Technology Solutions for Piece Picking Depend on a Variety of Factors
Technology Solutions for Piece Picking Depend on a Variety of Factors
Piece picking, also known as broken case and Pick/Pack operations, describes systems where individual items, sometimes called “eaches,” are picked. Eaches are usually defined as the lowest-level SKU or smallest individual packaging unit. So an example of a piece pick unit level in a CPG DC operation might be the small, single-serve package of potato chips. The case level would be some multiple of the individual piece packages like 48 pieces in an over-pack unit. Piece pick operations usually have many SKUs (hundreds), smaller quantities per pick and shorter order fulfillment cycle times. E-commerce companies and repair parts distributors are good examples where you might find piece pick operations.
A common piece picking methodology is called “pick-to-tote”. This is especially common for operations that have many SKUs, but generally small amounts in each order. An example of typical operations that would use pick-to-tote applications would be chain drug stores, pharmacies, office products and tobacco retail outlets. Totes provide an extra level of protection for the items being shipped and are reused by these operations. Each tote typically has a unique barcode label or RFID license plate number. At the beginning of the pick process the tote barcode label or RFID tag is scanned to “induct” the tote into the system and automatically matches the order number with the items to be picked for that order to the tote. This serves as a closed-loop system that helps track product throughout the supply chain.
As with the general picking methods, the piece-picking technology and equipment used will also depend on a variety of factors.
Some of the technology and equipment used includes:
- Static Shelving. Common equipment for storage in very low-volume piece pick operations, static shelving is designed with depths from 12 ft to 24 ft. Product is either placed directly on the shelving or in corrugated, plastic or steel parts bins. Static shelving is economical and is a good method where there are few picks per SKU or where parts are very small. Picking technologies favored for static shelving are voice and barcode scanning.
- Flow rack. Flow rack, sometimes called gravity flow rack, is similar to static shelving with the exception that rather than shelves, there are racks tilted at an angle from back (higher) to front (lower) with small rollers on the racking. Product is stocked from the rear of the flow rack and picking is done from the face. Product can be stocked in cases, cartons or small totes or bins. As a carton or tote is emptied, it is removed from the rack and another one will roll into place. Carton flow rack is most useful where there is a very high number of picks per SKU. Picking technologies favored for flow rack are voice and barcode scanning.
- Carousels. Carousels are similar to equipment used by dry cleaners to store and retrieve clothing. They have horizontal racks hanging from them that can be configured to accommodate various size storage bins. Generally an operator will run 2 to 4 carousels at a time, avoiding the need for the operator to wait while one unit is turning. Carousel picking is usually performed in batches, with orders downloaded from the host system to the carousel software. Horizontal carousels are most common in picking operations with a very high number of orders, low to moderate picks per order and low to moderate picks per SKU. Horizontal carousels provide very high pick rates as well as high storage density. Picking technologies favored for carousels are voice and Pick-to-Light (PTL) systems. Barcode scanning with handheld computers can be used, but a wearable scanning solution such as a ring or hand-mounted scanner/imager used in conjunction with voice is more effective and more common.
- Barcode Scanners. Though very useful in increasing accuracy levels, barcode scanners in a fast-paced piece pick operation tend to become cumbersome and can significantly help reduce pick rates. The reason for this is the high amount of product handling required and the ergonomic penalties of having a scanner in the hand while picking. Scanners are better suited to case pick, pallet load, put-away and order checking operations and in selected picking situations where the actual speed required in the picking function is mitigated to some degree with travel times
- Voice-Directed Picking. Voice technology is very effective in both productivity and accuracy across all picking applications. Voice picking is unique in that it combines the speed of listening and talking without having to look at, read and interpret instructions on a piece of paper or display, working with your head up with visual contact on the point of work and having the hands free to accommodate all forms of ergonomic product handling. In short, voice has been proven in thousands of installations and varied applications to be the most productive and also most accurate of the picking processes. Some customers may have high-density picking operations using PTL. They often cite their preference for PTL saying that it is faster. This is not the point to address with PTL users when comparing voice. In fact, most of the older PTL systems have a limit as to how many people can work in one zone of the lights. This is a limiter on the total throughput of the system. With voice one can put as many people into a pick zone as can fit, which usually greatly exceeds the number of pickers a PTL system can support.
- Pick-to-Light (PTL). Pick-to light systems consist of a complex system of lights and sometimes LED displays mounted on the front-facing rack edge for each pick location. The system uses software to light the next pick and display the quantity to pick. The picker goes to the location, presses the off button on the light and picks the quantity shown on the display. Since a significant amount of hardware is required for each pick location, PTL systems are effectively static, inflexible systems, more costly to implement and maintain, and suffer from switch and light failures. They are almost only cost-justifiable where very high pick rates per a limited number of SKUs can be located in a densely packed, small area. Also, in batch picking, put-to-lights for placing items into the totes on a pick cart can be effective.
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