December 2009

December Meeting

Invention on Demand:
Managing Innovation with TRIZ

Innovation is driven by the need to break out of a current paradigm and perform at superior levels. Achieving breakthrough performance is difficult because it is blocked by systemic contradictions that anchor you to the current paradigm. TRIZ (Russian acronym for Theory of Inventive Problem Solving) is a systematic approach to identifying these underlying systemic contradictions and then leveraging existing resources and subject matter expertise to create innovations and new performance paradigms. This presentation will cover the basics of TRIZ and provide concepts that can be quickly and easily used to improve personal creativity. Several polymer and chemical industry examples will be included.

Speaker: Peter Hanik is the founder and President of Pretium Innovation, LLC, a firm providing assistance to clients to generate sustainable economic value through structured innovation methods. Prior to founding Pretium, Mr. Hanik was Senior Vice President of Technology at Millennium Chemicals, President and CEO of Millennium Petrochemicals, Vice President Chemicals & Supply Chain at Quantum Chemical, Vice President Reengineering and Information Systems at Quantum Chemical, Director Applied Research & Technical Service at Quantum Chemical, Regional Sales Manager at Northern Petrochemical, Engineering Manager at Northern Petrochemical and Production Superintendent at Northern Petrochemical. Mr. Hanik holds a B.S. degree in Chemical Engineering from Illinois Institute of Technology and an MBA from the University of Chicago. Mr. Hanik is a registered professional engineer.

President’s Message

Dear Friends!

December is upon us and 2009 will soon be memory. I polled our office to get 10 things we will remember about 2009.

1. Pres. Obama – No shortage of hope and change
2. The economy – Too big to fail so let’s bail them out. General Motors / Government Motors
3. The Astros sum up the season by firing their manager Cecil Cooper
4. Mexican Flu, Swine Flu…no H1N1 – H1N1 won’t offend anyone
5. Gov. Perry threatens Texas secession
6. Michael Jackson – Pop cultures greatest…This is it
7. Cash for clunkers – Said goodbye to my Cordova with rich Corinthian leather
8. Global Warming – It certainly was the longest and hottest summer I can remember
9. Twitter – Does anyone really care what I am doing right now?
10. Don Witenhafer – One of our own is inducted in the Plastics Hall of Fame!

Congratulations Don, for being a high point we can remember and celebrate for 2009!

For those that did not get to attend our November Technical program, we joined with the AICHE to host Victrex in a technical presentation regarding PEEK in the oilfield. This was an excellent program that was very well attended by both organizations and will lead to other joint programs and profitable collaboration for both organizations.

Our Polyolefins committee has been actively meeting and preparing for our conference in February 2010 and promises to have a great topical line up of innovative technical presentations. We are doing very well signing up exhibitors and look for a strong conference for 2010.

If you have not been active in the South Texas section of the SPE, please consider coming to one of our monthly social breakfast or lunch meetings or contact any of the board members about participating in one of the committees. There are many opportunities to get involved, meet others in the industry, support education and learn something new. More information can be found at our website.

The mission of the SPE is to promote scientific and engineering knowledge relating to plastics. In addition to our professional technical programs, we continue our commitment to support local SPE student chapters, scholarships and grants at 10 colleges and Universities in our region.

As we say good bye to 2009, we can look forward to continued stabilization in our economy and healing for our companies. Those that have survived the recent adversity are stronger, wiser, and better positioned to profit from future opportunities. On behalf of all of the directors and chairpersons, we look forward to serving you in a way that will grow our businesses, expand our technical knowledge and our relationships.

Many blessings to you and your family in 2010!

Jeff Applegate
SPE South Texas President 2009-2010

Polyolefins Conference and FlexPackCon – Mark your calendars!

The 2010 International Polyolefins Conference and FlexPackCon will be held at the Hilton Houston North (formerly known as the Wyndham), Feb 22-24, 2010. 

This year’s program will again include both the traditional Polyolefins focus as well as the Flexible Packaging program. One of the themes for FlexPackCon will be sustainability and will include talks by Chet Rutledge, Director of Packaging Procurement,WalMart; Larry Dull, Partner, Packing Knowledge Group (PKG) LLC; and Victor A. Bell, President, Environmental Packaging International. They will discuss the WalMart scorecard and it’s extensions, how to used the scorecard to evaluate new opportunities, and packaging Life Cycle Analysis. FlexPackCon will also provide updates on food law (e.g. FDA) and potential regulatory expansions.

