 |
|
 |
September 2009 |
Why Did the Chicken Cross the Road? |
by Henry Stachura & Lester Wright |
 SWECO Round Separator When you order chicken pieces at fast food restaurants there is an excellent chance that it was sized by a SWECO Separator. Raw chicken meat cut into various sizes is breaded with spices then partially cooked in a fryer and frozen. The pieces exit the freezer by a conveyor belt onto a SWECO Separator for sizing. The demand from the fast food customers requires a uniform size so that |
when the pieces are cooked all of the pieces will cook completely and uniformly. Over the past year SWECO has sold several separators for sizing large chicken pieces for the fast food chicken industry. These pieces are a lot larger than the frozen diced chicken chunks that we have sized in the past with our equipment. The challenge here was the top screen mesh. The larger meshes are not easily mounted to a sanitary screen, and it is very difficult getting decent screen life with high feed rates of frozen chicken pieces. After many screen trials, we found that the best way to make these large mesh screens was to tig-weld each wire to the tension ring and then double pass epoxy for sanitation and appearance. The heavier wire |
diameter is key for better welding and stability. Standard wire diameters are too fragile. We then added a stainless outer pad, called a doughnut. The doughnut prevents the single wires from breaking and keeps large screened out pieces of irregular shaped chicken from upending and passing through the screen enroute to the spout. This is a stainless steel plate that is fastened to the screen. This rigid outer periphery apron strengthens the screen and discharges the chicken pieces very well. |
 |
 Premature Screen Failure Premature screen failure can be a frustrating and complicated occurance when dealing with pretentioned screens in a Round or Rectangular Separator. The reasons for premature screen breakage are numerous. Discounting any manufacturing defects or shipping damage (yes, that actually does occur), some of the more common causes for breakage can be attributed to things like poor installation, incorrect amplitude of vibration, material overload, screen blinding, and feed surges just to name a few. Here are a few ways you can deal with some of these issues. 
Poor installation is generally a factor of either having the clamp ring on too loosely, neglecting to include or incorrectly installing the jam nuts in the center-tie-down, or tightening down the center-tie-down before putting on the clamp ring. If the clamp ring is not tightened adequately, the frame or
|
frames above the loose clamp ring will tend to rotate with the motion of the motor. And since the center of the screen is stationary, the screen mesh will easily wrinkle or tear, causing premature screen failure. If the jam nuts are not installed properly into or are omitted from the center-tie-down, the tie-down will not effectively hold the screen in place. The center of the screen will bounce with the motion of the motor, stretching the screen mesh, causing undue stress and causing the screen to fail. Finally, if the center-tie-down is tightened down prior to the clamp ring, the clamp ring then being tightened can shift the screen and cause it to stretch in one spot and go slack in another. This will usually cause a fine screen to fail very quickly. The center-tie-down should be tightened down gently as the last step. Incorrect amplitude of vibration or overloading the screen with material will cause the solids to bounce on the screen, also causing early failure. This problem can be addressed by adjusting the lead angle to lessen the vertical amplitude of the machine, or the installation of another screen deck to reduce solids load may help in this situation. Often, raising the center of a screen using a reverse tie-down will increase solids discharge rate and rid the screen of the pooling effect you can get in the center of the screen where there is little vibration or amplitude to move solids out. Once pooling starts, it creates a vicious cycle since the worse it gets the more it causes the screen to concave in |
the center, wearing the mesh down in that area and causing premature failure. By raising the screen from below, which creates a convex screen surface, this problem is usually eliminated. Screen breakages from high vacuum have also been reported. A flexible connection from the table frame discharge spout into a closed pipe can create a "barometric leg" or high vacuum on a screen. This will be particularly severe if the pipe is below the liquid level in the receiving tank. Screens have been sucked out as a result. Cutting a hole in the top of the discharge spout to allow air in will solve this problem.  SWECO Magnum Screen As a general rule, a screen with a relatively coarse backup wire, often will increase screen life. Additionally, SWECO offers the Magnum™ Screen which was designed specifically for increased strength. Both of these product designs can help in the fight against premature screen failure. |
|
Fusion™ Screens SWECO Fusion Screens are the latest in a long line of technologically advanced products from SWECO, the originator of the vibratory round separator, Supertaut® Plus Screens, Magnum™ Screens and countless other innovations. Available in Fusion and Fusion Plus (FDA) construction, Fusion Screens have been designed to eliminate the use of adhesive, epoxy or silicone in |
screen manufacturing. Instead, the mesh is "fused" directly into the patented polymer construction tension ring. The repeatability of the robot construction assures precise tensioning, lower tolerances and smaller deviations of the screens. The robot construction also allows for rapid turnaround time so you get your screens faster. SWECO Fusion Screen |
Fusion’s unitary construction integrates the screen gasket directly into the tension ring. This design eliminates the handling and stocking of separate gaskets and provides a precision fit into the separator. This unitary design also reduces cracks and crevices, producing a more "cleanable" screen with less potential for cross contamination. And the one-time use ring is disposable, saving handling and shipping fees to return the rings. The next generation in vibratory screens is here. Fusion Screens. Available from SWECO ... your separation expert. |
||||
|
||||||
Home | Products | Find A Sales Person | Contact Us |