Sticky powders present manufacturers and processors with unique material conveying challenges involving volumetric auger fillers that dispense powders, granulars, and flakes for packaging. 

When the U.S. government decided to switch to a bio based laundry detergent for the military and other government entities, the Association for the Blind and Visually Impaired (ABVI) had the potential to expand its manufacturing and fulfillment division by coming up with a system where it could produce the detergent in an efficient and economical manner.

ABVI’s manufacturing and fulfillment division employs approximately 60 individuals who are blind or visually impaired. Its mission is to prepare and empower people who are blind or visually impaired to be self-sufficient and contribute to their families and the community.

ABVI employees convert, assemble, package, and distribute a wide range of high-quality products for federal and state government use and partners with companies like 3M and Ecolab.

“This was a totally new process for us,” says Leon France, Quality Manager at ABVI.  “Our first step was to work with a soap manufacturer that could develop a bio based product that met government specifications, and then create a production line that could give us the competitive edge.” 

After successfully developing a detergent with a supplier manufacturer, France contacted Per-Fil for an auger filling station to dispense the detergent into boxes containing two 13-pound cartons. However, he still needed a system that would deliver the detergent to the auger filler from 2000-pound super sacks, and “Per-Fil recommended we contact VAC-U-MAX for a solution,” says France.

VAC-U-MAX, an early pioneer of vacuum technology best known for handling free and non-free-flowing powders, specializes in design and manufacture of pneumatic conveyor systems and support equipment for conveying, weighing and batching of dry materials. The primary technology for conveying is vacuum, but positive pressure pneumatic conveying systems as well as mechanical conveyors, like flexible screw conveyors, are used as applications dictate.

Detergents are challenging to convey due to their adhesive characteristics and because moving and dispensing powder at high volume can potentially change the density, component blend and texture, producing inconsistent fill rates or volumes, causing production interruptions, and possible degraded particle size that compromises quality control standards.

With a vacuum conveying system, powder isn’t forced mechanically and there are no moving parts to come in contact with the powder to disrupt it.

France says that when he contacted the conveyor manufacturer and explained what ABVI was trying to accomplish and the nature of the product the company requested material samples to ensure particle size distribution didn’t change upon vacuuming from a super sack into the hopper.

The conveyor manufacturer has a fully functional test and demonstration facility equipped with a multitude of equipment configurations and vacuum conveying tests to simulate actual conditions at customer’s sites and performs testing at no charge to potential customers.

Because the powder can change density in the auger filler head, leading to improper fills, keeping the head full and at proper density is critical. VAC-U-MAX utilizes a variety of methods such as specialized finishes and a proprietary designed coneless vacuum receivers that reduce powder sticking inside the system eliminating the need for external flow promotion.

France says, “we decided upon this system because the manufacturer invited us to their facility to demonstrate their equipment with our product, offered us a couple different options based upon our product needs, and we were able to make a decision of which way to go.”

Pneumatic conveying systems are flexible, and when working with an expert that has intimate knowledge of  material characteristics and manufacturing processes, users can have semi-custom pneumatic conveying systems using standard components that are adapted to fit manufacturing needs.

Once ABVI was granted the contract, it commenced building a room with proper ventilation for the process and ordered the equipment.

Because the controls from the two systems needed to be integrated to signal the vacuum system to convey more detergent when the auger filler hopper emptied, France says, “we wanted to make sure that when we got the whole system on site, the line would be fully functional and everything worked properly.” 

To confirm this, the conveyor manufacturer set up its system at Per-Fil’s facility and demonstrated to ABVI representatives that the two systems were fully integrated and operational.

“We really appreciate the fact that VAC-U-MAX was willing to send someone to the auger filler manufacturer to guarantee their equipment was able to interface properly with the other equipment,” says France.

The conveying system vacuums the detergent from super sacks at floor level using a large wand that an individual moves around inside the sack when necessary, into the hopper of the filling machine. 

The filling system has been designed so that individuals who are blind or visually impaired can operate the line. Audible alarms on the auger filler alert operators that they need to move the wand to a different location within the bag in the event that the conveying system is not sucking detergent into the hopper.

When the boxes are full, an audible signal lets operators know they can move it away from the filling station to another location where the box is sealed and packaged. The system also utilizes a touch screen for further assistance that provides audible explanations of whether the process is working properly or not.

The production line has a demonstrated daily capacity of 200, two-carton boxes and is staffed with three operators.
 
“The system runs very clean,” says France. “Overall we are impressed with the system and the expertise that VAC-U-MAX provided in the process.”
www.vac-u-max.com.

Automated storage and retrieval systems (ASRS) are computer-controlled material handling machines for automatically depositing, storing and retrieving unit loads from defined storage locations. Central to the ASRS is its stacker cranes which permit full-pallet load and layered-pallet inventory to be moved quickly, safely and precisely within a high-bay warehouse environment.

Stacker cranes offer reliability and accuracy that exceed the capabilities of forklift trucks or turret trucks. Modern cranes operate within a set of top and bottom rails, eliminating the need for any flat-floor requirements. Since the crane is stabilized by the rail connections, greater load capacities are available, as well as higher rack heights, when compared to free roaming lift trucks.

ASRS cranes have a high efficiency of cycle time, a calculation of the movement of product within a DC’s storage system. Many manual operations in a warehouse transport product in only one direction, then return with an empty load. Stacker cranes place a load into a rack position, and then retrieve a load from storage on their way back out, optimizing the crane’s movements.

