MICHAEL PALOIAN, INTEGRATED DESIGN SYSTEMS, INC.

This article is written to highlight the numerous considerations, diverse body of knowledge and creative skills required to develop a successful product. It is based on more than 35 years of personal experiences working with many companies as well as individuals in many product markets. Hopefully it will provide the reader with a greater appreciation of what is required to design a product ranging from the deceivingly simple to the very complex. It is interesting to note that product design isn’t offered as a major in any college or university. Although MIT offers courses in product design and many colleges offer majors in industrial design or engineering, I am not aware of any higher educational institution offering product design as a major. The reasons for this are due to the vast diversity and complexity of products on the market today. Knowledge and skills required to design a commercial jet are very different from those required to design a rotationally molded tank making it virtually impossible for any one individual to amass all the required knowledge to properly design this range of products. However, product design can be segmented into groups based on market commonality and expertise. Examples of this segmentation might include markets such as medical products, floor care products, industrial machinery or toys. Examples of this segmentation might include markets such as medical and floor care products, industrial machinery or toys. Expertise might include electrical engineering, optics, mechanical engineering or plastics design engineering. Since most mass produced products include one or more plastics components, designing with some knowledge of plastics materials and processing has become an essential part of product design skills. This article will focus on those skills specifically associated with rotational molding.

Since the early 1960’s when rotational molding became a viably commercial plastics manufacturing process, thousands of new applications have emerged in diverse markets every year. Although the process’s original application for water tanks still represents a significant portion of the overall market in the US and most of the world, countless new innovative applications are introduced each year in a broad range of markets. These new markets have benefited from the process because designers have applied imagination, engineering know how and creativity to cost effectively develop successful new applications. A well-designed rotationally molded product does not occur by accident or by chance. It requires a thoughtfully-planned program to develop a concept into a viable physical product to comply with the market requirements of price, performance, reliability, safety, appearance and consistent quality. Desirable products, which outsell others in the same market do so because they offer more value to the customers. Value is defined as product features at the selling price. Features may include brand name, performance, appearance, reliability or safety. The remainder of this article will discuss these and other factors that should be considered as part of the product design at every stage of development.

It All Begins with an Idea

Products always originate from ideas, which can be conceived by virtually anyone. Good product ideas are typically based on a market need or a clever marketing plan to create a need. Market demand can be influenced by lower cost as well as unique benefits offered by a fresh product design alternative. Examples of product success stories in the rotational molding industry that have literally caused a paradigm shift in their respective markets include water tanks, kayaks, garbage containers, playground equipment and children’s toys. These markets have grown so large in the past 30 years that many in the industry have forgotten that water tanks were once fabricated from steel or wood, kayaks were made of wood/ canvas, garbage cans were heavy steel cylinders that always dented and playgrounds were once limited to austere galvanized steel pipe swing sets and slides. Imaginative application of rotationally molded plastics literally transformed these markets by substituting traditional forms with new shapes, colors and uses. These transformations spurred market growth, expanded product line offerings and improved performance as well as safety. Products such as these realized growth because the applications, designs, cost, performance and features were far more attractive to customers than those offered by previous offerings.

The Design Process: Transforming Ideas into Reality

Phase 1: Product Specifications
The most important and critical phase of product design is documenting specifications, which define all essential product requirements. Specifications can vary from an abbreviated list of overall requirements to a very detailed multi-page document detailing everything from physical and performance characteristics to manufacturing, cost, safety and user parameters. Additional factors pertaining to long term performance must also account for environment considerations such as operational temperature limitations, creep resistance, chemical exposure, ESCR (environmental stress cracking resistance), UV, oxidation and fatigue. These long term considerations are difficult to predict and often require prescribed testing guidelines for reliable long term performance data. Designers must have an awareness of material behavior as well as the application to define appropriate tests which closely emulate the product’s eventual use.

Although polyethylene accounts for more than 90% to 95% of all rotationally molded products, material specification is critical to performance, requiring designers to identify specific grades. In certain applications such as underground septic tanks or above ground water tanks, government standards require products to comply with specific performance standards. In such cases designers must verify that products perform in accordance with these standards utilizing structural simulation software such as finite element analysis. In addition to detailing functional requirements, product specifications might also include appearance standards, ergonomic requirements, color standards and graphics which will have a direct influence on market acceptance.

