CPIM Part 2, Module 6 - Detailed schedules Flashcards
What is the objective of scheduling?
Making the best use of manufacturing resources to meet delivery dates
A schedule in PAC exists out of five things, which five?
- The operations needed
- The sequence and routing of the operations
- The start and finish dates of each operation
- Time for each operation
- The work centers used in the operations
What is an operation set-back chart?
A graphical display of the bill of materials and lead-time information provided by the routing for each part
A variation of a gantt chart used in scheding is the control board, what is this?
A visual means of showing machine loading or project planning
There are two approaches to loading work centers schedules. Which two ways are these and what do they entail?
- Vertical: Each work center is scheduled independently. This approach keeps most work centers as fully loaded as possible
- Horizontal: Priority is on whole orders in order of overall priority. Does have lower capacity utilization.
What is de-expediting?
The reprioritizing of jobs to a lower level of activity. All extraordinary actions involving these jobs stop
What is block scheduling?
An operation scheduling technique where each operation is allowed a “block” of time
What is production activity control?
The function of routing and dispatching the work t be accomplished through the production facility and of performing supplier control
What is continuous process control?
The use of transducers (sensors) to monitor a process and make automatic changes in operations through the design of appropriate feedback control loops
What is a primary work center?
The work center where an operation on a manufactured part is normally scheduled to be performed
What are the four potential efficiencies to be gained from lot splitting and operation overlapping?
- Reduced total lead time
- Reduced work-in-process inventory
- Reduced floor space required
- Reduced size of transfer vehicles
What are the three potential downsides of operation overlapping / lot splitting?
- Increased cost of internal transport
- Disruption of work center schedule by expediting operations
- Lengthening of queue and lead time for other orders
What is the difference between a transfer batch and lot splitting?
A transfer batch is part of normal operations. Lot splitting is ad hoc
When is lot splitting not practical? (2)
- The setup time is high relative to run time
- A suitable work center or other additional capacity is not available
What is one less at a time?
A process of gradually reducing the lot size of the number of items in the manufacturing pipeline to expose, prioritize and eliminate waste
What is sequencing?
Determining the order in which a manufacturing facility is to process a number of different jobs in order to achieve certain objectives
What are priority rules?
The way in which orders are sequenced
What is order priority?
The scheduled due date to complete all the operations required for a specific order
What is dispatching?
The selecting and sequencing of available jobs to be run at individual work stations and the assignment of those jobs to workers
What are dispatching rules?
The logic used to assign priorities to jobs at a work center
Which type of scheduling is used for the critical operation and all subsequent operation? And which type is used for all operations before the critical operation?
- For the critical operation and all subsequent -> forward scheduling
- For the operations before the critical operation -> backward scheduling
What are the three ways that scheduling and PAC can be apporached?
- MRP - based
- TOC - based
- Lean - based
What is production reporting and status control?
A vehicle to provide feedback to the production schedule and allow for corrective action and maintenance of valid on-hand and on-order balances
What is the difference between batch and flow for PAC?
Batch processing systems need detailed feedback loops to keep queue and wait times reasonable. Flow systems only need flow control
What is flow control?
A specific production control system that is based primarily on setting production rates and feeding work into production to meet these planned rates, then monitoring and controlling production
What is input / output control?
A technique for capacity control where planned and actual inputs and planned and actual outputs of a work center are monitored
What is priority control?
The process of communicating start and completion dates to manufacturing departments in order to execute a plan
What are the four principles of job sequencing?
- Job sequencing rules determine order
- Sequencing commits one job at the time
- It loads jobs onto individual machines
- In a work center environment with variability, dispatching might not be able to determine next order untill prior job is done
What three things are included on a dispatch list?
- Total available load for a given shop date by work orders and part numbers
- Start and finish dates for each work order
- Total future load in standard hours
What are the seven objective of lean?
- Only make what customer wants
- Match production rate to demand rate
- Make product with perfect quality
- Make product with shortest possible lead time
- Only include features that are in demand
- Keep everything continually in motion with no waste
- Build worker learning and growth in each activity
How does the flow of information differ in a MRP system compared to a lean / conventional system?
In MRP from the front end, through the engine and to the back end. In lean from front end directly to back end
What is mixed-model production?
Making several different parts or products in varying lot sizes so that a factory produces close to the exact products that will be sold that day
What is Heijunka?
In just in time philosophy, an approach to level production throughout the supply chain to match the planned rate of end product sales. Abnormalities become immediately obvious
What are the four benefits of Heijunka / mixed-model production?
- Shorter manufacturing lead times
- Lower work-in process and finished goods inventory
- Avoidance of peaks and valleys in operator workload
- Smoother flow that enables standardized work
What is a pacemaker?
In lean, the resource that is schedules based on the customer demand rate for that specific value stream
What are the three advantages of only scheduling the pacemaker in lean?
- Work flows quickly in a cellular layout and is visible to workers and production controllers
- It requires only one production schedule
- Completion of an item needs to be reported only at the final assembly workstation or the store
What are the four things to organizations use TOC scheduling for?
