Picking
Picking of goods is the merging of items from the total quantity into one order. The warehouse management system controls the withdrawals from the storage bins using various picking methods.
In the article you will find not only the definition or meaning, but also important information about the picking methods and picking times.
Picking at a glance
The merging of orders in a warehouse or production is done manually by the employees(pickers / 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 automatic picking
Manual picking
(man-to-goods)
In a manual process, goods are assembled with the help of pick lists or various pick 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 control the picking of the goods.
The picker moves through the warehouse to pick the goods from the pallets, flow racks, shelf racks etc. For this reason, the method is called man-to-goods.
Semi-automatic picking
(goods-to-man)
The principle in the semi-automatic picking method is reversed. The goods are automatically transported from the warehouse to the picking station in load carriers(bins or even entire racks) and made available for the picker to access.
The picker therefore remains at his workstation and has the task of removing the goods from the load carriers in a suitable number of pieces and distributing them to the customer orders. For this reason, the semi-automatic method is often referred to as goods-to-man.
Fully automatic picking
In a fully automated picking method, the picking machines and picking robots completely replace the employee. However, this picking method is only suitable for certain items, and it is not always just the goods themselves that play a decisive role in the selection of the picking method, but also economic efficiency.
Often, the fully automated processes are too expensive in terms of purchase and operating costs and have some disadvantages.
In this article we will show you with which manual picking methods (man-to-goods) everything works best. We don't just give you tips or definitions for them, but explain in detail why paperless picking has clear advantages over traditional pick lists.
The manual picking methods
In addition to a pick list, many system-supported picking methods are available to us today. Depending on the requirements, different systems can be used. Among the best and often used picking methods are:
- 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 systems of LUCA can be found in the menu "Systems" or in the list on the right side above. All these systems are managed by a central LUCA-Server and can also be used as combinations in single-stage picking. In this case we speak of hybrid solutions. With all these systems picking orders can be processed faster, without 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 a sum of the individual times required for a pick:
Picking time = base time + travel time + pick time + auxiliary time (dead time) + distribution time
Base time
The basic time includes the organizational activities before and after the picking process:
- Printout of the pick lists from the warehouse management software (if not voucherless)
- Preparation of cardboard boxes, containers, corlettes or pallets
- Passing on the picked orders
Travel time
The travel time defines the time for the picker to travel between the individual storage zones and storage bins. This time can have a very large impact on overall picking performance. The most important factors include:
- Size of the picking zones and the path to the next pick
- Orientation in the warehouse to find the storage compartment (aisle, row of shelves, shelf level).
Here, the possibility of the Multi-Order-Picking method should also always be investigated.
Gripping time
Once the picker has arrived at the shelf, the time for accessing the goods is measured. The picking time is also called the removal time or the picking time. This includes the following activities:
- Access to the articles
- Counting the quantities
- Placement of the number of pieces into the picking bin
The optimization of the gripping time and the error rate is often related to a system-side support for counting the number of pieces. Otherwise, the gripping time itself cannot be optimized much and also depends on the type of storage of the products (pallet spaces, flow racks, shelf racks, etc.).
Secondary time (also called dead time)
Before the picker can access the goods, there are other additional processing activities that must be included. These include:
- Searching the storage compartments
- Opening and closing the boxes or containers in the storage compartment
- Climbing ladders or using assistive devices
- Recording of serial numbers, if required
- Article security packing
- Withdrawal acknowledgement
- Application of inscriptions and labels
The non-productive time (dead time) is strongly dependent on the required additional process steps and can certainly be optimized well. The time for training is not taken into account.
Distribution time
Distribution time includes non-productive activities that are highly dependent on employee motivation and attitude toward the work. These include:
- Break times for personal needs (WC, smoking)
- Unnecessary conversations with work colleagues (often about private topics)
- Waiting for next specifications from superiors
- Waiting for systems to respond (e.g., due to slow controls and non-optimal processes).
Optimization of distribution time is strongly connected with organization, motivation of employees and working climate.
Picking methods
In practice, it is a question of the optimum 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 to minimize the effort. 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 elaborate organization. The training and definition of responsibilities for the pickers is simple. Disadvantages of the method are long travel times (long picking routes) 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 the merging of the articles can be done in parallel. The division of orders into partial orders can be done according to different criteria, e.g. according to storage zones, according to article volume for transport, according to 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 when combining the partial orders and the uneven utilization of the individual storage zones are more problematic. However, they can be well regulated 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 are not to be grouped arbitrarily, but series-oriented in such a way that a maximum number of withdrawals is to 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 has to be approached once per series and not per individual order.
This saves the walking distances and shortens the order throughput time. The distribution of the articles can be carried out directly at the time of 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.
Read even more details about each picking method and learn exactly which picking method to use, when.
Example of the process 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 consolidation) 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 a picker with a paper pick list and a picker with paperless picking and present the advantages and disadvantages in each step. The training is simple.
Orders start
In a process with a pick list, the picker takes the next printed order and simply starts his activity.
The activation of paperless picking orders is done with different methods, e.g. by using barcode scanners (for example: delivery bill, 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 document-based picking at the start is that the pick slip can get lost, which can lead to a complete error in the order processing. For this reason, special printers for the pick slips are set up for this purpose, in order to avoid a possible loss of the picking orders by unintentional taking away of the pick 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 campsite
If the picker has a conventional pick list in his hand, he must read off the next storage location designation, find the storage location in the storage zone and visually check it. Disadvantage: Errors often happen here after many hours of work, leading to serious quality losses.
In 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. The best, fastest and safest picking methods here include: Pick-to-Light, Voice Picking, Pick-by-Frame, Pick-by-Point and Pick-by-Watch. Among the worst picking practices in a warehouse are data goggle applications: Pick-by-Vision.
The clear advantage over the paper list here is the safeguarding 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).
Goods withdrawal
If the employee has already arrived at the correct storage compartment with the pick list, he must find the appropriate text line again and read off the number of pieces correctly. Reading off the number of pieces is one of the biggest sources of error in document-based picking. This is where the order picker's ability to concentrate for several hours is very much in demand.
With paperless picking, the employee is shown the quantity directly at the storage location or on his mobile device. In the voice-guided system, the quantity is displayed in the headset. The advantage here is that the employee can concentrate better on the work and the system informs him about the next step at the appropriate time.
In both cases, the employee must count out the appropriate quantity himself. For large quantities, we recommend the use of counting scales and a Pick-by-Weight system.
Quantity confirmation
The withdrawal quantity is "checked 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 booked automatically and immediately in a voucherless system, which is a very big advantage.
Conclusion
Once all items on a pick slip have been completed, the picker can leave the storage zone, pack his order himself or hand it over for further processing.
The system-side completion is realized differently. Depending on the picking method used, the picker is informed and clearly requested to carry out the next steps. The exact time is recorded in the process.
Conclusion
Picking in the warehouse is one of the most important activities in a logistics or production company. The quality, the error rate, the picking performance and the consolidation of partial quantities are significantly better with paperless picking systems.
The warehouse management system can accurately track each customer order in the picking process. Several data collection devices and systems are available for electronic data collection. Talk to us. We'll be happy to help you get the most out of your picking.
Do you have any other questions about your picking?
Talk directly to our experts. We will be happy to help you.
