Philip R. Wahl
Product Assurance Engineer II
Peter L. Bersbach
Sr. Product Assurance Engineer
Hughes Aircraft Company
PO Box 92426
Los Angeles, CA 90009
This paper is the continuation of “QFD on a Defense Contract.” This installment will examine the application of Total Quality Management (TQM) to the later stages of a project. Statistical Process Control (SPC) and how Quality Function Deployment (QFD) and Design Of Experiments (DOE) help implement SPC will be looked at closely. The goal of the project is to develop a factory to build high-rate, low-cost microwave hybrids for the aerospace, automotive, and defense industry .QFD helped get the project off the ground; now other TQM tools are being used to help win the follow-on contract.
Implementing a successful SPC program on the production floor requires many TQM tools. The process includes three basic steps: (1) setting the foundation, (2) establishing controls, and (3) making sure that these controls meet our needs and our customer’s needs.
Step 1 talks about the use of QFD and DOE to def111e the best manufacturing approach, select the best equipment, and f111gerprint that equipment so pre-controls can be put on each process. Supplier networking is established to start a process that will work toward fewer and better sources for the factory.
Step 2 discusses how to go from pre-control to full fledged control charts. We will also cover the need to establish Process Action Teams, Process Control Logs, Out of Control Condition Procedures, and risk assessments.
Step 3 looks at ensuring that the controls in place meet our needs and the needs of our customer. During this step, we will discuss the use of process capabilities and Process Action Teams to monitor and improve the process.
This paper also covers supplier relations and the application of TQM in that area. We develop partnerships with vendors through the GM Targets for Excellence system. This system provides a method for continuous improvement at the vendor level so all can benefit.
Finally, this paper will cover the results of our efforts. We will look not only at the good things, but also at the obstacles and lessons learned. The ability to carry TQM throughout the life of a program will be discussed along with the difficulty communicating across disciplines.
The boardroom was thick with tension and anticipation. The only light came from the view graph projector with its squeaky, annoying blower. It was all on the line and everyone knew it! It was the last customer review of our product. It was the last chance we had before the customer decided if we would get additional funding for the next phase. We had worked long and hard to satisfy the customer and guarantee additional funding, but would it all pay off?
This was the setting in June 1990, the last customer review for the T/R Module ManTech Program, the purpose of which was to develop a factory to build high-rate, low-cost microwave hybrids for the aerospace and defense industry .The program was introduced last year with a paper entitled, “QFD on a Defense Contract.” It explained how we applied QFD in the early stages of a contract, when it was still in its infancy. This paper covers how we are applying TQM in the stages beyond the June 1990 review. The focus is on our SPC implementation plan and how other tools, such as QFD and DOE, helped shape and form it. We did receive the go-ahead for phase 3 (the next phase of the contract) and are still aggressively applying TQM. The implementation of our SPC plan is in progress.
The application of TQM to this program began early on with QFD. When the primary goals and objectives were set, they were definitely revolutionary. The desire was to go from a production rate of 100 per day to 1000 per day and from $3000 each to $200 each. We used QFD to identify key product characteristics that would help meet the goals and satisfy the customer. The time spent on our initial QFD chart was well worth it (see Fig. 1).1 Not only were key product characteristics identified, but team unity and spirit were created. The chart emphasized four key areas: yield, rate, module cost, and process capability. The TQM team used these four areas to progress through a functional tree diagram into ten more QFDs (see Fig. 2). Throughout this stage, both internal and external customers were actively and enthusiastically involved. Management support for all our TQM efforts has also been very strong. There is no doubt that this has been a primary contributor to the success of the program.
