Slovak University of Technology
Faculty of Material Science and Technology in Trnava
Planning in
production systems
MRP systems, MRP II, JIT
Material Requirements
Planning (MRP)
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MRP is a software based production planning
and inventory control system used to manage
manufacturing processes.
MRP is a calculation method geared toward
determining how much of which raw materials
are required and roughly when they should be
ordered to fulfill a set of product orders.
An MRP system is intended to
simultaneously meet three objectives:
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Ensure materials and products are available for
production and delivery to customers.
Maintain the lowest possible level of inventory.
Plan manufacturing activities, delivery schedules
and purchasing activities.
MRP generally consists of four steps:
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Bill of Materials Explosion - looking backward
from each product, determine which
intermediates and raw materials are required,
and in what quantities.
Netting - compare the above quantities against
current inventory.
Lot Sizing - determine how the needed
materials will be purchased or produced.
Start Date Determination - based on cycle time
information, determine when each order should
start production.
MRP system structure
Level of stock
Manufacturing Resource
Planning (MRP II)
orientation to production sources planning
 all information current, planning function
and production control integrate to one
logical chain cross material current,
 using continuous planning principles production process hierarchy support.
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Automated production
JIT (Just in Time)
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base idea – to optimized buffering stocks, which
help us to control supplies level; high supplies
level = small effectiveness,
more then supplies control – philosophy based
on continual deficit finding out and elimination on
all organizations levels.
JIT can see as:
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philosophy or full access to production
technics which are used for production system
design and operation
beam house control system - kanban = dispatch
note.
Objective of JIT
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Produce only the products the customer
wants.
Produce products only at the rate that the
customer wants them.
Produce with perfect quality
Produce with minimum lead time.
Produce products with only those features the
customer wants.
JIT Principles
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Create flow production
 one
piece flow
 machines in order of processes
 small and inexpensive equipment
 U cell layout, counter clockwise
 multi-process handling workers
 easy moving/standing operations
 standard operations defined
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Establish “TAKT” time
 rate
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at which the customer buys a product
Build Pull Product
 use
of kanban system
By decreasing supplies level we can
see hidden problems with two sources:
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extern – mistakes in delivery - customers
relations
intern – mistakes which reach as consequence
of quality deficient (material, production
engineering, production process organization,
work power, goods and technical documentation
design)
Solutions
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extern problems source
- build reliable stable delivers chain and reliable
customers
intern problems source
- complex quality increasing and monitoring –
TQM (Total Quality Management), active
production process quality assurance – SPC
(Statistical process control); it try to do ZD (zero
defects).
Aim of JIT
1.
2.
3.
Dodge to generality
Avoid the loss
Continuing improvement
1. Dodge to generality
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by the customers – fast change of claim and
preferences – although we need to retain
adequate costs, offer palette of goods and short
delivery dead-lines
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by the delivers – first step in production;
important in storage nonexistence to achieve
quality and right supplies or blank in right time
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by the workers
 absence
and another problems can be reduced with
right workers motivation, increasing the work claim,
work organization, higher work motley and easy
identification their portion to making good
 workers education - achieve decreasing level of
goods mistakes
 preference before making simply monotone
operations continuously by many workers have to be
making complex operations by one workers
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by claim of trade – is not anytime constant
2. Avoid the loss
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Overproduction
Idle time and production storages
Transporting
Mistakes
3. Continuing improvement
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effective increasing, looses elimination,
indemnity for reliability, making production
discipline etc. (unending process)
KAIZEN philosophy - sense to have trying
achieve production without mistakes for all
goods, because mistakes destroying continuous
production current (continuously increasing
process).
JIT Advantages
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Shortened lead time
Reduced time spent on non-process work
Reduced inventory
Better balance between different processes
Problem clarification
Limitations of JIT
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Preconditions to JIT
 trust
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must be present
labor/management
suppliers/consumers
 recognition
of processes
 familiarity with problem solving
 quality at the source
 agreement over value and waste
Limitations of JIT
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Right Settings
 applicable
in growth to maturity phases of
Product Life Cycle
 standard product
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Steinway and JIT
 standard/fixed
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pay-rate
problems with piece-rate scheme
Universal agreement that change needed