If you know of particular developments which should be presented at the conference, please contact Robert Portnoy for Polyolefins rportnoy@portnoytechnicalservices.com) or Andy Christie (andy@optexprocesssolutions.com) for FlexPackCon.  If you’d like to sponsor a coffee break or exhibit, please contact Emery Jorgenson (emery@jorgensonmachinery.com).

We look forward to seeing you at the conference!

http://www.linkedin.com/groups?gid=2073302&trk=hb_side_g

Join the South Texas Section of the Society of Plastics Engineers on Linked-In. Click on the above link and you will be directed to group page. Linked-In will serve as another communication tool for SPE-STX.

Linked-In  is a free web site for professional networking with over 40 million members as of May 2009.

Linked-In enables discussions and networking between SPE-STX members and those related to the plastics industry. Linked-In compliments the current SPE-STX web and membership to Linked-In is free. 

News Highlight
Linked-In SPE-STX group currently has 116 member as of 1 October. To date, the tool has been used primarily to promotes and discuss SPE-STX meetings. 

Members are also notified of meetings from board members plus email blasts sent by SPE International.  

As always, both the monthly newsletter and STPE-STX web site are the leading source of information on SPE-STX activities.  

Bulletin Board

Plastics Information: Check it Out

The Houston Public Library on McKinney has resources on plastics and polymers. Check out their catalog at www.hpl.lib.tx.us. If you are not near the McKinney location, you can arrange to pick up your books at your local branch.

The Fondren Library at Rice University has the most complete collection of books on plastics and polymers. This is also a prime resource for patent and trademark information, as well as other US Government documents. You cannot check out books there unless you join Fondren Library [$50], but you can arrange for books to be sent to your library by inter-library loan. Use their catalog at http://library.rice.edu/.

The next best place to browse is at the MD Anderson Library at the University of Houston central campus. South Texas Section has donated many plastics books to this library. If you plan ahead, you can get a TexShare library card from a library where you are a member, which will allow you to check out books from any U of H library. Their catalog is at www.library.uh.edu/.

