Stepping Away from the Dark Side Pick-to-light Picking System Benefits

Wholesale suppliers servicing their customers' small parts order demands in almost any industry know that orders requiring less than a case quantity grow with each passing year. Servicing the ‘just in time’ and replacement part needs of their customer base drives significant cost into a wholesaler's bottom line. Order fulfillment, which decades ago was the domain of manufacturers with lead times measured in weeks or months rather than days or hours, is one of the key facets of a good distributor's offerings to its customers. Over that same time span, the average order quantities dropped as well — from pallets to cases to individual units. Customers order more frequently and in smaller quantities, effectively pushing inventory back upstream within the overall supply chain and putting much of the burden for inventory holding capacity and rapid small order fulfillment onto distributors. For most distributors in today's environment, it is safe to say the slower and more costly their order fulfillment process is, the faster that customers will seek alternate sources of supply.

Order fulfillment picking at an individual piece level accounts for an average of 60 percent of all labor within a distribution center's operation. It is the most expensive part of the order fulfillment process, surpassing receiving, storage and nonspecialized packing combined. Given the large amount of a fulfillment center's labor effort and budget devoted to picking, time spent optimizing the productivity and throughput capacity in this area probably will yield the greatest return for the effort and capital invested. While there are many methods, technologies and equipment offerings that a distributor can pursue to keep their small parts order fulfillment costs down, picking productivity up, and accuracy levels at an acceptable level, some of the most prevalent and proven technologies in the marketplace are pick-to-light systems.

Pick-to-light and text bay display.

A pick-to-light system is a system of LED (or LCD) lights, buttons and display modules that are installed on each item's pick location. Pick-to-light systems are an alternative to manually picking items with a pick list or labels, and therefore some refer to it as “paperless picking.” The design of the pick system allows it to electronically assist the pickers in any picking operation by indicating the required pick location for each line item on a customer order and the quantity they need to pick. Though most often used to assist in picking less-than-case volumes and frequently applied in conjunction with case-flow rack, shelved racking or bin shelf pick locations, pick-to-light systems are not limited solely to those applications and storage mediums. You can apply this approach to almost any pick face types, including standard pallet positions (usually at the floor level in a conventional storage system).

For illustration, let's consider a discrete order picking environment for loose pieces that a picker puts in a shipping carton. In a conventional paper pick system, the picker references the pick list, travels to the first pick location indicated on the pick list, picks the appropriate product in the correct quantity, places the product into the shipping carton, marks that order line off the pick list in some fashion, references the pick list for the next order line, and moves the process steps again until the order or that shipping carton for the order is complete.

In a pick-to-light system, the operator indicates to the system (through a terminal or radio frequency scan gun) they are ready to pick an order, and every pick face with a pick in it for that order ‘lights up’ as the pick-to-light pick indicator lights up. The pick indicator light is usually a green or red beacon that illuminates in solid or flashing fashion. The operator moves to the first “lit” position. The pick-to-light module will have an LED or LCD indicator showing the number of units the worker must pick. The employee picks the correct number of units and presses the acknowledgement button on pick-to-light module. This extinguishes the pick indicator light (and the LED/LCD pick quantity indicator). The picker then moves to the next “lit” position and continues the process.

The productivity advantages of the pick-to-light system over a manual or paper pick system have been proven again and again over time. You can obtain these advantages in a discrete order pick environment, pick and pass environments and even batch picking operations. On average, pick-to-light applications can result in productivity improvements of 25 percent or more. They also offer an accuracy increase over paper picking that varies with the number of lines per order and the number of pieces per line. Many operations that formerly performed post pick audits on less-than-case orders to ensure order accuracy for their customers found that, with a pick-to-light system, pick accuracy increases are so significant as to allow for the elimination of post pick audits.