Phase 2: Research and Concept Development
Although most product development projects don’t strictly follow a linear path from phase 1 to phase 2 to phase 3, etc., most development steps are required to be completed before the following phase is initiated. The scheduling of this process depends on the product and management’s set of priorities. Traditionally, some information gathering or research is conducted after specifications have been accepted by the development team. In most instances concepts are concurrently developed and evaluated during this phase which provides a foundation of for the overall design direction. Concepts can be developed in numerous ways ranging from brainstorming sessions to simple sketches or more simple models to test ideas. Instances when product appearance is a top priority, designers focus their attention on aesthetics and image. Numerous concepts are typically developed exploring overall shapes, proportions and details that will influence customer perception, branding and ultimately the sale. In other circumstances, products require exploratory testing based on a concept. Models are typically constructed based on one or more concepts and evaluated under various conditions to determine an optimal design direction.

Phase 3: Concept Refinement
After concepts are developed and evaluated one is selected for further development with an emphasis on specific details pertaining to aesthetic, functional and manufacturing related parameters. The second phase of design refinement is conducted with the aid of CAD to accurately arrange components within an assembly, define individual parts and refine cosmetic details representing the overall product look. Since all products are developed with a team of individuals, good communication is an essential responsibility for the designer. He or she may be required to prepare photorealistic renderings of the product during this phase for approval of the overall look. The level of realism may vary depending on the product. Consumer products may require multiple detailed views illustrating surface colors, finishes, details of control panels, colors and embossed logos.

The skill set required for professionally executing these refinements require the expertise of industrial designers with specialized skills in art and technology. Industrial designers bridge the gap between engineering and marketing, finalizing design details with appearance and ergonomics as their primary focus. These features often conflict with technical requirements expected by molders and engineers who are ultimately responsible for manufacturing the product. This second phase of product development is never finalized until the product has been completely designed. Concepts are continually refined in an iterative process as the design undergoes a series of evolutionary stages of development in subsequent phases.

Aesthetic details are directly interrelated to practical considerations essential for product success. These include performance, material selection, tooling, molding, tolerances and cost. Industrial designers with a basic knowledge of the rotational molding process will have a much higher chance of realizing their concept in production with minimal compromises versus those with little to no knowledge. Close communication with good molders and tool makers will assure the development team that design objectives will be cost effectively attained.

Phase 4: Production Design and Engineering Details
Detailing design concepts into a set of plans that will ultimately result in a high quality product that faithfully represents the design intent is the most challenging and difficult phase of design development. Ironically this phase of design is the least appreciated and understood phase of development by nontechnical business owners. Design engineers are passively appreciated for doing their job if the product is launched into production without any complications or seriously held accountable if there are problems. Problems often arise from careless omissions, assumptions or mistakes usually stemming from ignorance or naivety. Design engineers responsible for detailing a production design must continually be vigilant about virtually any possible problem that could arise. This daunting responsibility becomes less risky as one gains experience, knowledge and most importantly the insight to pose questions to experts with the best answers. The final design of a rotationally molded product is exclusively dictated by the designer and his or her ability to manage the decisions directing the end result. A respected designer must obviously have a comprehensive knowledge of the process, tooling methods, materials and application as fundamental skills. However, this body of knowledge only represents a portion of the qualifications necessary to successfully design a product. Most design engineers can gain a basic understanding of design guidelines associated with rotational molding by attending design seminars offered by rotational molding trade associations or by reading excellent books such as Glenn Beall’s Rotational Molding Design book, offered by the SPE. Qualities, which distinguish the novice designer from an expert, reside in the subtleties pertaining to the designer’s ability to creatively integrate these parameters with the product requirements. Designers are normally confirmed with a continuous set of conflicting challenges, which must be optimized at every step of development. The proficiency with which these decisions are made depends on the individual personal and professional characteristics of the designer as well as his ability to creatively resolve these issues. Great designers typically don’t take the easiest path compromising critical design objectives. They also don’t stubbornly adhere to unrealistic expectations that will ultimately introduce unnecessary difficulties in manufacturing. Great designers contain their egos encouraging others to contribute invaluable insight and expertise which is intelligently modified to comply with overall design objectives.