The ASRS stacker crane concept has proven itself to be a viable method to reduce operating and distribution costs in the warehouse. Semi-automated and fully automated cranes reduce the number of people required to operate the warehouse. By incorporating stacker crane systems, a distribution center’s throughput can operate at a more cost-efficient level.

ASRS cranes have advanced to an extremely high level of performance, and continue to improve. The latest generation of cranes incorporates a unique flexibility, allowing single-deep, double-deep, triple-deep and up to 20-deep pallet stacking utilizing telescopic forks and shuttle cars, with the flexibility to handle one load at a time or multiple loads.

Such cranes can exceed 140 feet in height carrying payloads of 11,000 pounds, traveling at vertical speeds of 325 feet-per-minute (FPM) and achieving horizontal travel speeds of 787 FPM.

Most can operate in a wide sphere of temperatures, ranging from minus 38° F to 140° F, equipped with wiring, electrical cables and photo-electronic sensors that are designed to withstand these extreme environments.

High-speed PLCs with integrated controls architecture monitor the movements of the cranes. Receiving directions from the distribution center’s warehouse management system (WMS) and warehouse control system (WCS) via Ethernet, the cranes utilize barcode technology to direct their movement in the high bay and the crane’s movement of pallets.

The most efficient stacker cranes that provide the lowest operating cost per hour are now fully A/C powered. This eliminates the costs associated with DC batteries, charging, and associated maintenance. Such cranes have also eliminated hydraulics, which greatly reduces maintenance costs.

And then there is the power-saving technology designed into some of these cranes – the process of capturing and reusing electricity. As the crane carriage lowers, software allows the power to be captured from the lifting motor, which now becomes the generator. That captured power can be put into a grid inside the distribution center to help power other equipment like conveyor systems or other stacker cranes.

These progressive developmental improvements in stacker crane operation have made them one of the most efficient material handling systems in highly automated warehouses.

Streamlined Aisle-Changing Functionality
Now, aisle-changing functionality has pushed stacker crane operation to an even higher level of efficiency. Although aisle-changing capability in stacker cranes has been around in some form since the early 1990’s, the speed and efficiency with which these new cranes can now execute aisle changes makes them a serious option for use in any DC interested in reducing operational costs while improving throughput.

Most high-rise warehouses use ASRS cranes that are only capable of traveling in a straight line, in one aisle. The limitation of such a dedicated-aisle crane is that one crane is required to service each storage aisle in a warehouse. As cranes are a major part of the cost of high-bay warehouse solutions, by reducing the numbers of cranes significant savings can be realized. The number of stacker cranes can be matched to the warehouse throughput instead of to the number of aisles, therefore reducing the capital investment.

Unlike earlier models of aisle-changing cranes, which had limitations in their aisle-changing flexibility, some of the latest stacker cranes have been designed with efficient aisle-changing capabilities. One such crane is produced by LTW Intralogistics, a manufacturer of stacker cranes for warehousing. When the LTW crane gets to the end of an aisle, it can then travel perpendicular to the aisle and enter another aisle to continue storing and retrieving pallets.

The crane literally smoothly rotates around the end of the aisle on a curved track, without leaving the track. It makes for an easy and fast transition between aisles. LTW has designed and patented a specialized track to facilitate the move, which requires no transfer mechanisms, supervision equipment or costly and time-consuming maintenance, problems that have plagued earlier aisle-changing cranes.

The ability to switch aisles increases redundancy, in the event that a crane would go out of service. Each pallet position then becomes 100 percent accessible. This also allows cranes to be easily moved off line when service is required into an off-line maintenance area.

If an ASRS solution in place in a distribution facility has ten aisles and is employing ten stacker cranes each operating in its respective aisle, if a stacker crane breaks down there is no way to get products out of that aisle. With aisle-changing cranes operating in a situation like this, the DC operator could easily move the disabled crane to the maintenance area and the remaining cranes could complete the tasks required in that aisle. The redundancy system would assure that the pallets are retrieved. This is very important to maintaining a high level of delivery assurance.

These new aisle-changing applications require fewer cranes and less capital investment than solutions using fixed-aisle cranes. It is not uncommon for a distribution center with 24 aisles with 50,000 pallets to have just six state-of-the-art aisle-changing cranes servicing them. As the DC’s volume increases, it can add on more stacker cranes to accommodate the need, making the system quite scalable.

Depending on the throughput flow of a distribution center, the DC may employ a combination of dedicated-aisle cranes for aisles with higher volume throughput requirements, and use aisle-changing cranes for those aisles where the volumes are less.

Keeping Throughput on the Move
The most streamlined warehouses today are highly automated facilities, with maximized high-bay, high-density storage utilizing ASRS. These ASRS, in conjunction with the warehouse management system, maintain precision product identification and rotation, provide rapid throughput with over 99.9 percent accuracy levels, and are considerably more energy efficient than their manually-operated facilities.

To stay competitive, distribution centers need to implement systems that will have the flexibility to adjust very quickly and accurately to market conditions such as increases in SKU range and shortened lead times. Keeping throughput on the move is critical in any distribution center. It is here where the latest technology in ASRS aisle-changing functionality can provide the biggest benefit to a company’s distribution effort.
www.ltwusa.com

St. George, Ont.-based Gowing Contractors was tasked with rebuilding an existing waste-water digester system at the City of Cambridge, Ont.’s waste water treatment plant, which included the replacement of all of the mechanical components that were located around the perimeter of the inside of the digester.

However, the only way to get inside the digester was through a roof vent, located in the centre of the roof; once the vent was removed, there was a mere 97-inch opening, which provided a set of challenges in getting the right equipment in and out. They chose a mini-crawler crane provided by London, Ont.’s SpyderCrane Equipment Ltd., which was flexible and compact enough to access the area. The design of the digester floor also proposed additional challenges.