Thank You Letters

Book Bag

	Additives for Polyolefins Michael Tolinski, 304 pages, Jul-2009 ISBN-13: 978-0-8155-2051-1 $150.00 This book focuses on the polyolefin additives that are currently important in the plastics industry, alongside new additives of increasing interest, such as nanofillers and environmentally sustainable materials. As much as possible, each chapter emphasizes the performance of the additives in the polymer, and the value each relevant additive brings to polypropylene or polyethylene. Where possible, similar additives are compared by capability and relative cost. With major sections for each additive function, this book provides a highly practical guide for engineers and scientists creating and using polyolefin compounds, who will find in this book a wealth of detail and practical guidance. This unique resource will enable them to make practical decisions about the use of the various additives, fillers, and reinforcements specific to this family of materials. Contents: SECTION I: OVERVIEW OF POLYOLEFINS AND ADDITIVES 1 Introduction 2 Trends in polyolefin & additive use SECTION II: ENVIRONMENTAL RESISTANCE 3 Antioxidants and heat stabilization 4 Ultraviolet light protection & stabilization 5 Flame-retarding additives 6 Additives for modifying electrical properties SECTION III: MECHANICAL PROPERTY ENHANCEMENT 7 Overview of fillers & fibers 8 Factors determining selection of fillers and fibers SECTION IV: APPEARANCE ENHANCEMENT 9 Colorants 10 Nucleation and clarity SECTION V: PROCESSING AIDS 11 Processing aids for molding 12 Processing aids for extrusion SECTION VI: OTHER MODIFICATIONS OF FORM AND FUNCTION 13 Reducing density: Polyolefin foams 14 Coupling, compatibilizing, recycling, and biodegradability 15 Cross-linking 16 Sterilization & radiation resistance 17 Aesthetics enhancement and surface modification SECTION VII: CONCLUSION: INCORPORATING ADDITIVES 18 Adding Additives to resin References Index
	Flame Retardants for Plastics and Textiles: Practical Applications Edward D. Weil, Sergei V. Levchik, 2009 ISBN: 9781569904541 $100.00 An overview of flame retardants that are either in commercial use or in advanced stages of market development, reviewed polymer-by-polymer, supplemented by a brief overview of mode of action and interaction. It is more of a “how-to-do-it” book than an academic study. As such, it names trademarked materials as well as products in active stages of development, gives suggestions for selecting among alternatives, provides suggested formulations, and offers a starting point for the compounder or plastics fabricator to pass commercial flammability requirements. Contents: Flame Retardants in Commercial Use or Development for Polyolefins Polystyrenes and Thermoplastic Styrene Copolymers Flame and Smoke Retardants in Vinyl Chloride Polymers – Commerical Usage and Current Developments Current Practice and Recent Commercial Developments in Flame Retardancy of Polyamides Flame Retardants for Thermoplastic Polyesters Flame Retardants in Polycarbonates and Polycarbonate Blends Commercial Flame Retardancy of Unsaturated Polyesters, Vinyl Resins, Phenolics and their Composites Flame Retardants in Commercial Use or Advanced Development in Polyurethanes Current Flame Retardant Systems for Epoxy Resins Flame Retardants in Commercial Use or Development for Textiles Comments on Flammability and Smoke Tests Overview of Modes of Action and Interaction of Flame Retardants Directory of Flame Retardant Manufacturers, Distributors, and Compounders
	Plastics Manufacturing Systems Engineering: A Practical Approach David O. Kazmer, 2009 ISBN: 9781569904626 $100.00 Plastics manufacturing is a highly interdisciplinary endeavor requiring knowledge related to materials science, physics, engineering, and management. Because of this diversity, the plastics process engineer interacts with many stakeholders, including customers, designers, materials suppliers, machine builders, mold/die suppliers, systems integrators, operators, quality engineers, and managers. With so many stakeholders involved, it isn’t surprising that many plastics manufacturing processes are not precisely engineered systems. The resulting processes can be poorly designed, requiring too much investment to achieve too little productivity. This book was written to educate and support plastics processing engineers, but is also highly useful to others involved with plastics manufacturing who are performing process development, research, and even machinery design. It uses a manufacturing systems engineering approach to provide guidance about plastics manufacturing as an integrated system with broadly applicable analysis of the underlying subsystems. Contents: Background, Plastics Manufacturing Systems, Heating and Cooling, Hydraulics and Pneumatics, Electric Drives, Process Sensors, Signal Conditioning, Data Acquisition Systems, Machine Controllers, Process Control, Process Characterization, Process Optimization, Quality Control, Automation, Statistical Labor Data, Material Properties, Unit Conversions, Matlab Primer
