system to avoid missing parts. a priority plan for components. calculates the time when components are needed.
Major Objectives of MRP 1
Determine Requirements -what to order, how much to order, when to order, and when to schedule delivery
Major Objectives of MRP 2
Keep Priorities Current -reorganize as required
Three MRP Inputs
Master Production Schedule Inventory Records Bills of Material
The Bill of Materials show?
all parts to make one of the items
How many part numbers are connected to one part?
one and only one part number
A part is defined by?
form, fit, and function. Any changes must obtain a new part number.
Four different types of BOM
Single Level Multi Level Indented Planning
Planning BOM simplifies what?
Forecasting Planning Master Scheduling
What does the planning BOM represent?
An average, not a buildable product.
Time it takes for an item to be ready for use
Identifying components by usage to get BOM requirments
placing requirements in their proper periods based on lead time.
orders in the MRP, but not released for processing
Low Level Code
Used if part is on more than one level of a BOM Lowest level on which a part resides on the BOM
-open orders released for processing -Defined receipt time
-Total of a component needed to meet requirements -PRIOR to accounting for existing inventory
Actual amount of a component needed to meet requirements AFTER accounting for existing periods
-Launch orders -reschedule orders as required -Reconcile errors -Solve critical material shortages -Coordinate with other functions
A set of priority planning techniques for planning component items below the end item level is called what?
material requirements planning
document that shows component part and number of parts needed to make one of an assembly or sub assembly is called?
Bill of Material
In the short run, capacity can be altered by any of the following except what?
Purchasing new equipment
A multi level bill of material reflects?
the way the product will be manufactured
What is responsible for determining the capacity required and with methods of making the capacity available?
what is responsible for capacity planning at the master production schedule level?
Rough-cut capacity planning
what is responsible for capacity planning at the material requirements planning level?
capacity requirements planning
A bill of material for an item must change when?
A component changes
The percentage of time the work center is active compared to the available time is called?
The objectives of Material Requirements Planning are to?
Keep priorities current Issue orders to purchasing and manufacturing determine requirements
Independent demand is not related to the demand for?
any other product
Is independent demand forecasted?
Is Dependent demand calculated?
The MRP must determine?
what to order, when to order, how much to order and when to schedule delivery.
What drives the MRP
Master Production Schedule
What drives Production activity control
A statement of which end items are to be produced
Master production schedule
What are planning factors?
order quantities, lead times, safety stock, and scrap
What is a where-used report?
A listing of all the parents in which a component is used
What is a pegging report?
shows only those parents for which there is an existing requirement. Shows the parent creating the demand for the components, the quantities needed, and when they are needed.
What is exploding
multiplying the requirements by the usage quantity and recording the appropriate requirements throughout the product tree.
Releasing an order means?
authorizing given to purchasing to buy the necessary material or to manufacturing to make the component
What is a scheduled receipt?
orders placed on manufacturing or on a vendor and represent a commitment to make or buy.
What is an open order?
Scheduled receipts on the MRP record, on the factory or a vendor and are the responsibility of purchasing and of PAC.
What is the planning horizon?
the number of periods in the record
Low level code
lowest level on which a part resides in all bills of material. Every part has only one low-level code
Planned orders are?
automatically scheduled and controlled by the computer.
the amount of work that can be done in a specified time period
capacity of a system or resource to produce a quantity of output in a given time period
capacity of a system or resource needed to produce a desired output in a given time period
amount of released and planned work assigned to a facility for a particular time period. The sum of all required capacities.
Capacity management is responsible for?
determining the capacity needed to achieve the priority plans as well as providing monitoring and controlling that capacity so the priority plan can be met
process of determining the resources required to meet the priority plan and the methods needed to make that capacity available
capacity requirements planning
process of determining in detail the amount of labor and machine resources needed to achieve the required production
What inputs can be found in open order files, MRPs, routing files, and work center files.
open shop orders, planned order releases, routing time standards, lead times, and work center capacities.
the time it normally takes to move material from one work station to another
time a job is at a work center after completion and before being moved
time a job waits at a work center before being handled.
sum of queue, set up , run , wait, and move times
what is standard time?
the time it would take a qualified operator working at a normal pace to do the job
how many levels does capacity need to be measured on?
Three. Machine or individual worker, work center, and plant.
Demonstrated capacity is figured from?
