(Meatingplace) Conveyor belts are often the most over-looked equipment in a processing system but are probably one of the most important as they transport product and can significantly impact both quality and safety.
Therefore, choosing the right conveyor belt for your process systems can affect your down time, yield, and product safety. There are several types of belts available today for different needs including plastic modular, metal mesh and wire belts.
Typically, both plastic modular and mesh belts are used in raw product transfer. For improved yield, plastic and mesh belts can capture and move liquid with the product and there is less water loss. In addition, pieces or loose hanging meat particles (such as rib meat on the breast) do not fall through these closed type belts.
However, plastic modular belts can have differing percentage of open space. Therefore, the product and process should be considered when determining what belt to use for products. In general, the higher the open area percentage, the more drainage of the product can occur. So, if liquid or product drainage is a concern, and transfer of this liquid with the product is needed, then a smaller open space (closer to 0%) should be used.
Also, plastic belts with higher open space are better for heat transfer and cooling and are often used in spiral freezers. From a sanitation and food safety concern, plastic belts are easily cleanable with many improvements in clean ability over the last few years. In addition, these plastic modular belts are easy to repair with sections that are easily removable and a new portion inserted. Another use for these type of belts is use through a metal detection system.
Wire belts are also versatile in a processing and further processing system. They are mainly used in cooked products because of good heat control and stability. Even though wire belts have a high percentage of open area, there is less product loss when used in cooked products. They are excellent for breaded products for air flow during heating and cooking and provide more uniform results, especially in products that require some browning. An added feature of some of these belts is the belt grill looked that they can transfer onto some products, even though some of this look is done by other machines. Wire belts are also excellent for cooling of product for spiral chillers due to the high percentage of open area which allows for air flow.
An especially important consideration in food safety is the design of conveyor belts. Generally, all wire belts are made from series 300 stainless steel and operate with a non-exposed hinge mechanism to prevent bacterial harborage.
There are 3 types of finishes that can be used with stainless steel equipment. Most wire belts drive components are made with beaded finishes resulting in a microscopic “dimpled” finish to prevent deep crevices. Instead, stainless steel belt and equipment surfaces are made with a drawn finish produced by diamond dies to produce a smooth surface.
Plastic conveyor belts also have been modified to improve sanitation. Plastic belts are modular type belts which use a rod and barrel assembly to bind sections of the belt together. Plastic conveyor belts can be made from Acetal, Polypropylene and Polyurethane with mono polyester fabric which has a smooth top surface and a fabric bottom. Each of these belts can withstand different temperature gradients such as acetal (-50 to 200 ºF), Polypropylene (34 to 220 ºF), and Polyurethane with mono polyester fabric (-4 to 212 ºF). Each of these belts are approved for different food systems.
For ease of cleaning, these belts can use a clean–out-of-place (COP) system which uses agitation to remove adhering dirt and bacteria. In addition, angled sprockets ensure 100% cleaning ability and non-absorbant, non-porous, plastic materials are used to prevent crevices for bacterial growth. Some plastic belt equipment manufacturers are beginning to use broad spectrum, thermostable, antimicrobials imbedded in plastics to reduce growth of and control bacteria on the surface of conveyor belts, drive shafts, sprockets, belt guides and rollers.
Antimicrobials have also been incorporated in other equipment or used as coatings on such equipment as scales to prevent bacteria from harboring in crevices. However, proper usage and replacement of equipment with antimicrobials may be critical in retaining their functionality over long-term usage. Other bacterial harborage stations in equipment are bolt heads and threads. A solution to this problem is welded over bolt together construction.
Depending upon the product and process, there is a belt, whether it is plastic, mesh or wire for today’s needs. Most processors will have multiple belts within a facility depending upon need for quality and or safety.