Inspection System Improves Diesel Assembly: Flexible Plant Assembles V-6 Diesels
In addition to its Indianapolis facility, International Truck and Engine Corp. (Warrenville, IL) operates engine assembly plants in Melrose Park, IL, and Huntsville, AL. The later facility is the company's newest plant.
International purchased the 700,000-square-foot building from Onan Corp., a subsidiary of Cummins Inc. (Columbus, IN), in 1999. "The facility was gutted down to a dirt floor and built into what we believe to be a new standard for engine manufacturing anywhere in the world," says Donna Miller, plant manager.
The Huntsville plant was designed to be flexible. Unlike the Indianapolis plant, which builds a high volume of the same type of engine, the Alabama facility was configured with complexity and model mix in mind. Since production ramped up in 2001, the plant has assembled 14 different models of engines. The plant currently assembles VT 275 V-6 diesel engines used in International CF Series trucks.
"An enormous amount of thought went into error-proofing the entire build process," says Miller. For instance, the plant uses DC electric power tools to ensure that fasteners are tightened to the correct torque. With their computerized controllers, DC electric tools allow operators to achieve the correct relationship between torque and angle control as fasteners are tightened.
"No air tools are used," Miller points out. "Therefore, we are assured that parts and assemblies are fastened to the product with the appropriate specifications."
A total of 20 different integrated quality assurance stations throughout the plant automatically verify product specifications during the assembly process. "That ensures[that each engine meets] high quality standards at each stage of verification, rather than waiting until the engine is completely built," says Miller.
Quality and build data are electronically captured by serial number via radio frequency identification tags located on the engine pallets.
According to Miller, International was the first diesel engine manufacturer to incorporate a signature analysis, where the fingerprint of a perfect engine is compared to the product being built. This analysis detects even the slightest variations in the engine early in the assembly process. The quality assurance stations prevent engines with deviations from reaching the end of the line.
Each engine undergoes a comprehensive, multifunctional quality verification process. For example, finished engines are cold tested, allowing operators to check pressures, torque, operating sensors and mechanical attributes without actually running the diesel. After the cold test, each engine moves on to a startability station, where it is tested for idle stability and fuel system startup.
To create a more streamlined and efficient process, more than 75 of the plant's assembly operations have been automated, further decreasing the opportunity for error. As an engine travels through the assembly process, crankshafts, camshafts, connecting rods and cylinder heads are automatically installed.
The flow-through strategy extends beyond the assembly line and into the layout of the entire plant. For instance, Miller says the plant is laid out to efficiently direct parts from the loading dock through to the point of use. Most of the plant's inventory is handled by third-party logistics firms, a concept that started as an experiment at International's Indianapolis engine plant.
"Reducing the plant's inventory helps not only to reduce costs, cut also frees up valuable space to accommodate engine production," Miller points out. "The plant works closely with suppliers to make deliveries daily, rather than weekly."
Parts, components and subassemblies are consolidated into smaller shipments at a logistics center located less than one mile from the plant. "This strategy improves [our] profitability, because suppliers own the material until it's delivered to the plant's 28 strategically located docks," notes Miller. "The third-party logistics system facilitates just-in-time deliveries to the line and efficient shipment of engines to customers."
International invested more than $300 million in its Huntsville plant to create a bright, clean work environment, including production tools that are comfortable and easy to operate. "Throughout the build process, operator-machine interfaces incorporate ergonomic efficiencies that facilitate simpler assembly," boasts Miller.
For example, engineers have ensured that each operator does not reach further than 17 inches to perform an assembly task. And, along the assembly line, the engine is presented to operators at a height of 36 to 45 inches off the plant floor to ensure optimal safety and comfort.