	Lawsuit!: Reducing the Risk of Product Liability for Manufacturers Randall L. Goodden, 2009, 359 pages ISBN: 9780470177976 $80.00 Reduce your exposure to civil lawsuits. Addressing product liability and laws in both the U.S. and internationally, this book helps product manufacturers and engineers develop and implement proactive processes that can reduce liability concerns and potential lawsuits. It discusses preventive measures in the engineering, development, and manufacturing of products and explains the procedures and processes manufacturers must have in place to reduce the likelihood of liability – as well as to provide the best defense in case of a lawsuit.
	Qualifications, Startups and Tryouts of Injection Molds W. J. Tobin, 2003, All inclusive CD $32.00 The truth is you don’t need fancy gizmos to do scientific molding. All you need is a machine where you can read the settings, an accurate weigh scale, and a computer. A universal setup guide only needs a little homework on your part to read each machine’s manual and the ability to read the settings. If you had a few days and an engineering textbook you could actually write these spreadsheets yourself! It is NOT MAGIC. This CD uses a practical, down to earth, easy to use approach to bringing a mold on-line and producing consistently good parts. CD contains both filled in tutorials showing what inputs are required and worksheets for you to fill in. CD Contents: Contents of the 90 page book. Spreadsheets in Microsoft Excel .xls files: Optimum fill calculation – the melt viscosity curve, Gate Freeze off, Cooling time, Cavity balance for multi cavity tools, Cp CpK calculator, Universal setup sheet – includes how to translate from one machine to another, a waterline map, Runner size optimization, and a calculator to determine your process window settings. Microsoft Word .doc Files: Mold Check List, Mold History / Maintenance forms. The text includes a complete explanation of the experiments to optimize your injection molding cycle. Other Topics are: Mold Maintenance – Inspection and General Maintenance, Mold hang and Mold Pull procedures, Mold Storage, Basic Chemistry, Quality Control/ Quality Assurance – Cp and CpK explained and how to use them, Sizing Sprues, Nozzles and Runners for your mold, Hard Copy of the Mold Check List, Mold History and a Data Form to fill out for the experiments, and how to calculate a process window that will allow you to adjust the process as it drifts and still make acceptable parts.
	Plastic Conversion Processes: A Concise and Applied Guide Eric Cybulski, 2009; 165 pages $70.00 Many books describe a single plastic-conversion process, like injection molding, but until now, none has described and compared several processes. This book provides a basic overview of seven conversion processes used in the industry. These processes account for more than 97% of all plastic products. Each chapter begins with a process attribute table to serve as a quick guide. The particular conversion process is then briefly described, along with a short history. To better explain each process, sections detailing equipment, tooling, and materials have been added. Also included are sections on design guidelines and on how to identify which process was used to manufacture a plastic part. Contents: Injection Molding Plastic Extrusion Blow Molding Thermoforming Reaction Injection Molding Rotational Molding Compression Molding
	Mixing and Compounding of Polymers: Theory and Practice, 2nd Edition Ica Manas-Zloczower, 2009; 850 pages ISBN: 978-1-56990-424-4 $249.00 Finally available in its second edition, this classic monograph covers everything from the basic principles to the various practical applications of state-of-the-art mixing and compounding. It discusses the basic mixing mechanisms encountered in polymer processing; the latest results in modeling, flow simulation and visualization, and scale-up rules for the most important batch and continuous mixers; the properties of various additives used in the plastics and rubber industry and their effects on the properties of the compound; working principles and practices for reactive polymer compounding; compatibilization mechanisms applicable to blends and composites; mixing practices in the current commercial mixing devices; key aspects of mixing at nanoscale; and scale-down of mixing equipment and fundamentals of microfluidics. Contents: Part I: Mechanisms and Theory Basic Concepts - Mixing of Miscible Fluids - Mixing of Immiscible Fluids - Dispersive Mixing of Solid Additives - Distributive Mixing - Distribution Functions and Measures of Mixing Part II: Mixing Equipment - Modeling, Simulation, Visualization Batch Equipment Simulation - Batch Equipment Visualization - Continuous Equipment Simulation - Dispersive Mixing Devices in Single Screw - Twin Rotor Mixers - Co-Kneader - Visualization - Scale-up of Mixing Equipment - Scale-down of Mixing Equipment Part III: Material Consideration, Properties and Characterization Solid additives (inorganic) - Solid additives (organic) - Compatibilizers (mechanisms, theory) - Material Consideration for Mixing at Nanoscale - Effect of Mixing on Properties of Compounds - Effect of Mixing on Rubber Properties Part IV: Mixing Practices Internal Mixers - Single Screw Extruders - Twin Screw Extruders - Intermeshing Twin Screw Extruders - Reciprocating Screws - Reactive Compounding - Farrel Continuous Mixer
