Order picking

Picking at a glance

The merging of orders in a warehouse or production facility is carried out manually by employees (pickers) or automatically by picking robots and machines. The difference can basically be described as follows:

• Man-to-goods (manual)
• Goods-to-man (semi-automatic)
• Fully automated order picking

Manual order picking
(man-to-goods)

In a manual process, goods are put together with the help of pick lists or various picking systems. Working with paper is increasingly being replaced by paperless picking. The supporting systems guide the picker to the appropriate storage locations using various picking methods. They support him and monitor the removal of the goods.

The order picker moves through the warehouse to pick the goods from the pallets, flow racks, shelving racks etc.. This is why the method is called man-to-goods.

Semi-automatic picking
(goods-to-man)

The principle of the semi-automatic picking method is reversed. The goods are automatically transported in load carriers (containers or even entire shelves) from the warehouse to the picking station and made available to the picker.

The order picker therefore remains at his workstation and has the task of removing the goods from the load carriers in a suitable quantity and distributing them to the customer orders. For this reason, the semi-automatic method is often referred to as goods-to-man.

Fully automated order picking

In a fully automated picking process, the picking machines and picking robots completely replace the employee. However, this picking method is only suitable for certain articles, whereby not only the goods themselves, but also the economic efficiency plays a decisive role in the selection of the picking method.

Fully automatic processes are often too expensive to purchase and costly to operate and have a number of disadvantages.

In this article, we will show you which manual picking methods (man-to-goods) work best. We don't just give you tips or definitions, but explain exactly why paperless picking has clear advantages over the conventional pick list.

The manual picking processes

In addition to a picking list, there are many system-supported picking processes available to us today. Different systems can be used depending on requirements. The best and most frequently used picking methods include

• Pick-by-Scan
• Pick-to-Light
• Voice Picking
• Pick-by-Point®
• Pick-by-Frame®
• Pick-by-Cart
• Pick-by-Watch®
• Pick-by-Tablet

There are also some extensions and special solutions from LUCA Logistic Solutions:

• Pick-Radar®
• Pick-by-Weight
• Pick-by-RFID
• Pick-by-ePaper®

All LUCA systems can be found in the "Systems" menu or in the list at the top right. All these systems are managed from a central LUCA-Server and can also be used as combinations in single-level picking. In this case, we speak of hybrid solutions. With all these systems, picking orders can be processed more quickly without the need for separate training.

Picking times

To make manual picking efficient and deliver to the customer quickly, the following times must be recorded and optimized in the process.

What is a picking time?

The picking time is the sum of the individual times required for picking:

Picking time = base time + travel time + picking time + auxiliary time (dead time) + distribution time

Base time

The base time includes the organizational activities before and after the picking process:

• Printout of pick lists from the warehouse management software (if not paperless)
• Preparation of cardboard boxes, containers, corlettes or pallets
• Forwarding of picked orders

Travel time

The travel time defines the time it takes for the order picker to travel between the individual storage zones and storage compartments. This time can have a very large influence on the overall picking performance. The most important factors include

• Size of the picking zones and the route to the next picking point
• Orientation in the warehouse to find the storage compartment (aisle, shelf row, shelf level)

The possibility of the Multi-Order-Picking method should always be examined here.

Gripping time

Once the order picker has arrived at the shelf compartment, the time required to access the goods is measured. The picking time is also known as the removal time or picking time. This includes the following activities:

• Access to the articles
• Counting the quantities
• Storage of the number of items in the picking container

The optimization of the picking time and the error rate is often related to a system-side support for counting the number of items. Otherwise, the picking time itself cannot be greatly optimized and also depends on the type of product storage (pallet spaces, flow racks, shelving racks, etc.).

Auxiliary time (also known as dead time)

Before the order picker can access the goods, further additional processing activities must be carried out. These include

• Searching for the storage compartments
• Opening and closing the boxes or containers in the storage compartment
• Climbing ladders or using aids
• Recording of serial numbers, if required
• Safety packaging of the articles
• Withdrawal acknowledgement
• Application of lettering and labels

The non-productive time (dead time) is heavily dependent on the additional process steps required and can also be optimized. The time for training is not taken into account.

Distribution time

Distribution time includes non-productive activities that are heavily dependent on employee motivation and their attitude to the work. These include

• Break times for personal needs (WC, smoking)
• Unnecessary conversations with work colleagues (often about private topics)
• Waiting for the next instructions from superiors
• Waiting for system reactions (e.g. due to slow controls and non-optimal processes)

Optimizing distribution time is closely linked to organization, employee motivation and the working atmosphere.

