2) Jobbing process - High variey, low individual volume although some process may be repeated. (same machine could make numerous products)
3) Batch process - Moderate volume, moderate variety. (Drug companies making one drug, cleaning the factory then making another, hence in batches)
4) Mass process - High volume, low variety (sock company)
5) Continous / flow process - High volume, low variety on an endless basis (sugar company)
3 Major processes representations
1) Circulation plan (a campus map)
2) Process flow diagram (flow chart sequentially depicting the individual stages. parallel or series)
3) Piping and Instrumentation diagram (schematic representation of the piping and relate componants of a physical process flow)
Typical process parameters (5)
1) Throughput - time it takes a product to move through a process
2) Turnover - rate at which operation converts investment into returns. JIT reduces waiting time. Less time raw materials spend in the plant the higher the turnover.
3) Cycle Time - average time between units of outputs for a process
4) Downtime - fraction of time a process is unavailable for production
5) Rework Rate - number of items that require rework / correction
Effectiveness vs Efficiency
Effectiveness = Doing the thing right
Efficiency = Doing the right thing
Effectiveness metrics (4)
1) Financial
2) Conversion rates
3) Customer satisfaction
4) Usability
Efficiency metrics (5)
1) Throughout
2) Transaction speed
3) Availability
4) Response time
5) Information accuracy
Forecasting
Process for predicting trends. can use forecasts to arrange inputs (5M’s)
Why forecast? (5)
1) Waste elimination - too many people / materials wastes money
2) Workload smoothing - Too many people wastes money
3) Improve spares + raw material turnover - dont want raw material being stored for a long time
4) Prevent unplanned downtime - need to know when downstime will be
5) Improve response rate to customer demands - want to be ready to provide product / service when customer demand increases otherwise lose out on sales
Forecasting techniques (3)
1) Qualitative
2) Quantitative
3) Casual models
Economic Order Quanity (EOQ)
Point at which total annual cost (TAC) is lowest
Potential forecasting graphs (4)
1) Straight line - constant growth rate
2) Moving average - repeated forecasts
3) Simple linear regression - one independant with one depenant
4) Multiple linear regression - more than one independant variable with one dependant
Reliability
The probabiluty of an item performing its specified function under specified conditions for a specified time
Mean Time Between Failure (MTBF)
A failure rate whereby the likelihood of a failure event is constant with time
MTBF Formula
( Total Operating Time x Number of equipment ) / ( Number of observed failures )
Mean Time to Failure (MTTF) or MTBF units
hours / failure
MTTF Equation
Same as MTBF but divided by number of machines under test (instead of number of failures)
Series RBD reliability equation
Rsystem = Ra x Rb
Parallel RBD reliability equation
Rsystem = 1 - [ (1-Ra) x (1-Rb) ]
Series RBD
Failure of either A or B fails whole system. Most unreliable
Parallel RBD
System only fails if A and B fail together
Combination of both. How to calculate?
Times one in series (Ra) by the parallel system (which has been calculated first)
Minimum path set (MPS)
Shortest path to success (resolved horizontally)
Minimum cut set (MCS)
Shortest route to failure (resolved vertically)
Maintainability
Probability that a maintenance task will be completed (under specified conditions). Measured using MTTR.
Mean Time to Repair (MTTR) equation
1 / Repair rate
