Is a warehouse with no people pie-in-the-sky dreaming or future reality?
by Dick Friedman
It sounds like pie-in-the-sky, yet one of this author’s clients is considering implementing extensive automation to avoid ever-escalating labor costs. His vision would still involve some people – not a totally people-less warehouse – one in which, day and night, all physical movement of items is handled by automated equipment controlled by software. Few warehouses are so highly automated, and none are totally devoid of people. Almost all highly automated warehouses are totally custom-designed buildings, equipment and software; there’s little off the shelf. The following description of typical systems and machines in an automated warehouse is a look into the future of large warehouses in which many items are stored and many lines are picked per hour.
But no matter how extensively a warehouse is automated, the systems will not function accurately and efficiently unless the warehouse is organized properly, and procedures and controls are in place and followed. In fact, the less automation employed, the more organization and discipline is needed.
Because few, if any, even near-automated warehouses exist in this industry, let’s start with a general description of equipment for storing and moving items.
Conveyor. Think of a “moving sidewalk” at an airport as an example of a powered belt conveyor. Warehouse conveyors move items, cartons or reusable containers (such as totes), not people. A powered belt conveyor may be sloped so that items move forward and upward or downward. Another type of powered conveyor is a roller conveyor used to move cartons/totes or large items. Instead of a belt, there are individual rollers, all of which rotate together under power. A powered roller conveyor can also be sloped downward or upward. Manual roller conveyors are un-powered; if it’s horizontal, people push the items along; if it slopes downward, items move under the force of gravity. A conveyor can be loaded manually (as a truck is unloaded into receiving, cartons are placed on a conveyor) or by some other equipment.
Sorter. This equipment either directs an item to one of several conveyors, or literally drops it into the proper carton. Conveyors are designed to handle small or large items, totes or cartons. A sorter can be loaded either manually (remember, there are still some people involved), or by a conveyor, and sortation is controlled by software.
Automated Storage and Retrieval System (ASRS). One example is a “carousel”; it looks like cylinder oriented vertically, with storage slots at several heights around its circumference. To store an item or carton, the item is placed on a positioning device, a bar code (or increasingly, an RFID chip) is scanned and, based on data related to the item/carton and carousel, software determines where to store the item/carton. That software controls the rotation of the carousel so that the needed slot aligns with the positioning device, and software directs the positioner to the proper level, where it literally pushes the item into the designated slot. For picking, software determines the slot from which to pick, and it controls the positioner to retrieve the item (or multiple items for that customer order, branch transfer or multiple orders going on the same truck). A bar code is scanned every time a movement needs to occur (and in some cases, to monitor the
condition of an item); even the bar code of shipping cartons is scanned to determine loading and shipping paths (because the actual carton used is sometimes different from the size and strength of the theoretically calculated carton, and there can be changes in assigned trucks).
Automatic Guided Vehicle (AGV) – is typically a battery-powered, low-height motorized platform that follows along one or more wires recessed into the warehouse floor. A pallet, carton or piece is literally taken for a ride on the AGV. Special software determines the exact path taken when putting away or retrieving something.
Receiving. Imagine a powered belt conveyor with one end at a receiving dock, and the far end feeding a sorter. The sorter directs inbound cartons to one of two conveyors, each of which feeds an ASRS. Each ASRS stores the cartons in the slots determined by software. At another receiving dock, an AGV takes bulky pieces to an ASRS or to a section of the warehouse where people remove the pieces and place them on storage locations on the floor.
Picking. Based on sales order data and storage locations data, an ASRS retrieves one or more cartons, and positions the carton(s) on a conveyor. That conveyor feeds the carton(s) to a sorter, which directs them to one of two conveyors that contain an on-the-fly labeling workstation and feeds cartons to waiting trucks or trailers (on which the carton(s) are stacked manually). In addition to an ASRS positioning cartons on a conveyor, a person could remove cartons from a forklift that brought them to the conveyor, and place them on the conveyor. The forklift driver could use Voice Directed Picking (VDP) to pick the cartons and take them to the proper conveyor(s). Even in our hypothetical system, manual labor is involved because total automation is not realistic.
Cons. In addition to huge construction and equipment investment, a drawback of a highly automated warehouse is that it is designed for a particular mix of product sizes and weights. If the mix changes much, changing the warehouse technology can be an expensive, lengthy process.
Enterprise Resource Planning (ERP). An ERP mainly plans and manages the logical operations and administrative activities of a distributor (entering data for sales orders, generating recommended purchase orders). An ERP performs many functions in real-time (once a PO is created, immediately updating the on-order quantity of each item on that PO), but some are “batch” functions (printing A/P checks). Some ERPs contain a few of the functions that are also in the next kind of software.
Warehouse Management System (WMS). WMS software plans and manages the physical arrangement and activities of a warehouse. For example, it determines where to store items to be received on the next business day, based on purchases and customer order data transmitted by the ERP; after items are received, it determines where to store an item, and tracks how much of each item is stored in each slot. A WMS also does higher-level labor planning (how many people to bring in for a particular day and shift). Most WMS functions do not work in real time; however, as data about a picked item is captured, the WMS updatesslot-specific and item-level data. The WMS also interfaces to systems of vendors (receives advanced shipping notices).
Warehouse Control System (WCS). WCS software controls the physical activities of automated equipment such as starting and stopping conveyors and sorters, directing an AGV, directing an ASRS to store and to pick, and directing a sorter to route a carton to a particular conveyor. A WCS works in real time, using both data it acquires (status of a piece of equipment, and from reading a bar code on an item/carton/tote) and data transmitted by the WMS.
A WCS also can control the speed of a particular unit in order to balance loads on specific equipment and through the warehouse. It also makes real-time adjustments, such as when a jam at a sorter is detected, the WCS would stop those upstream activities that would result in other jams.
A WCS also assigns and manages labor (when a packer unexpectedly logs out, the WCS will determine which other suitable person is available and assign the function to him/her until the packer logs back in).
In the future, look for WMS to take on more of the WCS functions and vice versa. Eventually, the functions of WMS and WCS will be merged into a new category of software that may be termed warehouse planning and control (for large, high-volume warehouses). And look for more warehouses to use more automation, although not to the extent described here.
In the Absence of Automation
Don’t wait for automation to reduce warehouse costs and prevent costly mistakes. Many warehouse improvements can be done quickly and at no or little cost, and will also avoid the phone calls from angry customers who received the wrong items or quantities. Think organization, procedures and controls.
Dick Friedman is a recognized expert on warehouse operations, management and technologies for fastener, tool, industrial and MRO distributors. He is a Certified Management Consultant and is objective and unbiased, so he does NOT SELL warehouse systems or technologies. Call (847) 256-1410, or visit www.GenBusCon.com or to send e-mail.
This article originally appeared in the May/June 2012 issue of Industrial Supply magazine. Copyright 2012, Direct Business Media.