The Christopher Stephen Corp. has been designing and building custom automated assembly systems for 45 years.

This year, we built a machine to assemble and test an electronic control module for hydraulic pumps used in agricultural equipment. The machine handles a 29-step assembly process that includes fastening bolts and testing for leaks. The module’s main housing and internal componentry are loaded by an operator, while threaded fasteners and other parts are fed and assembled automatically. The machine produces a part every 3 minutes and integrates with the customer’s MES system for traceability.

The system is built around an eight-position rotary indexing dial. The dial features a bar code reader, pneumatic presses, vibratory bowls, a six-axis robot, fixtured screwdrivers and an inspection station. Photo courtesy The Christopher Stephen Corp.

The system consists of a pre-assembly station, a rotary indexing dial, and a robotic assembly station.

At the pre-assembly station, the parts are staged by an operator. This provides flexibility for part preparation, which aligns with the customer’s workflow. The operator starts the process by scanning a 2D Data Matrix code on the main module housing. This logs the parts into the facility’s MES system. A bar code is then printed to track the control module through the assembly process. Once the bar code has been applied to the housing, the part is loaded onto the dial.

The dial has eight positions. At the first stop, a reader scans the bar code that was applied to the housing at the pre-assembly station. This connects the part’s data to the start of the automated assembly and test process. All data developed as a part of the assembly and test process is connected to the unique bar code of that part.

At the next two stations, pneumatic presses from Schmidt Technology insert small parts into the housing. The parts are manually loaded, and the presses monitor force and distance during the press-fit process.

At position 4, an actuator picks the assembly off the dial, rotates it 180 degrees, and returns it to the dial. Two vibratory bowls feed a plug and a nut, which are picked up with tooling that has a detent to hold the parts. Then, Ingersoll Rand fastening spindles install the nut and plug to a specific torque.

Position 5 queues the assembly for the next operation. At position 6, a six-axis robot from FANUC America Corp. picks up the assembly and presents it to an inspection sensor, which checks for the presence and orientation of the parts.

At this point, the robot takes over the remaining steps in the assembly process. (The last two positions on the dial are empty stations.)

If the assembly passes inspection, the robot places the module in a build fixture. The fixture holds the module in a vertical orientation for assembly of two solenoids. Next, the robot automatically changes its end-of-arm tool (EOAT), so it can pick up three bolts and a solenoid from a tray. The robot presents the solenoid to a voltage-check station prior to installing it in the main module.

While the robot is picking parts from a tray inside the machine, an operator is reloading a second tray outside the machine. The trays automatically switch when one is empty and the other is full. Photo courtesy The Christopher Stephen Corp.

The solenoids are supplied in a two-tray system. While the robot is picking parts from the tray inside the machine, the operator is reloading a second tray outside the machine. The trays automatically switch when one tray is empty and the other is full.

When the bolts and solenoid are in place on the housing, a set of fixtured fastening spindles from Ingersoll Rand tighten the bolts to a specific torque. Once this is completed, the fixture rotates 180 degrees and the process repeats with a second solenoid.

Next, the robot automatically changes its EOAT back to the gripper for the module. The robot then removes the module from the fixture and places it on a leak test station, where the assembly undergoes a mass-flow leak test. The leak test instrument was supplied by ATEQ Corp.

If the assembly passes, the robot places the module on an outgoing conveyor. If it fails, the robot places the module on a reject tray for the operator to investigate at a later time.

This machine provided multiple benefits for the customer. The most important benefit is that it increased output of this high-volume product while reducing the amount of labor per assembly. The baseline assembly process was entirely manual and required several operators to complete. What’s more, the overall footprint of the machine is actually less than the manual process. Finally, the machine links directly with the customer’s MES and part tracking system, ensuring robust traceability.

For more information on automated assembly machines, click www.teamtcsc.com or visit the company’s booth at The ASSEMBLY Show. Schmidt, Fanuc, Ingersoll Rand and ATEQ are also exhibiting at the show.

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