Why McLanahan MD Vibratory Screens?
Since its founding in 1835, McLanahan Corporation has established and maintained extreme standards regarding engineering, manufacturing, and customer service and support for all of its equipment product line offerings. These standards were continued in 1989 when McLanahan began engineering and manufacturing this style of screening equipment. We have extensive experience with screening a wide variety of materials and our laboratory is fully equipped to provide screen testing on your material.
McLanahan MD Vibratory Screens are available in widths ranging from 19” (48cm) to 78” (198cm) with one to five screen decks depending on the application. The MD Vibratory Screen is capable of handling feed sizes as large as approximately 3” (7cm) and can make size separations down to approximately 60 mesh.
McLanahan Corporation maintains in-house equipment to conduct laboratory screening tests on materials to help ensure that you have the correctly sized MD Vibratory Screen for your application.
How MD Vibratory Screens Work
Woven wire screen meshes of progressively smaller apertures are mounted in the compact vibrating frame at increasingly steeper angles. The apparent opening through which particles fall vertically is smaller than the actual opening because of the angle of the screen deck. In other words, the McLanahan MD Vibratory Screen makes a separation at a given size using a mesh aperture of greater size. This design concept reduces the risk of pegging and blinding, while achieving high capacities.
The rapid, vertical movement of the material gives the MD Vibratory Screen its large capacity in relation to the machine size. Because of its smaller size compared to conventional screens of the same capacity, excess energy is not wasted to move material forward. Instead, gravity does most of the work as material falls through the screen decks.
Depending on the model, the MD Vibratory Screen vibrates using one or two counter-rotating eccentric weighted vibratory motors. The horsepower of the largest motor on the largest MD Vibratory Screen model is only 8.3 hp. Mounted directly to the frame, the motor(s) sits and spins within itself; there is nothing to pull or push, no reducers, no pulleys and no belting. Motor bearings on the eccentric weighted drive are the only moving parts that require maintenance attention, normally in excess of 15,000 hours of operating time.
Models of MD Vibratory Screens
- Traditional McLanahan MD Screen
- Utilizes two eccentric motors
- Commonly supplied with five screen decks
- Ability to produce as many as six different size fractions or as few as two products
- Mainly linear vibration pattern
- Developed for applications that do not require five decks of screening
- Utilizes single eccentric motor
- Supplied with one, two, three or four screen decks
- Ability to produce as many as five different size fractions or as few as two products
- Our largest multi-deck screening unit
- Utilizes two eccentric motors
- Typically supplied with three, four or five screen decks
- Offers capacities of up to 50% over the DM and SM models
Popular Applications for MD Vibratory Screens
The MD Vibratory Screen is successfully used in a multitude of industries, including aluminum, ammonium, animal and pet food, ash, basalt, bauxite, cement, ceramics, clay, coal, coke, dolomite, feldspar, fertilizer, glass, grains, granite, gravel, gypsum, iron, lead, limestone, marble, pharmaceuticals, potash, quartz, rock, rubber, salt, sand and gravel, shale, silica, slag, sugar, wood pellets and more.
Benefits of McLanahan MD Vibratory Screens
- Compact design
- Dust control – standard MD Vibratory Screen is totally dust enclosed
- Minimal maintenance
- Quick screen change – each screen deck on any MD Vibratory Screen is independent of other screen decks and can be changed out in less than 15-20 minutes
- Long screen life – larger particles are removed by heavier, larger screens, while finer screens see only smaller particles and only a portion of the incoming feed
- Low power requirements
- Optional components, including ball decks; pneumatic tensioning system, an automatic device that relaxes tension on screens that periodically creates a self-cleaning action; and anti-wear liners
- Reversing starter panel – allows for instantaneous vibration stoppage when power is turned off, reducing wear and tear on any flexible connections and premature fatiguing of the compression springs
- Minimal vibration – rubber plugs inside the compression springs absorb nearly all vibration forces
Frequently Asked Questions
My industry has specific certifications to which I need to adhere. Can you help?
Yes, we can certainly help. We will need the product specifications in order to make that determination. It may also be possible that laboratory screening tests will need to be conducted in order for us to be able to verify that product specifications can be met.
How much does a laboratory screening cost?
The cost for laboratory screening tests vary depending on the extent of the material testing. Any costs associated will be discussed/communicated before we ask for a representative sample of material.
What is the difference in the various types of screening media?
We only use woven wire screen media for our MD Vibratory Screens, typically mild carbon steel and/or stainless steel. Should a customer require anything other than these two types, that will have to be considered.
What is a reversing starter?
The reversing starter is an optional - but highly recommended - feature. Because of the excessive movement that is characteristic of the McLanahan MD Vibratory Screen during shutdown, it is desirable to stop the machine as quickly as possible. The optional reversing starter panel accomplishes this by temporarily reversing the two leads to the motor (MD Screen Model SM) or motors (MD Screen Models DM or DMX). This action is termed plugging the motor. When the motor is plugged, the machine will come to an almost instantaneous stop (typically less than one second).
Can the MD Vibratory Screen handle damp material?
While the MD Vibratory Screen is commonly known as a dry screener, it can handle certain amounts of moisture if the material’s moisture content falls within a general guideline that we’ve established based on our years of experience. This guideline is 1% moisture per 1.0mm screen opening. There are exceptions to this rule, but those exceptions are not very common. Usually, with damp material screen blinding occurs, which has a detrimental effect on the screening performance.
How do you keep the screen decks clear of blinding or pegging material?
We have several features that assist with keeping the screens cleared of blinding or pegging material. We have a pneumatic screen tensioning system, ball decks, nylon chain, and offer cross-slotted and long-slotted screen openings.
What is a pneumatic screen tensioning system?
Pneumatic tensioning is one of several methods used to protect against blinding of a screen mesh, and can be applied on all models of McLanahan MD Vibratory Screens. The pneumatic tensioning system governs the tension of a screen cloth such that it is periodically slackened and then re-tensioned. This slackening enables the screen cloth to rattle, removing sticking or pegged particles. Both the slackening period and the tensioning period can be adjusted at the control panel. Additionally, the pneumatic tensioning system is to be tied in with the machine's control logic so that the machine will shut down when the air pressure is insufficient to maintain proper tension on the screen cloth.
What information is needed to select an MD Vibratory Screen for my application?
We will need the following information: type of material, bulk density of the material, required capacity, gradation analysis of the material to be screened, desired product size(s), material temperature at time of screening and material moisture content at time of screening. We have a questionnaire that can be completed and returned to us at your convenience.