ROBOTICS An Introduction

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Production Planning, Scheduling and
Control by Ed Red
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INMASS/MRP Modules MRP (Materials Requirements
Planning) Inventory Control Bill of
Materials Job Cost/Work in Process
Purchasing Sales Order Entry General Ledger
Accounts Receivable Accounts Payable
Payroll Shop Floor Control Bar Coding
Forecasting StarShip Shipping Module
Customer Histories Vendor Histories Each
module includes built-in reports and the INQUIRE
Report Generator allows you to create customized
reports and forms.

• Objectives
• To review modern production control
  technologies - MRP - JIT - Shop floor
  control - Inventory control
• To study costs and complexity of manufacturing
  systems
• To consider application conditions (student
  presentations)
• To test understanding of the material presented

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• Production planning, scheduling, and control
• Objective ...managing the details of what and
  how many products to produce and when, and
  obtaining the raw materials, parts, and resources
  to produce those products. (Groover)
• Four activities of production planning
• Aggregate production planning enterprise level
  planning for product lines and output levels.
• Master production planning - Breaking down the
  enterprise product plans into a master production
  schedule (MPS) for producing models within each
  product line.
• Material requirements planning (MRP) computer
  plan to convert MPS into a schedule of raw
  materials and parts used in the end products.
• Capacity planning determine labor and equipment
  needed to achieve master schedule.

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• Production planning, scheduling, and control
• Four production activities
• Shop floor control compare progress and status
  of production orders to production plans (MPS)
  and release production orders to the factory as
  needed.
• Inventory control - techniques for managing
  inventory.
• Manufacturing resource planning (MRP II)
  integrates MRP, capacity planning, shop floor
  control and other production functions.
• Just-in-time production systems (JIT)
  scheduling discipline in which materials and
  parts are delivered to the next production
  station (cell, FMS, etc.) just prior to their
  being used.

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• Shop floor control
• Three phases
• Order release soft (modern factory) and/or hard
  (manual factory) documentation needed to process
  a production order through the factory.
• Order scheduling - assigns production orders to
  the plant work centers...often referred to as a
  dispatch list.
• Order progress monitors the status of the
  orders in the plant, WIP (work-in-progress), and
  any other characteristics which can be used to
  measure progress and performance. May depend on a
  factory data collection system for information.

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• Shop floor control order release
• Documentation consists of
• Route sheet documents process plan for part to
  be produced.
• Material requisition - draw necessary materials
  from inventory.
• Job cards report labor required to produce part
  .
• Move tickets authorize parts to be transported
  between work centers.
• Parts list needed if the product requires an
  assembly of component parts

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• Shop floor control order scheduling
• Concerned with machine loading and job
  sequencing
• Machine loading allocating orders to work
  centers.
• Job sequencing - determining the order in which
  parts are processed through a given work center.
• Priority control maintains the proper priority
  for the production orders under the dispatching
  rules first-come-first-serve jobs are
  processed in order received earliest due date
  orders with earlier due dates have higher
  priority shortest processing time those
  finished faster have higher priority least slack
  time jobs with least slack time have higher
  priority critical ratio ratio of time
  remaining until due date divided by remaining
  
  process time. Orders with lowest
  ratio given higher priority.

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• Shop floor control order progress
• Concerned with progress reports
• Work order status reports status of production
  orders.
• Progress reports - report performance of shop
  during a time period, including orders completed,
  orders not completed, etc.
• Exception reports deviations from the
  production schedule and other exceptions.

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Shop floor control software
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Shop floor control software
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Shop floor control software
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• Inventory control
• Concerned with minimizing cost of holding
  inventory and maximizing customer service. These
  seem to conflict.
• Types of inventory
• Raw materials
• WIP
• Components
• Finished products

• Inventory costs
• Investment costs
• Storage costs
• Possible obsolescence costs
• Spoilage costs

• Inventory as a function of demand
• Independent demand (order point inventory method)
  demand for a product is unrelated to demand for
  other items (e.g., final product and spare parts)
• Dependent demand (MRP method) demand for an
  item is directly related to demand for some other
  item (e.g., product component, raw material)

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• WIP inventory costs
• Concerned with minimizing costs of processing
  materials before the final product can be
  released to the consumer.
• Costs considerations
• Production consists of a series of operations
• Time is consumed in each operation (and time is
  cost)
• Time and costs are consumed between each
  operation (e.g., material handling with no value
  added)
• WIP represents money expended for material and
  processing, still considered inventory because
  goods are not yet delivered to the customer!

