Starting off right in receiving; streamlining the inbound flow of materials and data will help improve efficiency of downstream operations.
How you design, equip, and run the receiving area is important. Decisions made here can impact significantly the downstream steps of storing or staging materials, manufacturing product or picking warehouse orders, packing cartons, and, finally, shipping finished goods. And it's equally important to take actions here to begin getting a good handle on the parallel stream of data flowing through your facility.
Get things right in receiving and you're off to a good start. Make mistakes and you'll likely slow or halt the flow of goods and/or the flow of data throughout the whole operation.
Dockside juggling act
The goals in receiving are to accept incoming items as quickly, safely, efficiently, and accurately as possible. Meeting them is a dockside juggling act. That's particularly true given a presumably limited budget.
But you'll want enough of the right types of dock bays to swiftly and smoothly accept incoming shipments, for example. Yet trucks pulling up today are longer, wider, and lower than before as carriers seek to max out their shipping cubes. So the dock levelers, vehicle restraints, seals, shelters, and other dock equipment must accommodate this more varied mix of traffic.
Meantime, docks also may have to do double duty, serving as the receiving area for part of the work day, shipping for the rest. Scheduling inbound and outbound truck traffic thus becomes crucial as you seek to balance competing demands for labor and equipment. Good, timely communication with suppliers on the inbound side and customers on the outbound will be vital. Doing so electronically, if you add this capability, definitely will help facilitate smooth material flow.
Efficiency and accuracy in receiving will be enhanced, moreover, if you give automatic data collection (ADC) a big role at incoming docks--and elsewhere. Use of bar code scanners and radio frequency data collection (RFDC) terminals can cut out much of the paperwork of receiving--provided those shipping to you cooperate and put bar code labels on what you receive. Scanners and RFDC units provide benefits through greater accuracy in counting inventory, too, compared to pencil and paper methods. And, with this hardware tied into appropriate software, the entire process of managing inbound inventory becomes far easier (see "Warehouse management system streamlines receiving").
Selecting lift trucks
Getting inbound palletized loads off the trailers, onto the dock, and into your facility generally requires use of industrial trucks. To determine the suitability of specific types of lift trucks, pallet trucks, and related equipment in receiving, check out the different manufacturer's models for such factors as maneuverability, performance, reliability, and throughput capabilities. Compare with your needs.
In high throughput situations, there are several choices: three-wheel counterbalanced trucks, compact four-wheel riders, or stand-up stackers all do a quick job of unloading trailers with full pallet loads. All offer fast lift, acceleration, and travel speeds.
The three-wheelers have a tight turning radius and compact design working in their favor. But when loads are heavier, consider using a counterbalanced four-wheeler, sitdown truck. Some models come with a short wheelbase and maneuver well in close quarters. Standup counterbalanced trucks also will turn tightly, have good operator visibility, and usually are priced less than sitdown models.
Depending upon throughput requirements and distances traveled away from the dock, powered pallet trucks--either walkies or walkie/riders--can serve well for unloading/loading operations, provided that load stacking isn't involved. And manual pallet trucks offer a low-cost handling option when load moves are short.
If your warehouse receives high volumes of unpalletized materials, however, then consider having extendible conveyors available in the dock area to speed incoming items on to their destination.
Longer levelers are best bet
As you design a new dock area or modify an old one, don't just assess the features of lift or pallet trucks, of course. Consider how these trucks will work with what's used to bridge the gap between dock and trailer bed. Check to see what the grade will be that the lift or pallet truck must climb from dock to trailer, or vice versa, as it moves over a dock board or dock leveler.
With more and more of today's trucks either much lower or much higher than the standard 48-in.- high dock, the grade question becomes important. An 8 ft long dockboard or leveler, for example, bridging the gap from a 48 in. high dock to a truck bed only 38 in. off the pavement, creates nearly a 12% grade.
Some kinds of load-handling equipment won't readily climb a 12% grade, nor are they necessarily very safe moving back down that steep a decline. A rule of thumb applies here: longer is better. The longer the dock board or leveler, the less the grade and the easier and safer the move. With a 12 ft long board (instead of an 8 ft board), the grade is less than 7% (vs. 12%).
Here are the recommended maximum grades for: power operated hand trucks (3%); powered platform trucks (7%); low-lift pallet-skid trucks (10%); electric lift trucks (10%); and IC lift trucks (15%).
Dock leveler selection--up until some two years ago--was a rather straightforward process for most specific applications. After deciding on an appropriate leveler length, a specifier compared mechanical and hydraulic levelers in terms of their performance features and costs.
Put simply, hydraulic levelers cost more than mechanical models, but hydraulics deliver greater safety, better ergonomics, and more productivity to their users. In general, they are push-button simple to operate; the hydraulic unit provides the power to raise the steel leveler platform.