The implementation of SPC incorporates two main goals of our TQM system: variability reduction and continuous measurable improvement (cmi). SPC, including process capability analysis, is implemented in three steps: Pre-implementation, Initial Implementation, and Implementation Verification. Each of these steps has distinctive tasks to be covered in greater detail. An important pan of the SPC plan is that the “owners” of the processes are fully involved in designing and implementing it. The owners are those people who actually use and work with the process. For example, testing our product is a process where SPC will be applied. The test technicians are the owners. When the portion of the SPC plan that applies to test was developed, these people became pan of the team tasked with SPC implementation. This approach allows people to feel that it is their plan, which greatly enhances participation and overall compliance. QFD and DOE also play a vital role in the plan. The owners are involved in using QFD to review customer needs and select the best manufacturing approach and equipment DOE is used, if needed, to aid in that selection or help optimize other processes. The idea is to flow customer demands from the first QFD chart down to the manufacturing floor. This ensures that effort is spent on the areas that have the greatest potential for achieving customer satisfaction. Another important element of the plan is supplier review. Our program has adopted a vendor networking system from General Motors called Targets for Excellence (TFE). This vendor networking system strives to create partnerships between the supplier and customer. The process owners are the customers of the materials supplied to them. It makes sense that they have a partnership with those supplying the materials.
Step 1: Pre-implementation
Pre-implementation is essentially a period during which a detailed review of existing data takes place. This data will include all QFD matrices built on assembly processes, data from similar processes, and vendor capabilities. SPC training is conducted during pre-implementation for those who require it. Also during pre-implementation, preliminary data, analysis is performed to determine process capability, process parameters, and product characteristic correlation and distribution structure. Initial candidates for SPC are determined from this data.
Engineers participating in activities requiring SPC receive basic training in interpretation and development of control charts and other statistical tools, such as Pareto analysis and histograms. Operators and inspectors working on the program receive basic skills training applicable to SPC. The intent is to have the owners of the process collect and use the data on a real-time basis so that they can take immediate action to correct trends before the process produces an unacceptable product. This approach is effective, but requires a higher level of SPC awareness by those involved. That is why training is so important
Initial candidates for SPC will be examined and classified as critical, major, or minor characteristics. Minor characteristics will be addressed only after all critical and major characteristics have been reviewed. It is anticipated that controls will be placed on process parameters rather than product variables where appropriate data shows that process parameters correlate with product characteristics. Two events need to take place before, or at least during the same time as the selection of these characteristics: (1) selection of the manufacturing approach and (2) definition of the processing equipment needed to attain that approach. QFD and DOE are used heavily during the selection of the manufacturing approach and equipment
When the manufacturing approach is selected, a review o all QFD matrices ensures that the s of the customer flow throughout the program and into the SPC plan. As customer needs pertinent to the approach emerge, additional QFD charts may be needed to compare customer needs with available approaches. The result is an approach that best satisfies customer needs. This type of chart, called a concept selection matrix, is used quite often. Existing processes to be used again are reviewed QFD style to identify weaknesses. When an acceptable approach is hard to find, further study is undertaken through experimental designs. These DOEs are directed toward the development of a process that meets customer needs. Supplier networking, the purpose of which is to determine capabilities and recommend techniques, begins during step 1, Pre-implementation, through the TFE process.
When equipment needs are to be defined and individual pieces selected for installation, QFD will again be used. A matrix of customer needs and different pieces of equipment available will be constructed for each segment of the process. This approach determines the best equipment for the job. When information on equipment capabilities is not available, but the equipment supplier is willing to work with us to determine this information, experimental designs and capability studies are performed to obtain the desired information, Working together makes both equipment and materials vendor’s partners in the overall success of the program. These partnerships will ensure that our vendors’ perspectives are considered in the overall plan.
Once equipment is defined and purchased, the real use of DOE begins. Up to this point, mainly subjective information and a minimum amount of general data is used to relate product performance to process or equipment parameters. After production, equipment is purchased and is in the factory, DOEs and capability studies are performed to determine the exact relationship between critical product characteristics and process parameters. This relationship is identified as the “fingerprint” of the equipment. The fingerprint also identifies the process parameter target values, the process variability around that value, and the ability of the process to produce an acceptable product Once fingerprinting is complete the initial candidates for SPC can be determined.
Near the end of step 1 all available manufacturing/assembly data, including data obtained from the selection of the approach and equipment and from the fingerprinting of that equipment, is reviewed and, if necessary, further analyzed. This review leads to the determination of initial SPC candidates. The analysis will include a first refinement of the process capability, process parameter, and product characteristic correlations and distribution structure. The goal is to meet customer needs and maintain a capable process. This data will also be analyzed to determine the feasibility of using techniques such as highly repeatable tooling and tooling as a media of inspection.
