Directing and tracking workflow can become very complex from a software perspective in distribution centers that make use out of automated material handling such as carousels, automated storage and retrieval Systems (AS/RS) and conveyors. Numerous software systems may be in use, such as WMS, WCS, ERP and machine-level controls. Determining which of these systems should be responsible which decisions can be a very contentious topic. Often the IT team prefers to have as few systems as possible with the WMS and ERP interfacing directly with the equipment. However, it is not uncommon for the Operations team to prefer to utilize software such as WCS to provide increased functionality even though this may make for a more complex software architecture.
It is not surprising then that there has recently been a significant muddying of the waters when it comes to the ideal roles for WMS and WCS. Many WCS providers have sought to expand their software offerings and have marketed their products as an alternative to WMS. ERP and WMS companies are also pushing the limits of their systems to provide the Operations team with the functionality they need while giving CIOs the uniform code base they desire. With the overlap between WMS and WCS systems that now exists, companies have some decisions to make about the roles each system should play.
To help you make decisions about your company’s distribution center system architecture, let’s take a look at the relative strengths and weakness of WMS and WCS systems and examine the implications of pushing the limits of either one.
Warehouse Management Systems (WMS)
WMS systems are now in their fourth decade of use in American warehouses. Traditionally the WMS has performed:
- Global planning and confirmation for all warehouse functions
- Inventory allocation (shared with ERP system)
- Auditing inbound product against vendor purchase order
- Directed putaway
- Management of RF mobile devices to direct and confirm transactions
- Management of vehicle-based order picking
- Shipment confirmation
- Inventory management/cycle counting
- Bin replenishments
WMS Strengths
- Ability to maintain overall visibility and control by communicating with various subsystems such as:
- WCS
- Parcel manifesting software
- Labor management software
- Slotting software
- Ability to optimize complex picking processes such as:
- Cluster picking
- Zone picking
- Batch picking
- Ability to manage complex bin replenishment methodologies
- Ability to take advantage of regular upgrades and enhancement from software development
WMS Weaknesses
- Most WMS systems do not interface with material handling systems as part of standard functionality (customization required)
- Transaction speeds can be slower than for WCS
- Black holes of visibility often exist, i.e. no visibility into work flow in process within a material handling system
- Inability to dynamically re-plan work flows
Warehouse Controls Systems (WCS)
The concept of WCS is a slightly newer one which has evolved from decades old machine controls technology. Traditionally the WCS has performed:
- Communication with machine-level controls for automated material handling systems
- Conveyors, carousels, AS/RS systems, sortation systems, label printer applicators, weigh scales, etc.
- Bin-level inventory control within a material handling system
- Dynamic wave management
- Dynamic labor re-balancing
- Single points of visibility and control within a material handling system
WCS Strengths
- Tailor-made for MHE interfaces
- Large portions of this functionality can often be achieved without the need for source code modifications
- High rate of transaction speed for rapid decision making in high-speed automation
- Granular visibility into events which occur within a material handling system
- Ability to plan work flow to optimize use of equipment and labor at a more detailed level than WMS
- Ability to change workflow plans on the fly as unexpected events occur
WCS Weaknesses
- WCS is still a very loose term without a commonly accepted set of standards
- Many “WCS” systems are merely development platforms which are completely customized for each application
- Less ability to take advantage of standard upgrades from the software provider
- More fragmented and diverse base of providers
- Most WCS providers have much smaller budgets for R&D than do their WMS counterparts
- Most WCS systems are less adept at communication with RF mobile devices
- Most WCS systems have less sophisticated functionality for vehicle-based picking
- Minimal focus on receiving and inbound processes
When to Push the Boundaries of WMS and WCS
WMS
As noted previously some companies have attempted to have a single application perform the role of order management, warehouse management and warehouse controls software. While this may appear to have certain advantages in terms of maintaining a uniform code base across the company, there are significant limitations evident in this approach including:
- Giving up a WCS system in favor of a highly customized ERP or WMS usually means giving up significant functionality in the above areas.
- Many WCS systems have special functionality designed to perform complex processes with a material handling system such as: ERP and WMS systems are often not able to provide transaction processing speeds which match the requirements of a high speed material handling system.
- Zone routing
- Dynamic re-batching
- Labor balancing
This approach, while utilizing a common base of software code and programming language, ultimately creates a very highly customized solution that may be very difficult to maintain and upgrade
WCS
Many ambitious WCS providers have expanded the scope of their offerings. This has produced both good and bad results.
Positive Results:
- Some WCS systems have a more uniform set of business rules
- The software application architecture is more consistent from one project to the next
- Some WCS providers have adapted a regular schedule of enhancement and upgrades to their software
- WCS systems are moving towards being more hardware neutral and suitable for use with a variety of types of equipment
Cautionary Notes:
- Companies should be cautious when considering using a WCS as the single management system for the warehouse.
- Most WCS systems excel at controlling material handling equipment like conveyors, carousels and AS/RS but these systems are less frequently used to control processes on mobile RF devices.
- While there are many demonstrated instances of WCS systems being adapted or enhanced to perform these tasks, in general the focus for WCS companies is not on mobile device functionality, but is on material handling equipment.
- Furthermore, most WCS providers cannot come close to competing with the R&D budgets of even a modest-sized WMS provider. Generally speaking true WMS functionality will not be proactively developed and enhanced by the WCS provider, but will be customized at the request of the user.
- There have been numerous attempts in the last decade by WCS providers to morph their products into WMS systems, generally speaking however, the concept of using a WCS in the role of WMS had not gained broad support amongst users.
Companies should consider pushing the boundaries of their WCS systems under the following circumstances:
- If specific functionality is required in a particular area of the warehouse and it will be a significant undertaking to customize the WMS system. At times this functionality can be deployed more easily using a WCS system.
- Even in these instances, however, the WCS will generally not replace the WMS and control things like receiving, directed putaway and cycle counting.
- Many WCS systems offer robust dashboard capabilities to provide near real-time visibility into work flow. This capability can be extremely helpful in terms of optimizing resources on a dynamic basis.
In Summary
In summary, I believe that ERP, WMS and WCS should generally continue to play their traditional roles within an operation. However, under certain circumstances, great benefit can be realized by utilizing a more robust WCS to achieve specific functionality points that the WMS cannot easily accommodate.