May 16, 2020

Order-picking methods in Warehouse | What is order picking ?

This is the world during which advances in technology have transformed the picking operation and improved accuracy and productivity significantly. The introduction of barcoding, voice technology and pick-by-light systems isn't only improving warehouse picking operations but also producing a suitable return on investment.

The following picking methods are currently in use in today’s warehouses:
● paper pick lists;
● pick by label;
● pick by voice;
● barcode scanning;
● radio frequency identification;
● pick by light/pick to light;
● put to light;
● automated picking.

A paper pick list will normally detail the order number, location, product code, description, and quantity to be picked. If utilizing a WMS, each line are going to be shown in sequence, enabling the picker to travel the foremost efficient way round the warehouse and ending up as close to the despatch bay as possible.

The operator is however at liberty to choose a different route if it is felt that it is more direct. The fastest-moving items should be placed on the brink of the despatch area to attenuate travel. Stock control systems and manual applications
may not have this ability and thus some sort of manual intervention is required to scale back the quantity of pick travel undertaken. The picker will utilize a trolley, cage, pallet truck, or possibly a forklift truck.
The advantage of employing a forklift truck is that the pallet are often lifted to an appropriate height because the picker continues along the route.
Any discrepancies are written on the picklist. When the picklist is returned to the supervisor, the discrepancies should be checked immediately and alternative locations provided if there are shortages. Details of the pick are entered
manually into the system. This can cause errors if the writing is illegible or there's confusion over the way variety is written. This all adds time to the operation. Paper picking requires little investment; however, it can have low
accuracy and may require order validation.
Once an order has been picked the operator has got to return to the office for further pick lists or instructions. It is not a real-time system.

In this system, pick lists are a series of labels on a sheet, which are printed in pick order. The picker attaches a label to every item picked and returns any unused labels to the supervisor’s office. Any discrepancies are checked immediately
and additional labels printed if the stock is out there elsewhere within the warehouse. This can eliminate a step at the despatch area as address labels are
already attached. It’s also more accurate than paper picking as you can soon tell if there has been a mix-pick in terms of quantity.
These are both very manual operations and believe the operator, supervisor, and administration clerk all playing their part to make sure accurate information is recorded.
These manual sorts of operation and low levels of productivity and accuracy have led to a rise within the use of technology within the warehouse.

The use of voice technology is gaining ground in warehouses globally, particularly for order picking, although other processes like cycle counting, put-away, and replenishment also utilize the system. Many companies are moving directly from paper picking to voice and bypassing barcode scanning.
Operators are issued with a headset and a microphone along side alittle terminal that's attached to a belt or are often worn on the wrist. The WMS sends messages to the pc via frequency (RF) transmissions, utilizing transmitters installed throughout the warehouse, and these messages are converted into voice commands. The operator also uses voice to speak back to the system.
Voice was first employed about 20 years ago for cold-storage applications where gloves and extreme temperatures made it difficult to use scanners and paper based systems.
The list of advantages are stated as being very comprehensive. They include:
●●increased accuracy;
●increased productivity;
● reduction in paper usage;
● reduction in errors through elimination of re-keying data;
● improved safety through hands- and eyes-free operation;
● reduction in damage;
● real-time stock updates leading to fast and accurate replenishment;
● real-time updates regarding potential shortages;
● increased operator time on the warehouse floor;
● reduced training times;
● multilingual, accommodating a diverse workforce;
● easy to integrate with other systems;
● potential reduction in employee turnover; and
● normally a quick ROI.

A barcode consists of a series of vertical bars of varying widths that represent letters, numbers and other symbols. Barcodes are wont to identify products, locations within the warehouse, containers (totes, cartons, pallets), serial and batch numbers.
As with many areas of logistics, there's no conformity and thus no universal barcode. This can make it difficult to transfer products between companies and countries. The main barcode standards include EAN-8, EAN-13 and Code 128.
Appendix 2 features a comprehensive guide to all or any the barcode options. Recent developments include two-dimensional barcodes, the advantage being that you simply can store a greater amount of knowledge within a way smaller space.

