In this session, initially we will learn about Warehouse Layout / design and the products arrangement. We give below sample warehouse layout basis GSK products (25 SKUs) explained in the previous session.
I would like
to recall your attention to our earlier session wherein we have discussed 25
SKUs with FSN classification
basis sales movement such as F (fast), S
(Slow) and N (Non moving or Very Slow moving). Out of 25
SKUs, 6 are fast moving items, 8 are Non moving (or very slow moving) items and
11 are Slow moving items. Now let us understand the significance of doing such
analysis. Horlicks powder is packed in
2Kg, 1Kg, 500g and 200g. But the end consumers
prefer to buy 500g pack more than any other pack due to economic reason and
hence the retailers order more quantity for Horlicks 500g pack (bottle or
pouch) which makes that SKU fast moving.
Horlicks 2Kg pack cost more, resulting less demand from the end consumer,
which makes that SKU non moving or very slow moving.
In what way FSN classification analysis
going to help in Customer Order Picking ?
If we design
warehouse layout in such a way that all Fast moving items / SKUs are stored
near to outbound area, it would be easier to pick these items and keep it in
the shipping area with less effort while executing the customer orders. Since these items are fast moving, most of
the retailers or distributors, would places an order for the same. Now our reader can ask a logical question
that why should we store fast moving items near to outbound area and not near
to inbound area as inbound operation also critical in the warehouse management. Warehouse is receiving few SKUs or items in
bulk quantities from manufacturing unit in the inbound area and hence the
warehouse staff need to check the quantities and putaway the bulk quantities in
storage area. Whereas the outbound is the area where multiple customer orders (Number of orders) of various SKUs (Number of Lines / SKUs) in small quantities (Pick per Order) are arranged for final shipment. The outbound dispatches are time bound complex
activity which are error prone, and hence the warehouse managers pay more
attention to outbound activities.
In the above
warehouse layout example, are we following FSN classification model while
storing the materials ?. If you observe
the above diagram closely, you can easily identify we are not storing the
materials as per FSN model. FSN model is one method of storing items in the
warehouse. However in GSK, the customer order character influences the storage pattern and Order
Picking method. If you notice
in the customer order example given in our last session, the most of the
customers included even non or very slow moving items in small quantity in
their order eg., even though Horlicks 2Kg is non / very slow moving items, most
of the customers invariably ordered small quantity of Horlicks 2Kg to cater few end
consumers, along with other Horlicks product group (like 500g, 1Kg). Hence the company has decided to store their
products according to the product groups (all SKUs of Horlicks are grouped etc)
for easy pick up . In the above example
entire Horlicks ranges are stored in Aisle 1 and 3 which are adjacent side
(refer figure) so that the picker can pick all Horlicks items in a given order without
travelling much distance.
In case, If
the company decide to follow FSN Model to store materials, then the SKUs of different product groups according to FSN
classification are stored together in different aisle. For example Fast moving items like Horlicks
500g Bottle & Pouch, Boost 500g Bottle and Pouch, Choc Horlicks 500g Pouch
and Crocin Tablets are stored in aisles 1 , 2 & 3. In this case, the picker has to pick Horlicks
500g items which is fast moving from Aisle 1 and probably slow moving Horlicks
1Kg items from Aisle 5 and Non moving
Horlicks 2Kg from Aisle 9. This makes
the picker to travel more distance across different aisles to pick the products
of same group, makes the order picking more tedious and time consuming process.
Tips : I would like readers to pay special attention to yellow highlighted
portion. This is where I have explained
how the Customer Order Characters (eg Number of orders received, number of lines
or SKUs in a given order, Number of picks per order etc) effect the Order
picking method.
ORDER PICKING METHODS
In simple
words order picking involves movement of products and human (picker). According to the movements of products and
human, order picking is classified into Picker to Part and Part to Picker. These classification further sub classified
and the details are given below in the chart.
Now Let us
understand each of these terms.
Picker to Part is the most common system where an
order picker walk (may be with pallet Truck) or drive fork lift along the aisle
to pick the materials. Two types of
Picker to Part system are Low Level order picking and High Level (Man on board)
order picking.
High Level (Man on Board) Order
Picking - High-level
picking systems employ high storage (vertical) racks, Shelves or storage cabinets can be
stacked as high to the extent of floor load withstanding capacity, weigh
capacity, Product movement and ceiling
heights limit. Pickers travel to the pick locations on board of a picking truck
or crane. The machine stops in front of the appropriate pick location and
picker to perform the pick.
High-level
(man-on-board) order picking system has higher installation and maintenance
cost and lower reconfigurability. Ergonomic factors should
also be taken into consideration while choosing the proper system since order
picking can be heavy work. Hence this system are rarely used
in warehouse operation.
Low Level Order Picking
In low level order picking systems, products are stored in bins on
shelves or cartons on flow racks. The
height of the storage system is limited by the reaching height of a human being
and weight of the product. An order Pickers pick the requested items from
storage racks or bin shelving storage, while traveling along the storage
aisles.
