# Sustainable Manufacturing Decisions with Simulation: Part 1 - Savonia AMK

> Every design decision carries a carbon cost. Mapping its emissions turns sustainability into a real advantage.

## Introduction
Sustainability is a wide and increasingly important subject in the modern industrial environment. The pressure from institutions such as the European Union has required companies to adopt climate and sustainability policies to promote transparency in emissions reporting and carbon-reduction efforts. Most companies aim to document and monitor their CO₂ footprint since environmental responsibility has become both a strategic and regulatory priority. These efforts make the environmental impact quantifiable, comparable, and manageable, changing sustainability from a general objective into a concrete, data-driven parameter that supports informed decision-making and continuous improvement.

## Developing a Product-Specific Carbon Footprint Model
To make sustainability actionable, this study aims to develop a product-specific carbon footprint model within factory boundaries to illustrate how emissions are generated and identify where design or process decisions can have an impact. 

The machining system receives material from the material processing system and energy from the energy conversion system. During operation, auxiliary inputs such as cutting fluid, tools, fixtures, and other supporting elements are required, each linked to its own preparation system. The machining system produces finished products and removed material (chips), which are sent to a removed material processing system. Carbon emissions are generated at multiple stages, including energy conversion, material preparation, auxiliary material preparation, and chip processing, showing that environmental impact is distributed across the entire production chain rather than limited to the machine tool itself.

## Data Uncertainty and System Boundaries
Research on the life cycle assessment of machining processes shows that data availability varies significantly between process inputs:
* **Machine electricity consumption:** Can usually be measured directly and has relatively low uncertainty.
* **Upstream processes (cutting tool production, cutting fluid manufacturing, material processing):** Often rely on supplier information or assumptions, leading to greater uncertainty.

In reality, manufacturing machinery operates differently based on cutting parameters, load conditions, tool wear, and standby or idle times. If these factors—along with upstream and downstream processes—are ignored, the model risks oversimplifying reality and underestimating environmental impact.

## The Project Lifecycle and Decision Influence
The potential to influence sustainability outcomes changes across the project lifecycle. During early stages, such as planning and conceptual design, decision-makers have the highest flexibility in changing environmental, economic, and social outcomes. As the project progresses toward detailed design and operational phases, the ability to modify these decisions decreases because technical specifications, investments, and production commitments have already been established.

## Structured Decision-Making Model
This study introduces a structured decision-making model based on four main criteria, each containing four sub-criteria:

### 1. Environmental Impact
* Material footprint (kg CO₂ per kg of material)
* Process footprint (kg CO₂ per process type)
* Surface treatment impact (e.g., coating)
* Energy intensity category (relative energy demand of the process)

### 2. Economic Impact
* Material cost (€ per kg)
* Process cost (€ per kg removed)
* Surface cost (€ per m²)
* Expected scrap or over-removal

### 3. Manufacturing Feasibility
* Machinability difficulty
* Tolerancing demands
* Tooling requirements
* Availability of the process–material combination

### 4. Design Complexity
* Geometry difficulty
* Required precision
* Design dependency or freedom
* Design familiarity

## Project Information
This article is part of the *Simulation models in industrial processes* project.
* [Project Website](https://sitepro.savonia.fi)
* [Sustainable Manufacturing Decisions with Simulation: Part 2](https://www.savonia.fi/en/articles-pro/sustainable-manufacturing-decisions-with-simulation-part-2/)

**Author:** Sorayya Amirahmadi, Project Specialist, Savonia University of Applied Sciences

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