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Nifco UK Ltd Case Study

The Client

The client, Nifco UK Ltd manufacture a range of ferrous and plastic trim, clips and engine parts for original equipment vehicle manufacturers in the domestic and commercial automotive industries. In general manufacturing volumes are very high with short cycle times.

The Requirement

To provide a fully automated Booster Pin Insertion Machine that would insert a metal feature pin into a plastic housing, inspecting components prior to and after assembly before offload onto an automated unload system. The system was required to run for a minimum of 2 hours unattended with a cycle time of approximately 2.8 seconds per part (6 Million parts per year)

The Challenge

The system was required to automatically feed the metal pin and plastic housing into the assembly process. Prior to assembly the plastic moulding must be inspected through 360 degrees for defects in the moulding process. These defects could be short shot, contamination, flash and witness marks etc. The system was required to reject faulty plastic mouldings prior to assembly to eliminate non quality. In addition the metal pin was inspected to ensure the presence of an undercut feature which provided the locking mechanism into the plastic housing and again reject faulty components at source. Good components were then assembled by pressing the metal pin fully into the plastic housing. A final test was also required to check that the metal pin was correctly retained by the locking features in the plastic moulding. Finally, completed parts were required to be fed out of the system in differing quantities into a standardised collection container. The system was required to run for a minimum of 2 hours unattended

The Approach

To achieve the cycle time of less than 2.8 seconds seconds QM opted to use a 6 station rotary indexing table with vibratory bowl feeders for the supply of components and an indexing outfeed conveyor for component unload. Pick and place systems were used to load and unload the rotary table, an Omron vision system was used to inspect the plastic moulding and a force controlled push station was used to check the pin was correctly retained by the moulding.

Vibratory bowl feeders were utilised to supply both the plastic moulding and the metal pin to the machine.
The vibratory bowl feeder used to supply the metal pin contained a discriminating feature to check that the retention undercut on the body of the metal pin was present. If the undercut was missing the part was simply pushed back into the bowl feeder ensuring the part could not be fed to the assembly process whilst preventing machine stoppage. Faulty parts could then be cleaned from the bowl at end of batch run.

Station 1 utilised a very innovative ‘walking beam’ concept to marshall the plastic mouldings with a fixed orientation through the Omron vision inspection system. Here the parts were inspected through 360 degrees using a 4 camera system. A Pick and place system utilising electronic actuators for positional accuracy and pneumatic grippers was used to take the plastic moulding from the inspection station and place into the nest in the rotary table. In addition the Pick and Place system removed faulty components from the inspection station and passed them to a locked reject bin.

Station 2 utilised a Pneumatic cylinder together with a bespoke designed arrangement to insert the metal pin into the plastic housing.

The system utilises very accurate regulation of pressure to control the force applied to insert the pin, If the force required is too high the plastic moulding can split during the insertion process.

Station 3 utilises a pneumatic cylinder to apply an accurately controlled push force to the head of the pin. The force applied attempts to push the metal pin back in the plastic housing, providing the retention features in the plastic moulding have engaged with the metal pin correctly the metal pin cannot be pushed back. Faulty parts continue through the rotary cycle and are rejected at the exit station (Station 5)

Station 4 was unused providing future room for expansion and flexibility
Station 5 utilised electronic pick and place actuators to transfer the part from the rotary indexing table. Good parts are passed to a an indexing exit, reject parts are passed to a locked reject container.

Station 6 was unused providing future room for expansion and flexibility

The indexing exit conveyor receives good parts from station 5. Bin quantities are set at the start of the batch run and the system will decant the exact number of good parts required into the Tote bin. The conveyor will then index to remove the full box and replace with an empty box. The machine cycle continues whilst this operation takes place. Finished parts are held in a small buffer until the empty box is detected in position.
The system delivered provided an annual throughput of over 6 million assembled parts per year achieving a cycle time of less than 2.8 seconds

This particular machine was designed to be dedicated to one assembly, however thoughtful design resulted in flexibility that would enable simple repurposing to other assemblies if required in the future.  The fully automated system provided a solution that enabled the client to re-deploy 2 operatives to other areas of the factory, whilst significantly improving throughput and removing the potential for faulty components to reach the customer.

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