5. On Demand Management Flashcards
What does the Materials Requirement Planning consist?
The planing of materials requirements consists of the determination of:
What
How much
When
to order at every stage of the production process
Which are the Materials Planning approaches ( recordar las flechas!!?
- PULL: Based on STOCK
PULL is also called “Inventory Management”
Materials’ production/purchase orders are issued in order to replenish (“replace”) a stock
- PUSH: Based on Requirements
PUSH is also called “On demand Management”
Materials’ production/purchase orders are issued in order to satisfy a finished product requirement
What is the objective of the PULL (based on Stock) system?
and what is the information required by PULL system?
Having “always” the required product stored in the warehouse
order issuing criteria (re-order policy): the triggering mechanism:
example: Re-Order point (minimum level of inventory)
which are the Implicit hypotheses of the PULL:
- Demand stationary
- Demand as sum of “small” and independent demands
- Smoothed and uniform stock consumption
- Errors distributed normally
What is the objective of the PUSH (based on Requirement) system?
and what is the information required by PUSH system?
Calculating which, how many and when ,components, sub-assemblies, parts, raw materials, etc. are required to put a plan into operation, i.e. to ensure that the customers’ orders due dates (deadlines) are respected.
the objective lies in coordinating theproduction dates of components to manufacture finished products
Required information:
to know the master production schedule, the bills of materials (BOM) and to consider at the same time all the data referred to all the products and departments involved
which are the Implicit hypotheses of the PUSH:
*Requirements of components directly depend on a plan (e.g. the Master ^Production Schedule (MPS) )
What does the Materials Requirement Planning consist?
MRP: it represents the procedure that implements the data processing needed to manage inventories, so as the output of that procedure
MRPS being a procedure that consists of planning, on a time horizon in the future, the inventory level (i.e. the availability) of each item of the bill of materials
Material requirements planning is the second planning process that is associated with the production planning phase.
- The first objective of MRP is to plan the production of a company’s products in accordance with detailed customer demand data.
- The second objective is to determine the dependent demand for sub-assemblies, components, parts and raw materials.
Capacity Planning (black box) ?
inputs:
- MRP
- Routing file
Output:
-Material and Capacity plan
Capacity planning is run after MRP in order to verify production resource availability at a more detailed level than MPS (by considering the resources needed by all the materials, not only by finished products) and at a less detailed level than Scheduling (item sequence is not detailed at this moment, time buckets are more aggregate)
When is the Capacity Planning applied?
Capacity planning:
It is run after MRP in order to verify production resource availability at a more detailed level than MPS (by considering the resources needed by all the materials, not only by finished products) and at a less detailed level than Scheduling (item sequence is not detailed at this moment, time buckets are more aggregate)
Characteristics of MRP?
- Based on aggregate production plans -> push control
- Normally computer-based
- Centralised planning mechanism
- Most manufacturing companies use MRP
- Even those known for use of pull control systems
What is the Objective of Materials Requirement Planning (MRP)?
Identifying for each period of each component code the net requirement (i.e. the request) considering the availability existing at the initial period of individual items at different levels of the BOM of a finished product.
*Process
On the basis of net requirements, a plan of purchase orders and manufacturing orders is generated, with appropriate planning (i.e. mid-term schedule) and lot sizing
According to what approach does the MRP procedure operate?
MRP procedure operates accoridng to the 3S approach:
- Sum the requirements of the same component coming from different orders and referred to the same period
- Split the overall requirements per period of each component according to the lot-sizing policy
- Shift (backward) the lot-sized requirements along the time-related dimension (i.e. over time) according to the lead times reported in the bills of materials (to take into account the production routings)
NOTE: This leads to a plan of purchasing and manufacturing order proposals, which in turn generates
- falling to the lower level of the BoM which identifies a specific item. This is needed in order to be able to calculate the (gross total) requirements of the code
- gross requirements of lower-level components
BOM levels and related information ?
- item code
- relationships between items
- usage coefficient
- supplier scrap coefficient
- process scrap coefficient
- item lead time (supply/manufacturing lead time)
NOTE: DIstance among the various level in the BOM are related to the Lead Time (LT)
which are the MRP calculation problems leading to unfeasibility?
- Negative quantity in stock
* Order to be issued on the past.
What about the outpus of MRP (more in detail)?
Outputs:
- Recommends new manufacturing and purchase orders
- Recommends cancellation of existing orders
- Recommends adjustment of quantities / due date of existing orders
