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Automated Shimming Pokayoke Process Reduced Daily Downtime by 15 Minutes

Sometimes a successful automation project is not one that completely removes and automates a manual process. Sometimes an automation solution can be integrated to improve the quality and efficiency of an existing manual process. A recent example of this was the successful integration of an automated forklift lift bracket measurement and instructed shim picking system in the assembly of a forklift mast. This project was implemented over December shutdown 2023.

An associate uses the custom measurement tool to measure the inside diameter of the forklift mast rail.

An associate measures the outside diameter of the lift bracket.

To allow a lift bracket to smoothly raise up and down on a forklift mast, the rollers on the lift bracket need to be shimmed so that the lift bracket fits perfectly with a mast assembly. The old process involved the associate who worked on attaching the rollers on the lift bracket to essentially guess what shims were needed. Often times, additional shims had to be added or removed. This resulted in this process being the biggest bottleneck in the forklift mast assembly line.

Render of the custom measurement tool.

TOA SE worked with the customer to come up with a solution to measure the gap on the mast rails and relay that data to the associate installing rollers onto the lift bracket so that they would know exactly what shims to use.

The solution called for an associate to scan the barcode of the mast at the beginning of the assembly process using a Keyence barcode scanner and take a measurement of the inside diameter of the mast rail. The measurement tool used is a custom designed machined tool which uses a Mitutoyo Digimatic scale to record the measurement and wirelessly transmit it over to a PC and add it to the barcode data of the mast assembly. A second custom tool designed measurement tool using the Mitutoyo Digimatic scale takes another measurement on the lift bracket assembly. Once all measurements have been completed, the barcode data then gets transmitted via ethernet to the lift bracket assembly station. Based on the measurement, the control system tells the associate which shims to use in the picking bin using pick sensors that indicate which shim to use. A poke system was implemented that used clamps to secure the lift bracket assembly until all rollers and shims were installed. The Omron NX1P PLC was used for the controls for the system.

Omron NA HMI screen.

Shim Picking Bin with pick sensors.

Inside view of the main control panel.

Omron NX1P PLC was used for the control system for this process.

In the end, after adjustments and fine tuning of the process onsite, we were able to remove the bottleneck in the process. The removal of this bottleneck removed 15 minutes of downtime daily and continues to improve.

If you have a process that requires a custom solution to improve the efficiency of your existing manufacturing process, do not hesitate to reach out to us!

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