Amplitude must be matched to the size of aperture that we are screening at.

EXAMPLE: If i have a small amplitude and try to screen on say 2" this is a mismatch. Vibrating screen will not do its job.

IT WILL carry over fines that should pass thru. Why? not enough amplitude in the circle or stroke to get the coarse UP to allow the fines to sift thru the bed depth to then attempt to pass the aperture or opening in the screencloth.

VICE VERSA: if amplitude it too STRONG or circle size too big AND we are trying to fine screen at say.....1/2" minus we will carry over fines because they never get down to the deck to attempt to pass thru, because amplitude is too violent for small opg.

Cheers..... ■

The ‘g’ factor is the ratio of maximum screen acceleration to gravitational acceleration, and is a valuable unit to gauge the speed-throw relationship. A useful way to look at it is that when you drop your pencil to the ground, it has an acceleration of 1 'g'.

For practical purposes ‘g’ can be calculated from the following simplified formula:



g = (stroke (mm) x rpm x rpm) / 1,790,000

or, for our non metric friends:

g = (stroke (in) x rpm x rpm) / 70,000

Limits must be placed on the “g” factor in order to achieve good screening efficiency along with structural and mechanical reliability. These limits will depend on lot of variable design considerations, and also the type and size of the screen. However as a general statement most circular motion screens operate at 3.5 or 4.0 'g', whereas linear motion screens perhaps 4.5 to 5.7 'g'.

It should be emphasised that although the “g” factor is an important consideration in effective screening, it alone does not imply good screening, and must work in conjunction with an adequate throw for the particular application ■

a term I use a lot. I like it...........As JOHN says it means ACCELERATING FORCE.

It is very very important not to exceed the G FACTOR or ACCELERATING FORCE designed into the screen by the factory....as the results can be DISASTEROUS.

I have seen personally many unts in my travels in the field, that the customer has complained....."My screen is sluggish, not working efficiently......and theY SPEED THEM UP. They momentarily thrill at the increased ACTION, G FACTOR, or accelerating force........AND wow........the screen runs very nice, efficient and lots of TONS PER HOUR...."that is" "Til it spilts a SIDEPLATE OUT" because it is running too fast for the weight that is being accelerated.

JOHN's ranges are correct..........inclined screens or circle throw run around 3.5 - 3.8 G's and utilize gravity to do its job.

Horizontals run on the low side at around 5 G's and high side around 6 G'S (depends on manufacturer - some are more cautious than others or more conserative)

LOTS OF Mfr will operate at conservative or lower value G's and the screen will LAST FOREVER.......but, IT JUST WON'T SCREEN worth a fiddlers.......

Others will run a tad too fast and experience CRACKING of sideplates.....also not swell effect.

SO it is a combination of many various factors, SPEED, STROKE SIZE, TOTAL BODY WEIGHT including screen media.

THis is the most common reason for screen failure, people speeding up screen but, not reducing stroke or increase stroke and leaving speed the same. SHOULD ALWAYS check these type of changes with the FACTORY prior to proceeding. ■