Calculated or rated capacity is based on?
available time, utilization, and efficiency. The product of these three
hours in the shift times the number of days in the week times available hours in the week
Formula for utilization
hours actually worked over available hours times 100
Formula for Efficiency
actual rate of production over standard rate of production times 100
What does the work center load report show?
future capacity requirements based on released and planned orders for each time period of the plan
start with the due date, and using lead times, work back to find the start date for each operation
Production activity and control is responsible for?
executing the master production schedule and the materials requirements plan
The material requirements plan authorizes PAC to:
release work orders to shop for manufacturing take control of work orders and make sure they are completed on time immediate detailed planning of the flow of orders through manufacturing manage day to day activity and provide necessary support
what are the activities of PAC
planning, implementation and control functions
Manufacturing processes can be organized into what three categories?
Flow manufacturing, Intermittent manufacturing, and Project manufacturing.
Flow manufacturing is concerned with what?
production of high volume standard products
routings are fixed work centers produce a limited range of similar products little build up in work in process inventory capacity is fixed by the line
Intermittent manufacturing is characterized by what?
many variations in product design, process requirements, and order quantities.
flow of work through the shop is varied and depends on design of product machinery and workers must be flexible enough to do a variety of work throughput times are generally long and WIP inventory is generally large capacity required depends on particular mix of products being built and is difficult to predict
Project manufacturing usually involves what?
the creation of one or a small number of units. ex: large shipbuilders
What are the four planning files?
item master file, product structure file, routing file, and work center master file
What information must PAC have to plan the manufacturing of materials?
what and how much to produce when the parts are needed what operations are required to make the product and how long what the available capacity of the various work centers are
Manufacturing lead time
the time normally required to produce an item in a typical lot quantity
What five elements are associated with Manufacturing Lead time?
Queue time, setup time, run time, wait time, and move time.
What is forward scheduling?
material procurement and operation scheduling starts when the order is received. Determines earliest completion dates
Last operation on the routing is scheduled first and previous operations are scheduled back from the last operation. Determines when an order should be started
What is infinite loading?
capacity is available when required
What is finite loading?
there is a defined limit to available capacity at any workstation
What is operation overlapping?
the next operation is allowed to begin before the entire lot is completed on the previous operation.
What is operation splitting?
order is split into two or more lots, and run on two or more machines at the same time
when is operation splitting practical?
setup time is low compared to run time a suitable work center is idle possible for an operator to run more than one machine at a time
What is a bottleneck?
workstations where the required capacity is greater than the available capacity. Bottlenecks control the throughput of all products processed by them.
What is a throughput?
total volume of production passing through a facility.
What is a time buffer?
an inventory place before each bottleneck. The time buffer is only as long as the time of expected delay.
Explain the drum in Drum-buffer-rope theory of constraints:
the drum is the pace of production. It represents the master schedule for the operation
Explain the buffer in Drum-buffer-rope theory of constraints:
a time buffer is established in front of the constraint to protect the constraint from disruptions
Explain the rope in Drum-buffer-rope theory of constraints:
the rope pulls production to the constraint for necessary processing
What is dispatching?
selecting and sequencing available jobs to be run at individual work centers. Priority control
What are the dispatching rules?
First come first serve, earliest job due date, earliest operation due date, and shortest process time
What is a critical ratio?
an index of the relative priority of an order to other orders at a work center.
What is Just in time manufacturing?
elimination of all waste and continuous improvement of productivity
What is considered waste?
anything other than the minimum amount of equipment, parts, space, material, and workers time absolutely necessary to add value to the product. No surplus
What does it mean to add value to a product?
Not adding cost. Increasing value without adding cost
Anything in the product development cycle that does not add value to the product is considered?
What is Poke-Yoke?
Fail safe. a way to remove faults at the first instance and making a process or product "foolproof" eliminating the need to rely on human experience and knowledge.
What are examples of poke yoke?
color coded parts templates counters special designs to allow only one fit for assembly
What are work cells?
workstations set up into miniature flow lines
What is process flexibility?
operators and machinery must be flexible, and the system must be configured to be changed over quickly from one product to another
What is machine flexibility?
having two, generally purposed machines, rather than one large special purpose machine
What is operator flexibility?
cross trained employees
What is uninterrupted flow?
material flowing smoothly from one operation to the next with no delays
what are the conditions needed to achieve uninterrupted flow?
uniform plant loading, a pull system, valid schedules, and linearity
what is uniform plant loading?
work done at each workstation should take about the same time.
What is partnering?
a long term commitment between two or more parties to achieve specific goals. Long term commitments, trust, and shared vision.
What is Kanban?
a card or ticket system. it often identifies the material to which it is attached
What is the information on the Kanban?
component part number and ID storage location container size work center (or supplier) of origin