Conveyors are used widely throughout various manufacturing industries, and common types of these systems for the food, beverage, packaging and pharmaceutical industries in particular include belt, chain or roller.
High maintenance attention is essential for the operational lifespan of conveyor systems. Each requires different yet precise lubrication methods for optimal results. Furthermore, conveyor maintenance must be administered with a mind of food safety, especially for those used in the food and beverage industries. If not, the integrity of consumables will be compromised.
Selecting The Right Lubricant And Application Method
The lubrication method for a conveyor system depends largely on its design and purpose. Engineers must appropriately select lubricants based on operating speed and environment. These would also vary with contrasting temperatures in industrial ovens or freezers, humidity level in sterilisers, dust from feed or wheat processing, and daily equipment washing.
Machinery components cannot be protected optimally with only one type of lubricant under these varying conditions. Quality lubricants are designed for specific protection needs. Only with the most informed decision, then the application will receive maximum lubricating protection.
Chain conveyor systems can be lubricated manually via oil drip, bath or spray. The primary lubrication requirements are good penetration, sufficient film strength and good resistance to rust or corrosion.
Automatic single-point dispensers are sometimes selected. Usually, automation comes into play when the application operates in a high temperature setting or difficult-to-access areas.
Automated lubrication is easily programmable and controlled. The system applies small yet consistent amounts of lubricant at a calculated frequency rate. It is an investment, but a worthy one because in the long run it reduces downtime costs, lost production and product contamination from over-lubrication.
Manual lubrication is administered with a brush or spout can. It is suitable for slow-moving conveyors. Experts advise an eight-hourly re-lubrication, although a longer interval is very much possible with a quality lubricant selection. This approach is labour-intensive and manufacturing facilities need to shut down (for safety reasons) to make time for manual lubrication.
The drip method of lubrication (contact-free) is often required for medium to high speed conveyors. This is where lubricating oil drips onto the chain’s link plate or sidebar edges; ranging from four to 20 drops per minute. The oil drip rate depends on the chain conveyor’s operating speed.
The spray method is usually for very high speed chains. Oil is pumped under pressure from a central lubrication point to nozzles spread out along the conveyor. These nozzles deliver a stream to lubricate the insides of the chain links.
This is one of the more popular maintenance approaches in food manufacturing facilities because the spray uniformly distributes oil across the entire width of the chains. One must be cautious though, as care needs to prevent stray mist from contaminating the food products. Any excess oil will be collected in a reservoir at the bottom and pumped back to the central point.
Finally, for oil bath lubrication, a short section of chain will pass through a sump of oil situated at the bottom of the chain casing. However, maintenance personnel must be cautious with the oil level. In the case where too many chain links go through the sump, the conveyors will likely experience foaming and overheating. If left undetected, it may result in premature failure.
Whichever method the maintenance department may choose, it should be ensured that the lubricant is applied to the upper edges of the link plate or sidebar in the lower span of the chain. By doing so, gravity and centrifugal force will surely carry the lubricant into another critical area—pins, bushings and rollers.
There is no perfect or guaranteed technique, but errors and hazards can be minimised with the use of dedicated equipment and application of the right amount of lubricant. Any excess should be wiped off.
Understanding System Requirements For Lubrication
All things considered, it is recommended for engineers to plan and implement a preventive maintenance initiative that covers all equipment lubrication. This should indicate critical points of food safety, and the maintenance goals should optimise efficiency, extend re-lubrication intervals, and prolong the conveyor systems’ operating lifespan.
Lubricants are primarily responsible to protect any mechanism from wear. When it comes to conveyor systems, lubricants reduce risks of dynamic pressure and damage to manufactured goods that sit on top.
Acting as a supportive barrier between sliding surfaces, friction coefficient is consequently decreased. At the same time, operations are smoother and noise levels go down.
Engineers must be aware of the common ways a chain can fail; typically by high tension, fatigue and wear. When overloaded in tension, chains will be stretched so badly till they are unable to function properly.
