Information And Tips
Conveyor and Sortation Systems in a Cold Room Environment
By Greg Tuohy
Doing anything productive in a cold environment is difficult. Sorting your products in a cold environment can be especially physically demanding and technologically challenging. In the past, sorting systems were only located in the ambient temperature areas of a warehouse. Products were manually picked from cold rooms and transported to ambient temperature areas to be sorted and or palletized and then returned to the cold room areas of the warehouse.
Physically, our associates health and well-being should be an important part of our business. In an effort to protect team members from the rigors of operating in a cold warehouse, most companies have adopted written Personal Protective Equipment (PPE) policies to include boots, cold weather jackets, bibs and insulated overalls as well as gloves. Additionally, to combat the effects of the cold temperatures, many companies establish and enforce restricted exposure policies. In essence, these standards are meant to protect our most valuable resource….our people. OSHA establishes most of the worker safety guidelines. However, the personal protection and exposure restrictions differ from state to state and company to company. Due to the necessary PPE requirements and restricted exposure policies, sorting product manually is cumbersome and inefficient. As you can imagine, manually handling and sorting cases of frozen meat while wearing layers of cold protection clothing and gloves can be inefficient. Fortunately, given the material handling technologies available to us today, we can overcome many of these challenges by designing and implementing of well thought out cold room sortation solution.
Using automatic sortation will help companies overcome some of the issues presented by the cold temperatures and also reduce the amount of manual labor required in cold rooms. Conversely, the practice of sorting and palletizing outside of the cold room, returning product to proper temperature zones after it is sorted and palletized can make the product susceptible to temporary breaks in the cold supply chain.
Environmentally, cold temperatures have traditionally been tough on automation. Depending on the operating temperature, motors may need to be upsized, special bearings with non standard lubricants may need to be used, and non retro reflective photo-eyes substituted to account for any condensation. As a result of potential investments required for more cold resistant equipment, coupled with the additional cost of installation in very cold environments, cold storage warehousing has been a relatively manual operation. The inventories of cold rooms often turn very quickly due to the need for maximum freshness. Cold room storage is often leased for temporary storage. As such, our sortation methods must be flexible.
As Steve Hartley, Director of Facilities, Buckhead Beef in Auburndale, FL, shared during a recent cold room sorter installation completed by TriFactor Systems, “Our mission statement is “Provide the best possible product at the best possible price." In order to help our customers provide the best possible price, sorting automatically in colder environments can provide an efficient means of segregating product for palletizing, packaging and shipping with minimal labor content.
So why go through the trouble of placing a sorter inside of a cold warehouse?
Cold Chain Consistency. Products stored and manufactured in cold rooms are done so for a reason: TO KEEP IT COLD. Hofstra University defines the cold chain as “the process that involves the transportation of temperature sensitive products along a supply chain through thermal and refrigerated packaging methods and the logistical planning to protect the integrity of these shipments.” Products stored in cold rooms may include:
• Meat, pork and poultry
• Fruit and produce
• All natural and organic foods
• Whole wheat flour
Certain products require specific temperature settings and humidity controls. Great care must be taken to ensure refrigerated products do not sit outside its proper storage condition as they can absorb surrounding heat quickly. The Centers for Disease Control and Prevention (CDC) has estimated that $300 million worth of vaccines alone are destroyed each year due to improper storage and distribution. $35 billion of perishable foods are wasted annually. Half of this loss is temperature-related, leading to lost revenue. Produce losses lead to increased claims, and the lack of documented temperature variances throughout the transit and storage chain makes claims processing complex and traceability difficult and costly. In the case of seafood, the cold chain is broken every time the temperature of the seafood rises above 1°C. Sorting product while maintaining required temperature and humidity controls can help reduce the quality risks associated with temporary breaks in the cold chain.
Scalability. The future is not always clear in business. Because it is not clear, automation planning and, in this case sortation planning, must be scalable. Many case and pallet conveyor product lines offer modularity and scalability features that were not available in the past. Case and pallet conveyor, palletizers and unit load AS/RS Systems, featuring automatic cranes are prevalent in refrigerated warehouses. As an example, in the last ten years, 24 Volt Motorized Driven Roller (MDR) conveyor has have proven to be very modular and scalable equipment. Safe, quiet and efficient, 24 Volt conveyor and sortation offers a means of conveying product while reducing safety concerns for operators who wear cold environment personal protection equipment . Additionally, 24 Volt MDR conveyors may be easily reconfigured as SKU changes occur in cold storage facilities. Cold warehouses often have consistently changing customer product requirements and a variety of temperature and humidity needs. Therefore, the sortation system chosen must be adaptable to the changing needs of our customers.
Equipment Durability. A sorter is a specialized type of conveyor system that consists of a main line (the sorter) that diverts product to a conveyor lane or chute for delivery to other areas of a distribution center or manufacturing facility. A sorter is usually necessary when the speed and accuracy and environmental challenges are too great to handle manually. In a cold room, the environmental conditions and the lack of operator dexterity that accompanies the wearing of personal protection equipment required make automatic sortation a viable option.