	Injection Molding: Fundamentals and Applications Musa R. Kamal, Avram I. Isayev, S. Liu, 2009; 800 pages ISBN: 978-1-56990-434-3   $249.00 This book surveys the state of the science and technology of the injection molding process. It represents a comprehensive, balanced mix of practical and theoretical aspects for a wide range of injection molding applications. The authors of the 21 chapters are experts and leaders in their respective areas of specialization in the injection molding field. While it is not possible to cover all aspects of such a dynamic growing field, readers should find sufficient information and background to become acquainted, at various levels of depth, with key components of the science and technology of injection molding. Contents: Injection Molding: Introduction and General Background Injection Molding Machines, Tools, and Processes The Plasticating System for Injection Molding Machines Non-Conventional Injection Molds Gas Assisted Injection Molding Water Injection Techniques (WIT) Flow Induced Fiber Micro-Structure in Injection Molding of Fiber Reinforced Materials Injection Foam Molding Powder Metal Injection Molding Micro Injection Molding Internal Visualization of Mold Cavity and Heating Cylinder Injection Molding Control Optimal Design for Injection Molding Development of Injection Molding Simulation Three-Dimensional Injection Molding Simulation Viscoelastic Instabilities in Injection Molding Evolution of Structural Hierarchy in Injection Molded Semicrystalline Polymers Modeling Aspects of Post-Filling Steps in Injection Molding Volumetric and Anisotropic Shrinkage in Injection Moldings of Thermoplastics Three-Dimensional Simulation of Gas-Assisted and Co-Injection Molding Processes Co-Injection Molding of Polymers
	ANTEC™@NPE 2009 Conference Proceedings - Thumb Drive SPE, Chicago, Illinois USA, June 2009, Thumb Drive $250.00 In Chicago in 2009, ANTEC® (Annual Technical Conference), sponsored by the Society of Plastics Engineers, celebrated its 67th year of excellence. The largest peer-reviewed technical conference serving the plastics industry, ANTEC® is perfectly positioned to help the plastics specialist achieve new levels of professional development. Order the ANTEC® 2009 proceedings on thumb drive or CD-ROM. Includes 700+ papers detailing the latest developments in: Alloys and Blends, Applied Rheology, Automotive, Biopolymers, Blow Molding, Color and Appearance, Composites, Decorating and Assembly, Electrical and Electronic, Engineering Properties and Structure, Extrusion, Failure Analysis and Prevention, Flexible Packaging, Injection Molding, Joining of Plastics and Composites, Marketing and Management, Medical Plastics, Mold Making and Mold Design, Nano/Micro Molding, Plastic Pipe & Fittings, Plastics in Building and Construction, Plastics Environmental, Polymer Analysis, Polymer Modifiers and Additives, Process Monitoring and Control, Product Design and Development, Radiation Processing of Polymers, Rotational Molding, Thermoforming, Thermoplastic Elastomers, Thermoplastic Materials and Foams, Thermoset, and Vinyl Plastics.
	Injection Molding - Thumb Drive SPE, Chicago, Illinois USA, June 2009, Thumb Drive $50.00 Injection Molding Titles Include: Optimizing the Molding Process — Chapter from Plastics Technician’s TOOLBOX, by Jerry Golmanavich, Golmanavich Enterprises Shear Induced Imbalances and MeltFlipper® Technology, by John P. Beaumont, Penn State Erie & Beaumont Technologies, Inc. The Warpage Simulation with In-mold Constraint Effect in Injection Molding, by Dr. Venny Yang, CoreTech System Co., Ltd. The Investigation of Flow Behavior of Polymeric Melts in Water Assisted Injection Molding, by Dr. Chao-Tsai Huang, CoreTech System Co., Ltd. Injection Molding of Woodfiber Plastics Composites, by Michael Burgoyne State of the Art of Electric injection Molding, by M. Barr Klaus, Electric Injection Services, Inc. Mold Ejector Pin Melt Flow Volume Sensor, by Fred Buja, FjB PlasTechnology Water up to 400°F – The Best Way To Heat up Your Mold, by Anna Birkhofer, consultant Asia Tooling and Molding: How To Be Successful, D.B. "Dusty" Rhodes, Waypoint Bellwether, Inc. It Is as Easy To Be an Injection Molding Compounder as It Is To Be an Injection Molder, by Peter Lipp, Krauss-Maffei Corporation Effect of Injection Molding Process Parameters on the Morphology and Quality of Microcellular Foams, by Jingyi Xu Microcellular Injection Molding of Polylactide-Montmorillonite Nanocomposites, by Sarah Gong, Assistant Professor, University of Wisconsin-Milwaukee

