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Palletised Assembly Cells

Palletised Assembly Cells

At ALPHR, our years of experience have led us to our expertise and specialist knowledge of palletised assembly cells. Using our pallet systems, we have been able to assemble and test automotive instrument clusters, ensuring their seamless function and output. Our wealth of knowledge of palletised assembly lines has been channelled into the production of a variety of products and systems which can be assembled through this type of setup.

Allowing for multiple production cells to be integrated into a single product line, whether semi or fully automated, palletised assembly cells allow for the fully controlled assembly and testing of systems with the minimum number of operators possible.

Our pallet systems include:

  • Poka-yoke assembly cells
  • vision inspection
  • robot pick and place
  • robotic automated screw feed systems
  • laser marking
  • end of line testing
  • leak detection
  • LCD display testing
  • label print and apply systems
  • a variety of other processes

Production line overview 1 - Instrument cluster assembly and test line

Product – Automotive instrument cluster

Process – Full assembly and test

Palletised Assembly Cells

All stations are located on a palletised conveyor system. This concept reduces handling of the product as well as having the added benefit of reducing the load and unload time for each station due to the part remaining on the pallet at all times.

Product type is selected by means of a batcing system where the user creates lists of batches to be produced. This can be done at the start of the day and then left alone to manage the build of the parts.

Each pallet that arrives at the specified load station is assigned the exact product to be built. This is controlled by the master system. The master is not responsible for testing or assembly function, it purley controls the build of the parts and can be used to display SPC and other useful information while the line is running. Pallets are codes using RFID tags so the system can trace each pallet and test data from each cell can be written to the RFID tag.

When the pallet arrives at each station in turn, its ID is read and the pertinent data for that part can then be read across a network link to the master. This information is stored in a file, one is created for each pallet, and the file contains information such as part number, variant type as as any faults that have occurred and the overall status of the part.

Upon arrival of the pallet at the unload station, the data is read from this file. The master then decides whether all the required testing has been completed successfully, if so the part is ejected and a pass label printed. Any failed parts will not be ejected, the pallet will be automatically released from the unload station and continue on to the rework station. Here the faults can be printed onto a ticket and kept with the faulty part for later analysis. This system mean that good and bad parts don’t get unloaded at the same position and get shipped in error.

Production line overview 2 - palletised plastic moulding production line

Automotive component manufacturer

Process – An injection moulded part requires 8-off metal “captive” compression limiter to be fed, orientated and inserted into the moulded part. The compression limiters must withstand a specified “push-out” force to ensure they are correctly retained. 8-off “captive” screws require assembling into the limiters. Once the compression limiters and screws are inserted, a leak test is carried out to ensure the part is leak tight and the gaskets and o’rings are fitted. If all assembly and test processes pass, the part is laser marked.

Palletised Assembly Cells

Pallet system and controls

The line is based on a Bosch palletised conveyor system with the pallets also supplied by Bosch. An ASI control system controls the conveyor and associated pallet lift and locking. The main assembly control system is based on an Omron PLC. The robots are all supplied by Omron.

Station 1 – Limiter placement

An empty pallet arrives at station 1. The compression Limiters are bowl fed, orientated and retained in a specific orientation to allow an Omron robot to collect a limiter and place it onto a guide located on the pallet. The robot repeats the process until all 8 limiter locations have been populated. Once complete, the pallet is released.

Station 2 – Part pick and place

The operator takes a moulding, fits a rubber gasket to it and places it on an in-feed conveyor. The conveyor transfers the part into the station where a second Omron robot collects the part and places it onto the pallet, directly over the compression limiter. The Robot is fitted with an Omron FQ motion camera to align the gripper to the part on the in-feed conveyor. Prior to the robot loading the part, an Omron FZ vision system inspects the limiters on the pallet and ensures they are correct and aligned. Once the limiters are checked and the part loaded, the pallet is released

Palletised Assembly Cells

Station 3 – Screw feed and insertion

The screws are fed via a bowl feeder to an escapement where they are individually blow fed to a gripper mounted on a third Omron robot. When the palet arrives at the station, its locked in place whilst the robot visits 8-off limiter locations and places a screw at each location. When all 8 screw locations have been populated, the pallet is released.

Station 4 – Limiter insertion

The pallet arrives at the station and is locked in place. 8-off Cylinders are energised to retain the part at each of the screw locations and retain the screws whilst the limiters are pushed up from underneath the tooling. The cylinders used for pushing the limiters in are each fitted with a load cell to allow the insertion force to measured and ensure a minimum force is achieved. Once complete, the pallet is released.

Station 5 – Leak Test

The pallet arrives at the leak test station and is held in place until a cylinder lifts the entire pallet clear of the conveyor. The pallet is then locked in placed allowing any previously failed parts to bypass the leak test station whilst not holding up the line. When in place, the part is clamped and sealed to allow an air leak test using a Furness Controls leak tester to be carried out. This is double station allowing two parts to be simultaneously tested. Once complete, the pallet is lowered back onto the conveyor and released.

Palletised Assembly Cells

Station 6 – off-load and laser mark

The pallet arrives at station 6, which is the back of station 1. Station 1's Omron robot collects the part from the nest and for a "passed" part, transfers it to a laser marker where its time and dates marked. Once marked, its placed on a pass out-feed conveyor and returned to the operator for packing. The in-feed and out feed conveyors are separated with a flexlink and polycarbonate structure. A part failing any of the assembly/test process is placed down a fail chute where its fed into a locked fail bin.

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