Large jaw type rock crushers are very common in the stone and gravel business. They are generally portable and can be towed by tractor trucks. The jaw crusher creates a pinch point that fractures larger rocks and reduces them to about the size of your fist. They are further crushed in a cone crusher and reduced to gravel as small as 1/4 inch.
The jaw crusher has two large flywheels powered by a diesel engine that spins an eccentric which causes a crush plate to oscillate making a pinch point fracturing rocks. The flywheels are indexable and have bolt-on plates to adjust the counterweight size to compensate for wear.
From a balancing standpoint, the crusher acts very much like a one cylinder engine. The counterweights in the flywheels act exactly as the counterweights in a crankshaft. The theory for adjusting the counterweights is identical.
Single cylinder engines are balanced to 50%. That means a bob weight is placed on the crankshaft that represents 50% of reciprocating weight, added to 100% of rotating weight. Reciprocating weight is 50% of, one piston and wrist pin and top of connecting rod, added to 100% the bottom of the connecting rod That weight is clamped to the crankshaft journal. The crankshaft is now balanced with the flywheels and the counterweights are adjusted for phase and amount.
We recently received a call from a customer who makes fiber optic strands. Fiber optic strands are glass tubes that are heated and stretched into long optic fibers that are later incorporated into a data transmission cable. They hired us to help find the cause of a vibration problem in the fan enclosure used in the production of making the fiber optic strands.
The Job The main stranding room has a highly controlled atmosphere that is dust filtered, as well as, having the humidity and temperature control highly monitored. On a floor, just above the production room, sits a fabricated steel box enclosure with two 30 hp direct drive fans. The steel box is decent sized. To give you a good visual idea, it is about one-half the size of an overseas shipping container. There is some bracing in the long spans along with ductwork attached to the outside going in and out. The ducting is about 4’ square in cross section.
The Fans Inside the box are two 30 hp direct drive fans. The fan wheels are about 48” in diameter. The motors sit on a chassis suspended on vibration isolators with the required “more than an inch of static deflection.” The fans sit side-by-side. A series of airflow control devices are employed. There is an adjustable damper just outside the enclosure on the inlet duct. Both fans are speed controlled on variable speed AC drives. There are sophisticated inlet dampers built into each fan inlet. The complaint was that vibration was transmitting from the fans into the walls of the enclosure. During full production, the fan enclosure vibration was enough to concern the facility manager. His concern was vibration would begin to break apart the enclosure. Conversely, it seemed unlikely the fans were the culprit of the destructive vibration, as the isolators seemed to be doing what they were intended to do. The vibration seemed to be at much lower frequency than the fan speed. Finding the cause of vibration requires eliminating sources one at a time.
Rotating machinery is everywhere. We are often asked, ”What do you balance?” Rotating machines are responsible for making daily life possible. From heavy manufacturing to high rise building air conditioning – Rotating machinery utilizes high speed moving parts. These high speed moving parts need balancing. Over time those parts may go out of balance and begin to vibrate,causing the machine to run less efficiently. Also if the vibration and imbalance are not properly addressed it can cause adverse conditions on structures and the human environment. Severe vibration causes noise and human fatigue. That’s why there are companies such as ours that can analyze vibration and provide dynamic balancing and mechanical repairs and solutions to eliminate it.
There are any number of balancing service providers out there, so picking the right one to balance your machinery can be tricky. Here are three top reasons why you should balance with HI-TEK:
Vibration analysis and balancing is all we do.
Many companies and repair shops offer balancing as just one of many services. If balancing is not their primary business, you run the risk of getting just an okay balancing job that will eventually need to be rebalanced, costing more time and money. Just because a facility is certified doesn’t mean they’re especially skilled at balancing. From highly-precise micro and medical balancing to large rotator balancing – from prototype to production — dynamic balancing is our main business. Continue reading “3 Top Reasons for Balancing With Hi-Tek”→
All rotating components create some amount of vibration. When vibration becomes severe it can be very destructive when not corrected. Irregularities or asymmetries created either during the manufacturing process or due to wear are often the cause of vibration. They create a mismatch between the rotating axis established by the supporting shaft and bearings, and the axis of orbit around the actual center of mass of the rotating object. An unbalanced part tries to orbit about this axis of inertia while the shaft and bearings force the part to orbit about the different axis they dictate. This mismatch transmits the forces of vibration into the shaft and bearings, and their support structure causing stress and strain that these systems are not designed to handle.
Dynamic balancing is the process used to diagnose and correct the harmful vibration described above. We use purpose built dynamic balancing electronic instruments to aid in matching the axis of inertia about the center off mass, to the rotating axis established by the shaft and bearings.
Vibration is usually caused by parts that are unbalanced as a result of asymmetrical manufacturing. To really understand vibration and its sources, you need to have a thorough knowledge of manufacturing processes. Resolving a vibration problem requires going beyond just balancing components to address the manufacturing cause.
We know the questions to ask to get you the solutions you need. What sets us apart from the competition is our in-depth manufacturing expertise. Our firsthand experience in machining, molding, and finishing enable us to know where problems occur, quickly identify your vibration source, and provide the best, most economical remedy to eliminate it. Our vibration analyses and solutions are precise, practical, and presented in a clear, easy-to-understand way that enables you to implement them in hours or days, not weeks or months.
Complete vibration analysis and balancing services, from prototype to production Around the corner or around the world, we can accurately diagnose and solve your rotating or oscillating equipment vibration challenges quickly and cost-efficiently, in our facility or yours. Our in-house capabilities range from diagnosing and fixing components weighing under an ounce, all the way up to ten tons. From wire winders in China to prototype micro-medical breathing assist blowers, we can analyze and solve virtually any vibration problem, from the largest industrial applications to the smallest technological ones.
Whip balancing is an important part of maintenance for machines that have rotors. Resonant frequency is another name for whip. The resonant frequency is a measure of the speed, in cycles per minute, that a rotor will vibrate when forced off-balance.
A good example of this concept is a diving board. Having a long diving board means that after you jump off, it will vibrate much more than a shorter diving board. The flexibility or springiness of the longer diving board means that it has a higher resonant frequency. The frequency of these vibrations is high and the amplitude is low. A shorter diving board would result in vibrations with a lower frequency and a higher amplitude. Continue reading “What is Whip Balancing?”→
Vibration analysis is not exactly a service that just anyone can provide. Because of that fact, many people tend to ask us to explain what we do. Here are a few explanations for you!
Vibration analysis is a vital service for all rotating equipment, as anything that rotates is bound to vibrate. As components like bearings get older, it’s more likely that the machine’s vibration will increase. This is something that you need to keep an eye on, because the additional vibration can cause the machine to literally tear itself apart. By monitoring your machines & performing routine maintenance, you’re essentially lengthening the lifespan of each machine, which is definitely a good thing. Continue reading “What is Vibration Analysis?”→