- Identify and schedule constraints carefully
- Buffer constraint with inventory
- Maximize utilization at bottleneck
- Maximize system throughput
What is resource limited scheduling / resource-constraint scheduling?
The scheduling of activities so that predetermined resource availability pools are not exceeded
What is a resource limited schedule?
A project schedule with no early or late start or finish dates
What are control points?
Strategic locations in the logical product structure for a product or family that simplify planning, scheduling and control functions
What are the six steps of theory of constraints scheduling?
Step 1. Create network design
Step 2. Form a product network
Step 3. Assess capacity utilization by work center
Step 4. Schedule work center
Step 5a. Schedule bottleneck resources
Step 5b. Schedule non-bottleneck resources
What are the five steps of managing CCR’s?
- Identify
- Exploit
- Subordinate
- Elevate
- Repeat
What are the five steps involved in managing production activity control using the TOC?
- Scheduling the drum
- Exploiting the drum
- Material release, or rope
- proactive management of buffers
- Elevating the drum
What is process manufacturing?
Production that adds value by mixing, separating, forming and/or performing chemical reactions in batch or continuous mode
In which four ways is a continuous flow environment different?
- Divergent product structure
- Capacity planned first
- Continuous flow
- Perspectives on efficiency
What is a process train?
A representation of the flow of materials through a process industry’s manufacturing system that shows equipment and inventories.
Process units are combined into stages, the stages combined is process train
What is processor-dominated scheduling?
Schedules equipment before materials. It facilitates scheduling in economic run lengths and the use of low-cost production sequencing
What is material-dominated scheduling?
Schedules materials before processors… to facilitate the efficient use of materials
What are the four steps of processor dominated scheduling (PDS)?
- Prepare a finite capacity schedule, using finite forward scheduling and production capacity
- Check the projected inventory to see if it is within levels
- Revise the production schedule
- Schedule the raw materials to meet the capacity schedule
What are the four steps of material-dominated scheduling (MDS)?
- Create a time-phased record of material balances, with sort of MRP technique
- When inventory falls below the targeted level, add a lot to the schedule
- Compile a load profile for the unit
- Analyze and reconcile incompatibilities
What are the three approaches to building a process train?
- Forward-flow
- Reverse-flow
- Mixed-flow
What is forward-flow scheduling?
A process for building process train schedules that starts with the first stage and proceeds sequentially through the process structure until the last stage is scheduled
What is reverse-flow scheduling?
Start with the last stage and proceeds backwards through the process structure to create a process train
What is probable scheduling?
A variant of scheduling that considers slack time to increase or decrease the calculated lead time of an order
Is repetitive manufacturing MDS or PDS?
MDS
What is line balancing?
The balancing of the assignment of tasks to workstations in a manner that minimizes the number of workstations and minimizes the total amount of idle time at all stations for a given output level
What is the goal of line balancing?
A consistent flow of work through an assembly line at the planned line rate
What are the three steps to balance a manufacturing line?
- Establish takt time
- Set a target rate that is less than the takt time
- Support the process by identifying and eliminating all wastes and by improving the efficiency of the work cell layout
What is waste exchange?
Arrangement in which companies exchange their wastes for the benefit of both parties
What is budgeted capacity?
The volume/mix of throughput on which financial budgets were set and overhead/burden absorption rates established
What is productive capacity?
The maximum of the output capabilities of a resource
What are the five steps of CRP?
- Determine load on resources over period of time
- Simulate scheduling of load at work centers by period
- Create work center load reports
- Resolve load-capacity imbalances
- Prepare operating plan for execution
What are the three sources where information about load comes from?
- Open orders
- MRP planned orders
- Other sources
What is routing?
Information detailing the method of manufacture of a particular item. Includes operations to be performed, their sequence, the various work centers involved
What is rated / calculated capacity?
The expected output capability of a resource or system
There are three critical points in intermittent manufacturing. Which three are these?
- Transfer batch
- Lot sizing
- Reorder point
What are the four advantages of lot size reduction?
- Lower aggregate inventory thus less inventory cost
- Improved quality
- Improved manufacturing lead time with product mix flexibility
- Reducing run time through the use of small lot sizes as constraints
What are the four critical points in a flow manufacturing process?
- Identify and manage potential constraints
- Identify constraints on resources
- Minimize waste during the manufacturing and assembly process
- Optimize coupling and connectivity
What are balancing operations?
In repetitive just-in-time production it means matching output cycle times to final assembly or even the market
What are the four principles of push execution systems regarding batch processing?
- Creates time-phased schedules
- Releases and pushes orders to work centers
- Relies on production activity control to control quantities, routings and due dates
- Maximizes capacity utilization
What are the three principles of push execution systems regarding flow processing?
- Produces to rate-based schedule
- Moves material quickly and without interruption
- Creates finished goods inventory as necessary
What are the four key lean principles?
- Lean produces only to customer order
- It levels demand to smooth workflow
- It uses visual signals to link processes with demand
- It maximizes the flexibility of people and machinery