A current debate is whether or not the pharmaceutical industry should be investing in 2D technology or frequency identification (RFID) tags. Both are ready to hold more information than a typical linear barcode; however, certain types of RFID tags are rewritable. Currently there's a big difference in price between barcodes and RFID tags.
Barcode readers come in many different forms. They can be hand-held, static, truck-mounted, or wearable.
The hand-held scanner has a screen and a trigger. It scans the barcode, deciphers it, and stores or transmits it to a computer. These scanners have the power to read a variety of various sorts of barcodes, although this may depend upon the manufacturer, model, and price. Some PDAs and mobile phones even have scanners and cameras ready to read one-dimensional and two-dimensional barcodes. Data can be read, stored in the scanner and then downloaded by attaching the scanner to the computer via a USB connection. Information can also be transferred in real-time via RF.
A pen or wand scanner swipes the barcode through contact and reads and deciphers the knowledge.
Barcode scanning, utilizing hand-held scanners with real-time data transmission has made data collection faster and more accurate in today’s warehouse environment. It has also increased productivity by ensuring that operators don’t need to return to the office for instructions whenever they complete a task. The instructions are on the screen within the sort of text which the operator scrolls through and advances by choosing specific commands.
However, barcode scanning with hand-held devices does have drawbacks. These include having to line down the reader whilst tasks are administered or struggling to carry the unit and perform the task at an equivalent time. Errors tend to occur when using hand-held scanners if they're holstered or put down on a surface. This movement can cause the picker to select from the incorrect location
or miscount the items. There is potential for greater damage if scanners are dropped or mishandled. Safety is also an issue as operators try to read the instructions whilst in motion.
A stationary scanner will read the barcode because it passes by on a conveyor, for instance. This requires the barcode to be easily visible, intact and during a uniform position on the item. Static readers tend to be used with belt sorters and conveyors for example.
Recent advances in this area include the introduction of hands-free, wearable computers that enable the operator to handle the product with both hands as opposed to having to hold a barcode scanner, paper pick list or roll of labels.
A wireless-enabled, wearable computer allows operators to receive instructions in real-time, scan barcodes, enter data, and transmit in real-time. Wearable computers are typically worn on the wrist or lower arm and feature a screen and a small keyboard or touch screen, with the choice of a finger-mounted scanner that either plug into the unit or communicates via Bluetooth technology. These have gained popularity within warehouses where heavy items require both hands liberal to execute a task. Companies choose wearable solutions for a variety of reasons. Wearable computers require little or no change to existing warehouse operations that currently use hand-held computers. Wearable computers also require little re-training of staff and usually no software modification. The existing applications designed for hand-held or forklift mounted can usually run on a wearable device with no modification.
Workers simply got to suits putting the wearable components on, to the texture of the pc on their wrist, and if chosen, to the utilization of a hoop scanner. Today’s wearable units typically weigh just a couple of ounces, so fatigue and comfort are typically not an issue. Power is typically supplied from A battery pack worn on the armor at the tiny of the rear.
By using wearable computers, one task is eliminated, thus making the picking process quicker and potentially reducing errors. Productivity and accuracy improvements can quickly add up to
substantial savings.

The computers can also be supplied with easy-to-read touch screens and two-dimensional imagers. They can be configured to be voice-enabled, allowing pick operations to be even more accurate as items are often scanned to make sure the right item has been picked from the location.
his fingers are around the box, making it more difficult to grip. This compares with the operator in Figure 6.7, who is using both hands to hold the box.
These systems are also providing benefits in other areas including improved customer service, decreased training time, a reduction in damages and accidents, increased employee satisfaction and increased compliance.
One of the main disadvantages of barcodes is their potential to be damaged, thus making reading difficult and/or potentially inaccurate. A recent advance in hand-held units by companies such as Tecsys is visual logistics whereby instead of lines and lines of text operators are being presented
with a visual warehouse location map to quickly guide them to the assigned pick location and a visual guide as to the exact carton or tote into which to put the selected products, eliminating the wasteful and time-consuming process of searching for the pick slot. They are also being presented with product-specific images to enable a visual validation and to ensure that the appropriate quality
assurance checks are performed.