Preliminary control charts are designed to collect variables data where applicable. These preliminary, or pre-control, charts for variables data have upper and lower pre-control limits based on the product feature tolerance zones or its relationship to the process parameter being controlled. The initial pre-control limits are 77.1 % of the process or product specification limits. Pre-control limits of 77.1 % require process improvement during early SPC program steps to create a process that, in the long nun, produces a product with a defect rate of less than 100 parts per million (ppm).Pre-control chart limits for attributes data are based on historic data of similar assembly operations or based on a targeted process Acceptability Quality Level (AQL). Initial pre-control limits may, therefore, be based on attainable limits of mature existing processes (with a learning curve correction, if applicable) or on an AQL, if no acceptable similar process exists.
The use of QFD, DOE and a supplier networking program are emphasized. Our goal is to develop an SPC plan that incorporates all these tools. A simple check sheet has been developed (see Fig. 3) to track and monitor our efforts toward the use of these tools as they apply to our SPC plan. The SPC coordinator uses the check sheet to track and record progress. He is the SPC focal point and also provides SPC expertise and training.
T/R ManTech SPC Implementation Status
Step I: Pre-Implementation
Sample Check Sheet for Tracking SPC Progress
Ste 2: Initial Implementation
Step 2 is the early implementation period where initial process data is collected from production pans and analyzed to determine the true process capabilities and levels of control required by each process step. The duration of this step is determined by the time required to manufacture/assemble the rust 100 production units. The responsibility for performing measurements and plotting the data resides with the operator when practical, or with the inspector when inspection equipment limitations, machine cycle time, or some other requirements indicate a need for other than operator measurement. If special tooling, gages, or equipment is needed to ensure that the process is both stable and capable, the process engineer obtains that equipment at this time.
In the case of operator measurements of variables data, periodic random audits of pan measurements done by operators are performed by inspection. Parts measured by an operator, used to determine the most recent control chart point, are retained for audit or until a new control chart sample is taken. In the case of operator identification of attributes data, the most recent unit produced is identified so that audit/verification may be performed by inspection during random periodic audits.
For each process a Process Action Team (PAT) and SPC Log (SPCL) is established. Each PAT is responsible for its own process. The PAT is made up of operators, inspectors, and appropriate manufacturing, process, and quality engineers. It is their responsibility to monitor the process for out-of-control (OOC) conditions. If an OOC condition develops, the process is shut down, supervision notified, and the condition documented in the SPCL by the operator. Corrective action, as approved by the PAT, must be initiated and documented in the SPCL before the process is started up again. All corrective action must be verified as effective. This is done by increasing inspection to as much as 100%. Repetitive or ineffective corrective actions, as evidenced by continuing OOC conditions are referred to the Operations Team. The OT is the governing body in all plant operations.
Two main goals or our TQM system:
Variability reduction and continuous measurable improvement
The capability indices of each process are recalculated and recorded in the SPCL periodically by the responsible engineer. If the indices have shifted significantly in either direction without justification, the engineer convenes a meeting of the PAT .The team then investigates the cause of the shift.
Once the cause of the shift has been determined, the process is adjusted to have the best (largest) capability indices, and a report on the cause is written to the applicable OT. The capability indices recorded in the SPCL are subject to audits by the quality organization to ensure that shifts have been addressed. Any shifts not appropriately addressed are referred to the applicable OT.
Step 3: Implementation
Step 3 is a further data collection period during which enough data is generated by the processes to permit the computation of statistically valid process control limits. During step 2 only 100 units are produced as the new factory is demonstrated. In step 3, medium production rates of up to 1000 per day are reached. This increased production rate allows for the full implementation of valid SPC.
Many of the elements of step 2 carry over to step .3. The responsibility for performing the measurements and plotting data for the SPC charts remains the same. The PATs also remain intact and retain responsibilities as outlined in step 2. The PATs also maintain a history of the data used to derive all process capability indices, all original control chart parameters, and all parametric changes made to the control charts. A history of the actual control charts is maintained, which is the basic data used to compute the control chart plot points as well as the SPCL. The continuing goal of the PATs is to reduce process variability and improve process performance.
