There’s no doubt that technology and automation have made great strides in conveyor design. Historically, conveyors were typically viewed as an afterthought in the design process. Used simply to move parts from point A to point B, conveyors often were the last piece of equipment to be included in a packaging line.
That’s certainly not the case anymore. Today, the flexibility of conveyors allow engineers to be more creative in their use, which leads to packaging and material-handling systems that are more robust and comprehensive than ever before. Conveyors have become integral components of an application, an extension of a plant’s processing and packaging line. Recent trends in conveyor design and accessories are leading to increased throughput and productivity in equipment. While the most common type of conveyors are straight-line, many other designs are now becoming commonplace in plants.
Backlit conveyors use light fixtures installed at certain sections in the frame to illuminate items traveling on a translucent belt. These conveyors incorporate in-line vision sensors for visual-system interface and inspection. The contrast created by the light between passing product and the belt allows for inspection. Parts can stop directly over the lighted section or pass by uninterrupted, depending on the application. Some applications require inspecting products for metal-free design. In these conveyors, which also contain a metal-free belt, part of the steel bedplate is removed and replaced with a Delrin (an inflexible polymer that resists heat) bedplate over the inspection area. As a result, the metal-scanning device checks passing products without receiving false readings from the bedplate.
Single-drive multiple belts move two or more lanes of product. They use a common drive or shaft coupled to a single gearmount to move two or more conveyor belts. Multi-belt conveyors can mount two or more individual belts onto a single frame. Advantages of multi-belt conveyors include minimizing motor quantity, reducing space requirements by remotely mounting drives, and achieving the same belt speed with multiple side-by-side conveyors. Using permanent ceramic magnets placed in the bed, magnetic conveyors hold ferromagnetic parts to the belt during processing (including upside down applications) and accommodate changing elevations. Magnets are one inch wide and normally spaced at half the product’s width. Strength and size of the magnetic field are application specific. In general, two rows of magnets are installed: one orientated as north and one as south. However, multiple rows can be used for larger products or additional strength.
Vacuum conveyors are made by perforating the belt and drawing air, using a regenerative vacuum blower, through groves in the bed of a standard conveyor. The vacuum blower’s size is determined by the total area of vacuum holes open during product running, as well as the pressure to hold the product and its seal to the conveyor belt. Belt types are usually high friction or electrically conductive, and can reach speeds of 264 feet per minute. Vacuum conveyors hold parts securely to the belt for inspection and assembly/feeding applications, move items on an incline, and maintain control of flimsy parts or moving material. Mounted to a base, pivot conveyors swing out of the way to provide walk-through line access and only pivot upon sensing that no product is on the transfer point. Interlock switches and a timer clear the conveyor before the gate opens, preserving full product control. Product flow automatically resumes once the conveyor returns to its in-line position.
Timing-belt conveyors replace standard belts and work in conjunction with a toothed conveyor pulley. While belts in a standard conveyor slip over time, a toothed pulley provides consistent movement on the belt. This is important for accurate placement of parts during indexing or assembly runs. Toothed pulleys also allow heavier torque transfer to the belt. As a result, excellent belt-movement control positions parts and fixtures accurately. Accessories are also integral to successful conveyor operation. For example, manufacturers can mount shaft encoders to the conveyor’s drive shaft to sense rotations, count pulley revolutions, and control the belt in feeding or indexing applications. Diverters and gates manage the product’s continuous flow on the conveyor. Controlled by proximity switches, photo eyes, or counters, they guide and change product direction to single or multiple locations. In addition, diverters and gates meter flow to specific areas or separate products based on attributes.
Depending on the product and required stroke length, pushers mount overhead or on the conveyor’s side to remove items flowing perpendicularly from the conveyor. Servo drives accurately stop the conveyor to provide precise part location. They help control acceleration and deceleration and assist in assembly operations.
While there are many types of conveyors available on the market today, it still takes expertise to design and integrate a conveyor system into a packaging line. This can be a tricky dilemma for some companies, since downsizing has resulted in fewer on-staff engineers to manage these types of projects. That’s why companies are turning to material handling vendors and integrators to design, build, and implement these types of packaging projects. Vendors and integrators are skilled on material-handling solutions and can recommend the best system to deliver the throughput and performance to meet their customers’ demands. They can often build a custom-design conveyor system and have it operational in a short time frame. Additionally, by turning the project over to professionals, a customer can focus on the core business and not have to worry about allocating extra resources and personnel to oversee it.
Conveyors do so much more than simply move product from one point to the next. They are fully automated and work in conjunction with a processing or packaging line, receiving and delivering information to other systems along the product flow’s path. When designed by material-handling professionals, the results help improve a company’s productivity and profitability. Not too bad for a simple conveyor.
By: John Kuhnz, Dorner Mfg.