Materials%20Handling%20%20%20%20%20%20%20%20%20%20Ed%20Red

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Materials Handling Ed Red
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Objectives

• To review modern technologies for material
  handling - Part handling - AGVs - AS/RS -
  conveyors
• To consider application conditions (student
  presentations)
• To introduce assessment criteria
• To test understanding of the material presented

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Material handling principles
( from Groover )

• Principle 1 - PLANNING PRINCIPLE All material
  handling should be the result of a deliberate
  plan where the needs, performance objectives, and
  functional specification of the proposed methods
  are completely defined at the outset.
• The plan should be developed in consultation
  between the planner(s) and all who will use and
  benefit from the equipment to be employed.
• Success in planning large-scale material handling
  projects generally requires a team approach
  involving suppliers, consultants when
  appropriate, and end user specialists from
  management, engineering, computer and information
  systems, finance, and operations.
• The plan should promote concurrent engineering of
  product, process design, process layout, and
  material handling methods as opposed to
  independent and sequential design practices.
• The plan should reflect the strategic objectives
  of the organization as well as the more immediate
  needs.

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Material handling principles
( from Groover )

• Principle 2 - STANDARDIZATlON PRINCIPLE Material
  handling methods, equipment, controls, and
  software should be standardized within the limits
  of achieving overall performance objectives and
  without sacrificing needed flexibility
  modularity, and throughput.
• Standardization means less variety and
  customization in the methods and equipment
  employed.
• Standardization applies to sizes of containers
  and other load forming components as well as
  operating procedures and equipment.
• The planner should select methods and equipment
  that can perform a variety of tasks under a
  variety of operating conditions and in
  anticipation of changing future requirements.
• Standardization, flexibility, and modularity must
  not be incompatible.

5
Material handling principles
( from Groover )

• Principle 3 - WORK PRINCIPLE Material handling
  work should be minimized without sacrificing
  productivity or the level of service required of
  the operation.
• The measure of material handling work is flow
  rate (volume, weight, or count per unit of time)
  multiplied by distance moved.
• Consider each pickup and set-down, or placing
  material in and out of storage, as distinct moves
  and components of the distance moved.
• Simplifying processes by reducing, combining,
  shortening, or eliminating unnecessary moves will
  reduce work.
• Where possible, gravity should be used to move
  materials or to assist in their movement while
  respecting consideration of safety and the
  potential for product damage.

6
Material handling principles
( from Groover )

• Principle 3 - WORK PRINCIPLE Material handling
  work should be minimized without sacrificing
  productivity or the level of service required of
  the operation.
• The Work Principle applies universally, from
  mechanized material handling in a factory to
  over-the-road trucking.
• The Work Principle is implemented best by
  appropriate layout planning locating the
  production equipment into a physical arrangement
  corresponding to the flow of work. This
  arrangement tends to minimize the distances that
  must be traveled by the materials being processed.

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Material handling principles
( from Groover )

• Principle 4 - ERGONOMIC PRINCIPLE Human
  capabilities and limitations must be recognized
  and respected in the design of material handling
  tasks and equipment to ensure safe and effective
  operations.
• Ergonomics is the science that seeks to adapt
  work or working conditions to suit the abilities
  of the worker.
• The material handling workplace and the equipment
  must be designed so they are safe for people.
• The ergonomic principle embraces both physical
  and mental tasks.
• Equipment should be selected that eliminates
  repetitive and strenuous manual labor and that
  effectively interacts with human operators and
  users.

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Material handling principles
( from Groover )

• Principle 5 - UNIT LOAD PRINCIPLE Unit loads
  shall be appropriately sized and configured in a
  way which achieves the material flow and
  inventory objectives at each stage in the supply
  chain.
• A unit load is one that can be stored or moved as
  a single entity at one time, such as a pallet,
  container, or tote, regardless of the number of
  individual items that make up the load.
• Less effort and work are required to collect and
  move many individual items as a single load than
  to move many items one at a time.
• Large unit loads are common in both pre- and
  post-manufacturing in the form of raw materials
  and finished goods.
• Smaller unit loads are consistent with
  manufacturing strategies that embrace operating
  objectives such as flexibility, continuous flow
  and just-in-time delivery. Smaller unit loads (as
  few as one item) yield less in-process inventory
  and shorter item throughput times.

