A team approach to continuous improvement can speed production while maintaining product quality
By Doug Rich
US Machine Operations
Manufacturing Operations/Continuing Improvement
For the past four years, our company has worked to adopt lean manufacturing techniques in our own manufacturing facility. We are using lean both as a way to improve our own efficiency and also as a design driver. By using lean to improve the design of our products, we hope to help our customers reduce variability in their own processes, passing along the benefits of lean techniques to them.
In addition, as we began to implement lean techniques, we looked at the environmental/market changes that are affecting our customers and made those issues a priority for our own initiatives.
For example, we understand that market forces are putting pressure on our customers to reduce their cycle times. In the past, customers might be able to wait several months for a machine; today they need it in a matter of weeks. This customer need made it very important for Hardinge to reduce our delivery times and compress our Manufacturing Cycle Times (MCTs). While speed is a competitive advantage, however, we feel that we must balance this need to deliver products faster with our internal focus to deliver the technologies that add value. We never want to sacrifice design or performance to lower cost or reduce MCTs.
A good example of how we use lean techniques to achieve both goals is the initiative focused on our spindles. Hardinge has always been known for the precision and accuracy of our spindles; it has long been a differentiating feature. Today, however, many customers feel they must make a tradeoff between cost and precision.
We believe precision is of critical value for our customers because it enables them to reduce the variability of the parts they manufacture, and enables them to hold tighter tolerances over the life of the machine. One of the principles of lean is eliminating waste and variability. By delivering precision, we can help our customers reduce their MCTs because they do not have to continuously adjust their machines to eliminate variability, a step that can be extremely time consuming. Our solution: find a way to reduce the cost of our spindles by reducing the variation in our own manufacturing process, thereby making precision affordable.
While the implementation of lean manufacturing techniques represents a continuous effort, our spindle cell kaizen initiative began with some specific goals to improve several key areas of production.
- Achieve 80% utilization of the cell equipment and personnel.
- Develop a scaleable solution that can respond to fluctuations in production.
- Create a safe and ergonomic environment that eliminates all chances for injury.
- Compress the manufacturing process into a smaller area to reduce distance traveled to eliminate non-value-added material handling and queue time.
- Reduce MCT by 50%.
- Develop a visually managed work-and-material flow.
To ensure the kaizen remained focused on the areas identified for improvement, a cross-functional team was developed consisting of representatives from manufacturing, manufacturing engineering, planning, quality control, management, design engineering, and facilities maintenance.
Through this team, the current process of spindle manufacturing was analyzed, including part geometry, machine capacity, machine capability, annual demand, safety, and ergonomics, as well as manpower resources and existing floor space consumed by both inventory (WIP and finished product) and equipment.
The first thing the kaizen initiative did was to simulate the process layout. This was accomplished through a series of steps ranging from AutoCAD and paper dolls to an actual scale model set up on a portion of the shop floor. By going through this exercise, we were able to review the logical flow of all process steps, which helped ensure that we reduced the distance traveled by each spindle during the manufacturing process. At one point we even had a person walk the entire production cycle of the spindle manufacturing process so we could track the actual distance that each part traveled from start to finish.
This approach helped us address potential bottlenecks in the manufacturing process. For example, all critical grinding operations had traditionally been routed through the Grinding Department, as this was the only way to maintain the extremely high quality demanded by these parts. But this step resulted in a bottleneck for spindle manufacturing. To solve this problem we made the decision to dedicate a Kellenberger CNC grinder to the cell--thereby maintaining quality while reducing cycle time.
With the decision to include the grinder came the realization that the team needed to focus on reducing both internal and external setup times for the various grinding operations. The team focused first on reducing the external setups for the short term, with a longer-term continuous improvement effort planned for the internal setup reduction. Chief among the external factors affecting setup was the disposition of tooling (fixtures, step chucks, wheels, and pulleys) as well as the next job in queue.
The same process for setup reduction was followed for all equipment in the newly formed cell. Through these efforts, the team was able to realize a setup reduction time of 66% throughout the cell, with the majority of the gains shown on the Kellenberger grinder and large turret lathe.
Once the team was satisfied with the new process layout, setup reduction efforts, and part processing, the first initiative was to relocate machines and begin the process of offloading parts and programs from the old routing process to the newly formed cell. The process of relocation and part offloading entailed some 275 hr of reprogramming, as well as dedicated maintenance support during the relocation effort.
Since the completion of the initial phase of our work on the spindle cell, we've realized some significant gains in the manufacture of spindles.
The chart entitled "Spindle Cell Improvements Achieved By Lean Efforts" highlights some of the improvements realized after the implementation. As impressive as are the gains in the chart, interpretation reveals even more dramatic improvements. While each spindle still travels 1000' (305 m) during its manufacture, nearly 800' (244 m) represent the distance to and from the heat-treating operation. In lean manufacturing, material handling is considered a non-value-added activity, which points to this as a potential area for continued improvement.
The 27-day MCT reduction is even more impressive when you consider that the original 37 days was to process one spindle, whereas the current 10-day MCT is to process an order of 5 - 7 spindles. This MCT improvement was made using a process that both reduced the required manpower resources and showed a one-time inventory draw of $78,000 due to reduced WIP and queue.
While the results obtained from the implementation of the spindle cell are impressive, lean thinking demands a process of continuous improvement to further analyze and enhance the system. With this in mind, the implementation team developed a list of items that deserve some thought toward improving an already excellent manufacturing process. Some of the items under review include incorporating the thread-grinding operation on the Kellenberger grinder, consigned inventory in the form of slugs prior to the first machining operation, and evaluating the potential of changing material to reduce or eliminate the need for heat-treat operation(s).
With the dramatic changes already realized--combined with an aggressive continuous improvement system--the spindle cell is a model that can be used by all areas of our organization to justify the value of implementing the techniques of lean manufacturing. In fact, this cell was the first of what is today a philosophy that has spread throughout assembly and manufacturing, and is beginning to be felt in the company's administrative areas.
This article was first published in the May 2005 edition of Manufacturing Engineering magazine.