During step 3, the control chart type by specific operation will be determined by production volumes and data analysis of the specific product of the operation. The actual sample size and frequency of measurements for variables control charts is based on production rates determined at this time. Control charts for attributes data of assembly and test operations are determined by production volumes. The type of chart may be changed as volumes increase.
When SPC has been implemented and the processes have been demonstrated to be in a state of statistical control, the product conforms to final acceptance specifications, and the process capability indices are greater than 1.33, the quality organization reviews this information along with the cost of inspection (the current sampling control chart procedure) to determine if reductions in inspection (sampling) are warranted. If warranted, inspection is reduced, and all information used to make that decision is stored. The customer is then notified of the reduction.
SPC techniques are applied through the GM Targets for Excellence (TFE) program to subcontractor/vendor processes. In all cases, statistical quality control (SQC) techniques will be used to validate subcontractor/vendor product quality. As subcontractors/vendors progress in the TFE program by increasing their process capabilities, SQC techniques are reduced or eliminated.
In October 1990, Hughes Aircraft Co. and Delco Electronics formed a new subsidiary called HE Microwave. This new subsidiary is our factory of the future. Shortly after its origin, it employed 10 individuals, 6 of which have already received at least 30 hours of training in the use of TQM tools. The plant manager and the quality manager are already trained. Plans are underway to provide equivalent training to the others. All employees have previously worked in a high-rate production line for electronics equipment at Delco or a highly automated military production line at Hughes. With this strong knowledge base in the area of TQM, the organization is steadily focused on meeting customer needs.
With all the training and experience within HE Microwave, the best tool that keeps the team moving is teamwork itself. In the previous paper, teamwork was stressed, and here again it turns out to be a vital key to the success of both HE Microwave and the users of the TQM tools. It is so much a part of HE Microwave that the company does not have an organization chart. Management feels that an organization chart tends to pigeonhole people in specific jobs which leads to the “it’s not my problem” syndrome. They hope that the chart never exists so that all will look at problems as their own and work together to solve them.
As of October 1990, work has started on the selection of both the best manufacturing approach and the best equipment. In trying to do this our biggest, obstacle-communication-has surfaced. When HE Microwave was set up, a shift occurred from El Segundo, CA to Tucson, AZ where HE Microwave ‘-; located. As this shift occurred, it was necessary to get out the QFD charts and review the flow down of customer needs. The review caused many questions (as it should with new members joining the team). Most have been resolved but some are still being worked. The importance of what is happening is a transfer of vital customer information to new team players in a timely manner. This transfer could not have happened without the QFD charts.
The TFE vendor networking system is also well on its way. The supplier assessment team has come up to speed and started the process with four initial suppliers. The four suppliers have been assessed, and partnerships are being developed. After this first stage, the balance of the suppliers will be introduced to the TFE process.
Through it all, the team continues to remember the importance of customer satisfaction and the key areas of focus identified by the first QFD chart: Yield, Process Capability, Rate, and Module Cost. These are the goals for the entire organization. The SPC plan is a way to help us get there. It is important to keep the overall goals in sight so that the daily grind of the work place doesn’t become overwhelming.
The key element of this program is “the team.” The team is using QFD, DOE, SPC, and TFE to help satisfy customer needs. We are using the system, changing and adapting it to achieve this customer satisfaction. Most importantly, the system is not using us. It is very important to maintain this perspective. Without it, creativity is lost and we are slaves to a system that disallows anything but the standard way of business. The team can break these barriers and go beyond what is commonplace. It can use the system to bring customer satisfaction to new heights. This is where we are going and we are using the concept of TQM to take us there.
1. Bersbach, Peter L., and Philip R. Wahl. “QFD on a Defense Contract.” 1990 ASQC Quality Congress Proceedings, San Francisco, CA.
2. King, Bob. Better Designs In Half The Time. First Ed. Methuen, MA: GOAUQPC 1987.
3. ReVelle, Jack B. The New Quality Technology. Los Angeles, CA: Hughes Aircraft Co.,1989
 Bersbach Peter L.. and Philip R. Wahl. “QFD on a Defense Contract.” 1990 ASQC Quality Congress Proceedings, San Francisco. CA