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Material handling principles
( from Groover )

• Principle 6 - SPACE UTILIZATION PRINCIPLE
  Effective and efficient use must be made of all
  available space.
• Space in material handling is three-dimensional
  and therefore is counted as cubic space.
• In storage areas, the objective of maximizing
  storage density must be balanced against
  accessibility and selectivity.
• When transporting loads within a facility, the
  use of overhead space should be considered as an
  option. Use of overhead material handling systems
  saves valuable floor space for productive
  purposes.

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Material handling principles
( from Groover )

• Principle 7 - SYSTEM PRINCIPLE Material movement
  and storage activities should be fully integrated
  to form a coordinated, operational system that
  spans receiving, inspection, storage, production,
  assembly, packaging, unitizing, order selection,
  shipping, transportation, and the handling of
  returns.
• Systems integration should encompass the entire
  supply chain, including reverse logistics. It
  should include suppliers, manufacturers,
  distributors, and customers.
• Inventory levels should be minimized at all
  stages of production and distribution while
  respecting considerations of process variability
  and customer service.
• Information flow and physical material flow
  should be integrated and treated as concurrent
  activities.
• Methods should be provided for easily identifying
  materials and products, for determining their
  location and status within facilities and within
  the supply chain, and for controlling their
  movement.

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Material handling principles
( from Groover )

• Principle 8 - AUTOMATION PRINCIPLE Material
  handling operations should be mechanized and/or
  automated where feasible to improve operational
  efficiency, increase responsiveness, improve
  consistency and predictability, decrease
  operating costs, and eliminate repetitive or
  potentially unsafe manual labor.
• In any project in which automation is being
  considered, pre-existing processes and methods
  should be simplified and/or re-engineered before
  any efforts to install mechanized or automated
  systems. Such analysis may lead to elimination of
  unnecessary steps in the method. If the method
  can be sufficiently simplified, it may not be
  necessary to automate the process.
• Items that are expected to be handled
  automatically must have standard shapes and/or
  features that permit mechanized and/or automated
  handling.
• Interface issues are critical to successful
  automation, including equipment-to-equipment,
  equipment-to-load, equipment-to-operator, and
  in-control communications.
• Computerized material handling systems should be
  considered where appropriate for effective
  integration of material flow and information
  management.

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Material handling principles
( from Groover )

• Principle 9 - ENVIRONMENTAL PRINCIPLE
  Environmental impact and energy consumption
  should be considered as criteria when designing
  or selecting alternative equipment and material
  handling systems.
• Environmental consciousness stems from a desire
  not to waste natural resources and to predict and
  eliminate the possible negative effects of our
  daily actions on the environment.
• Containers, pallets, and other products used to
  form and protect unit loads should be designed
  for reusability when possible and/or
  biodegradability after disposal.
• Materials specified as hazardous have special
  needs with regard to spill protection,
  combustibility, and other risks.

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Material handling principles
( from Groover )

• Principle 10 - LIFE CYCLE COST PRINCIPLE A
  thorough economic analysis should account for the
  entire life cycle of all material handling
  equipment and resulting systems.
• Life cycle costs include all cash flows that
  occur between the time the first dollar is spent
  to plan a new material handling method or piece
  of equipment until that method and/or equipment
  is totally replaced.
• Life cycle costs include capital investment,
  installation, setup and equipment programming,
  training, system testing and acceptance,
  operating (labor, utilities, etc.), maintenance
  and repair, reuse value, and ultimate disposal.
• A plan for preventive and predictive maintenance
  should be prepared for the equipment, and the
  estimated cost of maintenance and spare parts
  should be included in the economic analysis.

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Material handling principles
( from Groover )

• Principle 10 - LIFE CYCLE COST PRINCIPLE A
  thorough economic analysis should account for the
  entire life cycle of all material handling
  equipment and resulting systems.
• A long-range plan for replacement of the
  equipment when it becomes obsolete should be
  prepared.
• Although measurable cost is a primary factor, it
  is certainly not the only factor in selecting
  among alternatives. Other factors of a strategic
  nature to the organization and that form the
  basis for competition in the market place should
  be considered and quantified whenever possible.

