CASE STUDY APPLICATION OF TRIZ TOOLS STRENGTHS & WEAKNESSES

Transcription

1 CASE STUDY APPLICATION OF TRIZ TOOLS STRENGTHS & WEAKNESSES Chia-Li Song, Teong-San Yeoh, Tay-Jin Yeoh, Intel Technology Sdn. Bhd. Penang, Malaysia ABSTRACT TRIZ is essentially a toolbox with a multitude of tools to choose from. Although users prefer one tool versus another, it is important to note that each tool does have its strengths/weaknesses. We have conducted a series of Advanced TRIZ (Level 2) training classes to students across different Intel sites in Asia (Malaysia, China, Philippines). As a class exercise, we introduce a problem of two threaded joints which causes liquid leakage when screwed together. The challenge is to provide effective solutions using the various TRIZ tools which they have learnt from Basic (Level 1) TRIZ till Advanced TRIZ. One discovery was solutions generated by students were similar when they applied the same TRIZ tools irregardless of their educational background, culture, or years of working experience. This paper will discuss the details of the problem and solutions generated with different tools, along with pros and cons of the various TRIZ tools. INTRODUCTION TRIZ contains many tools for problem definition e.g. Functional Analysis, Flow Analysis, and Cause & Effect Chain (CEC); and innovative solution generation e.g. 40 Inventive Principles, 76 Standard Inventive Solutions. From Basic TRIZ to Advanced TRIZ (TRIZ Level 1 and 2), approximately 12 tools are studied. In basic class, we have Functional Analysis, CEC, Contradictions, Process Analysis; and in advanced class, we have ARIZ, Substance Field (Su-Field) Modeling Trends of Engineering System Evolution (TESE), 9 Windows. There can be some amount of confusion for people who are new to TRIZ in terms of what is right tool to use when solving a problem. This is also a commonly asked question during class. So it s necessary to demonstrate to students the differences of some of these tools. To have a better comparison, we used one particular problem, so that students can appreciate and have better understanding. CASE STUDY BACKGROUND The case study we used is a unique actual problem from a basic class project. It is about epoxy leakage from dispenser equipment. The operation of this equipment is to dispense epoxy underfill into the gap between die and substrate (Figure 1). The epoxy is stored in cartridge. This cartridge is attached to equipment and connected to the dispenser through a luer joint (Figure 2). The operator has to manually connect the luer joint and sometimes improper manual work may cause leakage at this luer joint. The project owner who attended Basic TRIZ class built the CEC from this key problem and found that there were 3 root causes, under-tighten, over-tighten and misalignment of joints. When she applied Basic TRIZ tools to this problem, she managed to solve the joint under and over-tighten issue, but not the joint misalignment. With the help of the instructor who used the Advanced TRIZ tools, the joint misalignment was solved. This demonstrated that

2 different tools generate different levels of solution, and we found this would be a good example to show the tool comparison. Thus, we decided to use this actual problem as a case study in advanced class where more tools are taught. die underfill Luer joint Fluid Reservoir (contains epoxy) substrate Figure 1: Flip chip package Figure 2: Picture of a dispenser In order to make the problem more generic and understood by students who are not familiar with dispenser module, we reformulated the original problem (Figure 3). Assume there is Liquid A stored in container and Liquid A needs to be sent to equipment through a series of hoses and joints. Once the container is empty, it has to be replaced with another container by removing the joints. When operator screws the 2 joints together, they will sometimes either over-tighten or under-tighten the joints; or have a joint misalignment. Leakage will occur after a few hours of operation due to vibration of equipment. We use this case study as class exercise in advanced class. On the first day of the class, students can apply any tools they learnt from basic class. For second and third day exercise, we selected Su-Field Modeling and ARIZ respectively to apply on this case study. hoses Figure 3: Equipment configuration of the case study DAY 1: BASIC TRIZ TOOLS On the first day, students started with building the Functional Model and CEC, then brainstorm solutions. Most of the students chose Engineering Contradiction to model the problem, while there were others who used Trimming. The first step of the Engineering Contradiction is to define the improving parameter and worsening parameter of the contradiction if the threaded joints have better contact, then there will not be any leakage problem but it takes a longer time to screw the joints. This means that if we