SPE-STX Board Meeting

Location: Spaghetti Warehouse, downtown Houston
Date: November 2, 2009

Improvement of Mold Design: A New Method Based on Contradictions

Thomas ELTZER, corresponding author, eltzer@yahoo.fr
Denis CAVALLUCCI, Emmanuel CAILLAUD
LICIA INSA Strasbourg, 24 Boulevard de la Victoire, 67084 Strasbourg Cedex – France
Philippe LUTZ, LAB, 24 rue Alain Savary, 25000 Besançon - France

Abstract

Designing injection molds is of a critical issue in injection processing. In order to improve its design, we propose to focus on technical problems. We built and tested a design procedure based on technical problems mold design has to cope with. Using this procedure, design process duration is reduced; the mold cost and part quality might be improved.

Introduction

Injection molding is a widely applied process to manufacture plastic parts. Because of its influence on at least product quality and cost, the mold design is a key success factor. When the part is difficult to mold, the mold designer has two options: either to propose modifications of the part, or to develop the mold with the given part design. In the latter case, rapidly obtaining a mold both efficient and cheap is difficult. In this paper, we develop a new design procedure, contributing to the improvement of those situations.

The first section of this paper states the research problem we want to solve. The second describes the steps used to build our proposed answer. The third one details the results obtained while developing a case study to validate our contribution.

Problem statement

Ideally, the mold design process should be fast (to answer as early as possible the customer demand), should propose a mold which is very cheap, robust and ensuring a high production rate, but still ensures a perfect quality for any part (whatever its complexity). We believe that this ideal design process is not yet reachable partially because of the lack of powerful design procedures at early development stages. On the one hand, design has to overcome current technological barriers, as fast as possible, requiring the development of what we have named “innovative” solutions. But on the other hand, robust and optimized solutions, which we name “standard”, can be very efficient to implement.

Therefore, the research problem statement is: “What systematic design procedure, coherent with standard and innovative approaches, should be followed when designing injection mold?”.

In this paper, we propose a new design procedure to go in the direction of this ideal design process. The procedure focuses on technical problems representations to look for standard or innovative solutions.

Research steps

This second section presents the research methodology we use to solve the stated research problem. First we build the procedure, second we gather design knowledge and build the technical problems of injection molding, and third we test the procedure on real projects.

Build the procedure
The first step is to build the design procedure. Using knowledge about design theory, see [1, 2], we propose a procedure able to both reuse standard solutions and develop innovative ones. The procedure focuses on technical problems because:

• it brings clear criteria to evaluate proposed solutions, (innovative or standard);
• innovation requires technical problem solving;
• the key task of technical problem solving is problem identifying.

The procedure is made of seven steps, see Figure 3. (1) According to part design, and known technical problems, designers imagine a rough mold design, using standard solutions. (2) Using again known technical problems, designers evaluate the design and formulate the specific technical problems step by step, using the typology proposed in the next paragraph. (3) Then, designers evaluate whether the situation requires innovative solutions or not. (4) If the situation is seen as innovative, designers sharpen the problem definition using cause effect relationships in the set of problems formulated in (2). (5) Innovative solving tools and methods are then used by the designer to develop an innovative solution. (6) If the situation is seen as not innovative (standard), designers apply standard solutions. (7) Finally, designers evaluate the new mold design, according to known technical problems: the new version is either rejected and a new problem has to be formulated or accepted and the mold design goes ahead. The new problem can be a consequence of the applied solution, or a problem not yet solved.

Build the known technical problems network
The second step of our research is to build the problem network describing technical knowledge for injection mold design. Technical problems are shaped using TRIZ contradiction pattern, [3-5] because:

• • corresponding solving tools, to be used in step (5), are precise: Principles for physical and technical contradictions, ARIZ, Inventive standards;
• • TRIZ is the most systematic approach to technical innovation.

For example, one of the technical problems detailed in [6] is formulated with the contradiction pattern (see Figure 1): parameter X (runner length)of the element (mold) should be X1 (short) in order to improve parameter Y (wastes) but should also be X2 (long) in order to improve parameter Z (molded in stress). Parameters Y and Z are against each other. Parameter X cannot be adjusted for the two conflicting requirements.

Three types of parameters, see Figure 2, are then proposed to represent in mold design knowledge gathered as a problem network, [5]. Parameters (1) describe what the mold is (parameters of which designers choose values (a)). Their values represent how mold functions are achieved. The other parameters are used to evaluate (2) the mold and (3) the part (designers evaluate their value and compare it to the requested one (c)). Part design influences values of parameters (3). The arrow (b) illustrates the cause effect relationships between choices and evaluation. This cause effect relationship is studied in material, mechanical, or material flow sciences.