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Automated Guided Vehicle (AGV)
Definition - An AGV is an independently operated
vehicle that moves material along defined paths
between defined delivery points or stations.
Typically the paths are defined by either using
wires embedded in the floor or reflecting paint
strips on the floor.
Some of the more advanced technologies use laser
triangulation or inertial guidance systems
on-board the vehicles, with distributed
calibration stations for position updating.
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AGV classification
Driverless trains - AGV is a towing vehicle used
to tow one or more trailers forming a train
between stations. Pallet trucks - Used to move
palletized loads along predetermined routes.
Typically, personnel will steer the AGV to the
pallet, acquire the pallet, then steer it to the
guide-path where the automated guidance system
will then move it to its destination. In a sense,
it can be thought of as an automated
forklift. Unit load carriers - Move unit loads
from from one station to another station. A unit
load is a collection of items that is delivered
repetitively as a unit.
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AGV applications
Driverless train operations - Movement of large
material quantity over large distances (between
buildings, warehouses). Storage/distribution
systems - Uses unit load carriers and pallet
trucks to transfer material between stations,
sometimes interfacing with other automated
systems such as an AS/RS (Automated Storage and
Retrieval System). Works well in assembly
operations where the unit loads (or kits) can be
transferred from a central storage area to
assembly sites. Assembly line operations - AGVs
become part of the assembly operation by
transferring material along an assembly line
(such as moving an engine block between
operational stations) Flexible manufacturing
systems (FMS) - AGVs are used to transfer parts,
materials and tooling between the FMS process
stations. Miscellaneous applications -
Non-manufacturing applications include the
handling of sensitive waste, transportation of
material at hospitals, mail transportation.
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AGV guidance and control
Guidance and control functions Vehicle guidance
- on-board control system to move the vehicle
along pre-defined paths by a feedback loop
between the control system and the guide wire (or
paint). More modern systems use inertial guidance
to move the AGV between calibration stations. In
situations where the guide wire or paint is
discontinuous, the control system uses dead
reckoning to transition these points.   Traffic
control - collision avoidance between multiple
AGVs. The control system is designed with
blocking algorithms that use a combination of
on-board vehicle sensing and zone
control.   Systems management - programming
interfaces and algorithms for moving AGVs
between stations, and for scheduling the movement
of multiple AGVs.
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AGV material handling analysis
Terms vc - AGV average speed (c
conveyor, carrier, cart, etc.) ve - AGV empty
speed Th - load handling time Ld - destination
distance Le - empty move distance Tf - traffic
factor (lt 1) Eh - handling system efficiency A
- proportion of time vehicle is operational AT-
available time in min/hr/veh E - worker
efficiency
Rdv - rate of deliveries per vehicle nc - number
of carriers required Rf - specified flow rate of
system (del/hr) Tc - delivery cycle time
(min/del) TL - time to load at load station
(min) TU - time to unload at load station
(min) WL - workload (total work in min per hour)
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AGV material handling analysis
Equations del cycle time Tc TL TU Ld /
vc Le / ve (min) available time AT 60
A Tf E (min/hr/veh) rate of del per
vehicle Rdv AT / Tc (num del/hr/veh) work
by handling system per hr WL Rf
Tc (min/hr) num of vehicles for workload nc
WL/AT Rf / Rdv (num of veh for work load)
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AGV example (from text)
Given the AGV layout in the figure and the info
listed, determine the number of vehicles
required for a delivery (flow) rate of 40
del/hr. Info Loading time 0.75 min Unloading
time 0.5 min Vehicle speed 50
m/min Availability 0.95 Traffic factor 0.9
(from fig) gtLd 110 m Le 80 m E
1 Solution Ideal cycle time/del/veh Tc 0.75
0.5 110/50 80/50 5.05 min Compute
workload WL (40) (5.05) 202
min/hr Available time AT (60) (0.95) (0.90)
(1.0) 51.3 min/hr/veh Num of vehicles nc
202/51.3 3.94 veh gt 4 vehicles!
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AGV questions

• Who are major vendors of AGVs?
• Describe their components (power source,
  transmission system, communication system, etc.)?
• What are typical costs?
• What type of interfaces do they have? How are
  they programmed?
• How fast do they move?
• What are load to weight ratios?
• Unusual maintenance requirements?
• How do they avoid collisions?
• How are they scheduled?

