This is a collection of technical articles that have been pulled from published issues of the NIBA Belt Line since 2000.
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note: this is a members only section
Selecting the proper conveyor belt for today’s challenging industrial needs has become much easier with the help of modern software.
Parallel with their cousins the heavy duty conveyor belts, lightweight belts (belts under 150 pounds per inch of width), and in the majority of cases; the fabrics (top and bottom) for lightweight belts require protection by a compound - not just for wear resistance, also to achieve other desirable characteristics for conveying, processing food and non-food items, and in the transmission of power.
After a long winter (at least here in the upper Midwest) the days are getting longer, the snow is melting and spring planning has started for many of our customers for scheduled downtimes later this year. We have been busy doing conveyor inspections, and compiling a list of belts in need of replacement and quoting the same.
Flights, paddles, and pushers are all different names for cleats on a conveyor belt. Cleats are upright profiles attached to the top surface of belts to increase load capacity on incline systems.
There is a tremendous amount of work done in conveyor belt design and manufacturing to ensure a well performing belt but one bad splice can render the entire system a failure.
Wing pulleys were developed in the 1960’s to be the first welded steel self-cleaning pulley. At that time conveyor belts were cotton ply, belt speeds averaged 300 feet per minute (fpm) and wing pulleys worked. The intermittent contact (chordal action) would shake the belt and any sticky material would shake loose, falling and hitting
Allowable Working Tension is a figure that was commonplace in the North American belting (thermoset) community for years, and is still used by many manufacturers and distributors.
Most of the world classifies belts with the metric system and ultimate breaking strength while the United States most often uses PIW.
For many years, the technical recommendations for conveyor belt design were managed by the individual belt manufacturers, such as the “Handbook of Conveyor and Elevator Belting” published by The Goodyear Tire & Rubber Company in 1923.
Ceramic Pulley lagging has become the lagging of choice for many of our customers to provide maximum performance and wear life on all pulleys on conveyor systems.
The vulcanization cycle for conveyor belt splicing falls under three base components each supporting the other. If any of the three is out of balance a perfect splice cure is not possible.
This article will discuss the design of the belt as well as the design of the machine on which the PTFE belt will be used.
NIBA members spend hundreds, thousands, and possibly millions of dollars on preventative safety practices and procedures. However, it is equally important to also develop a Culture of Safety within your organization that allows your employees to maintain safety inside and outside of work.
WHAT IS PTFE? Polytetrafluoroethylene (PTFE) coated conveyor belting is a small but important segment of the lightweight belting market. PTFE is sometimes referred to as Teflon, a trademark of DuPont. The generic name is PTFE. For a specific product, check with your supplier before promoting the product as Teflon coated. For this article we will use the generic term PTFE only.
Bulk material conveyors with free flowing products commonly use troughed idlers sets along its length, increasing the belt load carrying capacity. Changing the cross belt profile to a wide “U” shaped high capacity configuration the belt must pass around flat faced terminal pulleys at each end of the system. Within these areas we find the conveyor transition.
What is Camber? Camber is the term used to describe an arc or curve that occurs in otherwise straight material. Generally, if camber occurs in belting, it is in a nylon (polyamide) core type material. Nylon core belting is more susceptible to camber than other types of belting because nylon tends to absorb humidity from the surrounding environment more than other materials such as polyester.
The researchers, in a study published in Food Control said that they investigated the occurrence and genetic diversity of L. monocytogenes in a Swiss sandwich-producing plant over a 12-month period, with the goal of evaluating the potential persistence of L. monocytogenes there in order to identify possible contamination sources. L. monocytogenes as a food-borne pathogen has significant public health and economic impacts with manufacturers of ready-to-eat foods required, under EU regulation, to examine the processing environment for microbe as part of their hazard analysis critical control point (HACCP) approach and sampling schemes.
In the world of conveyor belting, installation tension is a must to get the necessary performance levels out of the product. A belt simply will not support the necessary load requirements or even track properly unless the installation tension is sufficient. It is a simple topic relatively speaking, but for many customers it’s filled with misinformation and error-laden traditions. Hopefully, the following information will clear the air on this critical but often misunderstood topic.
This article covers the important aspects of fabric conveyor belt elongation and how to design the conveyor system take-up so that adequate take-up travel length is allocated.
On December 31, 2008, the U.S. Department of Labor’s Mine Safety and Heath Administration (MSHA) passed a new regulation for conveyor belts used in a coal mine. The new regulation (30 CFR Parts 14 and 75) requires higher flame resistance than the current regulation (30 CFR Part 18). Per MSHA, the new ruling allows the miners until December 31 2009, to place in service the underground coal mines conveyor parts accepted under existing Part 18.