To prepare the site for the job, they removed the roof top vent from the center of the digester. Using a 30-ton boom truck, they hoisted timber crane mats down to create a level work surface.

Next, they prepared the SpyderCrane URW295 for hoisting into the digester from standard lifting eyes. This product fits through a standard doorframe, reducible to two feet wide, 4.45 feet high and 8.9 feet long. In order to allow necessary clearance for the crane to pass through the 97-inch opening, the boom was elevated to 45 degrees. It was then hoisted into the opening and down on to the crane mat. And finally, they hoisted the replacement tools, components and materials required to complete work into the digester.

They set up the SpyderCrane URW295 with the machine half on and half off the wooden mat; independent outrigger controls allow the mini crawler to be leveled on uneven surfaces, keeping the machine on the outside perimeter of the mats for maximum lifting performance. This was extremely useful when replacing components around the inside perimeter walls of the digester.

Its full-function radio remote control allowed the operator to stay in close proximity to the load placement location, for precise handling. The radio remote control system also increased safety on the job, by allowing the operators to position themselves in an optimal location. This allowed for superior control, while additionally keeping workers from being in harm’s way. (It also has automatic throttle activation, emergency shut down and a pressure sensitive trigger for speed control.)

When all was said and done, the SpyderCrane URW295 was used to install wall brackets, hang pipe, position valves, and install pumps and grates along with material baskets. It saved the project countless hours and, subsequently, countless dollars. The job was completed three weeks ahead of schedule to the delight of both the City of Cambridge and Gowing Contractors.

There are sometimes unique challenges in the lifting business, and SpyderCrane mini crawlers can meet a range of applications. Engineered and manufactured by Japanese industry crane leader Furukawa Unic Corp., it offers versatility, maneuverability and generous lifting capacities in a compact design. Like at the this waste-water treatment plant, this enables contractors and maintenance teams to quickly and safely meet most restricted or confined area lift requirements, and do so in a timely and cost effective manner.

The smallest member the product line — the URW295 — was used for the treatment plant. The URW376 and URW547 are both 52 inches wide, while the URW706 — the largest model — is 63 inches wide when in the stowed position. At their hearts are their independent outrigger controls, allowing them to be set up on uneven surfaces, close to a wall or around certain obstacles. Their compact design also minimizes dead-lift areas, allowing the machine to be set up closer to loads while still providing a full 360 degrees continuous rotation of the boom.

The company says its patented turn-over-protection system is “one of the most advanced safety features in the crane industry today.” It continually monitors ground-bearing pressure at each outrigger, regardless of outrigger configuration, and automatically sounds an alarm while restricting unsafe crane functions. There is also an on-board diagnostic system that continually monitors the crane's operating status and provides complete service diagnostics.

Additionally, SpyderCrane crawlers are now available with battery power, making them ideal for the food and beverage industry and other facilities where noise or emissions are a factor. The electric-power package can also be purchased separately to allow new and existing customers to add this option as a separate power pack.

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David Smith does sales and marketing at Spydercrane Equipment Ltd. in London, Ont. For more information, visit www.spydercrane.ca.

The purchase of material handling equipment represents a significant investment for any organization. With this investment comes the responsibility to maintain the equipment in conjunction with the manufacturer’s recommendations, health and safety guidelines, and legislative requirements. Keeping the equipment ready to work is vital to maintaining product movement and flow within a facility.

In particular, lift truck maintenance can be a critical component in maximizing the productivity and throughput of a warehouse or distribution center. Whether a facility manager chooses to employ in-house technicians or outsource maintenance to a third party, basic lift truck maintenance requirements must be taken into consideration.

Scheduled maintenance
Each lift truck in a fleet should be assessed individually to determine the proper scheduled maintenance intervals for that particular truck. The frequency for maintenance should be scheduled in conjunction with the manufacturer’s recommendations and by taking into account the following factors:

• Annual utilization,
• Operating environment, and
• Age and condition.

The frequency of scheduled maintenance should be adjusted as these conditions change. In addition, service history and utilization reporting can be tracked through fleet management programs, which are more robust today through technological advancements. For example, with today’s fleet management technology, maintenance schedules can be triggered automatically through monitoring of the deadman hours on a lift truck. When a lift truck reaches a certain number of deadman hours, the system can trigger an email to the facility manager from the vehicle management system (VMS) to notify him or her that SM is due. The VMS uses the warehouse’s internal wireless infrastructure to pass data from the system to a central server. Usage data and emails are transmitted to notify key personnel regarding the status and health of their equipment.

Lift truck inspection
Another key area where a good VMS can bring benefits is the preoperator checklist. Having comprehensive checklists ensures all required components are inspected, tested, adjusted and lubricated prior to a lift truck’s operation. Any items requiring repair or replacement should be duly noted for follow-up.

By electronically completing the inspection checklist, operators not only fulfill the records requirement but also save time. Electronic filing eliminates the need for paper and storage, makes document retrieval easier and alerts key personnel if a truck needs repairs. Key or critical questions on the list can even “lock out” a truck, preventing its use if an unsafe condition is revealed.

Many locales have legislative requirements for annual inspections that must be carried out on each unit. Facility managers must ensure their facility conforms to these requirements and maintains on-site records as proof of compliance.

