How to make clean plastic prototypes or clean plastic parts?

When you’re looking for clear plastic materials for your new designs, do you often confuse acrylic and polycarbonate? Not only that, but do you know how many ways to make clear plastic prototypes? Here, this article describes the manufacturing options for clear plastic prototypes to meet the needs of different validation processes.

Generally speaking, there are 4 manufacturing methods for clear plastic parts, including 3D printing, CNC machining, polyurethane vacuum casting, and rapid injection molding.

SLA 3D printed clear plastic parts
SLA 3D printing is an automatically addictive manufacturing method. Unlike the complex CNC machining process, it has a fast turnaround and will print parts at a steady and fast speed. Its time and cost depend solely on the size of the model, which allows designers to control costs by removing unnecessary materials. In addition, the printed clear parts can also be mirror-polished to achieve a high transparency similar to that of the processed clear parts. In general, it can function as a window or model.

In terms of its limitations, the tightest tolerances for SLA prints are around +/- 0.1 mm. For some clear parts for optical functions, if it requires tighter tolerances than +/- 0.1mm, then 3D printing is not an option. In addition, SLA-printed clear parts are prone to form clear bubbles inside the material, which can meet the requirements for optical function or aesthetic appearance.

CNC machined clear plastic parts (processing acrylic V.s processed polycarbonate)

CNC Machined Clear Plastic Parts
CNC Machined Clear Plastic Parts

When it comes to clear plastics, while acrylic (PMMA) and polycarbonate (PC) are two of the most widely used materials, many design engineers may find it difficult to choose between them to achieve their unique applications. For CNC machining, acrylic and polycarbonate blocks present obvious advantages and disadvantages.

CNC machining of acrylic parts
On the one hand, it has excellent clarity after mirror polishing, transmitting light as effectively as glass; Good strength, 4-8 times that of glass; Good durability against a wide range of UV radiation, temperature and weather; Highly versatile, it can be easily processed in various ways, bonded with solvents and adhesives.

On the other hand, processed acrylic parts are more prone to cracking than polycarbonate compared to polycarbonate; More likely to crumble; Poor tolerance, loss of structural integrity at temperatures above 160°C, and deformation or melting when exposed to open flames.

CNC machined polycarbonate parts
On the one hand, it has high strength, 200 times that of glass; High transparency, is a suitable alternative to glass; Good durability and strong impact resistance; Good processability, easy to manipulate and form through various processing processes; The creep is small, unlike other plastic materials that deform or warp under pressure.

On the other hand, processed polycarbonate parts are more prone to scratches than acrylic; Due to better elasticity, dents are more likely to appear under impact; It is more difficult to mirror polish, leaving tool marks on the surface of the part unavoidably.

Clear parts cast in polyurethane
When the demand reaches dozens of Clear plastic parts, polyurethane casting is fast and cheap compared to CNC machining or fast metal molds.

vacuum-casting-3
vacuum-casting-3

As an alternative between CNC machining and rapid tooling, polyurethane casting technology offers a variety of material types similar to finished plastics, including Clear parts. Different polyurethane brands are different in material quality. For Clear parts, Axson’s PX-5210 (PMMA-like) and PX-527 (PC-like), are frequently used due to their premium quality. It has high transparency of clear water, good UV resistance, high copying accuracy, and easy polishing after casting. Although the material is only polyurethane, due to its high quality, it can be applied to industrial testing at the prototyping stage.

The finish quality of the cast Clear part is determined by the quality of the master. Most of the common masters are Clear polished PMMA parts that are CNC machined, which can meet strict tolerances such as +/-0.05mm. In addition, when making parts with complex structures, Clear masters printed on SLA are also considered.

Clear parts for rapid injection molding
As a bridge tool from prototype to production, rapid injection molding technology produces Clear parts from production-grade materials. You can specify certain materials with specific specifications. The material is the same as at the time of production, so Clear parts can be applied to almost all industrial tests before mass production. Unlike injection molding used in mass production, rapid tooling for aluminum or steel is able to hand over the specified parts within 2-5 weeks; At the same time, due to the semi-automatic operation, the mold structure is simplified, so the mold cost is much lower than that of mass production.

Last but not least – the Clear polishing quality of acrylic parts

clear-optical-prototype-machining
clear-optical-prototype-machining

Among all Clear plastics, acrylic polishing can achieve the best clarity. This requires special skills, as acrylic is sensitive to stress and is quite brittle. Manual polishing requires different grades of processing with sandpaper and polishing paste.

High polishing will begin with sanding work, starting with 400/600 sandpaper to remove rough tool marks, then upgrading the sandpaper to 800-1000-1500 and finally to 2000. The polished surface becomes smooth and completely devoid of tool lines or markings. Finally, a polishing paste will be used to complete the process. After all the processes, the finished surface of the acrylic part will appear super clear and Clear , without any invisible grinding marks and scratches.

So far, has this article cleared most of your confusion and doubts about the clear plastic prototype? I hope so, and if you still have questions, please do not hesitate to contact us through our website.

Scroll to Top