Designing Conveyor Belts for Industrial Projects: Practical Notes for Engineers & Makers

Introduction: Why Conveyor Belts Matter in Real-World Engineering

When we talk about industrial automation or mechanical design, conveyor belts often play a background role — silently moving parts, products, or components from one stage to another. But make no mistake: the type of conveyor belt you choose can make or break your project’s efficiency, reliability, and even safety.

From food processing plants and mining operations to packaging lines and automated warehouses, belts are everywhere. They are the connective tissue of many industries — often invisible, yet absolutely vital. But here’s the catch: not all belts are created equal.

For developers, engineers, and makers building DIY production lines, automated sorting systems, or even test rigs for robotics, the belt itself is not just a passive surface — it’s a functional material system. Its grip, durability, flexibility, and resistance to temperature, chemicals, or abrasion can dramatically impact how your system performs under load or over time.

In this article, we'll break down what makes a good industrial conveyor belt, how to select the right one for your use case, and how to integrate that knowledge into practical design and prototyping workflows.

Understanding the Anatomy of a Conveyor Belt

While a conveyor belt may look like a simple strip of material at first glance, its internal structure is anything but trivial. In industrial applications, belts are engineered systems — built from multiple functional layers, each tailored to withstand specific mechanical, thermal, and chemical stresses.

Let’s break down the typical three-layer architecture of a modern conveyor belt:

1. Top Cover — The Product Interface

This is the outermost layer that comes in direct contact with materials being transported. Whether it’s packaged goods, raw ore, or food items, the top cover determines how well the belt grips, protects, and resists wear.

• Common materials: NBR rubber, PVC, PU, and silicone
• Key properties: abrasion resistance, oil resistance, food-grade certification, surface texture (smooth or patterned)

2. Tensile Layer — The Structural Backbone

At the heart of the belt lies its tensile layer — the strength-providing core made from fabric reinforcements. These are often woven from polyester (E) and polyamide (P), forming what’s known as EP belts, or in heavy-duty cases, reinforced with steel cords.

• Determines: tension resistance, flexibility, and elongation characteristics
• Key spec: number of plies and tensile strength per ply
• Tip: A higher EP rating ≠ always better — match to load and pulley diameter

3. Bottom Cover — The Support Interface

This layer rests on the idlers or rollers and plays a critical role in minimizing friction and wear on the underside. It’s usually similar in composition to the top cover but may be optimized for slip, static discharge, or tracking stability.

• Common mods: anti-static additives, low-friction coatings
• Important in systems with high-speed or heavy reversing loads

Together, these layers create a belt that’s not just strong — but smartly adapted to the demands of its environment. Selecting or designing the wrong layer configuration can lead to early failure, inefficiencies, or unexpected maintenance cycles.
Check out this comprehensive guide written in Farsi — covering materials, structure, design tips, and real-world applications of industrial conveyor belts.

Choosing the Right Materials Based on Project Needs

Not all conveyor belts are created equal — and picking the wrong material can lead to wear, slippage, downtime, or even full-on project failure. Here's a breakdown of common belt materials and how to choose the right one for your needs.

🔸 NBR Rubber (Nitrile Butadiene Rubber)

• ✅ Excellent oil and grease resistance
• ✅ Durable and abrasion-resistant
• ❌ Not ideal for high-temperature environments
• 🔧 Best for: Automotive, recycling lines, oily parts transport

🔸 PVC (Polyvinyl Chloride)

• ✅ Affordable and lightweight
• ✅ Good for general indoor use
• ❌ Limited temperature range (~80°C max)
• ❌ Poor chemical resistance
• 🔧 Best for: Dry food packaging, parcel handling, logistics

🔸 PU (Polyurethane)

• ✅ Food-grade and hygienic
• ✅ Very abrasion-resistant
• ✅ Flexible and low-noise
• ❌ Higher cost than PVC
• 🔧 Best for: Wet food environments, pharmaceuticals, robotics

🔸 EP Fabric Belts (Polyester/Nylon Reinforced)

• ✅ High tensile strength
• ✅ Low elongation under load
• ✅ Great for long runs with high tension
• ❌ Needs protective outer layers (top/bottom covers)
• 🔧 Best for: Heavy industry, quarries, bulk materials

🔸 Steel Cord Belts

• ✅ Handles extreme tension with minimal stretch
• ✅ Suitable for very long conveyors
• ❌ Expensive and rigid
• ❌ Requires special pulleys and installation
• 🔧 Best for: Mining, large-scale aggregate systems

💡 Pro tip: For robotics or 3D printing farms, consider PU belts — they’re clean, quiet, and provide smooth motion without dust or static.

Conveyor Belt Design Using CAD Tools (with Code Example)

Designing a conveyor belt isn’t just about choosing materials — it’s about modeling it accurately to fit within your mechanical system. Whether you're designing components for 3D printing, CNC milling, or digital simulation, having a parametric CAD model gives you the flexibility to adapt to changing specs quickly.

🔧 Popular Tools for CAD-Based Belt Design

• Fusion 360 – Great for integrated parametric modeling + stress simulation
• SolidWorks – Industry-grade, excellent for layered assemblies and realistic motion
• FreeCAD – Open-source and scriptable; perfect for functional prototyping
• OpenSCAD – Text-based modeling; ideal for precise parametric parts and automation

🧪 Example: Simple Conveyor Belt Cross-Section in OpenSCAD

Let’s create a basic parametric model of a 3-layer conveyor belt using OpenSCAD, a script-based CAD tool favored by engineers who like code-driven design.