Service technicians
The competency of service technicians is important in providing thorough inspections and completing accurate repairs. In general, the manufacturers of material handling equipment recommend using factory-trained technicians. In many cases, local, provincial, territorial and federal requirements for licensing or certification set the minimum standard for the competence of maintenance technicians. An untrained technician may use the wrong parts or unnecessary parts, adding downtime and cost. A technician with proper understanding of the equipment can service the truck more quickly, often completing the work on the first visit and getting the truck back into operation.

There are many considerations when choosing whether to employ third-party maintenance technicians or use in-house staff. In-house staff must be considered when planning salary and benefits. In addition, conducting maintenance with in-house technicians may require the need for a distinct internal cost center to accurately track equipment service records and equipment costing, which also may require administrative support.

Third party, factory-trained technicians can help streamline maintenance record-keeping. In addition, third-party technicians focus solely on maintaining material handling equipment, which means they are able to focus on scheduled maintenance needs, including lift truck battery maintenance, so in-house staff can focus on other aspects of the business. Plus, third-party technicians are kept up to date on the latest equipment technologies and how to properly service them.

Conducting maintenance with in-house technicians may require space and time dedicated to parts inventory. Third-party technicians can cover the responsibility of ensuring proper parts inventory and bring parts with them when they arrive for service calls.

Maximizing productivity
Conducting regular scheduled maintenance and thorough daily inspections of lift trucks can help ensure a healthy, productive fleet. In addition, working with qualified, highly trained service technicians can streamline maintenance and enable facility managers to focus on other aspects of running their businesses. By ensuring a comprehensive lift truck maintenance program is in place, facility managers are taking a huge step toward maximizing their warehouse or distribution center’s material handling productivity.

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Mike Car is the national director of customer sustainment with G.N. Johnston Equipment Co. Ltd. in Mississauga, Ont., and Joe LaFergola is manager of business and information solutions with the Raymond Corp. For more information, visit www.johnstonequipment.com.

Time is money, so when it comes to caster maintenance in the workplace, it’s far more cost effective to be proactive than reactive: a proactive program that avoids the costly repair and maintenance issues associated with equipment breakdowns.

Maintaining casters and wheels requires a disciplined maintenance program that routinely inspects all aspects of its functionality. Casters make work easier, and routine maintenance generally is an easy task. There are three critical areas that require routine inspection: visual inspection of the caster body; the swivel head mechanism; and the wheel.

Look at What's Rattling
Casters that allow carts and equipment to maneuver and swivel 360 degrees are attached to carts or equipment in many different ways. The most common is a flattop metal plate that anchors the caster to carts and equipment using bolts and nuts. Other forms of anchoring include the use of a threaded stem, a friction fit press-in stem into a socket, using an expandable adapter to fit into a round or square tube, or using a cylindrical stem with a cross-pin lock.

First and foremost, the way the caster is fastened to cart or equipment should be inspected to ensure the anchor bolts, thread stem or other types of fasteners have not become loose through application wear and tear. Examine how the caster is fastened to ensure nuts and bolts are firm and tight. If casters are stem types, make sure the legs of the equipment are not bent. Inspect for wear and tear on the socket holding the caster stem. As well, make sure casters with expanding adapter stems are held firmly in place in tubular equipment. Always use lock nuts or lock washers to mount casters to equipment.

In examining the swivel head mechanism, look for fallen or destroyed grease zerk nipples and replace where needed. The zerk enables grease lubricant to reach the inner raceway where bearing balls require the lubricant to facilitate ease of caster rotation and maneuvering. It is best to order casters with grease seals, which help to retain grease in the caster raceway and dirt out of the critical ball bearing pathway. Periodic lubrication of casters and wheels is essential to prevent equipment downtime. The lubrication schedule depends on the specific application. Normal conditions may warrant lubrication every six months; however, for wet or corrosive applications, monthly lubrication may be necessary.

Damage Control
The caster swivel assembly should be checked for excessive play due to wear. If the caster is made with a kingbolt and nut, make sure it is fastened securely and that it is not stretched due to impact forces the caster may be subjected to in daily operation. If the swivel does not turn freely, check for corrosion, a lack of grease or dirt binding the raceways. If the cart or equipment has rigid casters at one end, make sure the caster fork legs are not bent, distorted or misaligned due to side-thrust forces or impacts during use.

If the caster has been subjected to harsh operating conditions, visual wear and tear will be obvious in that the caster may be tilted, misaligned, excessively wobbly or prematurely bent due to overload conditions. Other functional impediments can be caused by weak weld or limited weld penetration at the time of caster fabrication. The caster frame may be too light duty for the application, which can cause dangerous collapse of cart or equipment. If the cart or equipment is traveling over rough terrain, excessive shock load or side thrust applied to the caster will cause it to deform if the casters are underspecified for use or application conditions.

If any of the above mentioned conditions are apparent, consult the manufacturer for caster specifications details and suitability of applied operating conditions.

Annoying Squeaks
A squeaky wheel is a sure indication the axle is dry of lubricant; the bearing has disintegrated; string strapping or other material has twisted around the axle impeding the wheel’s rolling ease; or that the fork legs of the caster are misaligned causing interference with the wheel’s movement. If the equipment or cart is subjected to wash down, essential lubrication may also be required after each wash down application. Special high-temperature, water-resistant lubricants must be used for these applications. In wet environments, consider using stainless-steel casters that require less maintenance and offer corrosion resistance in frequent cart washing applications.

Some new products in the market offer maintenance free casters. These casters are constructed using sealed precision bearings in either the wheel or swivel head mechanism, thereby eliminating the need to lubricate casters especially in wash-down applications.

