Order Picking Assembly Flashcards
Functions
When is storage enough in a WH?
When
In-flow = Out-flow
No transformation is needed
Rare
When is picking needed in a WH?
when
Inflow different than outflow
Most likely
What is the Order Cycle?
Order processing+
Order Assembly+
Delivery
Within the Order Cycle,
What is Order Assembly?
Collecting the items = picking being the core activity
Process:
1. Picking list production
2. Picking
3. Sorting
4. Packaging
5. Transport Load Consolidation
Connection 1-2=picking list
Define better Picking
Selective retrival of unit loads from high level UL to prepare custumers orders
Tell me the 3 types and main characteristics of Picking types:
- Layer: full cartons layer
- Carton picking: specific cartons
- Pieces picking: from cartons
Design Variables/Parameters
Mention the 2 of them
SC
TC
How could be divided the SC
In reverse and forward storage
The SC is confomed out of which type of stock
Cycle stocks and Safty stocks
Forward Reserve Problem
How to split the capacity between reserve and forward stocks.
Internal decision tradeoff between
1. Picking efficiency
2. cost to transport from R to F
Picking Key Performance Indicators
Cost related:
Replenishment
Picking
Sorting
Packing
Labour
Space
Equipment
Systems
Picking Key Performance Indicators
Customer service
Accuracy
Order Picking cycle time
Flexibility
Whats the impact of order assembly in:
1. WH cost
2. Customer Service
- 50% WH cost = Order assembly (picking)
Complexity (fragmentation of units) and Labor intensity (difficult to automate)
Picking process
Activities
Picking
Sorting
Packaging
Picking process
Resource
Labor
Space
Equipment
Picking performance measurement
We said Cost & Service Level,
Develop on the SL KPIs
Picking accuracy: related to order accuracy/compliance
Picking Cycle Time: Part of the Order Cycle Tyme
Picking Flexibility: ability to adapt to changes
Picking Punctuality: On time deliery
Picking Systems
Mention the different Picking Systems
- Pickers to Parts
- Pick to box
- Pick and sort
- parts to picker
- Automated picking
Explain the Diagram Picking Systems
Who pick goods?
Machines: Automated picking
Humans: Who moves in the picking area?
Goods: parts to pickers
Pickers: convoyers connect picking zones?
No: Picker to parts (item/Order)
Yes: Order=Pick to box, Items=pick and sort.
Picking Systems
Picking Policy of:
Picker to parts
Pick to box
Pick and Sort
Pick by Item/Order
Pick by order
Pick by item
Picking Systems
The picker carries out a “picking mission” within the “picking area”, visiting in sequence all the locations which are detailed in the “picking list”
Picker to parts
I need structures racks, shelves, drawers
Pickers to parts
Explain how is this system conformed
Picking area (Configurated 2D, 3D)
Pickers (>1)
Picking mission: multiple-command mission (touch as many points) TPS: Traveling Salesman Problem
Pickers to parts
How is Picking mission time conformed
Picking mission time is the time a pickers take for one mission considering travel time and retrival time.
PMT= TT + RT
Different from Picking cycle time or Picking lead time
Pickers to parts
Design/management decisions
How do you decrease Travel Time TT
Reducing Area
or
Management pollicies
* Routing (sequence)
* Storage (allocation)
* Batching
Pickers to parts
Design/management decisions
How do you decrease Retrival Time RT
ICT Information Comunication Tech
Allocation of products
Pickers to parts
How is it in terms of:
* Labor productivity
* Space Productivity
* Investment (CAPEX)
* Reconfiguration (flexibility)
* Accuracy & Speed
- Labor productivity:
–/-Low (high OPEX), safty, security, compliance issues. (automatic suport helps) - Space Productivity:
—Low - Investment (CAPEX): Low (high OPEX)
+++ low investment - Reconfiguration (flexibility)
+++ high flexibility - Accuracy & Speed
–/- Low acuracy (bar codes helps)
Picking Systems
These 2 systems have a Picking Area, Picking Zones dedicated to pickers and conveyors
Pick to box (order)
Pick and sort (item)
Conveyor
mean of integration
Conects zones
Picking system
Pickers pick the items and put them in a box, one box per order
Picking and sorting toether
Pick to Box
Picking system
Pick and sort
Items picked are directly placed into the convoyer no box and then you have a sorting area/task.
Pick to box / pick and sort
Management decisions
No. Zones
Zones Balancing
Storage policies
Batching policies)
Sorting (manual automated)
Pick to box / pick and sort
How is it in terms of:
* Labor productivity
* Space Productivity
* Investment (CAPEX)
* Reconfiguration (flexibility)
* Accuracy & Speed
- Labor productivity:
+high (workers know the area) - Space Productivity:
– low - Investment (CAPEX): Low (high OPEX)
-high due to convoyers or machines - Reconfiguration (flexibility)
-low - Accuracy & Speed
-Unrelaiability risk
Picking systems
The aim is to eliminate Travel Time
There is a storage area + handling system+ picking area
The UL (big or small) is brought to the picker who takes the item(s) and the rest is sent back.