RFID may be a means of uniquely identifying an item using radio waves. Data is exchanged between tags and readers and counting on the frequency, may or might not require line of sight. Common uses in today’s world include library books, toll passes and access ID cards. Its use within the supply chain has been limited until recently. However, high-profile projects within the US military, Asda, Walmart and Tesco have increased awareness.
The system enables the simultaneous reading of multiple items as against barcodes, which require to be read individually.
There are two sorts of RFID tags: people who are passive, haven't any power source, limited data storage capacity, are read only and have a limited read range, and those that are active, have their own power source, have a bigger  data-storage capacity, have a read/write capability and are readable from a greater distance.
Passive tags hold little actual data but are ready to identify an item to a database where more comprehensive data is stored. For example, a conveyor-based sortation system can identify the item and interrogate the database to receive routing instructions.
Active tags have a better capacity and may have their item’s status updated once a task has been completed. They have a shorter writing range than reading range and the internal power source is likely to burn out within 5 to 10 years.
Frequency is a crucial think about transmission range and speed and not all frequencies are available to be used globally, which may cause issues from a supply chain perspective.
Individual-item-level tracking for the majority of products is unlikely to happen during the next 10 years or so due to the cost of implementation; however, unit-load identification is possible and potentially cost-effective. The tracking of roll cages, pallets and returnable packagings like totes, kegs, barrels and trays are often made simpler and price effective through the utilization of RFID.
The difficulty faced by proponents of RFID is that barcodes are so cheap to supply and remain an accurate and cost-effective method of identification.
The cost of operating an RFID system will vary tremendously counting on the appliance , the dimensions of installation, the frequencies used and therefore the quantity of tags purchased. As take-up increases, the costs will reduce.

The following items are required to introduce an RFID application:
● RFID readers (from £300 to £1,500);
● RFID tags (from £0.05 to £0.10 upwards counting on the frequency and method of application to the item);
● middleware;
● systems upgrades; and
● RF network within the warehouse.
Current disadvantages of RFID include:
● reading issues when in close proximity to liquids and metal;
● dead areas in the warehouse where signals are weak;
●tags can be damaged by liquids, static discharges and magnetic surges; and
● intermittent data capture, with the likelihood of some tags not being read.

Pick to light or pick by light uses light-indicator, LED or LCD modules mounted to shelving, flow racks, pallet racks or other storage locations.
This system tends to be utilized in conjunction with zone picking. To begin the method an operator scans a barcode on an arriving pick tote or shipping carton which denotes subsequent order number to be picked. This communicates
to the system that the operator is prepared to select . The system then sends a message to the zone during which the operator is stationed and every one the pick locations for that specific order illuminate directly .
A alphanumeric display tells the operator the number to pick; once this has been picked the operator turns the sunshine off to verify the pick. The operator can then move on to the next location indicated. The pickers continue until the pick in their area is completed. Some systems allow the operator to scan the item before placing it within the shipping carton to make sure accuracy. This does however hamper the method but may be a check on the accuracy of the put-away process.
Other systems provide a picture of the merchandise to be picked to extend accuracy.
The tote is then passed to the next zone for the rest of the order to be picked. This is a typical pick-and-pass method of picking.
All information is exchanged in real time with the enterprise resource planning (ERP) or WMS system.
Unlike scanning and voice picking, which are sequential in nature, all locations are indicated to the operator at an equivalent time. This means that the operator can choose the simplest pick path.
Pick by light necessitates operators being stationed in zones taking care of a particular quantity of SKUs. The order tote moves between zones on a conveyor, cart or other transportation method.
As operators are based in a specific area, this reduces the amount of walking required within the warehouse.
At the top of the pick an operator will check the order number, possibly check the load of the consignment, attach an address label, add the delivery documentation and signify the carrier if multiple carriers are used.
By getting the operator to the proper location whenever, the picking process is greatly improved and productivity increased. Training is relatively simple and is conducive to the use of temporary labor and seasonal employees. Some companies have introduced portable pick-by-light systems which will be moved round the warehouse as needed or to a short lived warehouse to hide peaks in business.
The lights can be retrofitted onto shelving and racking. The system can also be used in conjunction with carousels.
In terms of systems integration, pick to light is comparatively simple. It requires the downloading of a file with the order number, product codes, locations and quantities. It can easily affect part cases and individual items.
A further enhancement of the pick-to-light system is the SpeasTech system where indicator lights are automatically deactivated by the motion of the picker’s hand through an infrared window in and out of the bin.