🔷 The Layers:

• Top Cover: Protective surface in contact with product
• Core Layer: Tensile layer (e.g., EP fabric)
• Bottom Cover: Base support layer

💻 OpenSCAD Code Snippet:

// Conveyor Belt Cross Section
belt_length = 1000;            // mm
belt_width = 100;              // mm
layer_thickness = [2, 5, 2];   // mm [top, core, bottom]

// Top Layer
translate([0, 0, 0])
    cube([belt_length, belt_width, layer_thickness[0]]);

// Core Layer
translate([0, 0, layer_thickness[0]])
    cube([belt_length, belt_width, layer_thickness[1]]);

// Bottom Layer
translate([0, 0, layer_thickness[0] + layer_thickness[1]])
    cube([belt_length, belt_width, layer_thickness[2]]);

🧠 Why Parametric?

• Need a longer belt? Change belt_length
• Swapping a thicker EP layer? Update layer_thickness[1]
• Reuse the same code for belts in robotics, packaging, or test automation

💡 Pro tip: Want to simulate belt bending or stress? Export your model to Fusion 360 or FreeCAD and run FEA (Finite Element Analysis) on the tensile layer.

Testing and Prototyping Your Belt Design

Designing a conveyor belt is just the beginning. To ensure your belt performs reliably under real-world conditions, testing and prototyping are critical steps — especially when you're working with custom builds or experimental environments.

🧪 1. Physical Prototyping: From CAD to Reality

Once you've designed your belt in CAD (like we did in the previous section), you can prototype using:

• 🖨️ 3D Printing (TPU or PETG): Great for testing thickness, flexibility, and fit
• CNC Milling (Rubber sheets or Foamboard): Ideal for flat pattern cutting and layer simulation

While these won’t match industrial tensile properties, they’re perfect for checking:

• Pulley alignment
• Frame fit and support structure
• Initial deformation or fold behavior under tension

💡 Tip: When prototyping for motion systems, use flexible filament like TPU to replicate belt flex and return.

📏 2. Know Your Standards: ISO & DIN Guidelines

If you're building belts for real-world machines or commercial systems, it's essential to align your design with industrial standards, such as:

• ISO 14890 — Covers physical properties and testing methods for general-purpose conveyor belts
• DIN 22102 — Specifies mechanical requirements for textile conveyor belts, including cover grades (Y, W, X, etc.)

These standards help define things like:

• Minimum tensile strength
• Abrasion resistance levels
• Elongation under load
• Adhesion between layers

📎 Always refer to material datasheets from belt manufacturers — most will reference these standards directly.

🧮 3. Simulate Before You Fabricate

For digital validation, consider running basic simulations:

• Belt stress and tension: Tools like Fusion 360 (FEA) or SimScale can help estimate how your belt will stretch or fail under load.
• Belt drive simulation: Use tools like PulleyMate or even Onshape gear/belt simulators to test tension and wrapping over pulleys.
• Custom scripting: Use Python libraries like pybullet or cadquery for mechanical simulation and automation in prototyping pipelines.

🎯 Practical Checklist for Prototype Testing

• ✅ Fit test with full frame
• ✅ Check for misalignment, slippage, or tracking errors
• ✅ Monitor tension distribution across belt length
• ✅ Record flex fatigue (especially in curved paths or turns)
• ✅ Compare results with specs from ISO or DIN tables

Conclusion: Practical Notes and Tips for Belt Design

Designing a conveyor belt might seem like a minor detail in a larger mechanical or automation project — until it becomes the bottleneck. Having worked on multiple builds involving belts for robotic arms, automated sorters, and custom CNC material feeds, I’ve learned (sometimes the hard way) that belt selection and design deserves more attention than it usually gets.

Here are some final takeaways that can save you a lot of pain later:

⚠️ Common Mistakes to Avoid

• Over-spec’ing materials: Using steel cords when EP would do — it adds cost, rigidity, and installation headaches
• Ignoring tension specs: If your belt stretches too much, you’ll get slippage, misalignment, or breakage
• Neglecting layer compatibility: Top and bottom covers must match your working conditions (abrasion, oil, food, static)
• Skipping prototyping: Even a simple 3D-printed mockup can save hours of redesign later

🧠 Pro Tips from Real-World Builds

Always start with the environment: heat, humidity, oil, dust — they will decide more than you do

Use parametric design in CAD to stay flexible with layer thickness, width, and belt length

Simulate tension early, especially in closed-loop or curved systems

Keep a change log — belts are often the first component engineers hack mid-project, so track versions

📁 Want to Try It Yourself?

You can access the OpenSCAD file from this article — along with a STEP model and my original parametric FreeCAD file — on GitHub:

🔗 🔧 Conveyor Belt CAD Models – GitHub Repo

Feel free to fork, adapt, or improve. If you’ve built a better belt — or burned through a few in the process — share your story in the comments. I'd love to learn from your belt battles too.

💬 What’s next?

Thinking about simulating full conveyor systems with sensors and real-time control using Python or ROS? I may explore that in a follow-up article. Let me know if you're interested!