Parts to pickers
Parts to pickers
Design management issues
Handling system design
Ergonomy of picking station
Parts to pickers
How is it in terms of:
* Labor productivity
* Space Productivity
* Investment (CAPEX)
* Reconfiguration (flexibility)
* Accuracy & Speed
- Labor productivity:
++high (xTT) - Space Productivity:
++Picking dedicater area - Investment (CAPEX): Low (high OPEX)
–high due to chandling system - Reconfiguration (flexibility)
–low
-KIVA solution - Accuracy & Speed
++ high
Picking system
Machines robots instead of humans
Robots to parts
Robots to convoyers
Part to robot
Automated picking system
Picking system
Rank Order pikcing systems so that is true that:
* Labor productiviti increases
* Space productivity increases
* Accuracy/ speed increases
* Investment (CAPEX) increases so benefit decreases
* Flexibility decreases
- Picker to parts
- Pick to box
- Pick and Sort
- Parts to picker
- Automated
Logical Flow chart
Descriptive tool of WH flows
Pickind Design Management
How to set a problem?
What to consider
- Objective Function:
Cost & Service - System Capacity
Throughput Capacity - Data
Order / Item profile
Pickind Design Management
Design & Management decisions
Once we have the inputs of a Picking system in which iteration it enters?
- Picking system selection
1.1 Picking sub-problems
1.2 Picking Sub-problems solutions
2.System(s) capacity & design
2.1 Storage Capacity
2.2 Layout configuration
3.Management policies
Problem setting
When talking about the Order profile how can we dimension it:
Volumes: Lines/Order
Volumes: Volume/Order
Picking Units (UL, caron,…)
Volumes: Palletised UL
Problem setting
How can we clssify the SKUs (items)
- Frequency (order/lines/time)
- Volume
- Weight
- Fragility
Pareto always a good idea= cumulative curve
Design & Management decisions
- Selection of the picking System
- Segmentation of the picking problem in sub-problems
- Identification of elegible picking solution(sub)
Design & Management decisions
- Picking System Capacity and design
- Picking system Capacity (forward-reserve solution)
- Picking System configuration (layout)
Design & Management decisions
Management Policies
Space allocation
Patching
Routing
Location/storage
Design & Management decisions
I have to Design and define policies for all the sub-problems found?
Yes, is an iterative process.
The Forward - Reserve decision
How to split the overall inventory within the warehouse into a reserve stock and foreward stock (inventory dedicated to picking)
The Forward - Reserve decision
Output
The output is the Storage Capacity of the Picking System.
The Forward - Reserve decision
Subproblem
Embedded problem: Space allocation problem.
Allocation of the overal space (S) to single items (Si) in order to reduce the number of replenisments (R) from reserve to forward area.
The Forward - Reserve decision
Basic Trade-off
Basic trade off= replenishment cost and picking cost
Compare pros cons general and picking stock
General Stock
RS = PS
+No replenishment
-Picking efficiency decreases
Compare pros cons general and picking stock
Picking stock
RS>PS
+Picking efficiency increases
-Replenishment
space allocation problem od RSFS
Function and graph of TC(S)
TC: Total cost
S: Picking Stock capacity (stock)
TC=CPicking(s) + CReplenishment(s)
The TC cost is the sum of Cpicking and Creplenishment.
The Cpicking is a curve that increases as S increases
The CReplenishment is a Curve that decreases as s increases
Where Cpicking and Creplensiment intersect is the optimal S and the value of the TC of that point says the cost.
FRP
Items replenishes at same frequency
Storage capacity depends on replenishment frequency
less frequent = more space
Items volume flow is considered
Pro: cost to optimize the replenishment process
Con: Complex to allocate space and design layout
If location = size, no good saturation
Equal time supply
FRP
Each item have same volume
itemv = V/N
Replenishment freq is different
freq=flow/volume
pros: cost to allocate space and design layout
cons: cost to manage replenisment complex
Equal space
FRP solutions
Min(R)
Complex to allocate space and manage the replenishments
Optimal solution
Picking Management Policies
Picking management main 3 policies
- Storage
- Batching
- Routing
Picking Management Policies
The basic decision is to increse the picking density
Batching Policy
Picking Management Policies
Batching
What are the main decisions when Batching
- Sorting:
while pick (few orders)
ater pick (manual automatic) - Batch Size
Trade-off between Sorting Time and Picking time per order (Nopt) - Batching logic
Delivery date
Physical proximity
Picking Management Policies
Batching Pros/Cons
Pros:
Increase picking density
Reduce picking time
Increase orders’s lines overlaping
Set up time reduction
Cons:
Sorting!!!
Information intensive approach
Picking Management Policies
The basic decision is about the sequence of picks
The objective is to minimize the travel of the picking mission (Input-Locations-Output)
Routing policies
Traveling Salesman Problem
Picking Management Policies
What are the possible taken approaches for routing
- Order by Order
Each order is routed to min travel - Pre-defined
A pattern choosen once for all (stable, easy to apply other policies but travel not min)
a) Traversal policy
b) Return Polic
Picking Management Policies
Pros and cons Routing
Pros:
Picking productivity (as for all the others)
Decrease travel time
Cons:
Dynamic
Complex in an operational way
Picking Management Policies
The basic decision is about the allocation of a single itmens or classes of items in oicking locations
The main trade of is picking cost - operational complexity (congestion)
Increse density of proximity
Storage policies
Picking Management Policies
Storage policies 3 main classes
Random Storage
Picking travel = Access Index
Picking Time = Correlated Storage (items to be highlikly to be ordered together)
Operational needs
Picking Management Policies
Storage
The item with higher ratio between Picking Frequency and dedicated space go closer to the I/O.
Reducing Picking time, increasing congestion and it is dynamic
It needs to consider the routing policy
Access index based
Traversal decrease aisles visited
Return decrease visited lenght
Picking Management Policies
Pros and cons of storage
Pros:
Picking productivity (as for all the others)
Decrease travel time
Decrease retrival time
Cons:
Dynamic