Wheels should also be inspected for visible tread wear. For example, flat spots may indicate accumulation of floor debris, which can cause the wheel to bind. Alternatively, it may be due to excessive load beyond the capacity of the wheel to carry such a load. Inferior material and workmanship of low cost materials will also cause wheels to flat spot even at light loads. When it comes to casters and wheels, the lowest price is not always the best deal in town. Buyers beware! The addition of thread guards at time of purchase can also reduce build-up of string and thread wrapping between the wheel and axle. Maintenance should remove the wheel axle bolt and nut. Clean out the foreign material and check wheel bearings for wear and tear. Reassemble if parts are not damaged. After the wheels have been inspected and repaired or replaced, be sure the axle nut is properly tightened. Use lock nuts or lock washers on all axles.

Routine best practices in caster maintenance eliminate the costly down time typically associated with a lack of disciplined maintenance program. The use of casters should be an integral part of the cart or equipment design and fabrication, and not as an afterthought as to how to move the apparatus once designed and fabricated. To help you set up a maintenance program, consult the manufacturer of the casters that are now in use at your facility.

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Mike Titizian is the president of Colson Casters Ltd. in Cambridge, Ont. For more information, visit www.colson.ca or phone 1-800-643-5515.

The idea of going easy on the earth is becoming a fact of Canadian corporate life, and the supply chain plays a major role in these efforts. According to a recent Deloitte survey, 80 percent of Canadian supply chain professionals define green supply chain management as a corporate strategic priority.

According to research, the supply chain represents as much as 40 to 60 percent of a business’ environmental footprint. Consider the energy required for shipping goods, which include heating and cooling the distribution centre and fueling the trucks that transport products to their destinations.

If a company is not involved already, it won’t be long before it is mandated to improve, and opportunities may be found in areas such as material selection, product design, production process, customer use experience, and disposal/recycling options. A holistic awareness of the supply chain and its impacts is the foundation for companies that want to reduce risks and seize opportunities. As management scrutinizes the distribution centre to find small and large adjustments that will allow it to run a more energy-efficient business, attention eventually focuses on the loading dock.

Where else in a facility are there eight-foot-by-ten-foot holes on the wall? If the size of those holes isn’t challenging enough, consider their purpose, which is to allow forklifts to access the trailers parked at the door.

For many reasons, a hard-working dock area presents challenges when it comes to blocking air escape and invasion. If dock doors are not sealed properly, energy losses can be in the thousands of dollars, easily busting the operating budget and defeating the good intentions of the sustainability program.

Completely sealing the dock doorway requires a four-pronged attack.

1. At the Doorway
Forklifts are essential for truck loading and unloading, and a five-ton vehicle cruising within a confined space often results in damage to dock doors, especially those of standard design.

Similar to the door on a residential garage, dock doors are hardly a match for a forklift collision. Even when the door is not completely damaged or the guide rollers have not popped out of the door guide, a punch from a forklift can misalign the door panel and create costly gaps.

A traditional door style may be fine for low-usage docks, but for truly busy operations, “impactable” dock doors will save the maintenance budget and boost the building’s energy efficiency program. As the name implies, impactable dock doors do not resist the force of the blow when taking a forklift hit; instead, the door panel releases from the door guides. A quick pull sets the door back in place, making it operational in just minutes and once again protecting the doorway.

In addition to energy saving initiatives within the building, managers are looking to reduce truck idling time. Quickly restoring a door to operation and making sure a doorway is available for scheduled trucks minimizes that issue.

2. Along the Floor
Standard pit-mounted dock levelers provide safe trailer access for forklifts, but the nature of their design creates passageways for air infiltration and escape. The concrete pit design suffers from small gaps between the edge of the dock leveler and the pit wall, exposing the facility to interior–exterior airflow exchange.

There is a solution for this energy loss. Both new and existing pit-style dock levelers can be outfitted with an advanced weather-seal system composed of durable open-cell foam and heavy-duty vinyl.

This system effectively fills the gaps around the sides and rear of the dock leveler and provides a superior seal around the perimeter. For additional protection against energy loss, steel dock leveler platforms can be coated on the underside with spray foam insulation to minimize the platform’s ability to conduct heat.

3. Between the Wall and the Truck
Ideally, a truck trailer would fit precisely within a doorway, but even then, the facility must provide a means for sealing that gap.
Most docks have seals or shelters to create a mini-tunnel, and these flexible structures must withstand damaging force and compression when the semi backs up to the wall. Dock seals and shelters are critically important components in containing conditioned air in the dock areas.

Seals with galvanized steel backing offer many advantages over the wood backing used on some models of dock seals and shelters. Wood backing has a solid mass (1½ inches thick) that does not yield when the seal is compressed. Impact often results in damage to the building.

With steel backing, the solid mass is replaced with compressible foam on a steel frame. Steel backing also offers superior durability because it does not rot, split, crack or warp. It uses plated screws with load-spreading washers in the steel to provide a stronger, more durable hold on the fabric.

Truck restraints provide greater protection than wheel chocks for forklift drivers by preventing trailer creep, and they add an extra measure to the doorway seal. If the truck is allowed to “walk” away from the wall, the doorway seal becomes less effective than one that is snugly held tight to the dock doorway.

4. Above the Floor
Proper lighting on the dock and inside the truck trailer prevents injuries and damage to product. Changing out incandescent lights with LED bulbs can make a significant difference in energy usage, reducing it by as much as 69 percent. Switching out 100 incandescent lights with LEDs can save nearly $60,000 over the life of the bulbs.

A standard lighting fixture has the potential to suffer damage from a forklift. Dock managers have the option of changing out just the bulbs or installing a light arm and head that is ruggedly designed to withstand the dock environment.

