---
title: Design moulds for sunglasses
slug: design-moulds-for-sunglasses
description: For the past five years, Esfèrica has focused on maintaining the value of waste plastics. Our project, FOS Barcelona, produces eyewear from local waste and provides molds for others to produce them locally, promoting distributed design.

This guide shares insights from our experience.

1: Requirements
2-5: Sunglasses Design
6-10: Mold Design
tags: ["mould","injection","product"]
category: uncategorized
difficulty: Hard
time: 3-4 weeks
location: Barcelona, Spain
---
import { Image } from 'astro:assets'
# Design moulds for sunglasses
<Image src={import('./_IGP9762.jpg')} alt="Design moulds for sunglasses" />
For the past five years, Esfèrica has focused on maintaining the value of waste plastics. Our project, FOS Barcelona, produces eyewear from local waste and provides molds for others to produce them locally, promoting distributed design.

This guide shares insights from our experience.

1: Requirements
2-5: Sunglasses Design
6-10: Mold Design

User Location: Barcelona, Spain
## Steps
### Step 1: What you need

To complete the process independently, you will need:

1. A defined model concept.
2. A computer with CAD software experience.
3. Access to a quality CNC milling machine or a manufacturing partner.
4. An injection machine.

Let's proceed with the steps.


<Image src={import('./00.jpg')} alt="00.jpg" />

### Step 2: DESIGN THE SUNGLASSES

When designing eyewear, you can either choose bold designs aimed at a niche audience or opt for classic styles for broader appeal. Your decision depends on your goals. Once your target is set, you will need to make decisions about various components, as outlined in the following steps.


<Image src={import('./1.png')} alt="1.png" />

### Step 3: Sunglasses model - Hinges

Metal hinges: Common options include riveted (fixed with rivets), in-mold (placed before injection), screwed-in (attached post-injection with screws), and fused (secured post-injection with heat). Screw-in hinges are the easiest to detach after the product's lifespan.

Plastic hinges: See next step.


<Image src={import('./22.PNG')} alt="22.PNG" />

### Step 4: Sunglasses model - Hinges

Plastic hinges can be manufactured using molds. This method avoids material mixtures and can offer durability comparable to metal hinges if designed correctly. However, the perceived quality might be a concern when creating products for sale, as perceptions can vary globally and are not always aligned with actual quality.


<Image src={import('./3.PNG')} alt="3.PNG" />

### Step 5: Sunglasses model - Lenses 

There is a wide variety of lenses available. Your choice depends on the intended use and type of eyewear. The main types are:

- Polycarbonate: Suitable for sports and action eyewear due to durability.
- CR-39 (polymer): The most common type of lens.
- Mineral: Glass lenses, used less frequently due to weight and fragility, but offer high scratch resistance.


<Image src={import('./4.png')} alt="4.png" />

### Step 6: Sunglasses Model - Base

Certainly.

---

For eyewear design, the curvature of the frame is determined by the "Base" value. A higher base number results in a smaller curvature diameter. Base 9 is typical for sports eyewear, providing a snug fit to protect the eyes, while base 2 is used for fashion eyewear with a nearly flat appearance.

Previously, our Classic model featured a base of 6, whereas our new models utilize a base of 4.


<Image src={import('./5.PNG')} alt="5.PNG" />

### Step 7: DESIGN THE MOULD

When designing molds for eyewear, it is important to balance costs with quality. Achieving excellent inscriptions and surface finishes requires significant investment. For testing, molds can be produced more quickly and economically with basic equipment. It is crucial to recognize that creating molds comparable to industrial ones is not cost-effective. A high-quality mold requiring minimal post-processing was chosen.


<Image src={import('./6.PNG')} alt="6.PNG" />

### Step 8: Parting lines

If choosing a cheaper mold, place parting lines at the edges to simplify post-processing and achieve satisfactory results.

For high-quality molds, the placement of parting lines is less critical as minimal post-processing, such as slight polishing, may be needed. Design choices can guide your decision. The images illustrate how to obscure parting lines with a rounding technique, which increases mold cost—particularly for small features requiring multiple tool changes and additional time—or how to maintain a simple design.


<Image src={import('./7.PNG')} alt="7.PNG" />


<Image src={import('./8.PNG')} alt="8.PNG" />

### Step 9: Closing system: How complex? 

### Closing System: Complexity Overview

A closing system enabling quicker production can be expensive. The clamping pressure in an injection mold is crucial for optimal results and mold longevity. Finding a system that is affordable, accommodates frequent mold changes, and provides adequate, evenly distributed pressure is challenging.

Simple screws are a budget-friendly solution, offering excellent clamping pressure when correctly positioned. However, they may slow down the process of opening and closing the mold. We suggest beginning with screws to assess your actual requirements before considering other options.


<Image src={import('./9.PNG')} alt="9.PNG" />


<Image src={import('./10.PNG')} alt="10.PNG" />


<Image src={import('./11.PNG')} alt="11.PNG" />

### Step 10: Surface finishings

### Surface Finishing Options for Molds

1. **Tool Paths**: Leaving tool paths is cost-effective and allows for creative patterns by altering cutting directions.

2. **Bead Blasting**: Provides an even surface at a low cost but lacks a shiny finish. Standards vary regionally, so consult your manufacturing partner for guidance.

3. **Polishing**: Achieves the smoothest finish but is the most expensive. Choose the appropriate grade for your needs.


<Image src={import('./12.PNG')} alt="12.PNG" />

### Step 11: Logos and inscriptions

To finish your product, consider adding inscriptions to ensure recipients know its origin. Two main methods are:

1. Milling a logo or inscription. This approach limits production to one brand, but allows for high-quality inscriptions with minimal effort or time. The image shows molds made for Experiencia Emprendedora in Argentina.

2. Using pressure-marking to imprint logos and inscriptions. While the quality is lower, this method allows the mold to be used for multiple projects and brands as you establish your brand, if desired.


<Image src={import('./13.png')} alt="13.png" />


<Image src={import('./14.PNG')} alt="14.PNG" />

### Step 12: GET READY TO INJECT THOUSANDS!

Once you comprehend the process, adjust it to suit your machines, molds, and products to achieve your objectives. Automation may be beneficial as sales become consistent. Pay close attention to color formulas for your products.


<Image src={import('./15.PNG')} alt="15.PNG" />

### Step 13: EMBRACE DISTRIBUTED DESIGN

### Distributed Eyewear Production

At FOS, we enable local production of our eyewear designs, reducing the need for individual product shipments. We offer resources and moulds to facilitate this process, allowing the manufacture of eyewear products anywhere. 

Distributed design is an impactful approach that we support through our offerings. For more details on our packages, please visit our website.

#### Contact
- Website: [fosbarcelona.com](https://www.fosbarcelona.com/)
- Instagram: [instagram.com](https://www.instagram.com/)


<Image src={import('./FOS_sotllo_front15.jpg')} alt="FOS_sotllo_front15.jpg" />


<Image src={import('./isometriques_sotllo3.jpg')} alt="isometriques_sotllo3.jpg" />


<Image src={import('./16.PNG')} alt="16.PNG" />