Online Quality Engineering, OLQE, deals with balance between manufacturing cost and manufacturing quality a part of customer quality. The job of operators within manufacturing process is to manage a machine or a process by checking or diagonosing them. How may operators we need in the process is the job of manufacturing manager. Quality engineering can solve the problems using quality loss function. This article explains the methods using a simple case study from key manufacturing process. The more important area of online quality engineering is to balance cost reduction by increasing manufacturing speed and quality loss due to higher production speed. How to use the methods to optimize the speed is also at planed using the same key production process.

The function of directional handling for "silver cars"(the cars used by the elderly as a walking aid) was evaluated with the use of Quality Engineering. In the experiment, a college student given some kind of constraint was simulated an elderly person.

From the results of experimentation, it was concluded that the concept in Quality Engineering could be used for such evaluation. It was also concluded that the idea of having a young college student as an artificial or a pseudo elderly to participate the experiment, without having the elderly to participate, works.

In the processes of truing and dressing to treat super-abrasive grinding material called CBN or the grinding material made of diamond, it requires a special device, is difficult to set up and the time of processing is long.

To solve these problems, a new dresser was developed and the truing conditions were optimized using Quality Engineering approaches.

As the generic function, the dynamic operating window method that has been applied for chemical reactions was used. Processing time was considered as the signal factor, and the particle size of super-abrasive grinding wheels was used as the noise factor.

Contorol factors were assigned to an L18 orthogonal array. As a result, the truing capability under the optimum condition became 9.8 times greater compared with the traditional method. Also the dressing, which indicates sharpness, became equal or better than traditional soft steel processing. .It was therefor proven that with an effecient truing method, sharpness could be obtained simultaneously.

There is a trend that in recent years, digital cameras or PHS are becoming smaller and lighter. A new type of component called chip size package(CSP) is used for such purposes. But if a CSP which is either initially assembled or returned from the market is defective, it is replaced with a good one. The variability of the reliability of repaired units was worse than the one from the mass production line. Therefore, it was necessary to optimize the soldering work in the repairing process. In the study, the voltage-current relationship was considered to be the function for evaluation. To measure minute amounts of current flowing through the soldered part, special boards were made for the testing. A significant improvement was resulted.

In recent years, much attention has been focussed on Mahalanobis distance(MD) that treat multidimensional information systems for pattern recognition,diagnosis and prediction. Dr.G.Taguchi developed and proposed the MTS method which uses Mahalanobis distance. This paper describes a new inspection method for U.S. dollar bills using the MTS method. In the study, the pixel values that show black and white color concentration were converted by Fourier transformation to obtain frequency spectrum data. This data was used to construct a Mahalanobis space for inspection. As a result, the time to construct the base space and the time to calculate the distance has been shortened and a higher inspection speed can now be expected.

Welding is a method often used to join steel sheets to gether. In this report, a spot welding process was studied. Test pieces were prepared using zinc plated steel sheets with a good electric cconductivity. Load was added to welded pieces and was considered as the output. Displacement was measured and treated as the input. Electrode wear was used as a noise factor. SN ratio was calculated and then optimized. In the early experiment, an L18 orthogonal array was used. Since there were significant interactions between factors, control the confirmed gain was less than 20% of the predicted gain.

In the next experiment using an L9 orthogonal array, the sliding level technique was used. The results showed the confirmed gain was almost 70% of the predicted gain.

In mass production plants, there are many daily quality problems to be solved. For this purpose, it is desirable to conduct orthogonal array experimentation. But some quality items cannot be measured using the existing devices. Also there are no production lines available to make the products for testing. Under such situations, the static operating window method was successfully applied to solve the insufficient flux problem.

Flux(brightness) increases when the fluorescent material film thickness increases. But as the film thickness increases, the adhesion force between glass and film decreases, and it makes the film easier to peel off. The generic function of fluorescent lamps should be evaluated based on the relationship between power and flux. Data should be collected at different measured locations as a noise factor. But the study was not so conducted because the measuring device was not available.

In this study, static operating window was used to improve the two characteristics which behave against each other when the film thickness changes.

Color thermal ink jet printing is an important part of the industry's arsenal of printing technologies for the coming years. Efficient conversion of electrical and thermal energy into robust ink drop generation,(and subsequent delivery) to a wide variety of substrates is required. Quite complex manufacturing processes are used to create devices which can deliver ink drops with required target directionality, drop velocity, drop volume, image darkness, etc. over a wide range of signal and noise space. Inspection of image quality is used during online production operation to cost-effectively reduce outgoing variation among units. 100% inspection is justified based on loss function estimates considering inspection cost, defective loss, and quality loss after shipment. Classificaton of print cartridges as either acceptable or not acceptable is required, based on a multitude of inspection characteristics. The Taguchi/Mahalanobis system was applied to final inspection of image quality characteristics for a number of reasons :

1) To summarize multivariate results with a continuous number expressing distance from centroid of "good" ones.

2) To reduce measurement costs through identification and removal of measurements with low discrimination power

3) Balance misclassification cost for both type Ⅰ and Ⅱ error.

4) Develop case study from which practitioners and Subject Matter Experts in training could learn the MTS system.