Conveyor Belt Maintenance, Adjustment, and Replacement

Why Conveyor Belts Matter

From the encrusting machine's outfeed to tray loading, steaming, blast freezing, and packing, products spend most of their time on conveyor belts. Once a belt is dirty, damaged, or mistracking, products stick, deform, or fall off, and debris can even end up in the product. It's the most "ordinary" part, yet one of the parts with the largest food-contact area.

Do Conveyor Belts Need to Be Food Grade?

A belt that contacts food must be made of a material suitable for food. The reason lies in the regulations:

• Article 3 of the Act Governing Food Safety and Sanitation (食品安全衛生管理法) defines "machinery, tools, or utensils that come into direct contact with food or food additives" as food utensils. Conveyor belts that carry food directly fall into this category.
• Article 3 of the Sanitation Standard for Food Utensils, Containers and Packaging (食品器具容器包裝衛生標準) states that food utensils must not show undesirable discoloration, off-odors, off-flavors, contamination, mold, foreign matter, or shedding fibers; Article 6 requires compliance with the general provisions in Table 1, and plastic materials must also meet the migration test requirements for the corresponding material in Table 2.
• Article 7 of the Standards for Food Factory Buildings and Equipment (食品工廠建築及設備設廠標準) requires that equipment materials in contact with food not produce or leach toxins, be odorless, non-absorbent, and corrosion resistant, and withstand repeated cleaning and sanitizing.

Common materials for food conveyor belts include polyurethane (PU), polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), silicone, and stainless steel mesh, each with different resistance to oil, heat, sticking, and cutting. When purchasing, ask the supplier for test reports showing compliance with the Sanitation Standard for Food Utensils, Containers and Packaging; products for export may also need to comply with the destination country's food contact material rules.

Daily Cleaning

• Every day: Remove surface residue, wash with food-safe detergent, rinse, sanitize, and dry. Remove belts that can be taken off for washing, and also clean under the rollers and support plates.
• Mind the underside: Flour and oil often build up between the back of the belt and the rollers, leading to mold and slipping over time.
• Avoid scratches: Don't scrape the surface with blades or wire brushes; scratches harbor dirt.
• Clean with the power off: Always stop the machine and cut the power when cleaning rollers; the point where the roller meets the belt is a nip point.

How to Fix Mistracking

Mistracking (the belt keeps drifting to one side) is the most common problem. Common causes:

• The drive and idler pulleys are not parallel.
• Tension differs on the two sides.
• Residue stuck to the roller surface makes the diameter uneven.
• The frame is not level or is deformed.
• The belt joint is not square, or the edges are worn.

General adjustment principles (follow the manufacturer's manual):

1. Clean first: Clean residue off the rollers and the underside of the belt; this alone solves many tracking problems.
2. Check that the frame is level.
3. Adjust the tensioning screws: The general rule is to tighten slightly on the side the belt drifts toward (or loosen slightly on the other side), adjusting only a little at a time.
4. Run empty and observe: After adjusting, let it run a few turns empty, watch the direction, and fine-tune.
5. Don't overtighten: Excess tension accelerates wear on bearings and the belt.

The effect of an adjustment can only be seen with the machine running, so stop the machine when turning the adjustment screws, keep your hands away from the rollers while observing it run, and make sure you're in a safe position when using tools.

How Often to Replace

Belt life varies greatly depending on material, product, operating hours, and cleaning method, so there's no fixed interval. Replace the belt when you see the following:

• Surface cracking, fraying, or peeling that could let fragments fall into the product.
• Deep surface wear or scratches, with stains remaining after washing.
• Damaged, lifting, or open joints.
• Severe deformation, with mistracking continuing after adjustment.
• Mold or odors that can't be removed.

When replacing: use a food-grade belt of the same specification and material; choose a suitable joining method (heat welding or mechanical fasteners), since metal fasteners can come loose and become foreign matter; after replacement, run it empty to check tracking, then do a small trial run.

FAQ

Q: Do conveyor belts have to be food grade?
A: Belts that contact food directly are food utensils, and their materials must meet the Sanitation Standard for Food Utensils, Containers and Packaging.

Q: The belt keeps drifting to the right. What should I do?
A: First clean residue off the rollers and the underside of the belt and check that the frame is level, then fine-tune the tensioning screws. The rule is to tighten slightly on the side it drifts toward, a little at a time.

Q: How often should the belt be replaced?
A: There's no fixed interval. Replace it when you see cracking, fraying, damaged joints, stains that can't be cleaned, or persistent mistracking.

Q: Can I scrape residue off the belt with a blade?
A: Not recommended; scratches harbor dirt. Clean with a plastic scraper and brush.