What’s happening here? A manufacturer of engineered hinges, precision tubes and spacers, custom stampings and assemblies for the automotive industry fears the loss of current and future business from a customer because of defective parts. The business produces two products for different applications for this customer and both products have been found by their customer with defects. Electronic error proofing devices and 100% inspection have not prevented these defects. Nor did the outside service hired by the business to inspect the parts a second time. The cost for the internal and external sorting is more than the business can absorb and the customer is growing tired of a supplier that cannot deliver defect-free product.
The Situation as observed on the shop floor:
The assembly for these two products is located in a small area of the building confined by four walls and made even smaller with assembly benches and materials for these two products plus three more. Moving components and finished goods around in this area is difficult because of the congestion. There are two operators assigned to assembling each of the two critical products. The operators often trade tasks during each shift. Additional tables were added by the operators to hold the partially assembled products as they are passed from one operator to another. One assembly fixture has an electronic interlock installed to insure all 4 screws are added. A second fixture for this product was added to align the parts that these 4 screws hold. The fixture for the other product is programmed to sequence the tasks using sensors to detect the parts. Completed boxes of parts are then100% visually inspected for defects prior to shipment. A service at the customer’s locations is hired to re-inspect the products 100% again as required by the customer.
The assembly area is comprised of a hodgepodge group of leftover work tables and shelves to hold the parts being assembled. The lighting is too dim for employees to easily see paint defects or missing grease. The parts identified with “defective” labels remain in the assembly area and add to the overall clutter impeding operators from easily obtaining parts. There is no consistency in the training or the execution of the assembly processes, allowing each operator to create his/her own method.
One dedicated operator for each product, instead of two, now make complete assemblies one at a time in a defined sequence. Posted instructions consist of a physical model of the parts in order of assembly plus written instructions. Additional warnings to achieve quality assemblies are affixed to the physical model and to the assembly fixtures. All non-essential items have been removed from the area and task lighting added. Through iterative problem-solving questions and feedback, the operator discovers deeper insight into his or her work. The operator is challenged to achieve a certification by demonstrating zero defects in this assembly for three consecutive weeks. The certified operator is audited but no longer requires100% inspection. The transition for these two manufacturing areas including the training of the operators was completed within 30 days.
The operators achieved certification and assembles defect-free product. Using the new assembly methods consistently, one operator produces more than the two operators previously assigned. The operators are now empowered with larger proactive roles. They effectively communicate with the producers of the component parts, eliminating more frequent defects that these assemblers would have to sort out before assembling them into product. There have been no customer complaints since this transition.