Food Machinery Synchronous Wheel Anti-corrosion Practical Guide: Easy to Fix Corrosion Problems
In the food production process, synchronous wheel as a key transmission components, once corroded, not only affects the normal operation of the equipment, but also may contaminate the food. In the face of the complex challenges of the food processing environment, how to protect the synchronous wheel, to extend its service life? This guide will provide you with detailed answers.
First, food machinery synchronous wheel why easy to be corroded?
The environment of food processing workshop is not "friendly" to synchronous wheel. First of all, frequent cleaning and disinfection of water vapor, as well as processing juice, sauce and other juices, it is easy to remain in the synchronous wheel gear tooth gap and installation parts, the formation of corrosive environment. Secondly, the chlorine disinfectant, strong acid and alkali detergent used to clean the equipment, if the rinsing is not thorough, it will destroy the protective layer of the metal surface of the synchronous wheel. In addition, food residues attached to the synchronous wheel, will breed microorganisms, they produce organic acids will accelerate corrosion. Coupled with the production process of high temperature sterilization and low temperature storage alternation, will make the synchronous wheel coating material thermal expansion and contraction cracking, to corrosion can take advantage of the opportunity. Like bread production line mixing dough synchronous wheel, contact with flour moisture and grease, if the protection is not appropriate, just half a year may appear pitting; meat processing equipment synchronous wheel was splashed with salt water, not timely clean up, it is easy to stress corrosion cracking.
Second, choose the right material, corrosion prevention half success
1. How to pick the metal material?
316L austenitic stainless steel: this stainless steel contains molybdenum content of more than 2%, especially resistant to soy sauce, salt water, such as electrolyte erosion, more corrosion-resistant than the common 304 stainless steel, and through the FDA, NSF and other food contact safety certified, used in food machinery is very assured.
17-4PH precipitation hardening stainless steel: after special treatment, the hardness can reach HRC38 - 44, high strength and corrosion resistance, in the high load and corrosion requirements, such as large-scale food processing equipment, can come in handy, but also in line with the EU's food contact standards.
TC4 titanium alloy: it has low density and high strength, it is not easy to be corroded in seawater and organic acid environments. Although it is more expensive, it can ensure stable operation of synchronous wheels in high-end dairy equipment, and it also passed the biocompatibility test.
2. Non-metallic materials can also play a major role in
POM polyformaldehyde: self-lubricating effect, but also resistant to oil and grease, suitable for use in fruit and vegetable sorting machines, such as the load is not high on the equipment. But be careful, do not let it long-term contact with strong acids, or easy to get into trouble.
PEEK polyether ether ketone: can withstand 150 ℃ high temperature steam sterilization, excellent performance in hot and humid environments, such as canned food sterilization equipment in the synchronous wheel, it is very suitable. zirconia coated ceramic composite material: ultra-high hardness, the surface is also particularly smooth, can prevent food residues from sticking to it, in the high cleanliness requirements of the chocolate coating equipment, is an excellent choice.
Third. Surface treatment, to the synchronous wheel with "protective clothing"
1. Metal surface strengthening has a wonderful trick
Electrolytic polishing: through electrochemical dissolution, the stainless steel surface is polished to super smooth, the roughness can be reduced to Ra≤ 0.1μm, removing those places that are easy to hide dirt and reduce bacterial growth. Some cookie production lines use electrolytically polished 316L synchro wheels to clean up much faster and corrosion is reduced by a large part. Chrome-Free Passivation: Replacing the old method with a silane treatment to form a nano-sized protective film, the treated synchronizer wheels are able to withstand more than 1,000 hours of salt spray testing, and are also environmentally friendly.
Physical vapor deposition (PVD): TiN titanium nitride or DLC diamond-like coating on the surface of the synchronous wheel, although the coating is only 1 - 3 μm thick, but the hardness is very high, and there is hydrophobicity, which prevents the adhesion of sap, and strengthens the ability of corrosion prevention.
2. Food-grade coating is very critical
Polytetrafluoroethylene (PTFE) coating: must choose the FDA-approved food-grade products, a wide range of temperature resistance, from minus 200 ℃ to minus 260 ℃ are not a problem, the surface is particularly smooth, sauces and other viscous substances can not be sticky, in the condiment filling equipment used in a lot.
Thermal Sprayed Ceramics: Plasma sprayed Al₂O₃ - TiO₂ composite coating with very low porosity, the coating can withstand 80 ℃ hot water and 3% citric acid solution for long-term immersion test, to protect the synchronous wheel of meat processing equipment from corrosion.
Fourth, from the environment and structure to start, the source of corrosion prevention
1. Control of the environment is very important
In the food processing workshop, especially the packaging area, if the humidity is more than 70%, we must install rotary dehumidifier, the humidity control in 45% - 55%, but also in the synchronous wheel shield to put a bit of Food-grade silica gel desiccant, regular replacement to prevent moisture erosion. In addition, to avoid the synchronous wheel for a long time at a high temperature of more than 80 ℃, such as steam sterilization, ventilation and cooling in a timely manner, to prevent the failure of the grease, so that the metal directly friction rust.
2. Structural design clever anti-corrosion
Optimize the sealing structure, with FDA-approved double-lip Viton seals, with labyrinth dust-proof grooves, which can effectively block cleaning water and oil from entering the shaft hole. There are beverage filling machines so modified, synchronous wheel bearing cavity into the water is much less. Synchronous wheel mounting bracket should have a certain degree of inclination, not less than 3 °, to facilitate the flow of cleaning water away, wheel tooth edge inverted rounding treatment, radius of R0.5mm, to reduce food residue residue.
five. Daily Maintenance"
1. Cleaning and disinfecting with care
At the end of production every day, use 38 - 45 ℃ warm water to rinse the synchronous wheel, flour, sugar stains and other organic matter flushed out; weekly with a neutral detergent (pH value of 7 - 8) with a soft brush to clean the tooth grooves, do not use steel balls, easy to use, easy to use steel balls. Do not use steel wool, as it can scratch the surface. When disinfecting, prefer 75% food-grade alcohol or 0.5% peroxyacetic acid, don't use chlorine disinfectant, after disinfecting, use sterile water to rinse clean, and then blow dry with compressed air.
2. Lubrication and protection
Always use NSF H1 lubricant, such as Klüber ISOFLEX NBU 15 food, with a dropping point of not less than 180℃, good resistance to water flushing, and replenish the lubrication every 200 hours of operation. If the equipment is shut down for more than 72 hours, coat the surface of the synchronous wheel with food-grade antirust oil and wrap it with moisture-proof paper to prevent it from being corroded by the atmosphere.
3. Timely detection and treatment of corrosion problems
Monthly inspection of the surface of the wheel teeth with a 5 times magnifying glass, if you find pitting or continuous rust stains with a diameter of more than 0.5mm, replace the synchronous wheel in a hurry; minor rust spots can be sanded with 0000 fine sandpaper dipped in edible olive oil, and then disinfected with ethanol. Do a salt spray test once a year, with 5% NaCl solution, measured at 35 ℃ environment for 24 hours, if the coating blistering, flaking, sent back to the manufacturer for re-treatment.
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