Traditionally, many belt conveyors are driven by gear motors, including those used in the food industry. Yet motor rollers, referred to as drum motors, are growing in popularity as a modern alternative. The Department of Food and Drugs at the University of Parma compared the advantages and disadvantages of the two technologies.
During the course of modern production processes, goods need to be continuously transported from one place to another. This also applies to meat production. In the field of food processing, hygienic requirements also play an important role. Conveyor belts powered by electric motors are usually used for this. Gear motors are most often used. They are usually attached beside or underneath the conveyor line and are connected to one or more belt conveyor rollers via a power transmission system (belt or chain). In contrast, when compact drum motors are used, a complex transfer mechanism becomes redundant. A compact electric motor is integrated into rollers which produce the necessary torque. It is obvious that such systems would ensure certain advantages when they are first installed. The motors driving the belt conveyors here do not need to be attached externally but are directly integrated into the conveyor framework.
Compliance with hygiene requirements is of particular importance
A study carried out at the University of Parma in Italy could make a significant contribution to simplifying certain investment decisions. Scientists from the Department of Food and Drugs deeply explored the question of what advantages and disadvantages drum motors and gear motors have during practical operations. The researchers were supported in their work by Interroll.
In the run-up to the actual investigation, the scientists firstly analyzed the types of applications conveyor technology is used for in practice. One specific feature of food processing, in contrast to other commercial sectors, is the existence of very stringent hygiene requirements. The great, even business-critical, relevance of this subject is last but not least demonstrated by a series of strict nationally or internationally binding standards and regulations that businesses must meet.
Also measured was the heat generated by the systems, a factor that must be considered when assessing the suitability of a system that encounters perishable foodstuffs, such as meat, which are not allowed to be processed or stored at high temperatures. Energy consumption is closely related to this and is also a key contributing factor in operating costs. Yet this does not just apply to electricity costs, which are relatively simple to measure. This is why the study also examined the effort required for installation, cleaning and maintenance work. Depending on the application, the amount of space a solution takes up can also present an essential decision-making criterion. Noise emissions were also examined. When considering occupational safety provisions and the productivity of employees, it is especially important that noise emissions do not exceed a certain level.
Important for the food industry: Hygienic cleaning of the conveyor system
The study identified three possible cases within food industry applications in which various drive solution concepts are used. Conveyor lines located in the "non-food" area (i.e., away from actual food processing) are largely non-critical in terms of hygiene. These processing zones can be, for example, found in areas where already-packaged goods are transported. The second application, the "food" area, describes a situation in which foodstuffs come into contact with the environment around them and the conveyor system needs to be cleaned manually and without water. Finally, the third scenario encompasses "washdown" areas in which perishable foodstuffs come into contact with the environment around them, making it necessary to clean the conveyor system very frequently with water and cleaning agents (e.g., using high pressure, foam or gel.
Comparing various motor types from several different manufacturers
Gear motors and drum motors from different manufacturers were used in the course of the study. The study allows for the fact that, of course, the choice of a particular motor type could influence the result of the comparative study in an application. Wherever possible, the writers have made an effort to work out whether ascertained differences can be traced back to the specific design of the selected component or fundamental design features. On the other hand, they point out that equipment which is old or unsuitable is often used in practical applications and that therefore the advantages of converting to a different system may be even greater than the differences ascertained by this study.
Drum motors: Particularly major advantages in hygienically sensitive areas
These differences, as concluded by the study, clearly support the use of drum motors in most cases. It is not surprising that drum motors scored highly in the comparative criteria for space requirements, installation and maintenance. In terms of noise emissions, however, advantages are found that speak in favor of gear motors, at least in the food and washdown areas. In the food area, they also performed better in terms of heat generation and energy consumption. For these two assessment criteria, gear motors and drum motors are more or less equal in washdown zones.
The results of the study are clear when it comes to complying with hygiene requirements. Here, drum motors score better than the compared gear motors in all three application scenarios because of their encapsulation, which does not provide microbes with a surface they can attack and is easy to clean with high-pressure jets. In the sub-criteria, which include danger of contamination, cleaning options and accessibility as well as danger of microbe contamination, drum motors present the clearest advantages in the comparison. Only the danger of contaminating the material to be transported with lubricating agents and the danger from heat generation are greater, naturally, because of the smaller distance between the drive and the material to be conveyed.
Conclusion: In the food industry drum motors are convincing
The study shows that there are indeed good reasons why drum motors are becoming ever more popular in the food industry. In addition to their compact design and the inexpensive operating costs and low cleaning effort required, it is the hygiene aspect that speaks most favorably for using drum motors in the food and washdown areas. Having said that, it should be ensured that the motors used are from providers who use synthetic, non-toxic oil for lubrication. However, this shouldn’t be a problem with the systems considered at the University of Parma; moreover, these systems made a positive impression due to their low maintenance.