Hygienic Robotic Food Loading

Challenge

Our customer approached us with the challenge of automatically loading a high speed thermoform packaging machine with single-serve cheese sticks.  The upstream converting process could produce 720 portions per minute, but the thermoformer could not be hand loaded at this rate.  The customer was also concerned about the cost justification of the advanced automation required to eliminate 8 people on the line.  The most critical demand was for the entire line to be inspected for USDA-Dairy acceptance.  Ready-to-eat snacks are inherently high-risk and the customer’s quality team wanted Marchant Schmidt to focus on options to mitigate the danger.

Application Details

Cheese types:  Mild Cheddar, Sharp Cheddar, Colby Jack and Pepper Jack

Cheese temperature:  34–40 F (1-4 C)

Production rate:  720 snack sticks per minute

Cut dimensions:  ½ x ½ x 4½” nominal (12 x 12 x 112mm)

Finished product weight:  ¾ ounce (21 gram)

Control platform:  Omron Adept / Allen-Bradley

Electrical:  480V/60Hz/3P

Packaging:  Thermoform 12×4 pattern at 15 indexes per minute

Project Solution

Marchant Schmidt approached the application in a unique way to achieve the results requested by our customer.  First, we acknowledged that picking this high volume of sticks in random orientation would be futile.  So, we changed the upstream cutting process to produce sets of 24 sticks that discharge from the intelligent cutter in a tight group.

 

Using 2 delta style robots, we pick half of the sticks in an alternating pattern.  The first robot retrieves the left set of 12 and the second robot picks the right set of 12 sticks.  Omron Adept robots were selected due to their high payload capacity and clean design.

 

The end of arm tooling was specially designed to meet the high standards of USDA-Dairy.  All stainless construction with FDA approved plastics.  4A polish on any product contact areas which includes tooling that will be over the product zone.  Plastic spacers between metal to metal contact were added to provide a tight seal and prevent bacteria harborage.  Pneumatics were minimized, but catch pans were added beneath those that were used.

 

Another noteworthy approach to achieve speed and accuracy was the use of pins to positively hold the cheese instead of vacuum picking. Tiny pins engage with the cheese, then close or heal under pressure in the thermoformer.

 

The end tool was custom designed to pick a tight nest of 12, then spread out to match the thermoformer pitch spacing before ejecting all sticks into their pockets.

 

Accumulation was added to the cutting process to ensure the robots always had cheese to pick from.  This ultimately resulted in 15% increase in packaged product.

 

Robotic thermoform loading is very reliable, and our customer enjoys 99% accurate placement.  Cheese is a natural product and can have significant dimensional variation.  To ensure product remains within spec of the robotic loading system, automatic measurement systems were added to the upstream equipment.  This ensures consistent quality and reduces the need for operators to rework product prior to package sealing.