This article originally appeared in the May/June issue of PARCEL.
Bulk parcel flow requires singulation (i.e., each parcel is uniformly separated, spaced, and aligned) before entering a downstream automated sorting system. In the post and parcel industry, efficient unloading of bulk parcels (parcels, bags, and/or “smalls”) is critical to achieve required throughputs, service levels, and optimize building space. For the warehouse and distribution industry, high-volume e-commerce operations with a wide variety of package types (bags and small cartons) handle bulk parcels between the packing and shipping operation.
In both industries, operations are tasked with considering the benefits of manually singulating parcels vs. using automated singulators and the impact of each strategy on the bottom line. Additionally, the type of downstream sortation system (loop sorter vs. line sorter) directly impacts the type of automated singulator to provide the highest system performance and ROI.
Industry Challenges & Opportunities
Typical Manual Singulation Operations
Unload operators can manually singulate parcels by separating them into a one-dimensional (1D) flow and loading onto an extendable conveyor inside the truck. The advantage to this approach is that no automated singulation is required for the downstream sorting process. However, this manual singulation method allows a relatively low unload rate of approximately 850-900 parcels per hour (pph) per operator. Typically with two operators per truck, rates of 1,350 to 1,450 pph can be achieved. Due to the relatively low unload rates, additional unload doors (and therefore increased building costs and material handling equipment (MHE) costs) are required to achieve throughputs necessary to meet service levels and cutoff times. In addition, the conveyor system leading to the sorter is more sophisticated with controlled merges and additional metering/gapping belts.
Typical Bulk Unload and Automated Singulation Operations with 2D Flow
Bulk unloading is more common in the industry. Unload operators bulk unload parcels (mainly cartons) onto an extendable in a 2D flow (i.e., parcels are side by side without separation, but not stacked on top of each other).
Unload rates are increased significantly to 1,100-1,300 pph, with a resulting savings in load door positions, building costs, and MHE costs. Typically with two operators per truck, rates of 1,750 to 2,100 pph can be achieved. Accordingly, bulk unloading requires approximately 30% fewer doors compared to singulated unloading to achieve the same building throughput. Usually, loose smalls and polybag shippers are separated at the door for separate handling and processing.
Bulk unloading requires singulation downstream just prior to the automated sorting process. Conventional parcel singulators on the market today provide high throughputs, typically 7,500 to 10,000 pph and usually feed line sorters. These rates are achieved since the singulator “pushes” parcels to the line sorter at a constant speed. Conventional parcel singulators typically handle cartons only. Additional drawbacks include equipment footprint, maintenance, noise level, and energy consumption.
Bulk Unload & Automated Singulation Operations (3D Flow)
Bulk unloading of 3D flow is similar to 2D flow but with the added benefit of operators having the flexibility to stack parcels on the extendable conveyors. Unload rates are further increased to 1,300-1,600 pph with a single operator and 1,800-2,250 with two operators, enhancing the benefits of 2D bulk flow. A potential drawback of 3D flow for some companies is the higher probability for damage if parcels contain fragile contents.
With the strong growth of e-commerce, the post and parcel industry is faced with handling a significantly larger volume of smaller cartons and polybag shippers. Since conventional singulators are designed as a push system and generally handle cartons only, the downstream sortation technology is limited to line sorters. Loop sorters offer significant operational benefits including better handling of poly bags, flexibility in induction locations, flexibility in general arrangement with vertical and horizontal curves, built-in recirculation, virtual sortation to significantly increase throughput, lower noise, and lower maintenance. The decision between loop or line sortation is dependent upon the specific operation and application, but until recently, loop sorters were not a viable option due to limitations in automatic singulators.
As a further consideration, 3D bulk unload flow reduces a conventional singulator’s throughput to 5,000-6,000 pph, considerably reducing the capacity of the downstream line sorter.
For high volume e-commerce distribution companies, the packing area is often decentralized from the order fulfilment process (e.g. loop sortation), especially if a wide variety of carton and bag sizes will be used to optimize the cube and customer experience. Typically, the flow from the packing area is manually singulated by the pack-out operator or bulk flow. Manual singulation reduces pack-out operator efficiency and requires controlled merges and metering to the automated shipping sorter. For bulk flow, simple transport conveyor is used to transport the parcels to the automated shipping sorter. However, sorter induction operators are required to singulate parcels onto the automated shipping sorter.
Similar to the post and parcel market, automatic singulators to feed loop sorter inductions were not a viable option due to limitations.
Bulk Parcel Handling for Loop Sorters
There are few solutions available on the marketplace that can enable automatic singulation, which transforms a bulk flow of parcels into a flow in which each parcel is uniformly separated, spaced, and aligned before the in-feed to the automated induction of a high-speed loop sorter. With the capability to handle a wide variety of items, automatic singulation offers a single-system solution that can handle parcels, flats, totes, and bags from the collection and distribution sorting areas. Cyclical operation enables adjustments to the speed of the parcel flow in response to changing levels of demand at the induction. With a fully automated system, the need for manual handling and supervision during normal operation is significantly reduced.
The Singulation Process
With high-end automatic singulation solutions, the parcels are transported from the bulk unload area to the automated singulation machine by feed lines that can be configured with fully automatic container tippers, extendable conveyors, and loading conveyors. Some applications offer conveyors offset rollers that small batches of parcels pass over as they enter a singulator in-feed. These align the parcels so that they are released in a single flow with a uniform gap between each parcel. Seamless integration of the automated singulator into a loop sortation system enables a pull system that adjusts the flow of parcels to meet the demand at the induction. The downstream induction line controls the call-up of parcels from the singulator which, in turn, can call up parcels from the upstream bulk system. If a double detect data capture feature is available on the automated system, it can automatically check the dimensions of each parcel for items which are over length, over height, or an abnormal shape, such as double parcels. Items that are detected as out of gauge are automatically removed from the main flow via a dynamic, high-speed vertical diverter that is optimized to match the speed of the conveyor. The diverted out-of-gauge parcels are processed downstream of the automated solution.
Fast and Flexible Integration
Not all automated singulation solutions offer a high level of configuration flexibility. This flexibility allows for retro-fitting into the induction of an existing loop sorter or for integration into a new parcel handling system. Both retro-fit and new installations can be optimized to achieve a compact footprint and highly efficient use of available space, in addition to offering reduced installation and commissioning times.
A top of the line automated singulator can match the throughput of one high capacity induct line, up to 3,500 pph. For parcel applications, typically three to four inductions per induction area can achieve a sustained rate of 7,500-10,000 pph per area. Multiple induction areas can be configured on the loop sorter to achieve 20,000+ pph with a singulation accuracy of 97%+ without double detection, and even higher accuracy with double detection.
Making the Shift
Transitioning to automation doesn't necessarily mean a company will need to replace all of its existing equipment. As companies look to shift away from manual singulation, it can be done slowly and strategically where it is needed most. Start by implementing automated parcel sorting at the busiest distribution centers and work your way up to complete automation. As e-commerce continues to surge, the volume will soon justify the need for automation. Embracing the need for automation can lead to fewer misrouted packages, disappointed customers, and frustrated clients.
Terry Brown is Director of Sales, Sortation & Distribution, BEUMER Group. He holds a B.S. in Mechanical Engineering from the University of Wisconsin-Milwaukee and an MBA from the Keller Graduate School of Management.