Original Date: 02/09/1998
Revision Date: 04/22/2003
Best Practice : One-Piece Flow Manufacturing System
UE implemented a One-Piece Flow Manufacturing system in its 120/105 manufacturing workcell. This system allows the demand for parts (orders) to drive the manufacturing flow, and produces finished products in lot sizes of one. In the past, work was pushed through the manufacturing area to fabricate finished products for the stockroom, which resulted in large amounts of finished products in inventory. In addition, many piece parts are common among the different products. As a result, UE ran into part shortages whenever priority orders came into the factory because the parts had already been used to build other units now sitting in inventory. UE’s capital was tied up in inventory as finished products waiting to be sold.
The One-Piece Flow Manufacturing system uses Heijunka boxes to schedule the production of units based on demand (orders). When orders arrive, the customer service and scheduling group generates the production schedule by part number and options. The group maintains the Takt time of the workcell by taking into account the time required to build that part and the mix of part complexity (low, medium, or high) in the production flow. The Heijunka box is then loaded in three-minute increments (Takt time) by placing the proper card in the slot for the part number to be built.
Production is initiated by retrieving a card from the Heijunka box slot. Then the parts are kitted; the nameplate is stamped; and the kit is taken to the workcell and placed in the incoming location. The first assembler in the workcell takes the kit; checks the paperwork for the model and options required; and performs the assembly steps for the first station. The partially-assembled unit is then passed to the next station where further assembly steps are performed. The unit then goes to the third station where the last assembly steps are completed. If required, the unit will undergo set-point adjustments and/or testing. Finally, the unit is packaged and put in the outgoing location to be picked up for staging before shipping.
Benefits achieved from UE’s One-Piece Flow Manufacturing system include the elimination of excess inventory; an order-based assembly line; and the loss of only one unit when defects occur compared to multiple units with a batch system. The production operation is now more efficient, and does not require UE’s capital to be tied up in inventory as finished products waiting to be sold.
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