Sorting it Out: Modern Sortation in the Fulfillment Process

By implementing new automation technologies throughout your order fulfillment operation or warehouse, it is possible to make your operation more efficient, productive, and profitable. One technology, in particular, brings with it a lot of potential: Sortation.

In this blog post, we discuss:

• What sortation is
• The different types of sorters currently in vogue
• Traditional and alternative uses for the technology

What is Sortation Technology?

At its heart, sortation is essentially consolidation.

Sortation allows you to batch pick either cases or units and then put those batches—which are, ultimately, components of many different orders—through a sortation process which breaks that batch down into discrete orders.

Free Guide: Choosing a Sortation System for Your DC

This allows your picking operation to operate more efficiently compared to other forms of picking. It also allows for operations that may have different picking areas to operate independently of each other, so that work can be done in area A, B, and C at their own rates, and then brought together by the sortation technology or consolidated into individual orders.

Sortation can be broken down into two main types: Full-case and Unit sortation.

Full-case sortation refers to a sortation process which handles cartons or other large, individual units. Unit sortation refers to a sortation process which handles individual pieces (or units). Each of these types of sortation has its own unique challenges, making certain types of sorter tech better for full-case sortation and others better suited for unit sortation.

Types of Full-case Sorters

Below, we discuss full-case sortation tech, generally moving from the oldest and slowest types of sorters to the newest and fastest.

1. Pushers

Pushers are probably the original sortation technology. Pushers can handle cartons—and some units —up to about thirty cartons per minute. They handle primarily cases, and are very forgiving of cartons that may not have great bottom.

Pushers don’t steer anything. They simply positively divert the product.

2. Wheel and Roller Diverters

As opposed to pushers, wheel- and roller-based sorters work by diverting—and steering—your product.

Wheel diverters pop up either at 30 or 20 degrees and they steer the product off of the sorter. Wheel diverters can only handle cases, and they are not very good at handling cases that do not have firm and flat bottoms. They typically do not work well at high speeds or at handling unevenly weighted cartons. If your cartons are very, very high quality, very evenly weighted, then a wheel diverter may make sense for your operation. There are some wheel diverter sorters that can handle up to 150 cartons per minute.

Pop-up roller diverters are a cousin of wheel diverters. They work by popping up at 90 degrees to divert product away from the sorter and typically can handle approximately 50 cartons per minute. Pop-up rollers are more forgiving than 30-degree wheels and can handle a wider range of materials (for example, firm polybags and even some envelopes).

3. Shoe Sorters

Shoe sorters can handle rates from 150 to 400+ cartons per minute, which makes them very fast. They also handle product very gently.

Shoe sorters consist of a flat-top conveying surface, paired with a set of blocks (shoes). When a product needs to be diverted the shoes engage and very gently push the product, diverting it as necessary. Shoe sorter can handle the widest range of products, including some that are specifically designed to handle polybags.

4. Tilt Tray & Crossbelt Sorters

Tilt tray and crossbelt sorters are often spoken about together, as they operate in an extremely similar manner and at a similar speed.

A tilt tray sorter consists of trays mounted to carts which run on a continuous-loop conveyor. These trays “tilt” and transfer products into a chute when it has reached its sorting destination. Items are inducted either manually or automatically onto the trays via induction stations at multiple locations throughout the loop.

Crossbelt sorters consist of motorized belt conveyors mounted to carts running on a continuous loop. Like tilt-trays, crossbelt sorters transfer items into a chute when it reaches its sorting destination.

Both tilt tray and crossbelt sorters can handle about 100 to 150 cartons per minute. They can also handle an extremely wide range of product, from individual polybags to large cartons. They usually run in a loop, which means that a single loop can ultimately become multiple virtual sorters. This means that the 100 to 150 cartons/units per minute can easily be doubled or tripled using that loop as two three or four virtual sorters.

Types of Unit Sorters

Here, we discuss the types of sortation tech that can be used to handle and sort units, as opposed to cases.

1. Tray sorters

As discussed above, tray sorters consist of trays mounted to carts which run on a continuous-loop conveyor. These trays “tilt” and transfer products into a chute when it has reached its sorting destination. Items are inducted either manually or automatically onto the trays via induction stations at multiple locations throughout the loop.