Further toward the ceiling, high-volume/low-speed (HVLS) fans improve worker comfort and contribute to energy savings. These fans move a massive amount of air using a small amount of electricity. Fans control energy usage by enabling the facility to raise its thermostat by about eight degrees in the summer and lowering it in the winter. For every degree the thermostat is lowered, facilities save about three percent on their total energy bill. For an even more energy-efficient option, facilities can use solar energy to power fans, allowing them to operate off the grid.

Take Control
While installing this equipment is the first step, orchestrating equipment operation ensures that the dock offers protection for both dockworkers and the energy program. Master control panels combine the separate controllers that raise and lower dock levelers, engage the truck restraint and track door closing — ensuring everything happens in its proper order. In addition, having the necessary buttons and switches on one box reduces conduit run along the already tight dock wall.

Software-based yard and dock management systems enable a facility to integrate with other intelligent software systems to monitor, schedule and communicate trailer movement, load assignment and loading-dock status.

Along with keeping an eye on whether doors are open or closed, these systems provide truck–trailer coordination. This enables dock management to direct and coordinate yard traffic for maximum efficiency and to reduce fuel use by idling trucks.

The building envelope is key to a successful sustainability program, especially considering the amount of heat needed to withstand Canadian winters. A properly deployed loading dock system will enable operations to achieve both peak energy efficiency and peak truck traffic organization. Product enters and leaves the facility through the loading dock, and it is there that supply-chain sustainability begins.

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Steve Kalbfleisch is sales manager with Dock Products Canada.

Every distribution system can be divided into five basic functions which it needs to perform including receiving, product storage, picking for order fulfillment, sortation and shipping. Although each of these sectors have experienced improvements due to technical advances, sortation is where significant leaps in efficiency are now being made with Dematic’s introduction of its FlexSort integrated sortation sub-system.

FlexSort is defined by its unique system integration and the efficiencies that the system provides to the high-speed sortation environment. The logic on how the system is controlled is quite different. All sortation functions are controlled as if it is one unified machine. From the pre-merge to the merge, to the transport conveyors feeding the gapping, to the gapping function itself, to the linear sortation and finally the take-away conveyors, the entire process operates with single-source control and full integration.

The FlexSort system is also defined by its system-wide, distributed, variable-speed control, which is uniquely based on how much product is being fed into the system, and how much product is moving out. Unlike any other system, it will automatically adjust its speed incrementally as required.

The system is further defined by the absence of rollers and the extensive use of belts throughout the system.  Package control is lost with rollers, and FlexSort demonstrates a maximization of efficient monitoring, routing and control of packages throughout its entire system, unrivaled in contemporary sortation operations.

Finally, FlexSort is defined by its high-speed, parallel-divert sliding shoe sortation, capable of providing a 20-percent increase in efficiency while maintaining comparable throughput volumes.

As a composite system, it brings to high-speed distribution centers a new and unparalleled level of efficiency in product throughput, low operating costs and system availability.

Integrated Control
The philosophy behind FlexSort control of the sortation sub-system is different from what is typically done.  It is more along the lines of a PLC/PC-controlled unified machine. Dematic calls this an Integrated Sortation System (ISS). The philosophy if ISS is to treat all of the sortation sub-system separate components as one machine. As such, the system is constantly adjusting speeds based on how much volume is coming through this sub-system upstream of the merge, how much volume is coming off of the sorter, and how much volume is en route from the pre-merge through the sorter. 

From a speed-setting viewpoint, the sorter acts as the master device that everything else in the sub-system follows. FlexSort functions on a closed-loop speed control. The sorter is the variable speed unit, the system is watching how fast the sorter is going and all the other sub-system equipment adjusts to it. 

The system is fully integrated from a single point of control. Its PLC handles the system control, while the gapper and sortation equipment is PC controlled to handle the diverse I/Os. Dematic’s SortDirector program interfaces with the host system and the system scanners to tell it what to do with the packages once they are identified.

Precision Control of Gapping
The FlexSort system eliminates all roller conveyors in gapping, and between all functions from the pre-merge conveyor through sortation, replacing them with belts. Compared to rollers, belts require a much higher level of control over their speed and operation. It would be unacceptable to have one belt stop and another one upstream continue to run, for example. So the system uses variable-frequency AC drives in the gapping function, and throughout the entire sortation sub-system to provide precision control of its belts.

Traditionally, with high-rate sortation systems, very heavy duty servo-drives are used with their own separate servo-controllers. Because these drives are costly, systems are typically set up with a main servo-drive powering two or three mechanically-driven slave belts. The same drive is powering more than one belt, so the ratio between those belts is mechanically fixed. The speed of these interlocked belts cannot be change independently, they all operate at a constant speed determined by the servo-drive. This introduces inflexibility in the speed control of individual belts.

FlexSort overcomes this problem by utilizing an independent premium-efficiency drive for each belt in its FlexGap gapping device, equipped with a high-performance, variable-frequency controller instead of a servo-controller. The motor is driving each zone (belt) independently, so there is no gear reduction, giving very good control over the ratio from the speed of one belt to the next. This means more precise gapping. 

The quantity of belts being employed with FlexGap has been increased as well, compared to conventional gapping devices. The belt size, and each now being independently controlled, has sizably increased the precision of package movement within the gapping system.

Mechanically, the belts do not require tracking or tensioning, there is no adjustment needed. With direct-drive (no reducer) cog belts, there is virtually no maintenance required either. This simplified design has reduced the mean repair time to less than 15 minutes. 