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Automated Storage and Retrieval System (AS/RS)
Definition - An AS/RS is a combination of
equipment and controls which handles, stores, and
retrieves materials with precision, accuracy, and
speed under a defined degree of automation.
(Materials Handling Institute)
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AS/RS classification
Unit load AS/RS - Large automated system designed
to use S/R machines to move unit loads on pallets
into and out of storage racks.   Mini-load AS/RS
- Smaller automated system designed to move
smaller loads into and out of storage bins or
drawers.   Man-on-board AS/RS - Uses personnel to
pick items from racks or bins, reducing
transaction time.   Automated item retrieval
system - Items to be moved are stored in single
file lanes, rather than in bins or drawers.
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AS/RS applications
Unit load storage and handling - Warehousing for
finished goods/products.   Order picking - Used
to store and retrieve materials in less than full
unit load quantities, such as man-on-board or
mini-load applications.   Work-in-process -
Support just-in-time production activities,
buffer storage, and as integral part of assembly
systems.
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AS/RS control
The S/R is a large Cartesian type robot that
integrates modern control technology, I/O, and
sensors (compartment identification) to move
between storage compartments. AS/RS control is
integrated with modern material management
software for real-time inventory control, storage
transactions, and material delivery.
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AS/RS material handling analysis
Terms C capacity per aisle x - width of unit
load y - length of unit load (in horizontal
direction) z - height of unit load (in vertical
direction) nz - number of vertical
compartments ny - number of horizontal
compartments U - system utilization per hr W -
width of AS/RS rack H - height of AS/RS rack L -
length of AS/RS rack
vz - vertical speed (m/min, ft/min) vy -
horizontal speed (m/min, ft/min) tz - vertical
travel time (min) ty - horizontal travel time
(min) Tcs - single command cycle time
(min/cycle) Tcd - dual command cycle time
(min/cycle) Tpd pickup and deposit time (min)
Rcs - num of single commands per hr Rcd - num of
dual commands per hr Rc - total cycle rate in
cycles/hr Rt - num transactions per/hr
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AS/RS material handling analysis
Equations AS/RS dimensions W 3 (x a) a
6 in L ny (y b) b 8 in H nz (z
c) c 10 in capacity per aisle C 2 ny
nz single command cycle Tcs Max L/vy ,
H/vz 2 Tpd uniform racks,
random storage dual command
cycle Tcd Max 1.5 L/vy , 1.5 H/vz 4
Tpd utilization 60 U Rcs Tcs Rcd
Tcd hourly cycle rate Rc Rcs Rcd num
transactions per hr Rt Rcs 2 Rcd
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AS/RS example (from text)

• Given a 4 aisle AS/RS layout, each aisle contains
  60 horizontal racks and 12 vertical racks. Unit
  load dimensions are x 42 in, y 48 in, and z
  36 in. The S/R machine has a horizontal speed of
  200 ft/min and vertical speed of 75 ft/min. It
  takes 20 s for a PD operation. Find
• Num of unit loads that can be stored
• Total dimensions of AS/RS
• Single and dual command cycle times
• Throughput per aisle assuming utilization 90
  and num of single command cycles equals the
  num of dual command cycles
• Solution
• Total capacity 4C (4) 2 ny nz (4)(2)(60)
  (12) 5760 unit loads
• Width 3 (42 6) 144 in gt 12 ft/aisle
• Length 60 (48 8) 3360 in 280 ft
• Height 12 (36 10) 552 in 46 ft

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AS/RS example (cont)
Solution Single command cycle time Tcs
Max280/200,46/75 2(20/60) 2.066
min/cycle Dual command cycle time Tcd
Max(1.5)(280/200), (1.5)(46/75) 4(20/60)
3.432 min/cycle Utilization 0.9 2.066 Rcs
3.432 Rcd 60 (0.9) 54 min, but Rcs
Rcd Thus, solve and get Rcs Rcd 9.822
command cycles/hr System throughput is the total
number of S/R transactions per hour 4
Rt Throughput 4 Rt 4(Rcs 2 Rcd)
4(29.46) 117.84 transactions/hr
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AS/RS questions

1. Who are major vendors of AS/RS?
2. Describe their components (power source,
   transmission system, communication system, etc.)?
3. What are typical costs?
4. What type of interfaces do they have? How are
   they programmed?
5. How fast do they move?
6. What are load capabilities?
7. Unusual maintenance requirements?
8. What type of S/R control is used? PID?
9. Who are primary users?

