Reducing lead times using lean manufacturing and Six Sigma principles

A case study
George Vidonish
November 17, 2009

Traco's 1-million-square-foot production facility houses an advanced, vertically integrated process for manufacturing architectural windows and doors. Manufacturing on nine assembly lines is divided into three areas: glass processing, aluminum extrusion and final assembly.

Underpinned by the principles of lean manufacturing and Six Sigma, three initiatives at Traco’s primary production facility in Cranberry Township, Pa., have helped the window and door manufacturer reduce lead times by 50 percent, more than double customer field-testing approvals and deliver appreciable gains in product performance in the field.

The initiatives, which began or were refined in 2009, are an outgrowth of Traco’s continuous improvement efforts and a response to current market conditions that demand cost efficiencies and shorter lead times without sacrificing quality.

Advancing manufacturing
Our 1-million-square-foot production facility houses an advanced, vertically integrated process for manufacturing architectural windows and doors. Manufacturing on nine assembly lines is divided into three areas: glass processing, aluminum extrusion and final assembly.

In 2009, Traco stepped up its efforts to introduce lean manufacturing into this facility, focusing on the reduction of waste in time and material. We also began deploying Six Sigma, a set of practices to achieve zero defects.

The three new initiatives that Traco implemented were:
• Assembly layout and 5S (lean manufacturing);
• Production part approval process (lean manufacturing and Six Sigma); and
• In-process inspections and final product audits (Six Sigma).

A common pitfall in introducing new concepts and practices is not being able to sustain them, especially if the person who championed them no longer does. To avoid this, Traco officials sought the buy-in of all employees by engaging them directly in each initiative’s implementation and delivering quick, impactful results that either made their jobs easier or showed clear improvement in product quality.

Assembly layout and 5S
In early 2009, the addition of new product lines and the increasing complexity of the product offering required a new layout for Traco's assembly lines.

Traditionally, we operated under batch processing, where multiple pieces were completed at one step before being moved to the next. This form of manufacturing innately produces significant work-in-process, a major waste in the production process.

Traco designed its new layout to achieve one-piece flow, where a product moves immediately from one step to another once work is complete. We're not there yet, but our willingness to pick up a piece of equipment or an entire line and move it to another area to experiment with flow has already reduced lead times by 50 percent and WIP by at least 25 percent.

A major lesson learned: you need to design the line layout to handle 80 percent to 90 percent of the products. You will never be able to accommodate 100 percent of the products, so don’t get hung up on the one-off situations. Rather than sub-optimize your line to handle every product, optimize it to handle the majority.

We also discovered that once we completed our initial layout redesign, the production areas did not seem as neat and tidy as we wanted them to be. To address this, we introduced the lean manufacturing concept of 5S, which is a work space management philosophy that refers to the following:
• Sort: Eliminate unnecessary items from the work space;
• Set in order: Identify and organize everything in the work space, such as tools, equipment and parts;
• Shine: Conduct regular cleaning and maintenance;
• Standardize: Do the above in a standardized and consistent manner; and
• Sustain: Maintain what has been accomplished.

It was through 5S that we gained the highest level of employee engagement. Following an employee luncheon presentation on the concept and the areas in the plant needing the most improvement, Traco officials asked employees for the answers rather than giving the answers to them. This engaged every single person on the floor, and delivered a visible result that made everyone’s work easier to perform.

Production part approval process
Traco is a custom manufacturer, constantly churning out products that have never been made before. As such, we need to build new extrusions and tooling and do so flawlessly within a condensed lead time.

In 2007, Traco began an informal initiative to ensure that before any new product hits the production floor, it has been optimized to meet design, manufacturing and performance requirements. We formalized this production part approval process in 2009.

The process includes building one or more of the following pre-production samples to test and validate against specific checklists and audits:
• Prototype sample: Validates the product design meets customer requirements;
• Pilot sample: Validates the product can be manufactured at the highest quality level possible with the least amount of waste; and
• Mock-up sample: Used to obtain customer approval.

The entry point into PPAP depends upon the product. For example, if our engineers feel confident that the product’s design is valid because it has minimal variation from an existing product, we would enter at the pilot step.

Through trial and error, we have learned that we should never underestimate what step to enter the process. The time and cost required to build a sample can be slight next to the lost time and material waste that results when we have issues in the manufacturing process.

The PPAP can lead to engineering or tooling changes, or we may need to move equipment for better flow to increase overall productivity and improve our ability to deliver a quality product. Prior to instituting this process, we needed to make these changes once the product was in production—a waste of time and material.

Measuring our results is difficult, since we have no way of knowing what difficulties we would have experienced manufacturing a product if we didn’t use PPAP. However, we are seeing more flawless approvals from customers during the mock-up testing. These mock-ups are often field tested for performance, and our approval has more than doubled over previous years.

In-process inspections and final product audits
An important step on Traco's journey to zero defects under Six Sigma involves our in-process inspections and final product audits that we implemented in 2009.

During production, our quality and testing technicians use defined checklists to audit the product and the process. Not only do these audits help ensure high product quality, they provide an excellent opportunity to uncover and correct deficiencies in workforce training and work instructions.

Multiple times during each day, a quality technician conducts a final aesthetic and operating audit on a statistically significant number of finished products to ensure quality levels prior to shipment. In addition, we use an in-house test chamber to expose a sampling of finished product to air and water at the required performance levels for that project. This is a live audit of the performance criteria, especially important today because of the increasing number of products required to be field tested and the rise in performance-level expectations.

In 2009, Traco more than tripled the number of products undergoing in-house testing compared to the prior year. As a result, we’ve seen appreciable gains in our products’ performance in the field.

Continuous improvement
Implementing lean manufacturing and Six Sigma principles has significantly advanced continuous improvement efforts at our major production facility.

We have learned that these principles are our toolbox and our compass. When we start to struggle, we use them to help guide us back onto the path of meeting our customers’ need for cost-effective, high-quality custom products in the shortest time possible.

The author is manager, Quality and Manufacturing Engineering, Traco, Cranberry Township, Pa.