Typical gapping systems utilize one photo eye and a PPI (Pulse Position Indicator) on each belt of the gapping machine. The PPI is an electronic wheel that rides on a belt, or uses some other means of physically monitoring the belt. The wheel sends out a signal, typically a couple hundred times per rotation. When the PPI wheel is turning, the PLC is getting pulse signals that indicate the belt has traveled a specific distance. The PLC tells the gapper’s servo-controller what gap is needed between packages. The controller, via the photo eye, knows where each package is located on the belt, and using the PPI it can then predict where that package is located after it has been seen by the photo eye. It knows how fast the belt is moving and the distance traveled, so the system can track the time and predict where that package will be. When the package gets to the next belt transition it can adjust speeds accordingly to achieve the gap desired.

FlexGap handles this task differently and more precisely. It incorporates horizontal array sensors for gapping in place of the traditional PPI and discreet photo eyes. It uses a solid state photo eye array with a very small 2-mm pitch between photo eyes for the length of the gapping device, which is watching each package in real time. Because the system is tracking the packages and tracking the gap between packages in real time, it can adjust the speed of the belts to manipulate the gap much more precisely. By not using the PPI, it has eliminated a common failure point in normal sub-systems. If the PPI stops working, which occasionally happens, then the sorter will shut down. This liability to uptime has been removed with FlexGap.

Variable-Speed, Parallel Diverting Sortation
In a high-volume distribution environment, speed of package flow moving through the system as determined by the sortation equipment, is usually focused upon as the criteria for production. It has been a standard for some time that to increase throughput one must increase the speed at which the sortation equipment is running. Of course, running a sorter faster increases vector stresses on the equipment and on the packages flowing through the system, which means less package control and more maintenance effort. It decreases the life of the equipment and ultimately increases the equipment cost of ownership.

This scenario has now changed with FlexSort. Increases in throughput can be achieved without increases in system speed. The key is in the FlexSort SL Parallel Diverting sorter. Typical sortation equipment with angled diverts rotate the boxes to facilitate discharge to the takeaway conveyors.  When a package is rotated, essentially it becomes longer because one corner falls back, this means a bigger gap required between packages. FlexSort SL does not need to rotate the boxes, allowing for tighter gaps between the conveyed products. Instead of 6” to 12” between packages, which is common with sorters using angled diverts, the system requires only 1” to 3” gaps. The take-away is designed to complete the rotation to the correct orientation, using gravity wheels or powered rollers that rotate and realign the packages. 

Because the sorter runs at a slower speed, it can handle packages more positively than contemporary sortation equipment, which runs 20 to 30-percent faster and creates 35 to 50-percent higher dynamic loads (the effects on packages when they change direction or speed on the system).

When packages tip over or slide on the conveyor and lose their intended position, the potential for side-by-sides, jams and mis-diverts increases, resulting in reduced accuracy, reduced productivity per man-hour due to downtime, and reduced throughput. The overall effectiveness of the system suffers in quality and performance, not due to improper operation, but because of the inherent inefficiencies within the system’s design and application.

A package traveling in a straight line at a constant speed does not experience forces that would cause it to topple or move on the conveyor. But when packages transition from the merge inputs onto the merge (both a directional change and a speed change, from a slow moving input to a fast moving sorter feed), travel around a curve, speed up and slow down for gap adjustments and divert off of the sorter, they experience forces that vary in proportion to the square of their velocity.

A key feature of the FlexSort ISS technology is its ability to automatically vary the system speed with its real-time throughput requirements. The system provides not just a selection of pre-determined speed modes, but rather a gradient spectrum of automated variable speeds.

Because the system runs at a lower average speed, packages will experience significantly lower average forces when they change direction or speed. A system that is designed to handle a high peak rate, for example, but on most days is only utilizing 60 percent of that peak realizes a net speed reduction of 46 percent with FlexSort ISS versus a fixed-speed system. Force is not linearly proportional to velocity, so in this example the forces on the packages and components of the system are reduced by 70 percent. 

The Dematic FlexSort SL is capable of processing 300 cartons per minute (CPM) at the same speed that contemporary high-speed sorters can process 250 cartons. Conversely, it can process the same number of cartons at 590 feet per minute (FPM) compared to the industry standard of 650 FPM.

A unique feature of the sorter is its use of linear induction motors (LIM) – electro-magnetic drives that move a magnetic field across the face of the drive and move the aluminum slats of the sorter without mechanical contact. An air gap exists between the electromagnet and the slats, which have steel inserts inside.  The shoes are also electromechanically directed into divert rails and pushed across the sorter.

Normally on a slat-shoe sorter, all the slats are joined together by a chain that is driven by a sprocket with a conventional drive. The FlexSort SL sorter has no belts, drive chains, gears, sprockets or divert switches.  This feature eliminates the need for lubrication.

Most sorters use a mechanical divert switch.  This new system uses electromagnetic divert switches that eliminate pneumatics and significantly reduce component wear as the show pins are “pulled” into the divert rail rather than pushed (no mechanical impact).

Typical sorters provide a divert confirmation, but do not track individual slat IDs. This limits specific tracking of packages within the system. The FlexSort SL employs small magnets on designated reference slats which are read by a sensor, the data is constantly sent to and updated by the controller to determine slat location, speed and operational status. This allows exact real-time location of any package in the sorter. 

Sortation System Uptime
The uptime of a sortation sub-system is impacted by how long the equipment lasts, how much time it takes to repair, and how easy it is to perform preventative maintenance. It is also impacted by the availability of the system in terms if redundancy. Most sortation sub-systems use drive trains which can act as single points of failure bringing down the entire process. Because its drives are distributed throughout its system, FlexSort SL is designed to withstand losing up to 10 percent of its drives and still maintain operation and production for the facility. And because it can handle more packages within the same unit of time compared to conventional systems, the sorter can reduce the cost of ownership by lowering the operating cost.

