What’s happening here? An automotive supplier, a manufacturer of frames, is given the opportunity to bid on a new contract for 7 SUV frame models from a “Big 3” auto maker. This line of SUVs would match the current body style and features of the recently updated pick-up truck models. Of the two U.S. frame manufacturers, only one will win the SUV work. The competitor is already the manufacturer of the pick-up truck frames, so the competitor has the stamping tools to produce all four front ends. This supplier only has the stamping tools to produce one front end. In order for this supplier to win the new quote, this business will have to absorb $15 million in new tooling that cannot be charged back to the customer. Can this supplier create a process efficient enough to win this contract and be profitable with a $15 million disadvantage to start?
The Situation as observed on the shop floor:
The pick-up truck frames produced by this manufacturer are assembled on two lines each with 22 fixtures. The frame parts come together to be tack welded and riveted. Then the frame is rolled over to be tack welded and riveted on the bottom. Operators load more parts as the frame moves and rotates through the fixtures to be welded by the robots. The operators and robots do their work for 40 seconds and then duck away for 20 seconds while the frame transfers lengthwise overhead and is clamped into the next fixture.
The Findings
The weld lines currently produce three frames for the three models of the 2-wheel drive pick-up trucks. The seven SUV frame models include both the 2-wheel drive vehicles and the 4-wheel drive vehicles with different side rails, crossbars and brackets. The number of fixtures needed is based on two constraints: first the accessibility to fixture each part, and second the time to complete the welds. On the original weld lines, the actual working time spent welding vs. time spent transferring the frames is 66% of the total cycle time.
The Solution
The opportunity occurs by transferring the frame sideways rather than lengthwise, shortening the distance 75% and increasing the time in each fixture. Welding robots mounted overhead reach more welds and weld for longer periods of time, thus requiring fewer robots. Art Stout designed two weld lines: one for the 2-wheel drive frames with seven fixtures and one for the 4-wheel drive frames with nine fixtures, a substantial reduction from the 44 fixtures.
The Results
The working time available in each fixture increased from 66% to 92%. The frame transferred once instead of twice and required 11 seconds less to transfer. With the new process, 111 seconds out of every 120 seconds was spent producing the product. As a result, the need for fewer fixtures combined with a more efficient use of time allowed this frame manufacturer to absorb the added tooling cost, present a competitive bid, and ultimately win the new SUV contract.