What is picking?
Picking refers to an activity in which an order picker uses a picking method in a picking procedure to pick the partial quantity from a storage bin in an order-oriented manner. The picking performance, the picking time (pick time) and the error rate in the picking process are decisive. The sales order is often processed directly by the warehouse management system with the pick list in series-oriented storage zones.
In this article we explain the meaning of picking. We define exactly what picking is and what types and methods there are.
Order picking at a glance
A picking of orders in a warehouse in logistics or production is carried out manually by the employees( picker / picker) or automatically by picking robots. The difference can basically be described as follows:
- Man-to-goods, manual picking
- goods-to-man, semi-automatic picking
- Fully automatic order picking
The individual differences are presented here in the Dertail.
Manual order picking
In a manual process, goods are assembled with the help of pick lists or various picking systems. Paper picking is increasingly being replaced by paperless picking. The supporting systems guide the picker to the appropriate storage locations using different picking methods. They support him and control the picking of the goods.
The picker moves through the warehouse to pick the goods from the pallets, flow racks, shelving racks etc. For this reason, manual picking is called man-to-goods.
Semi-automatic order picking
The principle with the semi-automatic picking method is reversed. The goods are automatically transported in load carriers(containers or even entire racks) from the warehouse to the picking location and made available to the picker in the access area.
The picker therefore remains at his workplace 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, semi-automatic picking is often referred to as goods-to-man picking.
Fully automatic order picking
In a fully automated picking process, the automated 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.
Often the fully automatic processes are too expensive in terms of purchase and operating costs and have some disadvantages. We will deal with the characteristics of fully automated picking in a separate article.
In this article we will show you with which picking methods manual picking (man-to-goods) works best. We do not only give you tips or definitions for this, but we also explain in detail why paperless picking has clear advantages over the conventional picking list.
The manual picking procedures
In addition to picking with a picking list, there are many system-supported picking procedures available to us today. Different systems can be used depending on requirements. Among the best and often used picking methods are
- Voice Picking
There are also some extensions and special solutions from LUCA Logistic Solutions:
All LUCA systems can be found in the "Systems" menu or in the list at the top right. All these systems are managed by a central LUCA-Server and can also be used as combinations in order picking. In this case we speak of hybrid solutions. With all these systems, picking orders can be processed faster, without special training.
Definition of picking times
In order to make manual picking efficient and to supply the customer quickly, the following times must be recorded and optimized in the process.
What is a picking time?
The picking time is a sum of the individual times required for picking:
Picking time = base time + travel time + picking time + idle time (dead time) + distribution time
The base time includes the organizational activities before and after the picking process:
- Printout of the picking lists from the warehouse management software (if not paperless)
- Preparation of cardboard boxes, containers, corlettes or pallets
- Forwarding of picked orders
The route time defines the time the picker travels between the individual storage zones and storage bins. This time can have a very large influence on the overall picking performance. Some of the most important factors are:
- Size of the picking zones and the way to the next picking
- 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.
Once the order picker has arrived at the shelf compartment, the time taken 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 pieces in the picking container
The optimization of the gripping time and the error rate is often related to a system support for counting the quantities. Otherwise, the gripping time itself cannot be strongly optimised and also depends on the type of storage of the products (pallet locations, flow racks, shelving racks, etc.).
Non-productive time (also called dead time)
Before the picker can access the goods, there are other additional processing activities that have to be added to this. These include:
- Searching the storage compartments
- Open and close the cartons or containers in the storage compartment
- Climbing ladders or use of aids
- Recording of serial numbers, if necessary
- Safety packaging of the articles
- Withdrawal acknowledgement
- Application of markings and labels
The non-productive time (dead time) is strongly dependent on the additional process steps required and can be optimized quite well. The time for familiarization is not taken into account.
Distribution time includes non-productive activities that are highly dependent on employee motivation and their attitude to work. These include:
- Break times for personal needs (WC, smoking)
- Unnecessary discussions with work colleagues (often about private issues)
- Waiting for next instructions from superiors
- Waiting for reactions of the systems (e.g. due to slow controls and non-optimal processes)
The optimization of distribution time is strongly linked to the organization, motivation of employees and the working atmosphere.