These benefits demonstrate the unique capability of FlexSort to upgrade efficiencies in sortation systems within high-volume distribution centers.  It is inevitable that as distribution managers gravitate to more efficient systems to operate their DCs, they will need to consider the advantages that FlexSort brings to their distribution model.
www.dematic.us

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Jim McMahon writes on logistics automation. His feature stories have appeared in hundreds of industrial and high-tech publications throughout the world.

Many fresh-cut produce processors and packers have traditionally relied on belt conveyors to transport bulk and packaged product on their production lines, in part because low capital costs make these conveyors seem so affordable. But when on-going maintenance and sanitation costs are factored in, the affordability equation shifts in favor of other conveyor types. Add performance issues like gentle handling and throughput into the analysis and each fresh-cut product and application points to its own ideal conveying solution.

This look at the strengths and weaknesses of several options — belt conveyors, vibratory conveyors and horizontal motion conveyors — should help processors and packers identify the most effective conveying solutions for their applications.

Belt Conveyors
Belt conveyors typically offer the lowest initial capital cost of all the conveying solutions, which contributes to their popularity. But such a simple cost analysis is shortsighted because high maintenance and sanitation costs cause the total cost of ownership of a belt conveyor to quickly rise.

Although a total cost of ownership analysis indicates that vibratory and horizontal motion conveyors are less expensive than belt conveyors in the long run, there are fresh-cut applications that are best served with belt conveyors, warranting their use despite the higher cost. As for specific applications, belt conveyors are ideal for:

•    achieving significant changes in elevation (vibratory shakers are effective if the required incline angle is 10 degrees or less, but beyond 10 degrees, a belt conveyor is needed);

•    layering belts where incoming product is loaded either manually or automatically because of the slow rate of movement (typically three to four feet per minute) needed to achieve a well-mixed product;

•    serving trim tables since they offer the most flexibility in speed;

•    two-level storage conveyors that convey fresh-cut produce from a washer to a dryer; and

•    conveying packaged product, which can be achieved with either a belt conveyor or a vibratory shaker, but the sanitation advantage of a vibratory shaker is less of a factor with packaged product.

Vibratory Shakers
There are two main types of vibratory conveying systems: true natural frequency conveyors that feature mechanical drives and electromagnetic conveyors that feature electromagnetic drives. Both use frame-mounted drives and spring-arm assemblies to distribute energy to the conveyor bed, producing a diagonal, harmonic motion that moves product forward.

Compared to belt conveyors, vibratory conveyors are inherently cleaner with stainless-steel product zones and no belt-to-pulley/gear laminations. They also reduce maintenance, which results in a lower total cost of ownership over the life of the conveyor. Some newer vibratory shakers take low maintenance to the extreme with “lube-for-life” mechanical drives that eliminate the need to lubricate or change oil.
As for specific applications, vibratory conveyors are ideal for:

•    dewatering, as the vibration releases the bond between surface moisture and product;

•    product distribution on processing lines and packaging lines because gates can be easily opened and closed to divert product to multiple points;

•    scale feed applications where accurate metering to scales greatly enhances scale and bag performance;

•    feeding a cutter or slicer, where product orientation and singulation improves the effectiveness of the operation; and

•    cooling and drying as they can be equipped with a device that circulates chilled air through the product during conveying.

Horizontal Motion Shakers
Like vibratory conveyors, horizontal motion conveyors offer more gentle production handling than belt conveyors and lower maintenance and sanitation requirements lead to a lower total cost of ownership than belt conveyors.

Horizontal motion conveyors provide gentle handling for delicate products, such as whole mushrooms, that can slide on the conveyor bed without being damaged. Leafy greens, however, get scuffed and damaged by riding on the bed of a horizontal-motion shaker, so vibratory conveyors provide gentler handling for these types of products. This gentle handling advantage must be considered on a product-by-product basis. Also, the slower conveying speed of horizontal motion sometimes encourages processors to run product deeper to get the throughput they need, and loading delicate products deep can cause damage.

Another significant difference between horizontal motion and natural frequency vibratory conveyors results from dynamic loading. Horizontal motion shakers create high dynamic loads during operation and require isolation via a separate deck, while vibratory shakers require no additional isolation and can be suspended from overhead, mounted to other machinery or supported from the floor. Thus, horizontal motion conveyors have less installation flexibility and higher installation costs compared to vibratory conveyor systems.

Specific applications in which horizontal shakers are ideal include:

•    reversing product flow;

•    reducing product drumming because some products, such as baby whole carrots, would make a drumming noise on vibratory shakers (but horizontal shakers’ electromagnetic drives are the most quiet of all, so if product drumming is not an issue, an electromagnetic vibratory shaker will be the quietest solution); and

•    providing some bulk storage capacity on the production line when conveying product in which gentle handling is not important.

To help navigate this complicated analysis, processors and packers should consider working with an equipment supplier that offers expertise in the fresh-cut industry and provides a full range of conveying solutions to choose from because, if designed properly, conveyors can do much more than simply move product throughout the plant. Gentle handling, effective dewatering, and chilling, to cite just a few examples, can improve product quality and extend shelf life.

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Teri Johnson is the fresh-cut industry manager at Key Technology. For more information, visit www.key.net. This was originally published in the April 2010 Food & Beverage Engineering & Maintenance supplement.