Materials are used in all the products around us. Unfortunately, the material considerations that go into designing and manufacturing a product are too often minimal. Product designers need to understand the value of proper materials engineering and some of the misconceptions regarding materials engineering.

Most companies understand the relationship between materials performance and cost. However, few people appreciate the impact of materials properties on this equation, especially when buying more performance than needed. Understanding materials properties is critical in making decisions that optimize cost and performance.

Fig. 1.

Materials engineering involves understanding the correlation between a material’s cost, performance, and basic properties. The knowledge gained in the materials engineering approach facilitates timely and well-informed materials decisions relating to new designs, cost reduction efforts, supplier selection, and manufacturing yield improvements.

For example, in looking at Fig. 1, going from Material #1 to Material #2 results in cost savings without impacting performance. This change is made possible by understanding the specific material properties requirements. In this example, it is possible to substitute a different material to achieve the same performance, but at a lower cost.

In another example, changing from Material #1 to Material #4 achieves better product performance at the same cost. Again, this is possible by fully understanding the materials properties requirements and how they relate to performance.

Ultimately, a better understanding of the performance/cost/properties relationship will provide companies with a competitive advantage.

Understanding these materials relationships is critical for making well-informed product level decisions. With this information, it is possible to make timely and well informed decisions for new designs, cost reduction efforts, supplier selection, and manufacturing yield improvements. Companies that invest in gaining this knowledge gain a competitive advantage over companies that make materials decisions by trial and error.

Incidentally, the materials engineering approach is not new. Some larger companies recognize that a large portion of the cost of their product is related to the materials used to make it and the all the cost impacts of non-conforming materials. As a result, they have full-time materials engineers on staff.

Common attitudes

Fig. 2.

Some of the reasons why the benefits discussed above are not fully obtained are related to common misconceptions towards materials considerations and materials engineering. Here are some of those misconceptions:

1. Mechanical and electrical engineers believe that they have the required expertise to make well informed materials decisions. However, most of these engineers might have had one or two materials science courses. Also, these engineers typically do not have experience with all the tests and analysis techniques used to evaluate materials properties and performance. Still, these engineers typically believe their background is adequate for making decisions about the materials and suppliers used to make their products.

In contrast, a materials engineer completes a focused materials science and engineering curriculum in order to receive a bachelor’s of science degree. In addition, many materials engineers have advanced degrees. Also, materials engineers that focus their careers on understanding the relationship between materials performance, properties and cost gain experience with the analytical tools and materials resources available for obtaining knowledge and understanding about materials. Finally, a materials engineer may have design, reliability, quality, and/or manufacturing experience.

A materials engineer will also be familiar with various testing and analysis techniques, for both product level and materials level evaluations. These techniques are important to understand since their proper selection and use allows valuable knowledge to be obtained about the relationship between a material’s properties and its performance in the final product. This in turn enables data driven decisions for product design or cost reduction.

2. Materials decisions are treated as second order to a mechanical or electrical design. A large amount of effort is put into designing the mechanical and electrical functionality of the product. However, little attention is given to how the materials interact or degrade; the effects of suppliers’ process variation on the performance, reliability, and manufacturability of the final product; the relationship between a materials cost, performance, and reliability; just to name a few items.

3. When making materials decisions, design teams often use information from the Internet or rely solely on the technical data from suppliers. This is in contrast to the handbooks, databases, literature, and personal networks that are used by the experienced materials engineer.

Also, engineers must remember that the technical data from suppliers usually states nominal values for the materials properties. They do not offer information about the expected variations in the materials properties. These real-life variations can have a large impact on the manufacturability, performance, and reliability of the final product.

4. Most people believe that materials engineers work only on lab analysis and failure analysis, that is, forensics. Therefore, they are usually called upon only when there is a catastrophic problem such as a field failure or a manufacturing line-down situation. In these, situations, it is not atypical for the materials engineer to be treated more like a technician rather than as an engineering partner.

With these attitudes towards materials decisions and materials engineering many design teams, manufacturing teams, and sourcing teams struggle to make decisions regarding their products. In the end, the decisions are usually sub-optimum. Strangely enough, this struggling is accepted and tolerated as part of getting things done.

Key drivers

Everything we design and manufacture depends on some minimum level of materials understanding. For some products, the level of materials understanding is higher than for other products. Some of the key drivers of the required level of knowledge are:

Cost sensitivity.

Manufacturing volume.

Product reliability.

Product performance.

Typically, manufacturing volume and cost sensitivity are inter-related. For the case of a high volume manufacturing line, reducing materials costs by $0.01 to $0.10 per unit can result in significant annual savings. Alternatively, using a material that is not completely compatible with a manufacturing or assembly process or using a poor quality supplier can result in poor yields and significant annual losses. So, in the case of high volume manufacturing, having a strong understanding of the materials used to manufacture the product can have a huge impact on an organization’s bottom line.

In products with high reliability requirements, a strong understanding of the materials is an important factor in preventing validation test failures, redesigns, and field failures. In the case of products such as those for automotive, military, and medical applications, it is possible to design tests to evaluate the performance of materials without the need to build the entire product. This approach to product development saves a great deal of time since the materials evaluation tests can be done in parallel with the mechanical and electrical design process.

This approach also provides the opportunity to evaluate more than one material for any given use, providing even more information about the relationship between materials cost, performance, and properties. Again, the costs to include more materials may be minimal because the tests do not require building a complete product. Finally, with the knowledge gained from proper materials testing and evaluations, the likelihood of failing product validation tests due to materials performance issues will be greatly diminished.

As the required functionality of a product increases, the materials knowledge requirements also increase. This occurs because there are usually more materials and materials interactions in the product. Through proper testing during a product design phase it is possible to identify the materials that provide the optimum balance between performance and cost. Furthermore, the information will be useful to help make cost and performance decisions for future generations of the same product.

Materials considerations

When designing a product or making materials changes for manufacturing yield improvement or cost reduction, materials considerations should include:

Performance.

Degradation over the life of the product.

Interactions between materials.

Cost.

Availability.

Environmental compliance.

Expected materials’ variations.

Expected manufacturing and assembly process variations.

It is also important to consider all the materials properties of a component, instead of focusing on a single property. Some important properties include:

Physical. (Density, melting point, viscosity.)

Electrical. (Conductivity, dielectric constant.)

Mechanical. (Hardness, strength, fatigue, wear.)

Thermal. (Conductivity, thermal expansion.)

Chemical. (Corrosion, oxidation, stability.)

Fabrication. (Castability, weldability, formability.)

Product design process

The process for materials and supplier selection and evaluation, from a materials engineering perspective, is shown in Fig. 2. This process is the same for materials and supplier selection for new designs, cost reduction, and manufacturing yield improvement. During this process, good communication between the materials engineers and the other design engineers, manufacturing engineers, and suppliers is crucial. This will enable selection of materials that meets the design, reliability, and manufacturing requirements.

The complexities of materials engineering are often overlooked by many companies. Incorporating proper materials engineering into the engineering process will enable a company to make well-informed materials decisions about its products. The benefits of this approach are:

Reduced design cycle time.

Reduced product costs.

Increased manufacturing yields.

Reduced product issues, such as field failures, and supplier quality problems.