Picking methods

In practice, it is all about the optimal distribution and organization of order throughput times in order to pick a customer order quickly and cost-effectively. For this reason, the organizational processes are often designed differently in order to minimize the effort involved. The basic methods include the following variants of picking methods:

Order-oriented, serial picking

A customer order is processed one after the other in different storage zones by one or more warehouse workers. This picking method is simple and does not require any complex organization. The training and definition of responsibilities for the pickers is simple. The disadvantages of this method are long travel times (long picking routes) and the unregulated transfer of orders to the next picking zone. The overall order throughput time is not optimal.

Order-oriented, parallel picking

Each order is divided into several partial orders so that the items can be merged in parallel. The orders can be divided into partial orders according to various criteria, e.g. according to storage zones, article volume for transportation, packaging criteria, etc. After picking, the partial orders are then merged.

Order throughput times are significantly shorter in order-oriented parallel picking than in order-oriented serial picking. However, the overall material flow, the organization of the merging of partial orders and the uneven utilization of the individual storage zones are more problematic. However, they can be well controlled with an appropriate material flow control system and automatic conveyor technology.

Series-oriented, parallel picking

Before starting, the total orders are first grouped into series and distributed to the individual storage zones in parallel. However, the orders should not be grouped randomly, but in series, so that a maximum number of picks are made per storage bin. The articles are first collected and then distributed to the individual orders.

The advantage of this series-oriented picking method is that a storage bin only has to be accessed once per series and not per individual order.

Read more details about the individual picking methods and find out exactly which picking method should be used when.

This saves walking distances and shortens the order throughput time. Items can be distributed directly during removal with the help of Pick-by-Cart or Pick-by-Frame®. The alternative is later distribution at special workstations with Put-to-Point® or Put-to-Light. The series-oriented picking method requires sophisticated technical support.

Example of a simple order picking process

The individual orders are recorded in a warehouse management system and any partial orders are generated from them. The compilation (provision or merging) of the goods for packaging or delivery for production is then called consolidation, which we will describe in detail later in a separate article. The process organization can be very different here.

In the following points, we will directly compare an order picker with a paper picking list and an order picker with paperless picking and present the advantages and disadvantages in the individual steps. The training is simple.

Start of orders

In a process with a picking list, the picker takes the next printed order and simply starts working.

Paperless picking orders are activated using various methods, e.g. by using barcode scanners (for example: delivery bill, collection unit, container or carton), RFID or by activating the orders on an MDE terminal. The technology used depends heavily on the desired process and number of storage zones.

The disadvantage of paper-based picking at the start is that the picking slip can get lost, which can lead to a complete error in order processing. For this reason, special printers are set up for the picking slips in order to avoid any loss of picking orders due to unintentional removal of the picking slips, which would happen very quickly with generally used printers.

The advantage of paperless picking here is that the start time can be recorded precisely.

Guided tour to the storage area

If the picker has a conventional picking list in his hand, he has to read the next storage location designation, find the storage location in the storage zone and check it visually. Disadvantage: Errors often occur here after many hours of work, leading to serious quality losses.

With paperless picking, the employee is guided visually or acoustically to their picking compartment. For quality assurance purposes, the picker must confirm the storage location by reading the barcode or by voice, depending on the picking method. The best, fastest and safest picking methods here include Pick-to-Light, Voice Picking, Pick-by-Frame, Pick-by-Point and Pick-by-Watch. The worst picking processes in a warehouse include applications with smart glasses: Pick-by-Vision.

The clear advantage over the paper list is the confirmation of the storage location and the system's direct reaction to an error. The high picking performance is characterized by the short travel time (search time).

Withdrawal of goods

If the employee has already arrived at the correct storage compartment with the picking list, they must find the right line of text again and read off the number of items correctly. Reading the number of items is one of the biggest sources of error in paper-based picking. This is where the order picker's ability to concentrate for several hours is in great demand.

With paperless picking, the employee is shown the quantity directly at the storage location or on their mobile device. With the voice-guided system, the quantity is displayed in the headset. The advantage here is that the employee can concentrate better on their work and the system informs them of the next step at the appropriate time.

In both cases, the employee must count out the correct quantity themselves. For large quantities, we recommend the use of counting scales and a Pick-by-Weight system.

Confirmation of the quantity

The withdrawal quantity is "ticked off" on a picking list with a ballpoint pen or the shortfall is noted, which then has to be manually reworked later in order processing.

The withdrawal quantity is posted automatically and immediately in a paperless system, which is a great advantage.

Conclusion

Once all the items on a picking slip have been completed, the picker can leave the storage zone, pack his order himself or hand it over for further processing.

Conclusion

The system-side completion is realized differently. Depending on the picking process used, the picker is informed and clearly requested to carry out the next steps. The exact time is recorded.

Picking in the warehouse is one of the most important activities in a logistics or production company. The quality, error rate, picking performance and consolidation of partial quantities are significantly better with paperless picking systems.

The warehouse management system can precisely track every customer order in the picking process. Several data collection devices and systems are available for electronic data collection. Talk to us. We will be happy to help you optimize your order picking.