Concept Refinement and the Road to Design Perfection

Previously, I’ve written about the importance of developing many concepts before settling on a final product design direction. Developing a concept is a critical step in product design that defines the premise for all subsequent decisions throughout the development process. Design concepts loosely define the project direction.

The specificity of a concept may range from something as vague as a scribbled sketch or cardboard model to a photorealistic industrial design rendering. In any case, concepts always require further, detailed development.

Concept refinement can take any number of paths depending on the project and the designer. Here are some design concept examples and refinement options.

Industrial Design Concept Refinement

Industrial designers create industrial design concepts based on design considerations that are alien to most design engineers and plastics part designers. Industrial designers focus their attention on the user versus the product or part performance. This perspective drives design decisions that are often in conflict with the priorities of engineers.

What are user-centric design parameters? Factors include ease of use, aesthetics-over-form, product branding, proportion, symmetry, weight, safety, and product character. Industrial designers can invest hundreds of man-hours optimizing these factors throughout the development design refinement phase.

Optimizing ease of use can be essential for products like electric hand tools, garden equipment, medical products and virtually every product used by a human. Let’s consider a chainsaw for example. What are some of the essential human considerations for the product design of a chainsaw?

  • Overall balance and location of the center of gravity relative to the handle
  • Chainsaw weight, motor location and overall layout
  • Handle size, shape and clearance for gloved or ungloved hands
  • Button size, shape, location and activation force
  • Safety brake size shape, activation force, travel distance and location
  • Pull cord location and handle grip design
  • Bar chain attachment, dismantling method, chain tightening method, etc.

There are hundreds of other considerations to be integrated in the design of a chainsaw. Optimizing these parameters affects overall product design, safety, comfort and efficiency of use.

Industrial designers must integrate the mechanical components within the boundaries of the overall product form. Further, to optimize these parameters, it’s necessary to strategically locate each subcomponent. Often a minor change in a dimension or activation force could change the product from a safe to a highly dangerous condition.

Creative concept refinement—and the road to design success—is accomplished through an iterative development process of sketching, CAD design, model making, testing and redesign.

Mechanical Design Concept Refinement

Concept refinement also includes the work of mechanical engineers, designers and plastics engineers. The aim is a more developed state before attaining a production-ready design. These concepts are typically functional and must conform to performance-related parameters.

Examples of this include mechanisms, attachment details such as snap locks, or structural design features that must perform within strict fatigue or deflection limitations. Concepts can be refined using CAD, simple models or machined, highly-detailed models.

Concept refinement and prototyping are crucial to refining ideas. Rapid prototypes have become a popular means of refining concepts, but they have many limitations. I’ve used all the rapid prototyping methods including FDM, SLA, laser sintering, wax FDM and ZCorp’s powder process. These processes have been used to form both plastic and metal parts.

The major limitations for all these processes are material choice and size limitations.  If you are trying to evaluate a design based on chemical resistance and impact strength you may discover that a machined prototype in the particular material will be much more representative of the final product than an SLA or FDM prototype.

You may be involved in designing a rotationally molded part in polyethylene and want to know the strength of a particular molded-in feature. The part may be the size of a small car and impractical to prototype. So how do you verify the design before you commit to thousands of dollars in tooling for a design that may not work?

You can simulate the conditions with a computer or you can make a small mold of the area of interest and test it under a variety of actual-use conditions. I’ve used this technique many times with great success. It’s critical to constrain and load the section being analyzed in a manner similar to its use.

I’ve also simulated large structures and applied finite element analysis to the product based on specific materials and load conditions. It’s easy to develop concepts, but the real challenge is to translate the ideas to a level that works and can eventually be manufactured.

The concept refinement stage should evolve on multiple levels—you should develop concepts with considerations of all factors affecting the final design. These may include tool design, molding, aesthetics, human factors, assembly and safety, to name a few. And it would include medical product design, plastic design, and rotational molding projects.

This phase of design is the most crucial in the development process since it will influence all subsequent development steps. What’s more, poor decisions during this phase can introduce complexities that might not have existed if a more refined concept was developed.

Process Selection, Tooling Cost and Production Costs

Concept refinement will also be influenced by decisions concerning process selection, materials, tooling and production costs. For example, an initial rendering from an industrial designer may only illustrate its basic form with some indication of colors and graphics. If the design is well thought-out, the basic shape should represent its function and be ergonomically optimized for ease of use. These types of preliminary concepts are typically proposed by industrial designers.

Plastics designers and product engineers are required to translate these concepts into a production design. I don’t agree with this design approach since the manufacturing process should be considered from the earliest phase of development. If an industrial designer has a basic understanding of various manufacturing processes and their effect on part cost, investment and overall product design, he or she can propose concepts that can be more easily translated to a production design.

After the initial concept is accepted, plastics design engineers can work with the industrial design team to translate the embryonic concept into a more defined embodiment based on one or more plastics processes. Process selection will play a major role in tooling investment, lead times and reoccurring costs. It also has an influence on appearance, number of parts and product details.

During the concept refinement phase, an idea should be sufficiently detailed to define the number of parts based on a particular molding process as well as the estimated tooling costs and unit cost. Early estimates for these basic building blocks of product design will minimize redesigning a product after it has been completely designed. It also provides a platform for everyone to converge based on risk, appearance and potential tooling complexities.

This method of designing on multiple parallel paths leads to a smoother product design program since all parties can agree on basic objectives from an early phase of the project. Experienced designers can also anticipate draft angles and split lines from this early stage of development. Although these considerations may seem to be premature in the design program, they are not. Draft angles and split lines will have a major impact on aesthetics, part count, tooling cost and overall product quality.

For example, let’s look at a sculpted injection molded handle. If a concept for this handle is being refined without considerations for split lines and draft from the early stages of design, an impossible molding condition can be created. This will force the designer to either totally redesign the handle or seriously compromise ergonomics and aesthetics. The problem becomes even more difficult if a surface requires a heavy texture and additional draft is required to mold the part. More about these topics in future articles.

I’d like to hear from you. What do you think about concept refinement steps? Send your comments today. Please contact me directly at: