Lightweight Conveyor Systems are described by NIBA as having "a working tension of less than 160 pounds per inch of width". In general, lightweight belting is used in a wide range of conveying applications, including the conveying of automotive parts, baggage handling, the graphics and computer industry, finished wood products, medical distribution, tobacco processing, confectionery, distribution centers, canneries, cattlefeeder lots, and sortation systems, just to name a few. Belting used for these applications come in a variety of widths, lengths, colors, and configurations. Speed, weight, and coefficient of friction are but some physical considerations necessary to support lightweight demands.
Conveyor designs that utilize the lightweight belt vary in size and purpose. A lightweight conveyor system can be as complex as a computerized distribution center several stories tall or as simple as moving the product at a slow speed through an X-ray machine in an airport.
Lightweight belting has numerous construction characteristics to match the demands of the overall end-user. Belts may be plied, interwoven, and constructed on multifilament or monofilament yarns which have been fully impregnated with PVC or plied with rubber or other elastomers that are commonly used by belting manufacturers.
Lightweight conveyors are many times incorporated into machinery that process goods of all types. The belts are supported with either a slider bed, roller bed, live rollers, or are suspended without support.
These conveyor systems can be complex in their own right where they incorporate bends, crowned pulleys, scrapers, return idlers, lagged rollers, actuating systems, etc. In addition to the above, some end-users require that these lightweight belts have the ability to run over small radius nose bars, be v-guided, cleated, and made endless. The end result may be something as simple as conveying your weekly supply of groceries to be tallied by the checkout person in your local super-market, or as complex as flipping and turning envelopes at blazing speeds in a fully automated mail/sortation system in postal service facilities.
Choosing the correct belt for an application can be quite confusing. There are many different styles and types of conveyor belts available and they are offered for practically any type of conveying requirement. Full understanding of the application, including the operating environment, is necessary when choosing a conveyor belt for a particular application.
There are many components and factors of a conveyor system which must be considered in order to maximize performance and achieve the optimum life from the conveyor belt. Remember that the conveyor belt is one component of the entire conveyor system, and that the belt performance will be affected by the other components of the system and its operating environment.
The following components of a conveyor system are key factors when choosing the proper conveyor belt:
- Width - distance between both edges of the conveyor belt
- Length - total length of belt, end to end (consider pulley diameter)
- Pulleys - diameter, type, lagging, size, etc
- Type of material conveyed - weight, abrasion, size, density
- Speed - feet per minute
- Incline - degree of incline
- Decline - degree of decline
- Horizontal - flat system parallel to ground
- Slider bed - material that supports or carries belt; usually wood, steel or plastic
- Rollers (idlers) - rollers carrying or supporting the belt
- Fabrication - any cleats, v-guides, or sidewalls, etc
- Oils and/or chemicals - if the belt is exposed to oils or chemicals
- Temperature - temperature of the material being conveyed & the working environment
There are other factors which may also be considered such as noise restrictions, FDA/USDA or Canadian Food Approval, cleaning methods and conveyor operating time.
Installation of Lightweight Belt
Installation of Lightweight Belt is covered by the same guidelines as heavy black belt:
- Protect the belt from injury during installation.
- Obtain intended orientation, i.e. right side-up, texture or cleats facing in correct direction, threaded as designed over all pulleys, idlers, slider beds, etc.
- Engage drive and take-up systems correctly (no excess tightness or slack)
- Apply secure splice, appropriate for intended operating conditions
Since lightweight belts handle foods and other sensitive materials, care should be taken to keep the belt clean during installation.
As with heavy black belt, a lightweight belt will usually require some break-in and adjustment to obtain central tracking and training. However, unlike troughed black belts, many lightweight belts run on flat rollers or sliderbeds. This eliminates the training option of skewing troughing idlers to steer the belt.
Adjustments to track lightweight belts (assuming conveyor structure and splice are not misaligned) are made at terminal pulleys and return rollers, if any. Adjustable snubber pulleys are also effective in guiding lightweight belts, especially on reversible conveyors. Some package and unit handling conveyors have side ribs which prevent the belt from shifting excessively to one side or the other.
The belt tracking sequence is to start on the return side behind the drive and work toward the tail. Return rollers can be skewed or tilted to center the belt. If the belt is square going over the tail pulley, it will usually run true on the carrying strand. Snubber and take-up adjustments can also be used to track the belt.
Lightweight Belt Maintenance
Unlike heavy black belt, lightweight conveyor belts do not lend themselves to major hot vulcanized repairs. Relatively minor injuries can be sealed or bonded with self-cure cements depending on the economics and other factors. In some cases, lightweight belting can be repaired by insertion of a "saddle" section with either metal assistance or vulcanized splices.
In general, the most effective maintenance for lightweight belting is protection from damage or injury, or "Preventative Maintenance". Often, a damaged lightweight belt is replaced rather than repaired.