WAREHOUSES OVERVIEW Flashcards by Maria Padilla

Q

A distribution network is conformed by:

A

transport
warehouses

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Q

Warehouses, part of a DN, have 3 characteristics:

A

Functions
Types
Functional areas

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Q

Functions
What are they?

A

a) Storage: static.

Decoupling point, leverage of unpredictability of demand and LT.

b) Transformation and sort the flows: dynamic

Flows management

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Q

Types
What are the main types of nodes?

A

a) Warehouses:
Inventories are present.
Safety and Cycle stocks
Materials planning and management needed. down and upstream flows.
Static +Dynamic functions

b) Transit points
Inventories absent, goods stored only to sort them.
In transit stocks.
Re-packing, cross docking, delivery
Dynamic functions only

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Q

Activities:
What are the main activities (5)

A

Receiving
Put-Away
Storage
Picking
Shipping

1-3 Inbound
3-5 outbound

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Q

What warehousing activity is characterised by:

Schedule carrier
Unload vehicle
Inspect for damage
Compare to P/O

A

Receiving

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Q

What warehousing activity is characterised by:

Identify the product
Identify the storage location
Move products
Update records

A

Put-away

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Q

What warehousing activity is characterised by:

physically maintaining the products in the designated or random area of the WH

A

Storing

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Q

What warehousing activity is characterised by:

Managing order info
Picking goods
Moving goods
Labelling package

A

Picking

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Q

What warehousing activity is characterised by:

Scheduling carrier
Loading vehicle
Bill of landing
Recording update

A

Shipping

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Q

When we talk about designing a WH, what are we defining? (2)

A

Handling system & layout

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Q

3 Handling storage parameters:

A

Design parameters
Descriptive parameters
Cost Parameters

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Q

Handling storage parameter,
Design 1/2 :

Number of UL locations (UL)

A

SC: Storage Capacity

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Q

Handling storage parameter,
Design 2/2 :

Flow of UL. (UL/h)
Input Capacity
Output Capacity

A

TC: Throughput capacity

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Q

Handling storage parameter,
Descriptive 1/3 :

Number of units I can store per m2 (UL/m2)
SC / WH Area

A

AUR: Area Utilisation Rate

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Q

Handling storage parameter,
Descriptive 2 /3 :

Directly accessible UL locations / SC
Ratio <= 1

A

Selectivity

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Q

Handling storage parameter,
Descriptive 3 /3 :

UL stored / SC
Ratio <= 1

A

Saturation

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Q

Handling storage parameter
What are the 2 Cost parameters

A

Storage cost per UL
[ € / UL*year ]

Handling Cost per UL handled
[ € / UL]

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Q

What are:

Block stacking
Rail Racks
Selective pallet racks
Flow racks

A

Storage Systems for big size UL

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Q

What are:

Miniload
Carousels
Vertical AS/RA

A

Systems for small size UL

OR

Picking Systems

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Q

Mainly used to move pallets both horizontally and vertically

A

Counterbalance forklift (sit)
Straddle reach (standing)

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Q

Mainly used to move pallets both horizontally and vertically usually in the aisles
Expensive

A

side loaders
turret trucks

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Q

Used to move horizontally and unload trucks

A

walkie stackers

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Q

You storage in the floor
No racks
UL must be stackable (3/4)
Low selectivity
LIFO
Low AUR
High Inventory level

A

Block stacking

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Racks UL non or stackable better selectivity Special trucks 1m LIFO High AUR High Inventory level

Drive in/through

Storage system that enables gravity-based moving with inclined roll conveyors Low selectivity Low retrieval Medium to high stock level High cost

Paet/case flow rack system

amount of time it takes to locate, pick, and retrieve a specific item from the warehouse once it has been requested.

retrieval time

Couple of racks separated by working aisles uprights and beams High selectivity (1 if 1 dept) Cost is low 20 € / UL

Selective Pallet Rack system

2 solution we could distinguish when designing a storage system with trucks:

1. Traditional + truck 2. Storage system + AS/RS

What are: 1. Management of Operative cycles 2. Space Allocation

Warehouses Management policies

1. Management of Operative cycles:

1. Single Command Cycle to store or retrieve. 1UL 2. Dual Command cycle to store or retrieve. 2UL

How Single Command Cycles time is conformed:

Variable time: Related to distances horizontal (transfer) & vertical (lifting). With or without the load. Fixed time: Wait for data transfer Curves Positioning Load / Unload

Compare Dual vs Single cycles in terms of: Efficiency Cycle length Fixed time incidences Requirements

Efficiency: 2 instead of 1 UL per cycle. Cycle length: Longer but in proportion to 1UL shorter. Fixed time incidences: Lower Requirements: The UL has to be ready for storage and retrieval.

2. Space allocation What is it?

Criteria to decide where to placate UL of an article and the space subdivision criteria

Number of ULi RETRIEVED from the storage system during a time window T

Retrieval Index

Retrieval Index of i,T divided the number of locations assigned to I during T.

Access Index (how visited is a location)

What happens when I have different items with different Access index

I wan to place the items that I visit most (higher AI) closer to the I/O to decrease operative cycles. Dedicated space or classes needed for this approach.

What are the main allocation policies?

a) Random storage: location shared b) class based storage: Locations assigned to class of Items c) Dedicated storage Locations are assigned to specific Items

Rank the three allocation policies in terms of: Efficiency of cycle time, complexity and storage capacity. 0 is low 1 is high

0 Random storage .5 class based storage 1 Dedicated storage

If I take a Dedicated storage policy, how do I calculate the capacity of the system?

As it is dedicated I need to make sure that the max qty of each of the scheduled items, in a year for example, will have a place in the WH. Take the highest qty among items and sum it up.