A sortation system consists of the induction (entrance into the sortation system), the sorter itself and divert lanes or chutes. Typically, the items to be sorted have a bar code label that serves as the license plate for identification purposes. This license plate contains the information required to determine where the item should be diverted and transported. The induction to the sorters typically has a photo-eye mounted at the infeed point of the sorter. This eye signals the system controls that a package has entered the sorter. Once the signal is received, the package is tracked using encoder pulses to determine the proper point at which it reaches the assigned divert location. Additionally, the photo-eye measures the length of the package so the number of shoes (in the case of a shoe sorter) may be designated for use with diverting.
Another consideration when designing the sortation system in the gap in between products. A gap is required between cases and it’s necessary to isolate the item to be sorted for a good scan. The required gap size is a function of many variables, including the product dimensions, location of the barcode label, the type and size of barcode label and the speed of conveyance. This gap is created using a variety of means to include speed changes, special gapping belts or physically stopping the cases before the scan.
It is through sorter induction that the item label is read by either a laser scanner or camera (single or multi-side reading) to transmit the data and determine the assigned lane or chute it should be sorted. After scanning, the item is tracked using encoders that aid in the calculations of distance and time along with the Programmable Logic Controller (PLC). The divert lanes or chutes destinations are usually maintained in a database maintained by the end user in their warehouse management system or ERP system.
The actual sorter can be one of many types including:
• Sliding Shoe Sorter
• Turbo & Narrow Belt Sorter
• 24 Volt MDR Sorter
• Pivot Wheel Sorter
• Pop up wheel sorter
• Pusher and swing arm sorters
• Cross Belt Sorter
• Tilt Tray or Bombay Sorter
• Activated Roller Belt
Much has been written on the subject of sortation types and the proper selection of sorters to use for each application. For our cold room discussion, in addition to understanding product dimensions and weight, throughput requirements, bar code (quality, position and type), we must also understand if the equipment can hold up to the environmental rigors of a cold room.
Different products require different temperature ranges. Vegetables can be stored at 55°F, dairy products are stored just above freezing at 34°F, meat is stored just below freezing at 28°F and ice cream is stored at –10°F. Medicines such as vaccines are generally stored at 41°F.
Using sorters in cold room applications will require an examination of temperature sensitive components of the system. In the case of shoe sorters, generally the minimum operating temperature is 28 °F. Looking beyond the minimum temperature, it is important to look at all the aspects of the system.
The lubricants used on the chains found on most shoe sorters will change SAE ratings from SAE 20 at (20° - 40°F) to SAE 30 at (40° - 100°). Lubrication, grease and bearings should be designed to support the temperature requirements of the warehouse.
Motors should be rated for high efficiency operation. Using variable speed motors with soft starts can improve the performance of the system considerably in cold warehouses. Photo-eyes are susceptible to condensation as temperatures shift during transitions from one temperature to another. To combat the effects of the cold, the use of resistance heating elements can be used. Alternatively, in place of traditional photo-eyes, limit switches may be used to avoid the condensation effects. This issue is especially prevalent as cases or pallets pass through a wall penetration. The wall penetration may have plastic curtains that reduce the transfer of cold air or high speed doors that open and close as a photo-eye or limit switch is triggered.
The extensive use of bar code scanners in refrigerated warehouse sorter applications calls for durable, cold resistant equipment. Cold storage environments can be particularly tough on your equipment. Long-term use of non-enhanced equipment in cold conditions can cause screens and housings to become brittle, and repeated condensation can cause internal components to corrode, short-circuit and fail. Bar code scanners normally operate in a temperature ranges from 32°F - 104°F which covers most cold room applications. However, through the use of heating elements, bar code readers may operate in temperatures as low as -31°F. Careful planning for the environmental conditions will ensure selection of the right equipment.
Camera technology used for bar code identification has been growing in popularity over the last several years. As the technology continues to improve, it has its place in applications with bar codes that tend to be inferior in quality, skewed bar codes and in reducing the gap required with laser scanning applications. Image based readers are suitable for high speed conveyor applications.
Cost of keeping it cold. Refrigeration is expensive. Refrigerated warehouse space costs about $120 per square foot compared to just $20 per square foot for traditional dry storage. According to Energy Source, an objective research and advisory service, “Non-refrigerated warehouses in the United States use an average of 6.1 Kilowatt-hours of electricity per square foot annually. Lighting and space heating account for 76 percent of the total use. Refrigerated warehouses are more energy intensive than their non-refrigerated counterparts because of the large amount of energy consumed by refrigeration equipment. They consume an average of 24.9 Kilowatt-hours of electricity per square foot per year. “Therefore, it is in our interest to efficiently use the lateral and cubic space available.
According to William Salom, Operations Manager at Passion Growers, Miami, FL, “In our business, its not only important to control temperature and humidity, its vital that our product be accessible to the flow of refrigerated air and not blocked from the flow of temperature controlled air for time periods where they can sustain damage and lose freshness.”
In times that demand safe and quality products that are available when and where we want them, it is imperative that we take advantage of the technology available to us. Sortation in cold room warehouses allows us to meet the physical and environmental challenges faced in distribution and manufacturing. The current sortation technology available is durable and cold resistant, allowing us to bring scalable solutions to meet the demands of the cold chain and our customers.
Greg Tuohy is a Systems Sales Engineer for TriFactor Systems, LLC, a material handling systems integrator based in Lakeland, Fla. He can be contacted at 863-577-2244 or firstname.lastname@example.org. For more information visit www.trifactor.com.