Fatigued chains will develop microscopic cracks in the link plates or sidebars. Subsequently, the chain material will start to wear thin from a combination of sliding, abrasion and corrosion. As a result, the chain will not fit with sprockets. Hence, engineers need to carefully plan maintenance scheduling and lubricant application.
Conveyor lubrication is not just about the chain, though. Its motor, coupling, gear reducer, pulley and bearings require protective coverage as well.
This applies for belt conveyor systems too. These are part of an operational process that strictly adheres to regulations that ensure finished products are safe for consumption.
Hence, it is crucial that manufacturers select not just any high performance lubricant, but certified food-grade lubricants.
Realistically speaking, the likelihood of lubricant contact with food products cannot be entirely negated. The National Sanitation Foundation (NSF) registers lubricants that are safe for use in a food, beverage, or pharmaceutical processing facility.
Most of the time, H1 lubricants are applied. H1 lubricants are defined to be chemically safe, up to 10 parts per million (ppm), despite any incidental contact with the food product.
They are not to be confused with ‘edible’ products. Lubricants categorised as 3H are able to come into direct contact with food but it is not safe to assume that these can be used with little care. 3H lubricants are also subject to certain specific limitations set by the US Food and Drug Administration (FDA). Registered food-safe lubricating products are easily verifiable via the NSF website.
Food-grade lubricants exist because the FDA has a zero tolerance for contamination by non-food compounds. It is compulsory to include food-grade lubricants into the Hazard Analysis and Critical Control Point (HACCP) programme. ISO 22000 and HACCP strongly advocate that H1 lubricants play a vital role in avoiding contamination.
Many food-handling companies have adopted the HACCP system but their plans do not always recognise the prominence of lubrication surveys. The collaboration and understanding of all sectors within the company must work towards on-going inspections. It must be acknowledged that every lubrication point is a critical control point or area of potential risk. This includes conveyor systems.
Should a mix of non-food-grade chemicals, of any kind, be found during an audit; it is likely that lubricants on hand may have been used inappropriately.
Non-food-grade lubricants may pose a health risk if there is cross-contamination. It will implicate the entire production process and incur costs beyond money. The manufacturing company or its brand line will be affected at an intangible level too.
To prevent all that, some manufacturers prefer full utilisation of food-grade lubricants everywhere in the facility. This strategy helps avoid accidental mixing or confusion.
Building On Dry Lubricants
Till today, there is still a constant performance debate between mineral and synthetic lubricants. Synthetic-based lubricants are arguably more superior due to advancing chemical technology and formulation.
Operational requirements have become more challenging, and synthetic lubricants are more appreciated now because they are engineered to meet demands and last longer. They also have a much wider temperature range than conventional oils.
Regarding conventional oils, wet lubrication may be deemed as the next conventional approach when it comes to conveyor belt lubrication. At present there is a revolutionary lubricating technology for belts—dry lubrication. Dry, food grade lubricants are silicone-based and are administered onto belts with low amounts of specific substance.
Advantages of using dry lubricants include reduction of water and sewage, no foam formation and minimised moisture damage on packaging. However, it comes with some setbacks as well.
Dry lubricants take longer to optimally lubricate the whole line, especially after the facility’s downtime. This may lead to greater wear. Plus, this method only works for plastic conveyor belts and is limited to bottling and carton packaging lines.
With this in mind, the concept of dry lubrication is already on its way to further development. Just like with food-grade lubricants, the idea was not well-received initially. For the sake of efficient operations and safe consumption, food-grade lubricants continue to improve in formulation. The future of dry lubrication is expected to go through a similar path of eventual acceptance and success.
Looking To A Smoother Future
Tribology, the study of friction, wear and lubrication, will always be moving forward with new formulation breakthroughs. Simultaneously, food safety regulations will continue to evolve and lubricant specialists need to keep up with the trends.
Both topics have the same efficiency goals and a keen focus on keeping toxic and contaminants out of the food handling process and its products. Ensuring the usage of food-grade lubricants in the facility is logical for effectively mitigating chemical hazards.
Measures like these are put in place so that consumers are protected on a world-wide platform. It may be a huge paradigm shift and investment at first, but companies should realise that the long-term benefits from food safety would also impact their brands positively.