Six Sigma Case Study
Aluminum Casting Lead Time Reduction

This Six Sigma case study looks at how a company that manufactures aluminum castings was able to increase efficiency and reduce production lead times by using Lean principles.

The Problem

In this six sigma case study, an aluminum casting company wanted to increase efficiencies and reduce lead times.

Since there was never a good indication of when a certain product would be required by the customer, all products were made to order. For a standard order, it typically took three weeks for the factory to produce, pack, and load the products into the container for shipment.

The sales team had mentioned to the factory operations multiple times that if they could push out a typical order in two weeks, they would be able to nab even more customers.

The Method

A kaizen event was held with all key operations people involved. The goal of the event was to figure out how to get a typical order out of the factory within 2 weeks.

The first step was to create a current state value stream map for the full aluminum casting and assembly process. The data input into the map came from data within the ERP system as well as time and motion studies which were conducted 3 months prior.

From the value stream map, it could very easily be seen that there were 4 main points of focus where delays tended to happen. These areas were easily identifiable since they had high levels of WIP waiting in queue to be worked on. These problems could easily be solved with line balancing principles.

Other inefficiencies were also detected where instead of having one man per mold, one man could easily handle two molds as there was enough waiting time for the operator while the aluminum was forming in the mold.

Another example of delay was that when the items came out of the mold, they were thrown into a large wooden box. A huge batch of the product would collect in this box and it would have to wait there for 4 to 6 hours before moving to the next process because it was too hot to be touched by the finishing man at the next process. On top of that, a forklift would have to come and move the large box over to the next process whenever it was free.

A creative solution was found for this where the products would now be thrown into smaller custom made trolleys. Only about 30 to 40 pieces of product could fit in these trolleys. The storage contraption in these trolleys was made so that it could be revolved and could open from the top or the bottom. Now, once the first operator had filled up the trolley, he would push it to the next operator. This operator would then revolve the storage contraption and open it from what was essentially the bottom. This is where the first molded pieces would be and they should be cool by now even if the newer pieces are still hot. By the time the second operator gets to the bottom of the pile, even those pieces would be cool enough. This allowed the 4 to 6 hour delay to be reduced to minutes.

All the solutions (including line balancing, waste removal, and one piece flow at the assembly and packing areas) were implemented into the future state value stream map. Standard operating procedures were revised to follow the new process.

The Result

The factory was now able to push through a typical order in just about two weeks. Productivity and capacity was also increased.

The sales team kept their promise and lured in more customers with the short lead time. Even better, the factory could easily cater to these orders since they had just increased their capacity with this project!

Finally, the cost of the product also came down as it now used less overhead and labor man-hours. This finally contributed to the bottom line as a double winner with lower cost per unit and more units sold.

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