Updated on April 15, 2026

Trimming

Trimming is an analytical tool for improving an engineering system by removing (trimming) certain components and redistributing their useful functions among the remaining system or its supersystem components, while preserving quality and performance of the system.

Overview

Trimming is one of fundamental analytical tools. Like feature transfer, it is a problem-generating tool since it creates problems that have never existed before. Solving these problems leads to entirely new and unexpected solutions.

Trimming aims to improve an engineering system by reducing the number of its components and simplifying the system. Eliminating components responsible for key disadvantages increases the system’s value by reducing its costs while maintaining or enhancing its overall functionality.

Trimming offers multiple options for eliminating the same component. These options represent a spectrum of possible innovations – from incremental to more radical. It also reveals a set of problems that other approaches cannot detect. It yields new problem statements, and also points toward effective solutions. 

The input into trimming are the following: The function model provides information about which useful functions of the trimmed components should be preserved in the system and what new carriers can be used. The key disadvantages, on the other hand, indicate components to trim, as those directly associated with key disadvantages are recommended to be removed from the system first.
The output of trimming is one or more trimming models, and a list of trimming problems.
Trimming is guided by a set of rules that determine which components to trim and/or how to redistribute their useful functions. However, a different set of rules applies to devices and another to processes.
In some projects, completely removing a component recommended for trimming may be impossible or impractical. In such cases, partial trimming can be applied.

Selecting components for trimming

When selecting components for trimming, the decision should align with the project’s goal. If the goal is to reduce costs, consider removing the most expensive component. If minimizing weight is a priority, eliminate the heaviest one. For size reduction, focus on the largest component.

To determine which component to trim, it is advisable to use the following approaches:
  1. Utilize the list of components directly linked to key disadvantages identified through CECA. This method is widely applied in most projects. By removing the component responsible for a key disadvantage, the associated issue is effectively addressed.
  2. In cost-reduction projects, rely on cost assessments, such as those derived from function-cost analysis. This provides insights into the costs of units and their individual parts. When the project aims to cut costs, it is logical to trim the most expensive components.
  3. For general system improvement, refer to strategies like those outlined in the function-cost diagram. One effective approach is to eliminate components with the lowest value, typically found in quadrant D of the diagram. This method helps in improving the overall system by removing elements that contribute the least value.

The decision to complete the trimming process is made by the team. After removing the selected component and addressing the trimming problems, the process can be concluded or repeated for another component.

Difference between trimming for devices and trimming for processes

The key difference between trimming for devices and trimming for processes lies in the trimming rules.
For devices, there are three trimming rules that can be applied to functions of any rank, with some limitations for rule A. In the process, a trimmed operation comprises a set of functions with different ranks, and each function requires a distinct approach to be effectively addressed. Therefore, there is no universal set of trimming rules, but there are different sets of rules for carriers of function of a specific rank.

Trimming for processes is usually more radical than trimming for devices. While for devices, component by component are trimmed, for processes, an entire operation is eliminated, along with its associated equipment, tools, labor, energy, raw materials, etc.

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