Today, we're back at Farris Automated Systems, a custom machine builder based in Wisconsin.
The Rear Hatch Assist Machine is a custom build for Nissan. The machine looks relatively simple, but as we all know, it takes a lot of design and development work to make this process look this easy.
The Rear Hatch Assist is designed to safely lift the rear hatch of five Nissan vehicles -- each with a different height and hatch -- so a pair of operators can install the shocks. The alternative was to lift the hatch manually for each vehicle.
Nissan is assembling up to 60 cars per hour. When your job is to lift a 40-pound hatch to install shocks, it adds up.
The rear hatch assist creates a safer work environment for Nissan employees as it eliminates the risk of the hatch falling on the workers who are installing the shocks. Arms fatigue, people trip, and accidents could happen.
Nissan also had strict design criteria that the new machine couldn't touch the outside of the hatch. This part of the assembly process occurs while the car has pretty fresh paint on it. An older designed lifted the hatch from the outside and could accidentally scratch the paint. Nissan also demanded that the design fold back into itself to clear the hatch after installation.
For this particular build, timing is everything.
Here's how it works:
The machine has automatic line tracking that uses a touch plate. As the vehicle pulls in and hits the plate, the variable frequency drive reads the angle and automatically follows it.
The machine scans the vehicle profile to determine which model is in the pitch. If it sees the wrong vehicle, it notifies the operator.
Next, the lifting assembly (a telescoping arm) reaches inside the window and picks up the hatch from the inside of the door. A servo motor is programmed to stop the hatch at the exact height required to install the shocks without any compression.
Area scanners protect the operators. It's pretty straightforward, but safety lights indicate when the operator can enter the work zone. Everything operates using safety over ethernet (SoE) and remote I/O.
The rear hatch assist is designed for ease of installation. To remove it from the track, the company has to do little more than pull a few bolts and lower it onto a custom shipping cage. The installation had to be carefully considered during the design process because once the machine reaches Nissan, it has to be pretty close to plug-and-play.
To make sure the machine is ready to roll during install, Farris built a permanent overhead rail system to simulate a moving production line. It took the company three weeks to build the structure, but it sets them up for future jobs that fit into moving assembly lines. To hear how some shops simulate an automated line is fascinating -- one company was towing equipment with a rope attached to an employee's truck.
While the overhead rail system was a significant investment, Farris can now simulate about 45-feet of a production line. According to Farris President Mark Johansen, the rail system not only allows his engineers to test machines at real line speeds, but it improves programming quality and dramatically decreases the installation and start-up time in the assembly plant.