The danger of a price-only comparison

Material discussions often begin with a price per kilogram. This is useful, but it can be misleading. The material price is only one part of component cost and only one dimension of product value. Density changes the required mass, strength changes wall thickness, machinability changes cycle time, and corrosion resistance may eliminate coating or maintenance.

A lower-priced material can therefore create a more expensive component, while a premium material can reduce total cost. The correct comparison is based on the function and the complete manufacturing and lifecycle system.

Define requirements and functions first

Material selection should start with measurable requirements: load, stiffness, temperature, chemical exposure, electrical behaviour, weight, surface quality, lifetime, regulatory constraints and recyclability. Requirements should be separated into mandatory criteria and preferences. Overly conservative values should be challenged because they can exclude cost-effective alternatives.

A function-oriented description helps avoid attachment to the current material. Instead of asking for an alternative to a specific alloy, the team asks what the material must achieve and under which conditions.

Compare total component cost

The cost model should include purchase form, yield, scrap, forming or casting effort, machining, heat treatment, coating, joining, inspection and logistics. Tooling and qualification costs matter, especially at lower volumes. The model should also account for the effect on adjacent components. A stronger material may reduce section thickness; a polymer may integrate several functions; a corrosion-resistant grade may remove a coating line.

Scenario calculations are important because volume, location and market prices can change the result. The best option for a prototype may not be the best option for high-volume production.

Include supply and sustainability risks

Availability, number of qualified suppliers, geopolitical exposure and price volatility should be part of the evaluation. A technically ideal material can create unacceptable supply risk. Recycled content, embodied carbon, repairability and end-of-life pathways may also influence the decision.

These factors can be evaluated in a weighted concept matrix. Weighting should reflect the product strategy rather than applying a generic score. For a safety-critical product, reliability and qualification may dominate; for a consumer product, appearance and recyclability may carry more weight.

Validate with experts and tests

Databases and AI-supported search can quickly identify candidates, but final selection requires engineering validation. Material experts, process specialists and suppliers should review the assumptions. Critical properties need to be tested in the intended manufacturing route and application environment.

A transparent selection process improves both cost and technical quality. It documents why a material was chosen and makes trade-offs visible to stakeholders. The result is not simply the cheapest material, but the material concept that delivers the required function with the best total value.

RENNET perspective

RENNET combines industrial expertise, Cost and Value Engineering methods, manufacturing knowledge and digital tools to support fact-based product decisions.

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