3 improve the joint reliability, it slows down the productivity as longer time is needed. So, the improving parameter is Reliability and the worsening parameter is Productivity. Students generated some ideas based on 4 suggested principles from contradiction matrix. The two most common solutions were to use a damper to secure the joints from vibration and change to rubber joint to absorb vibration. There were also some students who went through all the 40 principles and they managed to generate more ideas. For example, use torque wrench to control the maximum torque applied on joints, apply teflon tape at the joint or put marker on joint to indicate final joint positions. Those were some of the solutions for joint under-tighten. To overcome joint over-tighten, the solutions were quite similar to under-tighten. Use torque wrench or redesign the thread, have a small protrusion at the edge of thread to act as stopper. For joint misalignment, install alignment pin or quick connect. For groups which applied Trimming, they calculated the trimming value, and assessed what to trim from the lowest value. One of the ideas was to trim away the joint since joint is the most problematic component in the whole system. Then, integrate the container into equipment. This solution definitely helps in eliminating the leakage problem, but this may not be desired in most manufacturing facilities which require minimal change to the system. DAY 2: SU-FIELD MODELING On second day of the advanced class, Su-field analysis is taught. At this time, students applied Su-Field modeling to work on the case study again. As zone of conflict is introduced, students started to focus on problem area which is the joint itself. The two substances (S1 and S2) are female joint and male joint. These two substances interacted with each other through a mechanical field. For over-tighten and under-tighten, the interaction type is ineffective. In this case, the joint threads are aligned, however problem is that these joints are either under or over tightened. However, misalignment is a harmful interaction. Once the type of interactions are determined, next step is to apply the 76 Standard Inventive Solutions to generate idea. Based on the flow of the methodology, use Class 1 or 2 for over and under-tighten problem while Class 1.2 is used for misalignment which is for harmful interaction. Some ideas were generated from Class and In comparison to Basic TRIZ solutions, solutions generated by Su-Field were more convergent as the problem is focused on the joints. Solutions generated from Day 1 involved changes around the equipment including removing joint, redesign joint or do something to prevent vibration. However, the solutions are quite similar to Basic TRIZ although they narrow down to problem area, e.g. apply Teflon tape, add stopper, add aligning groove or pin. There was still no breakthrough idea at this point of time. Either Basic TRIZ or Su-Field will provide effective solutions to under/over-tighten of joints, but effective solutions to misalignment remain elusive. DAY 3: ARIZ On Day 3, we want to see how ARIZ helps in eliminating misalignment problem. The 3 main categories of ARIZ algorithm consists of steps as follows: 1) analyze the system, 2) analyze the resources, 3) define the Ideal Final Result(IFR) and formulate the Physical

4 Contradiction, 4) resolve the Physical Contradiction, 5) apply the knowledge base, effects, standards, and principles, 6) change the mini problem, 7) review the solution and analyze the removal of the Physical Contradiction, 8) develop maximum usage of solution, and 9) review all the stages in ARIZ in real-time application. The following problem solving step cover only the first category where students found solutions before moving to step 4 to resolve Physical Contradiction. For the first 3 steps, they consists many sub-steps: define mini problem, define Engineering Contradiction, identify the operating zone, analyze the Substance and Field Resources (SFR) and define IFR. By defining the operating zone, students are clearer on where to focus. Misalignment is as shown in Figure 4. Useful zone is where the male thread contact with female thread, holding each other to prevent leakage, and harmful zone is where female thread damages the male thread. The zone of conflict is where the useful zone intersects with harmful zone. Besides, from SFR analysis, a table which consists of all elements of existing resources in engineering system is created. This table captures the substances, parameter and fields of each resource. For example, pitch, diameter, radius, depth and angle are the parameters pertaining to the joint cross section (Figure 5). After listing all the elements in SFR table (Figure 6), each of the elements will be substituted into X-component of IFR and evaluated to determine possibility of resources to eliminate leakage problem. Female thread Male thread Useful zone Harmful Zone Figure 4: Operating Zone Figure 5: Joint cross section Figure 6: SFR table Solutions generated from ARIZ especially X-component are more focused and changes on system are minimum. But not all students are able to get the right parameters as this is relatively new way of looking at things, some may still be looking at high level. Thus,

5 solution may not completely solve the problem but it doesn t change the system a lot. Based on the parameters from the joint cross section, depth, radius, angle, pitch are the parameters which may contribute to the joint performance. The biggest modulator would probably be the thread depth. The joint misalignment should be able to be resolved by increasing the thread depth. OBSERVATION After compiling all the ideas of this exercise from various classes, we found solutions generated were similar although students may be from different countries, have different educational background or years of working experience. Engineers from Malaysia, China and Philippines generated quite similar solutions when they applied the same TRIZ tools. We also observed some pros and cons of the three tools used for the case study. Contradictions & 40 Inventive Principles in Basic TRIZ are very effective in providing innovative ideas even though user may not be the expert in the area being worked on. However, these tools may give rise to major changes in the system as they are not as detailed as ARIZ. Su-field is fast and easy as there is no necessity to identify the contradiction. However, it provides focus through Zone of Conflict. One limitation is that the Standard Solutions can be quite generic, e.g. add third substance S3, but question is what should S3 be? However, for ARIZ, it helps to provide some potential solutions from SFR table. It is more focused and considers all the existing resources. This is suitable for working environment which only allows minimal change to the systems. However, ARIZ is time consuming and tedious. Most students may give up along the way. Concept of tool/product can be confusing in some cases. SUMMARY This paper shares the solutions generated, pros and cons for Basic TRIZ tools (especially Contradictions & Principles), Su-Field and ARIZ. Use of each tool is dependent on boundary conditions of engineering system and user's knowledge/competency/comfort level. Each tool is complementary to each other i.e. breaks down psychological inertia and offers fresh perspectives on problem solving. BIOGRAPHY Chia Li Song is an engineer in Intel. Chia Li joined Intel in year 2004 as an ESD engineer, with focus on manufacturing ESD control. In year 2006, she started to involve in Theory of Inventive Problem Solving (TRIZ) program. She has published articles in internal and external conferences which include IEEE National Symposium on Microelectronics (NSM), TRIZ Summit in Intel.