The extent of designer’s experience pertaining to a specific application may vary according to the product and market. Mature markets such as kayaks, tanks, toys and playground systems would require a more specialized insight than a unique rotationally molded application. Kayaks for example have evolved into a wide range of styles. Manufacturers have developed a wide range of body types, seating, hardware and options which have enabled them to brand their products and successfully distinguish themselves from competitors. Engineering parameters associated with body weight, buoyancy, fluid dynamics and maneuverability must be considered as well as market appeal associated with ergonomics associated with seat comfort, safety and styling. Water tanks which constitute the majority of rotationally molded products are often designed and produced with little to no design consideration. Ironically, well designed tanks are crucial for many reasons including reliability, reputation, safety and most importantly sales. A well-designed tank could provide a manufacturer with a competitive advantage if the tank warrantied for an extended period of time, easier to install, more attractive or molded with less material. Such products would command a higher price or offer a significant benefit to the consumer.

Production Documentation

Nowadays the information displayed on production drawings are limited to critical dimensions with specified tolerances, material specifications, special notes, textures and other information which documents the manufacture’s expectations.

At one time not too long ago production drawings were required to include all geometric details illustrating every feature of the part as well as all dimensions. These drawings were used to machine molds as well as establish production quality standards. Today the majority of products are designed with the aid of 3D CAD, which are used by mold makers to machine patterns or molds with CNC machinery. This direct transfer of information from the designer to mold maker eliminates potential errors resulting from interpretation by human intervention. It also places a greater responsibility on the designer to include geometric details affected by parting lines, draft angles and all other mold design related issues in CAD geometries. Production drawings should be treated as part of a contract between molders, tool makers and their customer, the OEM. A complete drawing package will include assembly drawings and a bill of materials. Depending on the product and its requirements, production drawings can provide very basic information or specific details related to quality, appearance standards and geometric tolerances stipulating perpendicularity, concentricity, flatness, etc. A well designed product always includes a comprehensive set of production drawings which are often revised throughout the life of the product.

Production Liaison

The last and final stage of product development is experienced at that momentous occasion when first article samples are molded and assembled. A conscientious and experienced designer will either be at the site to witness first articles being molded and assembled or will participate in the evaluation of the production samples. Although it’s rare to experience first articles assembling together perfectly, these moments do occasionally happen bringing joy of all those involved in the development. More frequently, first article production samples require some level of problem solving intervention by the molder and designer. If parts are designed to properly fit together, problems usually originate from a tooling problem or error, production related issue or material problem. Experienced designers will refrain from making hasty decisions requiring mold or design changes before carefully analyzing the problems. A designer’s understanding of part inter-relationships and potential tolerance stack-ups can be very helpful in assessing problems with minimal cost or lost time. Diagnosing originating causes of problems associated with rotationally molded plastic parts can be very difficult. Subtle warps on a surface or non-uniform shrinkage can be difficult to detect by a molder, mold maker or designer. If the root cause of these problems is not properly identified, costly time consuming tooling revisions can be made which will further exasperate the problem. An experienced designer will methodically examine part interrelationships, comparing geometry and dimensions to the CAD files and pinpointing the exact source of the problem before making any serious tooling revisions.

Hopefully this article has clearly articulated the role of the product designer and critical decisions he or she must face throughout a product development project. Although every project is unique, the basic skills and process of developing a design remains fairly consistent. Respected designers typically share a common set of traits which include creativity, intelligence, insight, excellent listening skills, effective managerial skills and leadership. A combination of artistic and engineering abilities provides specially gifted designers with fluidity in their thought process to see the big picture as well as the minutest technical details associated with any product. These rare qualities provide a limited number of designers with an ability to quickly identify the critical factors defining the success or failure of a product. Hopefully next time you see a product that catches your eye you will appreciate the tremendous effort that went into developing it.

Michael Paloian is President of Integrated Design Systems, Inc., Great Neck, New York and Design Editor for RotoWorld^® magazine. Over the past 25 years, Mike has developed a broad range of plastic products utilizing various processing methods including rotational molding. Mike’s B.S. degree in Plastics Engineering and Masters in Industrial Design, combined with his extensive experience, has formed the bases for his branded and unique insights into the field of plastics part design.