Food and beverage processing facilities provide big challenges for OEMs and machine component manufacturers.
Factory-automated machines and conveyors have two basic modes of operation: running efficiently and earning money verses down and unproductive, losing money. Equipment downtime costs factories from 5 – 20 percent of capacity each year, according to Intech magazine.
Several components are culprits for maintenance and down time that is so expensive to U.S. factories: bearings, belts, chains, wiring, electric motors, and yes– gearboxes.
Gearboxes are high wear items, transforming power from electric motors (high speed, low torque) to the requirements of the load application (lower speed and higher torque). There is a general assumption in power transmission: “Speed is cheap, torque is expensive.” Using motors to generate high torques required by many loads (direct drive technology) is typically much more expensive than generating the torque with a motor/gear reducer combination.
Gearboxes can be used creatively to eliminate other mechanical components, such as bearings, belts, chains and pulleys. Possibilities are limited only by designer imagination and various geometries of the gear reducers.
Any time we convert power from one state to another, losses occur in the conversion process, generating unwanted heat and wasting energy. “Power out” is always lower than “power in.” In the case of a gear reducer, rotational power is converted from high speed/low torque to low speed/high torque. Energy losses are primarily from friction in the gearing, bearings, between the seals and shaft surfaces. Oil turbulence also causes losses.
Superior gear reducer efficiency is achieved by high efficiency gearing, such as helical, bevel, and spur gearing. Premium lubrication reduces friction in all internal moving parts. Premium quality bearings– roller, ball, or cylindrical– also limit friction losses.
High-efficiency gear reducers have many benefits. They reduce the heat generation, which prolongs a gear reducer’s life increasing the application reliability and reduced cooled space cost. Superior gear reducer efficiency also decreases total machine cost by allowing the use of smaller motors, and reducing energy consumption. Environmentally, efficiency means a reduced carbon footprint and lower electrical power consumption.
Excessive heat generation in inefficient gear reducers can be a safety issue, too– hot gear reducers can burn employees.
Machine down-time is expensive, especially in the 24-hour, seven-day-a-week operations that rely on high productivity such as the meat, dairy, egg, and poultry industries, as well as general food and beverage processing industries. Additionally, maintenance and replacement costs of wear items add up. So, what will make gear reducers last as long as the machines on which they are assembled? The answer is details– doing everything at the highest possible quality and precision level.
It is critical to create and maintain a pristine, contamination-free environment inside the gear reducer. This means a clean, self-contained environment that does not let air, water or contaminants into the reducer. It also requires keeping internal parts wear to a minimum, as any parts wear results in lubrication contamination. Additionally, internal heating needs to be controlled, as excessive heat accelerates lubrication breakdown, causing damage to moving parts that require lubrication. Excessive heat breaks down sealing materials, causing brittleness and premature wear of the seals, which leads to leakage.
Everything in a gear reducer that contributes to high efficiency contributes to durability and the life of the gear reducer.
Machined surfaces on every component in a reducer need to be precise. All internal moving parts should be exactly where they are designed to be, precisely-oriented in relation to each other. Misalignments or out-of-tolerance conditions can cause noise, vibration, friction and binding.
Gear teeth must be perfectly shaped, hardened, then ground or honed in order to reach a quality grade that ensures minimal wear once inside the sealed gear reducer environment.
Seals must be compatible with the lubrication, as well as any environments, chemicals and contaminants they may be exposed to from the outside.
Housings should be manufactured with the minimum number of joints possible as each joint represents a potential premature failure caused by internal component misalignment or a leak path. Multiple fixturing steps in the manufacturing process of a housing during machining can result in looser tolerances and misalignment of internal components in the reducer.
Handling and assembly of components also needs to be perfect. Ensuring components are corrosion-free and contamination-free before assembly is critical.
Using outdated technology and engaging in poor washdown practices in food and beverage manufacturing and processing can have deadly consequences as well as ruin a business. Unsanitary conditions caused the 2011 listeria outbreak at a cantaloupe-packing facility in Holly, Colorado. The outbreak was the deadliest since 1924, claiming 29 lives and causing 139 illnesses across the nation.
There are about 800 laboratory-confirmed cases of listeriosis and three or four outbreaks reported to the Centers for Disease Control and Prevention each year.
To make equipment as sanitary as possible, make sure equipment and components stand up to washdown from high pressure, high temperature chemical solutions. Severe cleaning and sanitation procedures can compromise gearbox paint if it is not of excellent quality, possibly contaminating the product and gearbox.
Also, water or washdown solutions must drain easily from components, preventing liquids from puddling or creating harborage points for bacteria to multiply. This requires smooth, clean surfaces with no nooks or crannies for water to accumulate.
Stainless steel is the perfect material for the reducer exterior. Although cast stainless steel housings are expensive, they are required in many “ready to eat” areas and other areas where painted surfaces cannot be tolerated. Also, because stainless is a poorer conductor of heat than cast iron, the inefficiency of worm gearing is especially detrimental when combined with stainless steel housings, increasing the potential for burns and premature gear reducer failure. High-efficiency helical gearing is therefore a great advantage in stainless steel gear reducers.
No manufacturer wants to expose customers or employees to unhealthy or dangerous situations due to outdated technology or unsafe machinery. We all benefit from making our factories cleaner, safer and more productive.