On December 31, 2008, The U.S. Department of Labor’s Mine Safety and Health Administration (MSHA) published a final rule in the Federal Register that implemented the findings of a Technical Study Panel, pertaining to flame-resistant conveyor belt, fire prevention and detection, and use of air from the belt entry.
When considering what type of bottom cover or finish to use in a slider bed application for an industrial conveyor belt, there are a few options to go with. The main factors to think about when making this decision can include anything from the amount of protection needed for the bottom ply to the amount of friction needed or not needed. Hopefully this article will give you a better understanding of these options.
Part 2 of 2 Equipment Set-Up While impact management and load support equipment is not rocket science, this equipment must be set up properly. Particular attention must be given initially to the height of the wear bars in relation to the preceding and following three roll troughing idlers. The bars may be positioned on a straight line between the tops of each roller can or just slightly lower—but never higher. This line may be straight through at 20 or 35 degrees or it may be in some transition. Your equipment must include the ability to be positioned properly in the field; most often the user does not realize exactly what is needed until the bed is being installed. Few include this feature.
Today it takes more than a firm handshake and a tool box to be a sales and service conveyor belt distributor. Customers require an ever-higher degree of expertise in the distributor they select to supply, install, splice, and maintain those thousands of miles of conveyor belt in service today.
Part 1 of 2 Modern advances in conveyor belt design have resulted in higher tonnages, greater speeds, more advanced drives, and longer lengths. Many times the bottleneck in the entire conveyor system is the ability to properly and safely load material fast enough to maintain and haul the desired or design tonnages to meet production demand and expectancies. Loading too fast and too heavy can result in damage to the belt—the single most expensive belt conveyor component of all. Unsafe conditions due to spillage and fugitive material are created, as well as unscheduled downtime and unbudgeted cleanup and repair costs.
When you walked into your warehouse last time, were you happy with what you saw? Did you see this? Materials strewn about; material not in its proper place; people wasting time looking for items to complete a job and having to move items before finding what is needed.
In the world of conveyor belt, there is light duty, medium duty, and heavy duty. The delineation between these is relatively clear, and is generally based upon working tension of the belts. When you talk about light duty belts, the first thing everyone pictures is thin, lightweight, food belts, or black PVC package handling types. There is however, another small group that falls into this category that is mainly overlooked.
One of the most important properties of a conveyor belt is cover wear resistance. As conveyor systems have improved qualitatively in recent years because of improved maintenance and alignment, premature or catastrophic failure has been reduced and gradual wear of the belt covers has become a more common reason for belt change out.
Over the past several years, motorized pulleys have become a very versatile and dependable solution to power most belt conveyor applications. Plant and facility managers are constantly searching for more reliable conveyor components that will create greater operating efficiency while reducing the costs associated with maintaining their equipment. Recent technological advances have resulted in a virtually maintenance-free product that can reduce maintenance costs, enhance safety and improve the overall sanitation of a conveyor. Each of these areas can impact the performance of the conveying system and certainly the conveyor belts running at the facility. Safety and sanitation continue to grow in importance as more plants are operating under greater scrutiny from outside agencies, and management is striving to hit efficiency levels for the benefit of all stakeholders.
Sanitation is a key issue in food processing, but the hygienic design of conveyor belts transporting food products is often overlooked. Staying current with changes in conveyor belts, applications and required design criteria can help to optimize belt selection for performance and sanitation.
As consumers we share mutual concerns about the suitability of food products produced for public consumption. Likewise, as suppliers to different segments of the food processing industry, we should be aware of the current standards for safe, sanitary food processing and the respective agencies responsible for the maintenance and enforcement of these standards; this is the world in which many of our customers live.
Bonding rubber to metal years ago was known as a “black art.” Now with the improved technology and adhesive systems, it is virtually failure free if done correctly. In order to do it correctly you must:
The only number of conveyor mishaps acceptable in a plant is zero. Every injury in a plant is costly, affecting worker morale, availability of trained labor, lost production, and increased overhead due to insurance premiums, mountains of paperwork, and possible ?nes from government regulatory agencies. The U.S. Department of Labor, Bureau of Labor Statistics has reported that over 50 workplace fatalities a year are the result of conveyor accidents.
Ant hills, gob, carryback, fugitive material, dirty *$%#^&!—no matter what you call it, it’s that nasty material that has ended up in places other than where it was intended to be conveyed. And it is the stuff that can bring a bulk handling conveyor system to a grinding halt, costing the operation countless dollars in lost material, downtime, clean-up, personnel injuries, and/or damaged conveyor components. There is no doubt that a clean conveyor system makes for a more pro?table operation, but before elaborating on “how” to achieve this lofty goal of a clean conveyor, let’s ?rmly establish “why” it should be viewed as a necessity for any well-managed operation.
