Flow manufacturing is the best way to manufacture with the least amount of waste. Flow manufacturing is building the product in a continuous manner w/o any stoppages or bracktracking.
Variation killed Ford's flow concept. Customers wanted more options.
Very few plants can afford to purchase and dedicate equipment to each product.
Share equipment for build multiple products is common. With more new products and demand variation, complexity sets in. Better scheduling systems are added which in turn adds more to the complexity. Where is complexity?
- High product mix: products with many options, variation in lead time and cycle time.
- Information flows: scheduling is difficult and change by the minute. constant review of inventory and priorities to adjust schedule. MRP.
5. It looks very straight forward so why many lean initiatives stall after creating?
The difficulty lies in applying these steps in factories that have a high mix of products that must travel through the same value stream.
Mixed model production means producing a large variety of mix of products or products variation through the same value stream at the pull of the customer.
Mix model is really a countermeasure to variability. We applied mixed model techniques where variability is high. Therefore, lean principles apply in a non consistent and level schedule.
- We use the total demand of the product family rather than the individual volume for each product.
A product family is different to a product type: wrenches and clamps can be one product family. Processes define a product family not functionality of the product.
- Any mix of products for a product family can be produced, as long as the total volume does not exceed total family volume.
The key for creating a mixed model factory is selecting the right product family, understanding the total demand for the product and treating it as one product for scheduling.
- When alternative machines (could run but are not the primary choice) use "A". If there are multiple alternate processes, use A1, A2, A3, and so on.
- If product variation does not affect manufacturing processes (e.g. packaging, graphics,different languages, etc,) it may be easier to place only the base model number.
- sort by similar downstream processes. Downstream, starting with the customer, the point when continuous flow must end and pull begins.
- Products in a product family share about 80% of the same downstream processes.