Ever wonder why so many of us hate grocery shopping? A trip to the local supermarket to collect your weekly groceries can be a tedious experience. First, you locate a cart and wander up and down the aisles looking for the items you need. After youve zigzagged through the entire store, you backtrack to find items that you missed the first time you went down that aisle. Finally, after checking off everything on your list, you stand in line to check out. The checkout process involves re-handling each item to pay and pack your items. After all of these steps, you can finally load the car and go home.
Your companys order fillers may very well feel the same way each time they fulfill an order in your distribution operation. The processes can be remarkably similar if you consider the supermarket to be a broken case picking operation where shoppers select a single order from SKUs slotted in one large zone and the orders then must go to a final operation for inventory control and packing. This order filling approach works well for some, but there are ways to tailor a more efficient approach to your operation.
There are many picking alternatives; it takes a careful approach to identify the right methods and equipment for you. The first step in this approach is defining your goals for the order filling process. These typically include getting customers the right product, in the right quantity and at the right price. Then you must be able to move your products to market quickly. You should develop procedures that minimize distribution, transportation and customer receiving costs but are flexible enough to meet current requirements as well as future business model changes. And lastly, you should have the ability to flow new products to your customers as well as be able to replenish current SKUs efficiently.
With these goals in mind, what is the best way to design an order filling operation? Should you consider batch picking, zone picking, pick and pass or automation? The answer to that question is very specific to your SKUs and customer order profiles. The general rules of thumb may provide some direction, but there is no substitute for a well-thought-out approach and some hard work. It helps to remember that the definition of a world-class distribution operation is one where costs are one percent to sales or less, not necessarily the one with the latest order filling technology.
To tailor an order filling procedure to your specific situation, you should consider different approaches to the solution, the data required to make informed decisions and the alternative selection process. This is assuming that your warehouse management system (WMS) is adaptable to most mainstream picking processes. If this is not the case, your next step may be to update your software, relying on the picking efficiency improvements to justify the upgrade.
There are three approaches to consider when analyzing your order filling needs. The first approach is one we are already familiar with: the supermarket. This basic approach is a good place for many new operations to start. Its advantages include: flexibility, scalability, low capital investment and easy implementation.
The second option is an approach that is tailored to the specifics of your SKUs and order profiles. It improves on the supermarket approach by reducing the costs of picking and replenishing by stratifying the approach based on the velocity of your SKUs (you pick A and B SKUs differently than C and D SKUs). Any company whose order volume is greater than 100 orders per day should explore this approach.
The third option is the highly automated approach. For companies with high order volume, well-defined SKUs, a large capital budget and a concern about labor availability, this can be a very effective solution. Labor costs to fill an order from this type of distribution center can be dramatically lower than those filled in more conventional systems.
The more data you collect and analyze, the better your order filling solution will be. Here are some data analysis issues to consider:
You will want to collect as much data as possible, usually one full year to capture all of the seasonality in your business. With this much data, you will be able to review your average and peak operational values and can set the design targets appropriately.
As you analyze your orders, you will want to divide them into sublines based on how they will be picked. For example, if an order line consists of 101 units, the sublines would be one pallet of 75 units, one full case of 25 units and one broken case unit.
Some other data points to collect and analyze include: daily orders, lines and units by subline; lines per order; units per line; daily one line orders; A, B and C SKU velocity reports; lines, units and full orders shipped by A, B, C category; volume and SKU growth expectations for the next five years; number of non-conveyable SKUs and their growth; and broken case picking growth.
The data collection process can take some time, and several of the metrics are difficult to calculate. Dont approach your design with inadequate data. A few incorrect assumptions at this stage can increase your order filling costs significantly. Spend the time to get as much accurate data as possible.
There are many different methods for actually filling the order. Using the data collected earlier will help you select the approach that meets your goals in the most cost effective manner. Some of the most common picking methods are:
Single order picking Each order filler selects a customer order and picks it complete.
Batch picking A picker fills several orders at a time in order to reduce the amount of time spent traveling.
Pick and pass Each picker concentrates on his own area or zone and orders pass (mechanically or manually) from one picker to the next.
Zone picking with aggregation on the shipping dock Each zone sends a carton to shipping for each order, and the completed cartons from each zone are palletized together on the shipping dock.
Zone picking with aggregation at packing Each zone sends a tote to packing with its portion of the order. At packing, all totes for an order are consolidated, and the outbound cartons are packed.
Zone picking without aggregation Each zone fills its carton for the order, and these are sent directly to the shipping trailer (shotgun loading).
Unit sortation Pickers pull batches of product from their zones that are then sorted to the order by a tilt tray or cross belt sorter.
Put system Full cases of SKUs are run past locations that contain orders. As a SKU passes an order that requires it, the system directs the order filler to remove the correct quantity of product and place it in the outbound container for that order.
Once you have identified your picking method, you must select the material handling equipment to support the operation. The options for transporting the order are pick to cart, pick to pallet jack or pick to conveyor.
The racking and shelving selections for storing your SKUs are based on each SKUs specific cube and velocity. It is common to have a mix of different types of racking and shelving depending on the variation in your SKUs. The options include pallet flow racks, carton flow racks, bin shelving or pallet racking.
This selection is crucial because it affects your picking productivity, replenishment labor and layout. Spend time identifying the right storage equipment for your SKUs. For maximum ROI, you must use different storage equipment types for your different SKU velocity categories. Treat high volume SKUs differently from slow movers. You may also want to consider the use of automated picking equipment like A-frames or carousels.
Keep in mind the storage media selection dictates the amount of walking required in your process. Walking typically represents 60% of the total time to pick an order.
Equipment options for issuing the picking tasks to your order fillers include paper pick tickets, radio frequency (RF) terminals, pick-to-light and voice activated picking. Moving away from paper tickets will improve your picking accuracy by validating that the right item was placed in the right carton as well as track your order fillers productivity.
Selecting the Layout
Now that youve decided on the method and equipment, its time to lay out the picking zones. A multi-level pick module is a space-efficient arrangement for carton flow rack, pallet flow rack and bin shelving. If you can locate the A and B SKUs in the same module, you may be able to pick a majority of your orders from one area. Lay out the picking zones for a smooth product flow from reserve storage to the pick zones and then into shipping.
Although there are many alternative approaches for order filling, some careful thought and a defined approach will help you identify those that would work best for you. Careful consideration and planning can be the key to get your distribution operation to that world-class level and help you avoid feeling like you're at the supermarket.
Phil Godden is with Fortna, Inc. For more information, e-mail him at firstname.lastname@example.org or visit www.fortna.com.