Classifying Fabric Yarns and Cord Sizes; Weave Styles There are several methods of classifying fabric yarns or cord sizes. Natural ?bers (cotton) are classi?ed by the English system in which the yarn size number is based on the weight of a hank. Staple ?bers are twisted to form single yarns. These yarns are then measured as a hank, which is 840 yards of material; therefore, a #10 cotton yarn has ten times 840 (8400 yards) of yarn per pound. A #8 cotton yarn would be 6,720 yards per pound. It must be noted that the higher the number, the higher the yield in yards per pound, consequently, the lighter the gauge. A yarn speci?ed as 8/1 means that there is one end of a #8 twisted single and will yield 6,720 yards per pound. A yarn speci?ed as 8/3 means there are three strands of the #8 yarn twisted together. The yield will be approximately 1/3 of resultant yards per pound and about three times the cross sectional area (not gauge). Some yardage and gauge is lost in the twisting. This is referred to as a plied yarn.
Reinforcing Materials for Belting The structure of belting is basically a composition of elastomers and reinforcing materials. The most common forms of reinforcements are either textiles or metal utilized as wire, cord, yarn, or fabric. The reinforcements fulfill four basic functions:
The NIBA Technical Committee recently held a raffle, the prize was getting to write this article. No, it doesn’t get much more exciting than this folks, so for those that need to, start popping those nitroglycerin pills and please keep your hands and feet inside the vehicle at all times.
Wear and abrasion problems in chutes are commonplace, and in some ways, the solutions are not what one may expect. Our goal (and the goal of most operations) is to keep the solution as close to the beginning of the “process” as possible. In other words, let’s make the solution one that is easy to access, easy to install, and easy to monitor. Let’s put the solution right at the beginning of the process and keep the problem from affecting more of the process than necessary.
Most NIBA members are keenly interested in helping customers keep their conveyors running efficiently and effectively. A major key to achieving this objective is using a belt that is properly specified and properly installed on the conveyor. The two options most frequently pursued to install a belt are vulcanization or some type of metallic mechanical fastener. There are times when a mechanically fastened belt would be prescribed, but is precluded from use because the fastener’s metal construction is inappropriate for the application. It is in applications like these that a third option might be worthy of consideration – non-metallic belt fasteners.
General Uses: To Transmit Power—One of the basic tasks for transmission belting is to transmit power from a source to a driven pulley. This is done through friction between the pulley and the belt, which is transferred through the belt’s core or strength member by way of surface contact and tension.
Unit handling systems encompass a broad range of applications and market segments. One could almost say that any conveyor moving an item from Point A to Point B could be considered a unit handling conveyor. Today, conveyors used in warehousing, distribution centers, and baggage handling systems have come to define unit handling applications.
This is the second in a series of articles designed to inform readers about the many different types of bucket elevators and their various functions. In the March issue, we’ve already talked about the three types of elevators: centrifugal, continuous, and positive discharge.
Bucket elevators are designed to move flowing powders or bulk solids vertically. They are attached to an endless spliced loop of belt/chain which travels in a continuous fashion around the tail pulley/sprocket from the boot section of an elevator, where the buckets are loaded.
The overall belting market share for lightweight conveyor belting has increased modestly over the past several decades. The primary reasons for the increase are process automation, market globalization, and competition. Process automation has resulted in increased demands on belting that often require the properties of a lightweight belt design. The move toward faster process and transport speeds, combined with compliance to increasingly strict standards in areas such as noise and sanitation, has also favored the growth of lightweight belting.
Conveyor belt elongation properties are critical in determining how heavyweight belts will react when subjected to varying stress levels. These stresses change along the length of the conveyor and across the width of the belt due to system influences such as tension, transitions, vertical and horizontal curves, turnovers, and crowned pulleys.
The vulcanization or curing process occurs in three stages and each stage is of importance and affects the service life of the finished product:
The pretensioning of lightweight conveyor belts is critical to the long- term performance expectations of the customer. In the field I often get asked by my lightweight belting customers, how do I know we have pretensioned our belts properly?
Since their introduction more than 30 years ago, the popularity of plastic modular belts has grown steadily. Constructed of injection-molded modules and hinge rods, plastic modular belts are positively driven and tracked by plastic sprockets. This positive drive and tracking system eliminates slippage, preventing damage to the belt’s edge and the potential for product contamination or premature belt failure.
The vulcanization or curing process occurs in three stages and each stage is of importance and so thus affects the service life of the finished product:
In the conveyor belting industry, it is well known that a thorough understanding of an application’s data is preferable (if not always possible) in order to make a proper belt selection. The reason is clear—we want to know that the selected conveyor belt will operate properly in its environment.
The vulcanization or curing process occurs in three stages and each stage is of importance and thus affects the service life of the finished product:
It is a common scene, played out in plants throughout North America every day. A plant changes out a high-tension conveyor belt... the one that brings the rock out from the pit to the surge pile.