On the basis of this problem network representation, a double typology is built, representing any specific problem of mold design, Figure 4. The first typology is linked to the nature of the conflicting requirements, the second to the function that cannot be adjusted.

The first typology is A, B and C-type. We give an example of each of them, Figure 5:

• A-type exists between parameters (1) and parameter (2). For example, according to [7]: (1) ejector number of mold should be low in order to improve (2) ease of construction of mold, but should also be high in order to improve (2) ejector deformation. In this case, we can say that the a mold requirement is against another mold requirement;
• B-type relates to (1) and (3). For example, according to [8]: (1) gate location of mold should be on thick zone in order to improve (3) packing but should also be on thin zone in order to improve (3) jetting. Here, a part requirement is against another part requirement.
• C-type is based on (1), (2) and (3). For example, according to [9]: (1) cooling line depth of mold should be high in order to improve (3) warpage but should also be low in order to improve (2) cycle time. In this last case, part is against mold.

The second typology is based on mold functions: parameters of type (1) are grouped according to the functions of the mold they fulfill. We propose first a very simple set of functions: Conduct material flow, Shape the material, Eject the part, Cool the material. A third typology could be built by decomposing types (2) and type (3) parameters. This is relevant to coming research.

This double typology groups all the mold design problems found in the literature and in mold design practice. Listing the complete set for each of the twelve types shown in Figure 4 is not necessary in this paper. Each type of problem has its own type of solution. Standard technical solutions are stored according to the type of problem they solve. For the examples of Figure 5:

• an internal runner can solve the B-type conflict about gate location (an internal runner, [8], is a rib that connects the gate to the thick section);
• an ejector plate (stripper plate) can solve the A-type conflict about ejector number.

According to this double typology of mold design technical problems, the step “(2) Formulate the problem”, Figure 3, is decomposed in three sub steps:

• (2.1.): Define the conflicting requirements (mold against mold gives an A-type, part against part a B-type, part against mold a C-type);
• (2.2.): Define what function cannot be adjusted (Conduct, Shape, Eject, Cool);
• (2.3.): Specify the conflict (Choose a specific problem within the type, and adapt its definition).

According to the nature of the link (b), see Figure 2, the step “(4.a) Sharpen the problem formulation” is achieved by decomposing this cause effect link. Even in complex problematic situation, the formulation is converged in a single technical problem that can be solved with TRIZ tools.

Test the procedure
The third step of the research requires testing the use of the procedure on real design projects.

Four projects, Figure 6, are assisted within two injection molding companies. In project (a) and (d), modifying the plastic part is close to impossible, because of the other components of the whole product. Hence, solving technical problems is impossible by part changing, but only possible by correct mold design. In projects (b) and (c) only slight part modifications are allowed. For each project, engineer’s team follows the proposed procedure. Each team consists of at least the mold and part designers. Part designers point of view is very important for any B-type or C-type problems, Figure 4, to evaluate whether the part is satisfying or not. A computer simulation expert participates in project (a) because of precise filling results requirements.

For project (a), a set of problems of different types are formulated in the step (2) of the procedure. As the situation is considered innovative, it is sharpen in the step (4.a), by analysing cause effect between and within each formulated problem. The obtained problem is a B-type, related to the cooling function. Proposed solutions, developed by using TRIZ solving tools in the step (4.b), are under development and might be accepted.

For project (b), the formulated problem is a B-type, related to the conducting function. According to the pattern shown in Figure 2, this technical problem is specified as: (1) Gate location of mold should be X1 in order to improve (3) filling but should also be X2 in order to improve (3) weld line location. X1 and X2 are specific geometric zone of the plastic part. This first problem is solved by applying a standard solution, which generates two new technical problems. They are both C-type problems, related to the shaping function. Another standard solution is applied to solve one of them, and the other is considered by designers as not important.

