Friday December 16th, 2022

The four most common methods of rubber prototyping

With the development of design softwares, one might think that prototyping would lose its function, but this is far from the case today. Prototypes and their creation still play an important role in the plastic and rubber industry. It enables testing the prototypes themselves and the processes by which they are made. In this article, we present 4 rubber prototyping methods that are common in product engineering, which are:

Rubber prototyping methods in use today

Of course, advances in computing are also being felt in the rubber industry. 3D printing technology has been the main driver of change, but like other prototyping methods, it has its limitations.

In addition, the intended material of the product may also influence the choice of process used to make the prototype. Especially if you want to test the process as well as the product. It is not a coincidence that prototypes make an appearance in rubber testing methods and their evaluation too.

Large volumes of rubber products can be made by injection molding, but the cost of tooling is high

Large volumes of rubber products can be made by injection molding, but the cost of tooling is high

Custom molding with silicone and 3D printed molds

Injection molding is one of the most common forms of plastic part production when it comes to high volume mass production. The disadvantage of the technology is that manufacturing the mold takes time, requires specialised machinery and design, and therefore it is expensive. On the other hand, the process can be used to produce accurate products with complex geometries and a wide range of material qualities and colors. It is a widely used manufacturing solution today but is not economical for product testing at an early stage, due to the high entry costs.

However, for testing purposes the expensive and long-lasting metal molds can now be replaced by 3D printed or CNC machined silicone versions. This can speed up prototyping time and greatly reduce costs.

CNC milling solutions

The CNC milling machine carves the defined shape from a block. This requires a pre-made block of the intended material, so it is at least a two-step process, but has the advantage of producing very high-quality products. However, only from a material with the minimum hardness required for milling.

Most cylindrical or other solid rubber prototypes that require only external machining are made by CNC milling, as making more complex or hollow shapes with this technology is a long and overly resource-intensive process.

Stereolithography, SLA

Stereolithography is a less well-known process than others. It is similar to 3D printing. The machine consists of a vertical movable base, a bowl and a laser. The bowl holds the base material – an oligomer solution – in which the base is immersed. Where the laser is applied to the solution, it solidifies, and a layer is formed. Then the base moves further into the solution and the laser draws another layer.

These layers are approximately 0.1 – 0.2 mm thick, so prototypes made with the technology will be dimensionally accurate, detailed and smooth-surfaced, therefore they are ideal for visual prototyping.

The drawbacks of the technology are that the prototypes made with this process may require supports, which can leave visual marks on SLA parts, and that stereolithography-printed models are usually not suitable for mechanically stressing tests.

3D printing

In 3D printing, not only the software, but also the hardware and the usable materials are constantly evolving. Today, it is even possible to print flexible materials such as silicone, given the necessary technical background.

The biggest advantage of the technology is its geometric diversity, meaning that virtually any shape can be 3D printed. In addition, the lead time and cost are almost negligible compared to injection molded rubber prototyping.

The disadvantage of this technology is that the printed material has a poor surface quality, the layers are visible, so it requires a relatively large amount of finishing work, such as sanding. As with stereolithography, a support structure may be needed around the product. In addition, the structural strength of the product can be affected by the direction of printing.

RTV silicone prototyping

RTV silicone prototyping

Custom rubber parts – from idea to serial production

At SIC, we believe in the importance of proper prototyping, which is why all our product engineering and development processes include prototyping and testing. In each case we create the prototype using the most suitable process regarding the final product, so the quality of that will be close to the quality of the prototype. This ensures reliability for our customers.

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