Based on our experience and feed-back from our long established processing customers, there are 3 effective methods for sizing process-grade blueberries at production rates of up to 12,000 lbs or more per hour.  We can manufacture or supply the sizing solution that will best fit your sizing needs.

Spool Sizer:
On unfrozen blueberries, a spool sizer is widely considered the best sizing method to ensure “true” sizing at production rates of 12,000 lbs or more per hour while still being gentle on the product.  Like a rod destemmer, a spool sizer conveys the blueberries or cranberries forward on rods that are attached to 2 chains that ride on a parallel track.  These rods are milled out of aluminum to form a grid of “true” round holes.  Like a rod destemmer, these aluminum spools spin so that the larger fruit sits and spins on the spools as the spools get conveyed forward (by the chains) until the fruit leaves the conveyor on the out feed end.  The sized off fruit falls through the milled holes onto a solid top discharge conveyor that discharges the sized off fruit in a perpendicular direction to the large fruit flow.  Since the spools are always spinning, any fruit that is even fractionally larger than the hole size will not fall through due to this spinning action.  This spinning action also ensures that the larger fruit will exit the spool sizer when the rods convey around the out-feed end of the conveyor (so that clogging does not occur).

If the spool sizer has a disadvantage it is the fact that it can only size off one size per system.  Therefore if you are trying to break out multiple sizes, a separate spool sizer will be required for each individual size. 

Unfortunately, there really isn’t another “true” sizing method for unfrozen blueberries that doesn’t also cause some damage to the fruit.  String/belt sizers are gentle on the product, but with sizing in one direction only, and with the belts being flexible, they simply do not provide an accurate enough sizing job to satisfy the sizing demands of today’s buyers. 

Ball-deck Shaker Sizer:
A shaker with a ball-deck is an excellent way to break out multiple sizes from a frozen pack.  Depending on the throughput volume you are trying to run, one or more decks can be used to separate out several fruit sizes.  A ball-deck sizer has a grid of round holes cut into its’ surface, so when combined with the shaking action of the shaker the sized berries fall through the sized holes and get diverted on a lower deck to an exit.  If more sizes are required, a percentage will get sized on another sizing deck again and fall to a third deck (and so on).  Since the holes on the decks are static, fruit does get stuck in the holes (this is called blinding).  To counter this, a couple inches below the sizing surface we install a ball deck stocked with several small durable food grade plastic balls that bounce around and dislodge the fruit.  This deck is made of open wire mesh to allow the sized fruit to fall through while still retaining the balls. 

You can also purchase a wide array of decks that are interchangeable for different sizing purposes.  The amount of fruit being run per hour will determine how much deck surface area will be required to effectively size your fruit.

Drum Sizer:
Another way to size small round frozen fruit (for fruits that are very durable when frozen) is to use a drum sizer.  A drum sizer is virtually the same as a drum destemmer except the wire mesh surface of the drum has a specifically sized hole pattern in to perform a sizing function.  Depending on the length of the drum and how much fruit per hour you are trying to run, we can have 2 or more sizing sections in the drum.  As the fruit conveys forward (due to the drum being angled), the sized fruit falls through the sized mesh holes onto diversion chutes that divert the fruit into bins, lugs or conveyors below.  Any fruit that gets caught in a hole, gets pushed through by the constantly tumbling fruit (thus keeping the holes from blinding).  This sizing method works well on frozen blueberries or cranberries but is not gentle enough for the more fragile berries like blackberries, marion berries or raspberries.    It is also possible to have a combination drum destemmer/drum sizer where the first section of the drum serves a destemming function and the subsequent section(s) serve a sizing function.

Please call us today toll free: (888)437-2144 for a free needs assessment regarding your blueberry sizing or other processing needs.