GP Graders

- Cherry Grading Machines


GP Graders manufacture turn-key solutions for the world’s leading cherry packers with the hero being the AirJet™ electronic cherry grader which sorts cherries according to colour, size, shape and defects.

GP Grader’s electronic AirJet™ grader sorts cherries by colour, size, shape and defects for greater market prices and reduced sorting costs.

  • Each lane of the AirJet™ conveyor moves at speeds of up to 32 units per second allowing high productivity while maintaining grading accuracy.
  • Be assured that the AirJet™ grader is gentle on your fruit so your product retains its high quality and high value.
  • 97% sizing accuracy gives you and your customers confidence in your product and can allow sizing into smaller size increments so each high value grade can command the highest price.
  • 100% accurate colour separation leads to large returns for valuable dark fruit.
  • The AirJet™ grader can detect over 80% of defects including cracks and softness, reducing the number of inspection staff required by up to 60% and therefore lowering your overheads.

GP Graders is an industry hot-house for Research and Development. With approximately 90% of our R&D projects embarked on becoming commercially successful. The entire culture of our company revolves around innovation and development of practical and market driven solutions.

A brief list from the hundreds of innovations we have bought to the market include:

  • Our full-rotation conveyor cup on our AirJet rollers
  • Our unrivalled accuracy for optical cherry sizing. Our ability to process 32 cups per second per lane.
  • Our technology to see a full range of defects on cherries including shape defects, stemless, moulding, aged cracks and discolouration.
  • Our mechanical undersize fruit eliminators with digital linear adjustment to define cherry size according to micro millimetre
  • Our grooved cluster cutter belt on our cherry graders.
  • Our roll-over steps on cherry sorting belts.
  • Our rovral chemical applicators for cherries.
  • Our three belt electronic trickle fill carton fillers for cherries.
  • GP Graders are leaders in innovative solutions for each market we participate in. We will not enter a market unless we have something truly unique and beneficial to offer our customers.

And those solutions must either:

  • drive down costs through improved efficiency,
  • increase profit through improved product presentation and refined grading parameters,
  • be a lower cost alternative to what is currently available in the market,
  • meet a market demand that is not being satisfied,
  • reduce or eliminate manual processes to automated ones
  • Despite being in business for 50 years GP Graders are a young and dynamic company recruiting only the most intelligent team members in their field of specialisation. We are fully abreast of the latest technology available and adopt it across our entire product range.

  • To achieve the best results in grading cherries electronically the fruit must be positioned in a way that best allows rotation of the fruit as it passes under the camera to reveal its full surface area.
  • The singulation system places cherries in single file and delivers individual fruits into conveying rollers.
  • The singulator has two thin v-shaped belts, one running slightly faster than the other. The first set of belts separates cherries to a lesser degree and the second set of belts refine the process of perfectly situated cherries in single file.
  • From this point cherries are delivered between each of the small roller conveyors.
  • The process has been tested intensively and is the key to high volume processing.
  • The AirJet™ conveyor is a series of rotating concave rollers travelling up to 32 cherries per second.

Size grading

  • Each cherry is sized according to its commercial dimensions, the widest side of the fruit.
  • Seven images of the cherry are taken as it rotates under the camera revealing its full surface area.
  • The software first detects the location of the stem connection to the cherry. From this point a line is drawn across the shoulders of the cherry and a perpendicular line drops down the side width of the fruit.
  • Across all images taken of the individual cherry the largest widths are recorded, being the commercial size grade.
  • The AirJet™ consistently achieves a 95% sizing accuracy

Colour separation

  • Cherries are separated according to colour using CCD colour cameras.
  • For simple separation of light and dark red the user selects the range of colour intensities from very light red to very dark red.
  • These colour grades are selected along with a size grade, thus combining the parameters for each outlet.
  • More than one colour can be identified through selecting multiple colour bands within the full colour spectrum.
  • For multi colours such as Rainier different colour bands within the colour spectrum might be selected.  This allows the user the ability to detect the percentage coverage of different colours on the cherry. For example, a buyer may only accept no more than 30% red colour on a cherry and the remainder yellow.

Defect identification

  • All defects are identified by variations in light intensity and colour.
  • A user-defined colour spectrum for defect sorting is used to measure all blemishes with the aid of defect-sorting algorithms.
  • The defects identified by this technology include:
    • softness, bruising, cell breakdown, shrivelling and compression damage.
    • pitting, wind rub, cracking (stem, side and nose),cuts, open wounds, mangled cherries, skin peel, under or over mature.
    • stemless cherries, deformities in shape and doubles.

AirJet™ exit flumes

  • Once the grading software has graded each item it is delivered to an exit flume dedicated to that grade by an air solenoid.
  • The air solenoid emits a burst of air which pushes the cherry into the exit.
  • The exits are fluming trays with continually flowing water for a gentle water landing.
  • Fluming trays are easy to clean and water flow is adjustable.

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