Low-level
order picking systems are widely used in warehouses because of their low
initial cost, easy installation, easy reconfigurability, and low maintenance
cost.
Low level
order picking is further sub classified into Pick by Order, Pick by Part and
Zone pick (Progressive zone pick & Synchronize zone pick).
Pick by Order - In this method,
products are stored in fixed locations on static shelving or pallet rack. An order picker picks one order at a time covering
each aisle until all items in the order is picked. In this method, it is advisable that the picking document (pick list) should have the picks sorted in the
same sequence as the picking flow. Preferably, Fast moving product should be stored close to the main cross aisle and
additional cross aisles put in to allow short cuts.
Pick
by Order method can work well in warehouse operations with a small number of
orders and a high number of picks per order. Operations
with low picks per order will find more travel time in this type of
picking and operations with large numbers of orders will find that the
congestion from many pickers working in the same areas slows down the
processing.
Pick by Part / Batch Picking – In this case, multiple orders (say 2 to 10 orders) are grouped into small batches.
An order picker will pick all orders within the batch in one pass using a consolidated pick list.
Batch
sizes usually run from 2 to 10 orders per batch depending on the number of
lines or SKUs per order and low picks per order.
In operations with low picks per order, batch picking can greatly reduce
travel time by allowing the picker to make additional picks while in the same
area due to consolidation of orders.
For example
3 customers placed order for Horlicks 500g Pouch 20 cases each. In batch
picking all these 3 customer orders are consolidated due to low pick and less
number of SKUs. An order picker will
pick 60 cases of Horlicks 500g Pouch for all orders from Aisle 1 for dispatch. Otherwise the picker has to pick 20 cases of
Horlicks 500g Pouch by visiting Aisle 1 at 3 different time.
In
busy operations like large customer order with high pick per order and more
lines or SKU per order, batch picking is often used in combined with zone
picking (will be explained shortly) and automated material handling equipment.
Since the order picker is picking multiple orders at the same time, systems and procedures will be
required to prevent mixing of orders.
The sub systems of batch pick are
Sort while pick – picking multiple orders followed
by immediate sorting (on the pick cart or at the shipping dock) by the order
picker.
Pick and Sort
- In this case sorting
takes place after the pick process has finished
Zone Picking - In zone picking, the picking area is broken
up into individual pick zones (Refer warehouse layout figure eg Horlicks 500g
Bottle in Zone 1 and Boost 500g bottle in Zone 5 etc). Order pickers are assigned to a specific zone, and only pick items
within that zone. In zone picking it’s important to balance the number of picks across all zones to maintain same work load among the zones. In our example, we have combined the areas of
Boost 1kg bottle, Boost 200g bottle and Eno Bottle to form zone 2 to balance
the number of picks and maintain the equal work load across all zones.
Separate
zones also provide for specialization of picking techniques such as having
automated material handling systems like mechanized fork lift in one zone and
manual handling in the next zone. One
can observe from our warehouse layout example, we can use mechanized fork lift
in zone 1, 2,5,6 & 7 and rest of the zones can use Order Picker with pallet truck.
Zone Picking
has got two sub system.
Progressive Zone Picking (Pick & Pass) – In this method each order or
possibly batch of orders are moved from one zone to the next, once the picking from the previous zone is
completed. Hence this method is also
known as pick-and-pass.
Progressive
Zone picking is most effective in large operations with high numbers of skus,
high number of orders, and low to moderate picks per order.
Synchronize Zone Picking (Wave
Picking) - In synchronized zoning method, all zone
pickers can work on the same order (or normally a batch of orders) at the same
time and the items are later sorted and consolidated into individual
orders for shipments. Wave picking is the
quickest method for picking multiple
item orders due to shortest cycle time, however
the sorting and consolidation process require more attention.
Operations
with high total number of SKUs, high total number of orders and moderate to
high picks per order may benefit from wave picking.
Tips : Cycle time is the amount of time the process takes to get an
customer order from order entry level to move the all items of the given order
to the shipping dock for final dispatch.
Parts to Picker -
In this system the part or items are moved towards the picker, so that
he can keep the items in the shipping dock.
The two most popular parts-to-picker systems are
Carousels - A carousel consists of a number of
bins and shelves that rotate either horizontally or vertically. It is fit for
small load storage and retrieval. Control of the carousal can be either manual
by the order picker or automatic. Example,
at airport the luggage are kept in the conveyor system and move towards the
passenger. The passenger need to pick up
his luggage from the conveyor.
Automated Storage and Retrieval
Systems (AS/RS)
- An AS/RS is a system of rows of rack,
each row having a dedicated retrieval unit that moves vertically and
horizontally along the rack, picking and putting away loads.
Very few warehouse operation uses Carousel or AS/RS system. Due to prohibitive cost,
cumbersome installation process, difficult in reconfigurability, and high maintenance
cost, most of the operation not to go for carousel or AS/RS system.
In the next session, we will recap what we learned so far about Order Picking method in chart form for easy reference. and let us analyse which order picking method is most appropriate for GSK customer order example.
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