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WIP inventory cost analysis - terms
Cm material cost Tp average production time
(setup plus operation time) Tpk production time
for process k (setup plus operation time) Tsu
average machine setup time for a batch
process Tno average non-operation time for a
machine Tc average operation cycle time for a
machine Ta average operation cycle time for a
machine including setup and non-operation
times Q average batch quantity for batches of
parts being processed
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WIP inventory cost analysis - terms
Co production costs rate Cok operational
costs for process k Cno average non-operational
costs (material handling, inspection, etc.) Cnok
non-operational costs for process k (material
handling, inspection, etc.) Csu setup costs
and/or ordering costs for an order(/setup or
/order)
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WIP inventory cost analysis - terms
Cpc part costs accumulated through all
processes, inspections, and material
handling no total number of operations/processes
MLT manufacturing lead time (the longer the
MLT, the greater the
WIP) t time of part
spent in process sequence h holding cost
rate Ch holding costs HCpc holding cost per
part TCpc total cost per part including WIP
carrying costs
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WIP inventory cost analysis graphs
Linear approximation of part costs as function of
time in factory
Part/product costs as function of time in factory
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WIP inventory cost analysis graphs
Linear approximation with WIP holding costs
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WIP inventory cost analysis
Equations avg batch operation cycle time Ta
Tsu Q Tc Tno MLT (batch process) MLT no
Ta cost per operation Cok Co Tpk Cnok
total cost after all operations Cpc Cm
Sk Cok ( k 1, .. no) total cost
after all operations Cpc Cm no ( Co Tp Cno
) assuming Tpk and Cnok are the same for each
operation
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WIP inventory cost analysis
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WIP inventory example
Problem Inventory Holding Cost for WIP During
Manufacturing
The cost of the raw material for a certain part
is 100. The part is processed through 20
processing steps in the plant, and the
manufacturing lead time is 15 wk. The production
time per processing step is 0.8 hr, and the
machine and labor rate is 25.00/hr. Inspection,
material handling, and other related costs
average to 10 per processing step by the time
the part is finished. The interest rate used by
the company i 20, and the storage rate s
13. Determine the cost per part and the holding
cost.
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WIP inventory example
Problem Inventory Holding Cost for WIP During
Manufacturing
Solution The material cost, operation costs,
and non-operation costs are from Cpc Cm Cp
Cm no ( Co Tp Cno ) 100 20(25.00/hr
x .8 hr 10) 100 600
700/pc Next, determine the holding cost rate h
201333. Expressing this as a weekly rate,
h (33)/(52 wk) 0.6346 /wk 0.006346/wk.
The holding cost/pc HCpc (Cm Cp/2) h
(MLT) (100 600/2)(.006346)(15 wk)
38.08/pc This gives a total cost of TCpc Cm
Cp HCpc 700.00 38.08 738.08/pc
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JIT production systems
Problem - to reduce inventory costs by delivering
the correct components to the manufacturing
operation exactly when needed, minimizing WIP and
MLT. JIT is the solution.
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JIT production systems
JIT must have Pull system of production control
Kanban (card) system is often used to implement
a pull system. The cards authorize 1) parts
production (P-kanban) and 2) parts transport
(T-kanban). A P-kanban authorizes an upstream
process to produce only the parts that will fill
a batch container, no more. A T-kanban authorizes
the transport of the batch to a downstream
station. These procedures are duplicated in
sequence, eliminating much of the paperwork, but
uses more labor, although said to promote
teamwork among stations.
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JIT kanban examples
The withdrawal Kanban shows that the preceding
process which makes this part is forging, and the
person carrying this Kanban from the subsequent
process must go to position B-2 of the forging
department to withdraw drive pinions. Each box of
drive pinions contains 20 units and the shape of
the box is B. This Kanban is the 4th of 8 issued.
The item back number is an abbreviation of the
item.
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JIT kanban examples
The production ordering Kanban to the right shows
that the machining process SB-8 must produce the
crankshaft for the car type SX50BC-150. The
crankshaft produced should be placed at store
F26-18. The production-ordering Kanban is often
called an in-process Kanban or simply a
production Kanban.
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JIT production systems
JIT must have Small batch sizes and reduced
setup times uses improvements in fixturing,
part handling, group technology, automation, etc.
to minimize batch size and setup.
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JIT production systems
JIT must have Stable and reliable production
operations also includes a stable supplier
base, good relationships, committed workforce,
defect free materials and components (in other
words, you must have your act together from A
Z)
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Lean versus agile production systems
Lean production Agile
manufacturing Enhancement of mass
production Emphasis on mass customization Flexible
production for product variety Flexibility for
customized products Focus on factory
operations Scope is enterprise wide Emphasis on
supplier management Formation of virtual
enterprises Emphasis on efficient use of
resources Thriving environment with continuous
change Relies on smooth production
schedule Responsive to change
Minimize change! Embrace
change!
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Production planning, scheduling and control
What have we learned?