When it comes to handling individual units, tray sorters can handle anywhere from 8,000 to 10,000 units per hour. For operations handling product as small as jewelry, those rates can be in excess of 20,000 units per hour.

Tray sorters can handle polybags that are at least an inch and a half long, and up to full-sized cases.

2. Crossbelt Sorters

As discussed above, Crossbelt sorters consist of motorized belt conveyors mounted to carts running on a continuous loop. Like tilt-trays, crossbelt sorters transfer items into a chute when it reaches its sorting destination. The main difference between tray and crossbelt sorters is that crossbelt sorters can center product on the crossbelt because it is a powered divert, as opposed to a tilt tray (which uses gravity).

With crossbelt sorters, divert centers can usually be spaced closer together. This allows you to have more diverts in any given length compared to a tray sorter. Crossbelt sorters may also be able to run a bit faster than tilt tray sorters, depending on the product you’re handling, up to 8,000 to 10,000 units per hour.

Like tilt tray sorters, crossbelt sorters can handle everything from units to polybags to other very small product.

In order to get more diverts in a given length (depending upon the product you’re handling), they can run a little bit faster than tilt trays. And like tilt trays they can handle both cases and units, poly bags very, very small product.

Hybrid Sortation Technology

In addition to the sorters that we’ve discussed above, which fall neatly a category of case or unit sortation, there are newer sorters which have been developed in the last 5 or 6 years which we call hybrid sorters. We discuss some of these below.

1. Pocket Sorters

Pocket systems use overhead garment handling technology with a pouch or a pocket hanging from them. They are very versatile, with a weight limitation of up to about 6 to 10 pounds. Pocket sorters can handle any kind of product that you can fit into the pouch, up to 10,000 units per hour. Pocket sorters are the best sequencing device, performing a mix of duties including conveying, storage, and sortation.

2. Plastic Belt Conveyors

Plastic belt conveyors are technically belt conveyors with rollers. But they are manufactured in a way that incorporates very small rollers, placed very closely together. This lets you handle a very wide range of product: Virtually anything that you can induct onto the conveyor can be sorted. These will typically handle between 50 and 75 units or cartons per minute.

On a per-foot basis, these can be very expensive, but they can perform double duty, as both a merge/induction unit and as a sorter.

Sortation Applications

Sortation can be implemented to perform a variety of functions throughout your operation. We explore each of these below.

1. Receiving

Receiving systems are best used on product that is received floor-loaded on trailers. Implementing a sorter as a part of your receiving process allows you with two touches to a carton, unload it from the truck, while in the truck convey it out, and then sort it out by any way that you would prefer, whether by SKU, SKU family, or location.

2. Split Case Picking

As discussed above, the right sorter will allow you to implement split case picking as a part of your order fulfillment operation. This potentially allows you to go out and pick randomly the units for anywhere up to between 100 and 500 orders at a time, allowing you to maximize the efficiency of the travel and the time used in picking. The product is then brought to the sortation device in bulk, and the sorter splits it into discrete orders.

3. Order Consolidation

Unit sorters like a tilt tray or crossbelt sorter work by sorting individual units into discrete orders. This is essentially the automation of what is referred to in the industry as put-to-light. Simply put, put-to-light is manual unit sortation and is best applied when 70 to 80 percent of the orders will get at least one unit of the SKU that is introduced.

4. Packing

Many operations are designed to pack orders differently depending on the type of order. This requires a different type of pack station for each type of order. Sortation allows you to pick a variety of order types, convey them together, and then sort them into the right type of pack station that you need for a particular type of order. Sortation can also be used by operations that use multiple packers, and who need to distribute the work evenly to your pack stations and packers.

5. Shipping

Sortation can be used for both full case and split case systems, reducing the amount of time spent traveling while picking and shipping. In addition to optimizing your pick strategy, you can also sort orders by:

• Carrier or carrier type: For example, FedEx vs. UPS vs. USPS
• Delivery timeline: For example, next-day air vs. two-day ground
• Rates

Modern Sortation for Modern Operations

Sortation technology was originally designed and built to perform and very specific task. But as the technology has grown and become more specialized and advanced, the number of applications for various sorter tech has exploded, opening many possibilities for operations looking to automate. Though it may be overwhelming to determine on your own which type of sortation will be best suited to your operation, a trusted systems integrator can help you find the right solution for your business goals.