End of Line “Pass Through” Conveyor General Motors – Team 2 Professor – Dr. Reuben Kraft Sponsor – A. Mark Sutton

Background General Motors Pontiac Stamping Plant Robotic Arm End of line conveyor General Motors Pontiac Stamping Plant Press lines stamp various parts for car production (car hood, side panels, etc.). Two main operating press lines: AA1 and AA2. Press Line AA1 pictured to the right. Robotic arms move parts from the centering table to the end of line conveyor. Centering table Exit conveyor

Background With a recent switch to running aluminum parts as opposed to steel parts on the AA1 production line, problems have arose during part transfer. Parts will become misaligned, causing the robotic arm(s) to either drop the part or trip a position sensor which shuts down the line. Misalignment

Problem The problem that GM has is that the line is only running at 50% efficiency (150 parts per hour) due to frequent line down scenarios. Our task is to improve line efficiency by 50% to output 300 parts per hour.

Customer Needs Meet a return on investment within a one year time frame. Could not add any additional labor to the line. Concept had to fit GM’s Single Minute Die Exchange. The line operation rate could not be slowed. Limited amount of space around the press line. Stay within budget of $150,000-$300,000.

Root Cause Analysis In order to design a proper solution, the root cause of the failures needed to be identified. It was determined that failures and misalignments occur due to the reduced weight in aluminum parts. Lighter parts move too quickly when moved out of the stamping press and bounce along the conveyor belt. Some heavier aluminum parts did not see failures, only the extremely light parts (2-5 pounds).

Fishbone Analysis

Concept Generation Deformable Part Stoppers Portable Conveyor System Shock Absorbing Material Small Conveyors Aluminum Frame Wiring Harness Aluminum Mounting Frame Deformable Part Stoppers Portable Conveyor System

Final Concept—Initial Tray Design FANUC R-2000iB 100P Connector Frame Aluminum Tray Tray Arm Tooling

Tray Design Die Change Mount to Dynamic Arm Die Change Mount to Stationary Arm ATI Q210 Tool End Connector

Tray Details Tray end of arm attachment allows GM to ignore part misalignments because it accounts for tolerance errors that cause failures on the centering table. The tray was modeled to fit the largest parts on the AA1 conveyor line in order to account for the entire range of part sizes. The design of the tray features two slots which allow the tray to lower overtop of the centering table conveyor belts. The robotic arms can then lift the tray to move the part to the end of line conveyor.

Tray Details—Finite Element Modeling The heaviest part weights 8.77 pounds (17.54 pounds with factory of safety of 2). Tray is made out of 6061-T4 Aluminum to maximize strength and machinability and to also minimize weight. Loading simulated as horizontal strip to replicate a curved part’s primary contact points resting on the tray. FEM results showed a yield strength of 21 ksi and the maximum Von Mises stress on the tray was 3.273 ksi. Max Von Mises Stress: 3.273 ksi.

Tray Details—Finite Element Modeling Exaggerated front view of the tray. Max deflection of 0.5579 inches. With a 17.54 pound force acting on top of the tray, a maximum deflection occurs at the bottom right hand corner of 0.5579 inches. Due to the increased weight for a factor of safety of 2, this deflection should not be enough for parts to slide off of the tray.

Tray Details—Attached to Robotic Arm

Estimated Costs and ROI Cost to run the press line is $1,302/hour 16 laborers @ $23/hour with a 150% labor burden rate $750/hour machine costs Quote on the PLC programming for the robotic arms is 25 hours @ $75/hour for each robot ATI female quick connector costs $5,000 (two needed) Total project cost: $57,000 Estimated ROI Time: 34 weeks