For project (c), the procedure is followed three times in parallel to solve three different technical problems, each linked to the ejecting function. Each of them is solved by a standard solution, slightly modifying the part:

• A-type: Diameter of ejector pin cannot be adjusted for both (2) ejector bending and (2) ejector breaking;
• B-type: Location of another ejector pin cannot be adjusted for both (3) flash and (3) part deformation;
• C-type: Location of a third ejector pin cannot be adjusted for both (2) ejector breaking and (3) part deformation;

Even more, within this third project, mold designers identify probable part defects. They propose other part modifications, as solving these defects with mold design generates C-type problems difficult to solve.

For project (d), the first rough mold design is criticized because of probable part warpage, linked to gate location. Formulating the problem in step (2) reveals a B-type problem. The standard solution applied and accepted is the gate location change. The problem formulated on the new mold design is then a C-type (packing was not considered as an issue): Gate size of mold should be large in order to improve mold construction, but should also be small in order to improve gate vestige. Two solutions are proposed to mold designers to solve this problem: “dynamic gate” or “magnetic curved pin point gating”.

Finally, a mold is obtained for each project, using the proposed procedure, and satisfying design requirements.

Results

This third section of the paper evaluates how the proposed procedure brings the current mold design process closer to the ideal one described in the research problem statement.

Time of development
Time of development is reduced by using a systematic rather than a more or less chaotic design procedure (for innovative and standard application). Even in complex situations like project (a), innovative direction is identified very soon and precisely, reducing time of research. However, developing an innovative solution requires time for at least testing and optimising, as in projects (a) and (d). Number of loops in the procedure, like in (b) and (d), can be the second source of time.

Cost of mold
Cost of mold can be analyzed as a technical problem, detailed through one of the twelve proposed types, and then solved. Therefore, the procedure provides a systematic way to design cost effective molds. However, for the same part design, it is difficult to confirm that an innovative mold is cheaper than a complex standard one, as seen in projects (a) and (d).

Mold robustness
Projects (b) and (c) bring the conclusion that robustness of standard mold is guaranteed for simple parts by the use of standard solutions known by designers. As this procedure can be used from the beginning till the end of the design process, problems of any level are solved. For innovative design, reliability of the formulated problem is enhanced by the fact that it is obtained using designer’s expertise. However, robustness of innovative solutions, as proposed in projects (a) and (d), is not obvious: they still have to be optimized.

Collaboration
Collaboration, according to project (c), is enhanced by the fact that any designer involved can participate through the problems he foresees. Mold designers have a systematic way to propose part modification: they know exactly what problem can be solved by part modifying (type B and C), and can discuss it with part designer precisely.

Part quality
Part quality is improved by the fact that designers check the mold according to almost any possible technical problems. The proposed procedure assists solutions generation for any stages of the design process. However, we notice through projects (a) and (d) that solving the innovation problem in step (5) depends on the designers. Creative designers will be able to solve technical problems fast and very easily. Less creative will estimate that the problem cannot be solved. Even more, the procedure does not help in predicting problems not yet faced.

Our proposed design procedure has in all cases improved the mold design process. The design procedure uses technical problems represented with TRIZ contradiction pattern. A typology of injection molding technical problems assists designers in formulating their specific problem. On the basis of this formulated problem, either standard solutions are reused or innovative ones are developed. The advantage is the possibility to merge the robustness of optimized solutions and the power of innovative ones.

Therefore, the whole design process is systematized and sped up, using engineer’s knowledge in both standard and innovative directions to ensure part quality. Hence, taking into account the know-how of the company is optimized, as advised by [10]. Collaboration within concurrent engineering is also enhanced.

Therefore, a new way to capitalize results of researches in injection molding is provided (mechanical, thermal, material flow, etc.), as well as a coherent and precise procedure to use them in a collaborative environment, resulting in solutions of any innovative level. This gives new directions for mold design software.

However, human factor (creativity, abilities to work in team, etc.) and strategy of the company (innovation management, relationship with customer) are still poorly taken into account. Even more, the efficiency of the procedure depends on the amount of problems previously capitalized.

The coming researches will have to complete the set of known technical problems and to improve the structure of the problem network. Standard solutions retrieval will also have to be improved.

Acknowledgement

We wish to acknowledge Region Alsace who granted this research. We thank also TRIZ experts Nikolaï Khomenko and Dmitry Kucharavy for their support (http://www.trizminsk.org).

Bibliography

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