The picking methods
In practice, it is all about the optimal distribution and design 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 sales 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 extensive organization. The training and definition of responsibilities for the pickers is simple. Disadvantages of this method are long travel times (long picking distances) and the unregulated transfer of orders to the next picking zone. The total order throughput time is not optimal.
Order-oriented, parallel picking
Each order is separated into several partial orders so that picking can be carried out in parallel. The division of orders into partial orders can be carried out according to various criteria, e.g. according to storage zones, article volume for transport, packaging criteria, etc. After picking, the partial orders are merged.
The order throughput times are significantly shorter in order-oriented parallel picking than in order-oriented, serial picking. However, the entire material flow, the organization when merging partial orders and the uneven utilization of the individual storage zones are more problematic. However, they can be easily regulated with an appropriate material flow control and automatic conveyor technology.
Series-oriented, parallel picking
Before picking is started, the total orders are first combined in series and distributed to the individual storage zones in parallel. However, the orders should not be combined arbitrarily, but rather series-oriented so that a maximum number of picks can be 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 needs to be accessed once per series and not per individual order.
This saves walking distances and shortens the order processing time. The distribution of the articles can be carried out directly at the picking stage using Pick-by-Cart or Pick-by-Frame® are carried out. The alternative is a later distribution at special workstations with Put-to-Point® or Put-to-Light. The series-oriented picking method requires sophisticated technical support.
Example for the process flow of a simple picking
The individual orders are recorded in a warehouse management system and any partial orders are generated from them. The compilation (provision or combination) of 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 a picker with a picking list on paper and a picker with paperless picking and present the advantages and disadvantages in the individual steps. The training is easy.
Start of the orders
The activation of paperless picking orders is done with different methods, e.g. by using barcode scanners (for example: delivery note, collection unit, container or carton), RFID or by activating the orders on a MDE terminal. The technology used depends strongly on the desired process and number of storage zones.
The disadvantage of paper-based picking at the start is that the picking slip can be lost, which can lead to a complete error in order processing. For this reason, special printers are set up for the pick slips in order to avoid a possible loss of picking orders due to unintentional taking along of the pick slips, which would happen very quickly with commonly used printers.
The advantage of paperless picking is that the start time can be recorded exactly.
Guided tour to the campground
If the order 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 visually check it. Disadvantage: after many hours of work, errors often occur here that lead to serious quality losses in order picking.
In the case of paperless picking, the employee is guided visually or acoustically to his picking compartment. For quality assurance, the picker must confirm the storage location by reading the barcode or by voice, depending on the picking method. This is one of the best, fastest and safest picking methods: Pick-to-Light, Voice Picking, Pick-by-Frame, Pick-by-Point and Pick-by-Watch. Among the worst picking methods in a warehouse are applications using data glasses: Pick-by-Vision.
A clear advantage over the paper list is the security provided by the confirmation of the storage location and the direct reaction of the system to an error. The high picking performance is characterized by the short travel time (search time).
If the employee with the picking list has already arrived at the correct storage compartment, he must find the appropriate line of text again and read off the number of pieces correctly. Reading the number of pieces is one of the biggest sources of error in paper-based picking. Here the ability to concentrate the picker for several hours is very much in demand.
With paperless picking, the employee is shown the quantity directly at the storage bin or on his 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 his work and the system informs him about the next step at the right time.
In both cases, the employee must count the appropriate quantity himself. 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 must then be reworked manually later in order processing.
The withdrawal quantity is booked automatically and immediately in a paperless system, which is a great advantage.
Completion of picking
Once all items on a picking slip are completed, the order picker can leave the warehouse zone, pack his order himself or hand it over for further processing.
The system-side closure is implemented in different ways. Depending on the picking procedure used, the picker is informed and clearly requested to carry out the further steps. The exact time is recorded.
Order picking in the warehouse is one of the most important activities in a logistics or production company. The quality, error rate, picking performance and the combination of partial quantities are significantly better with paperless picking systems. The warehouse management system can track every customer order in the picking process exactly. Several data acquisition devices and systems are available for electronic data acquisition. Talk to us. We will be pleased to help you to design your order picking system in an optimal way.
Which order picking is best suited to your company?