This system is particularly prevalent in retail store replenishment operations. The WMS will consolidate all the shop orders for a specific group of stores. This might be done by region or despatch times from the distribution centre (DC). The system must make sure that each group of stores has similar volumes where possible. Depending on daily volumes, staff can increase or decrease the amount of locations (stores) that they appear after. Large-volume stores could also be situated during a number of various zones with the totes/containers being consolidated at the despatch area. Individual product lines required by the stores are going to be picked in bulk and
transferred to the right operator station by cart, pallet truck or via a conveyor. Each store will have a tote or totes assigned to it.
Once the SKU has received the ‘put’ station the operator scans each item and a flashing light displays at each location indicating which containers (relating to a specific store) require that product and the way many items are required. Confirmed ‘put’ results are uploaded to the system in real time to update the WMS. With pack-to-light or put-to-light systems there is a requirement to set up a central processing area, which can result in the design of a new layout and the introduction of further equipment.
In terms of systems, put-to-light technology requires order consolidation and a batch pick of products. Part pallets or cases will got to be returned to stock if stores don't order in complete cases or the entire number of units ordered does not equate to full case quantities.
Pack or put to light are often more dynamic and works well with cross-dock operations where product are often received, allocated, picked and despatched on an equivalent day if required.
One further note to feature here, which is additionally relevant to other picking strategies, is that the introduction by retailers of pick sequences that duplicate store layouts, enabling retail staff to replenish shelves efficiently.
A UK clothing retailer installed a put-to-light system at one among its DCs. Twenty stations were installed, each with a capacity of up to 24 stores. Product is automatically delivered to every station, utilizing an automatic storage and retrieval system.
The light display at each location indicates what percentage items must be placed into each of the order totes, which suggests that one operator can take care of 24 store orders at the same time. Once an order tote is full, the display instructs the operator to push the tote onto a conveyor system, which takes it to the despatch area.
The high-rate put stations (up to 1,000 items per hour, counting on order profile) significantly reduce the time taken by staff travelling between store orders.
Operators are fed with a continuous supply of products and each workstation is ergonomically designed.

Table 6.1 shows the varied methods of picking utilized within today’s warehouse.
These show a mixture of picker to goods and goods to picker. In section one we tend to possess a single-pick operation where the picker collects all the things for a specific order then takes it to despatch before picking the next order. Picks can be made from a floor-level pick face or, if there are significant numbers of SKUs and too few floor locations, from a higher-level pick face. In this situation the productivity reduces significantly as soon because the  operator has to go up into the air.

In section two we've a two-stage process where product is picked in bulk, for instance by batch, followed by a sortation process into individual orders. Although in two stages, the pick rates are reasonably high and it also includes a countercheck of things and quantities, thus improving accuracy. 

Systems use batching to collect all the items for specific orders.
In section three we've the utilization of carousels, conveyors, flow racks and fully automated AS/RS systems.
Utilizing this form of picking, we see pick accuracy rates increasing together with the ability to handle large numbers of SKUs and items. Table 6.2 provides a comparison between the different pick methods in terms of advantages and disadvantages.
Marc Wulfratt of MWPVL provides the following (Table 6.3) in terms of cost and accuracy comparisons. Costs are based on 2013 prices. The costs are approximate and are based on a 100,000 square foot warehouse with 25 operators and 2,500 SKU.

It is an accepted incontrovertible fact that increased errors cause increased costs. There are many calculations for the value of a mis-pick. The elements involved in an incorrect pick include:
●● cost of recovering the item;
●● labour cost of in-handling and checking the item on its return;
●● cost of picking the replacement item;
●● cost of re-packing;
●● cost of re-delivery;
●● administration costs of handling credit claims, etc;
●● income with regard to non-payment of invoice;
●● potential loss of sale for the product incorrectly despatched;
●● cost of re-training staff; and
●● possible stock write-off if the returned product is outside an acceptable shelf life or has been damaged in transit.

In addition, if the error is an under-pick then it could end in a lost sale and therefore the associated margin. If it’s an over-pick and is reported, there is the cost of transport to collect the item and labor costs as above or potentially a loss of
margin in persuading the customer to keep the item. If not reported, the value becomes the loss of the merchandise and margin.

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