If I take a Random storage policy, how do I calculate the capacity of the system?

Random the location is shared, so I need to make sure that the highest period qty will fit in the WH. monthly sum and I take the max as the capacity needed.

Class based storage, How do I know how to place the zones.

In a selective storage system served by counterbalance lift there are two arrangements that follow ISO-TIME-CURVES. In triangle if the II/= is only located in the middle or rectangular if I/O is all along the side. Always A closer to I/O and normally 2 or 3 classes.

Class based storage: How do I define the classes

1. AVG of all AI 2. AI A > AI avg 3. AVG remaining AI 4. AI B > AI remaining avg 5. C remaining (or again)

True or false The higher the # of classes the higher the managerial complexity of the system

True

Explain the ABC curve: Access / occupied space

x: occupied space in terms of % UL locations y: % access Curves represent the relationship of how the behave when one of them changes.

If I manage to concentrate as much as possible my access in 20 % of my sace...

I get benefits as reduction of the operative cicle VARIABLE time with respect to random storage. And having +1 class reduces it even more! But increases complexity managerial.

1. Clustering the items by storage system 2. Required performances (SC-TC) 3. Constrains 4. Storage system selection 5. Area PRE-design 6. Modeling and simulation 7. Technical - Economical checks 8. Design

Main Design Principles

Criteria to cluster items:

Technical features: dimensions, weight, fragility Environmental req: Temperature, humidity Safety req:}Fire prevention, hazardous, non compatibility

Design constrains:

Urban: heights, distances Technical: Surface and shape of the ground Safety: Escape routs Economical: Available resources

If we divide the design framework into 3 phases wha are those:

1. Identify design parameters SC-TC 2. Layout design to cover SC 3. Throughput capacity assessment TC

What are the assumptions we make for a conventional manual storage system?

# trucks not connected to # aisles Data exist Singledeep selective racks Full pallet loads not mixed counterweight forklift trucks No picking activities

# Is the analysist that: Takes into account the values of the flows (hr/day) from storical data

Analysis of phisical flows ## Footnote Throughput capacity

# Throughput Capacity TC How is TC assesed in terms of handling system for storing and retrieving

If same system: TC= Fin+Fout If diferent: TCin= Fin TCout=Fout

How can I chose a best storage solution?

Calculating the NPV NPV=-Io-OCt+TV

Io in NPV

Initial invertion: Storage (racks) Land (area) Handling system (trucks) | The price I pay to get them

TV in NPV

Terminal Values after T period: Storage (racks) Land (area) Handling system (trucks) | What they will value as assets

OCt in NPV

Operative cost: How much i will pay to handle the pieces of one year during the period T and considering the increase of annual cost capital (K).

# True or false In a Drive in and in a sigle deep rack the pallets are places in the same way the diference is the truck where it take them from

True

U side of my warehouse divided the dimension U side of the UM | Uum= 2*DeepUL+aisle width

Number of aisles NA | I use dimentions

SC divided how many PL I storage in 1 column | UL per column = 2*BayUL*NA*NL

Number of Columns NC | I use capacity

The I/O point is in the **corner**

U=V P=2*( U/**2** + V/2) a=**2**

The I/O point is in the **midle**

U=2V P=2*( U/**4** + V/2) a=**4**

The I/O point is **all along**

U=1.5V P=2*( U/**3** + V/2) a=**3**

How to calculate the Time of a single comand cycle

TSCC= FT + VT FT given VT=P/Vh + S/Vv | If Access aisle, sum it to P

How you calculate the TC by truck

TCtruck= **UF***3600/TSCC

How you calculate needed trucks

SC/SCtruck

# Automated Storage Systems Compare an automated storage system against a standard one on terms of **layout**: Height Aisle Width Lenght AUR

Height: higher Aisle Width: narrower Lenght: higher AUR: Strong impact

# Automated Storage Systems Compare an automated storage system against a standard one on terms of **Handing system**:

AS/RS machines Automated I/Osystem Positive impact in TC

# Automated Storage Systems Main choices about system configuration regarding: **Structure**

1. Standard 2. Sunk 3. Rack supported

# Automated Storage Systems Main choices about system configuration regarding: **S/R macines / #aisles**

=1 diff 1

# Automated Storage Systems Main choices about system configuration regarding: **Rack Depth**

1. Single Deep 2. Double Deep

# Automated Storage Systems Main choices about system configuration regarding: **Telescopic Forks per machine**

1 2

# Automated Storage Systems When to select this type of solution

Low vailability / high cost area High storage capacity High TC Specific conditions of the product

# Automated Storage Systems Drawbacks

Low flexibility Investment Reliability

# Automated Storage Systems Which type of coordinates can we use?

Spatial or Time

# Automated Storage Systems How can I calculate time coordinates:

Tx=X/Vx Ty=Y/Vy | The time is the one from the highest between X or Y

# Automated Storage Systems Management policies 1. Operative Cycle types 2. Optimization of dual command

1. Operative Cycle types Single Dual 2. Optimization of dual command NCZ No Cost Zone MTB Minimum travel between

# Automated Storage Systems VT Variable time depends on pallet location FT does not | T or F

True

# Automated Storage Systems Why are Dual Command Cycles more efficient than Single Command Cycles?

They can move 2 UL in less than 2 single cycles

# Automated Storage Systems The idea is to couple a storage/retrival in a specific paallet location with a retrival/storage in the closest pallet location. Minimize the interleave without the load.

MTB Minimum Travel Between

# Automated Storage Systems Cople a Storage/Retrival in a specific pallet locoation with a retrival/storage withough increasing the Variable time of the cycle.

NCZ No Cost Zone

# Automated Storage Systems Autonomous Vehicle Storage and Retrieval System

Decouples Vertical and Horizontal movements Increases SL and reliability