A mechanical leveler, in contrast, requires the dock worker to bend over and pull a chain before the deck rises up and starts to move into position. Then the worker literally has to walk the leveler down onto the trailer bed, using his or her body weight to counter the force of the leveler's inherent upward bias.
Now, however, the choice of equipment is more difficult because of the introduction in recent years of two new types of dock levelers: One type uses the lifting power from a high-volume, low-pressure air bag to raise the leveler deck. Another type accomplishes a similar lifting action through the "power-assist" provided by an electrically-driven linear actuator motor working together with a counterbalancing spring.
The costs to the user of these newer kinds of levelers have been set by their manufacturers at intermediate points between the prices of low-end mechanical levelers and the costs of upper-end hydraulic levelers.
Cost isn't the only consideration, however. You also should compare different leveler designs on their operational, performance, and safety features. Included in this analysis are questions such as (1) how the unit performs if the trailer bed being serviced is below dock level, (2) what happens if a trailer suddenly moves away from the dock with a forklift load on the platform, and the leveler goes into an uncontrolled platform drop, or free-fall, and (3) what safety measures are there on non-hydraulic levelers to stop or prevent free-fall. (Most hydraulics stop free-fall after just a few inches of drop.)
Vehicle restraints represent another important class of dock equipment that ensures that the receiving area is not only geared up for high productivity, but also will provide your workers and carriers' truck drivers with a high level of safety.
Restraints act to stop or at the very least to minimize two types of hazards: The trailer that "creeps" away from the dock during unloading because of the cycling forces of a lift truck moving in to and out of the trailer. Then there's the trailer driver who tries to make a premature, unscheduled departure with his truck before unloading is finished.
Here, too, equipment selection is more complicated than it once was. First, however, let's quickly discuss one practice that is generally discouraged: use of simple wheel chocks. Most dock safety experts agree that the chocks provide scant assurance the truck won't move.
Instead, the experts suggest use of equipment that applies a restraining force to either (1) the underride guard (ICC-bar) of the trailer, or (2) to the vehicle's rear wheels.
Some form of restraint working on the underride guard or ICC-bar has fulfilled this safety function since the first models were introduced in 1980. The ICC-bar restraints come in a variety of designs, depending upon the way the device's mechanism applies force to the underride guard. Generally, they can be classed as either impact- or non-impact restraints.
Much more recently, however, dock equipment manufacturers have brought to market automatic wheel chocking or wheel "locking" (or blocking) equipment. These units act directly against the wheels, not the ICC-bar.
Is it necessary to have both ICC-bar and automatic wheel chocking or "locking" restraints? It all depends. Typically, one in four trucks arrives with a damaged or missing ICC-bar. And with some types of trucks--notably lift-gate vehicles--the design eliminates the ICC-bar. So, depending upon the mix of trucks at your docks, it's advisable to have some of the wheel chocking or blocking restraints installed at a few docks, plus ICC-bar restraints elsewhere. This combination gives your facility more flexibility in safely unloading whatever truck type pulls in.
RELATED ARTICLE: Warehouse management system streamlines receiving
A warehouse management system (WMS) teamed up with bar coding and radio frequency data communications, is fast becoming an essential part of any modern, efficient operation for warehousing or distribution. The WMS begins performing in receiving and carries out other functions straight through to shipping. Here's what to expect from the software in receiving:
* Receives inbound items
* Identifies and records inventory receipts by SKU
* Updates physical inventory
* Generates labels
* Directs putaway/storage activities
* Automatically assigns storage locations
* Confirms accurate putaway
* Tracks all inventory by location
In addition, a WMS assigns and directs picking activities, tracks exceptions, manages packaging, verifies all items in an order, cubes orders for carton packing, manages labeling requirements, directs shipping and order delivery to outbound docks, generates shipping documents, and updates the host computer for invoicing customers.
RELATED ARTICLE: Would crossdocking work for you?
Your facility may be in position to crossdock--to move incoming materials directly to shipping, bypassing storage and other internal operations. Crossdocking works particularly well when the supply chain provides receiving with timely and accurate data on inbound materials through barcoding of items, advanced shipping notices (ASNs), and the like. Here are some criteria that suggest when this practice is feasible; if your plant or warehouse meets two or more of the criteria then crossdocking probably will work.
* The destination of inbound inventory is known when it's received.
* The customer for this inventory is ready to receive it immediately.
* You ship to fewer than 200 locations daily.
* Daily throughput exceeds 2,000 cartons.
* More than 70% of inbound inventory is conveyable.
* You receive large quantities of individual items.
* Inbound inventory arrives at the dock pre-labeled and/or bar coded.
* Some inventory is time sensitive.
* Your warehouse or DC is already near capacity.
* Some inbound inventory is pre-priced.
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|Title Annotation:||includes related articles on warehouse management systems and crossdecking|
|Publication:||Modern Materials Handling|
|Date:||Apr 15, 1997|
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