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Conveyors
Definition - A conveyor is a mechanized device to
move materials in relatively large quantities
between specific locations over a fixed path.
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Conveyors
Roller conveyors - Series of tube rollers
perpendicular to motion direction, which can be
powered or use gravity for motion. Skate-wheel
conveyors - Similar to rollers but use skate
wheels parallel to motion direction. Belt
conveyors - Drives move flat or belts shaped into
a trough.
Belt
Skatewheel
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Conveyors
Trolley
Chain conveyors - Uses loops of chain that are
typically moved by sprockets as driven by
motors. Overhead trolley conveyors - Items are
moved in discrete loads by hooks or baskets
suspended from overhead rails.
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Conveyors
In-floor towline conveyors - Similar to overhead
trolley but carts are pulled by hook to in-floor
conveyor. Cart on track conveyors - Items are
moved by a cart attached to a rail system, which
uses a rotating tube to move the cart along the
rail.
Towline
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Conveyor material handling
Terms vc carrier average speed (c
conveyor, carrier, cart, etc.) sc material
spacing on conveyor TL loading time (min)
TU unloading time (min) Rf material flow
rate (parts/min) Ld distance between load and
unload Le distance of return loop (empty) L
length of conveyor loop Td delivery time
np number of parts per carrier nc number of
carriers RL loading rate (parts/min) RU
unloading rate (parts/min) Tc total cycle time
(min) Np total number of parts in
system Note If one part per carrier, then part
flow rate is carrier flow rate.
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Conveyor handling analysis
Equations single direction time from load to
unload Td Ld /vc (min) delivery time
delivery distance divided by carrier
speed material flow rate (np 1) Rf RL
vc /sc 1/ TL (num carriers/min) system
flow rate loading rate flow rate of carriers
on conveyor material flow rate (np gt 1) Rf
np vc /sc 1/ TL (num parts per
min) system flow rate loading rate of
parts flow rate of parts on conveyor unloadin
g constraint TU TL (min) unloading
time must be less than loading time or else pile
up carriers
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Conveyor handling analysis
Equations continuous loop time to complete
loop Tc L /vc (min) full loop
carrier time loop distance divided by carrier
speed time in delivery Td Ld/vc
(min) delivery time delivery distance
divided by carrier speed number of carriers
nc L /sc num of carriers loop
distance divided by carrier spacing total
parts in system Np np nc Ld/ L parts
in system num of parts per carrier times num
carriers with parts material flow rate Rf
np vc /sc (num carriers per
min) material flow rate num parts
per carrier times carrier flow rate
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Conveyor handling analysis
Equations recirculating Speed rule
operating conveyor speed must fall within a
certain range from load/unload rates Rf np
vc /sc ³ MaxRL , RU flow rate of parts on
conveyor must exceed the max load or unload part
rate to maintain part spacing from time to
load/unload carriers vc /sc Min1/TL,1/TU f
low rate of carriers on conveyor must exceed the
max load or unload carrier rate to maintain part
spacing Capacity constraint conveyor
capability (np vc /sc ) must exceed
desired/specified flow rate Rf conveyor speed
and carrier parts np vc /sc ³ Rf Uniformity
principle loads should be distributed uniformly
over the conveyor
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Conveyor questions

1. Who are major vendors of conveyors?
2. Describe their components (power source,
   transmission system, I/O subsystem, etc.)?
3. What are typical costs?
4. How are they programmed and controlled?
5. How fast do they move?
6. What are load capabilities?
7. Unusual maintenance requirements?
8. Who are primary users?

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Material handling
What have we learned?