Crowned pulleys are designed to assist in tracking belting in conveyor systems. There are several approaches to the design of crowned pulleys, but they all have the same basic design feature, the center of the pulley has a larger diameter than the outer edges of the pulley, thus the “crown.”
Generally, in the past, finger splices were known and used in lightweight PVC and rubber belts of varying types. The finger splice has also seen limited use in the past on some heavy-duty conveyor straight warp construction belts.
What type of belt cover will withstand magnesium sulfate? Will rubber work? What type of rubber? How do you explain the term “dynamic fatigue” to a non-belting person? What can you use as a quick introduction to help anyone with belt tracking? Need to know about ISO standards that pertain to conveyor belting?
Monofilament: “Any single filament of man-made fiber, usually of a denier higher than 14. Instead of a group of filaments being extruded through a spinneret to form a yarn, monofilaments generally are spun individually.” (From the Hoechst Celanese Man-Made Fiber and Textile Directory)
When dealing with conveyor belt tension ratings, it is not uncommon to hear references to working tensions or maximum working tensions and ultimate breaking strength or ultimate tensile strength of a belt. At times there is confusion about the meanings of these ratings. Both of these ratings refer to the capabilities of the carcass of the belt and are interrelated.
Synthetic rubber is manmade crude rubber. The majority of synthetic rubbers such as Neoprene, Butyl, Nitrile, Hypalon, SBR, and EPDM were first developed just before World War II. Knowing that the United States’ supply of crude rubber from Asia would be in jeopardy when war broke out, development was started to try to produce a synthetic rubber with the properties of crude natural rubber. The Rubber Reserve Company, a U.S. government corporation, started this development. Synthetic rubber enhanced the properties of natural rubber and expanded the vast market for rubber products.
For most soft rubber and plastics a Shore A scale is used. The scale covers from 0 to 100 but most instrument makers do not consider it as reliable below 10 or above 90. Softer materials including foams use an OO scale measurement device, while harder materials will be measured using a Shore D scale instrument.
Pure crude rubber is a colorless or white hydrocarbon. Natives of South America found uses for this product long before the discovery of America in 1492. However, as this knowledge was shared within Europe, it became possible to successfully manufacture water resistant products like capes, coats, and shoes. In 1771, a British chemist discovered that rubber could be used to erase pencil marks by rubbing. In 1823, the first factory was established to manufacture rainproof garments using rubber as a key ingredient.
The two primary components of conveyor belting are elastomers and textiles. For Distributor/Fabricators, the common language is compound (elastomers) and fabric (textiles).
Abrasion resistance of conveyor belt covers is one of the most important properties of a belt. As conveyor systems have improved in quality in recent years because of better maintenance, alignment, and rip detection systems, premature or catastrophic failure has been reduced and gradual wear of the belt covers has become a more common form of belt change out.
Noise (typically loud disagreeable sound) is a term that describes vibrations that are audible to the human ear. The average person can hear sounds in the frequency range between 16 to 16000 HZ (hertz is a term that denotes cycles per second).
Defined Transition Distance is the distance between the centerline of the first fully-troughed idler and the centerline of a terminal pulley.
What is the best method to suggest to the customer and why? Most manufacturers will suggest or recommend a splice type depending on the physical characteristics of the belt and the application requirements.
An impact bed will absorb the impact of an object falling on a conveyor belt. Unfortunately, the impact bed will not protect the conveyor belt from impact damage in most cases.
The following splice tips are not intended to supercede any of the various belt splicing manual techniques. Rather, to be a guide to offer plausible solutions when properly installed splices fail due to abnormal conditions under which the belt is expected to operate.
The Discovery of Rubber The discovery of what we today call “rubber” goes back a long way. Both the Mayas and Aztecs tapped rubber trees, which they called “Caoutchouc” or the weeping tree. By heating the sap over a smoking fire, they produced elastic balls which were used in ritual games. It took another 2000 years or so for the advantages of rubber to become known outside its native South America, but today it is one of the world’s most important resources.
Sometimes a hole in a belt can help provide a valuable operation in mechanical applications. Perfectly placed holes or slots punched through a belt in a specific pattern typically describes perforated belting. This fabricated belt is utilized in industry to provide a variety of functions. Wood finishing, agricultural, and filtration applications are common.
Here is an amazing fact. If you take a bucket of sand and pour it out on the same spot ten times, the piles that you make will always have the same shape. Why? Because every material has a specific Angle of Repose. From an engineering perspective, this is the limiting steepness of the slope, beyond which the material will slip downhill. In other words, the pile of sand cannot get any steeper than a certain angle, no matter how you pour it. The angle is greater for large particle sizes, irregular shapes, and wet material. So wood chips have a greater angle of repose than sand, which has a greater angle of repose than aerated Portland cement.