What is the Smoothest Mold Surface Finish?

When it comes to micro mold manufacturing, achieving the smoothest surface finish is essential for industries that demand unparalleled quality and precision. In this blog post, we delve into the world of mold surface finishes. Here, we’ll shed light on SPI surface finish standards as well as innovative micro molding technologies that are breaking the limits of these conventional standards. These technologies create surface finishes as smooth as Ra 1.5 nano meters, unlocking new opportunities in applications that rely on flawlessly smooth finishes.

Advancements in micromolding technology allow for surface smoothness as low as 1.5 nano meters!

That’s on the scale of ~10 atoms in length. 🤓

What are conventional molding surface roughness’s?

SPI (Society of the Plastics Industry) finishes are a set of standards that provide a common language for specifying the desired surface finish of injection molded plastic parts. The SPI finish standards range from A-1 to D-3, with A-1 representing the smoothest finish. These standards help communicate the desired level of surface roughness, texture, and glossiness for different applications. Achieving the desired SPI finish involves meticulous mold polishing, surface treatments, and careful attention to detail to ensure the highest quality and performance of the molded parts.

💡 The smoothest SPI (Society of the Plastics Industry) finish is SPI A-1.

That’s about 12 to 25µm.

Achieving the Smoothest Mold Surface Finish for Ultra-Fine Components


Nano-machining provides unparalleled precision in creating structures with nano-level precision and exceptional surface quality. This advanced technology opens up possibilities for machining free-form surfaces and optical elements. Nano-machining allows for mass production of ultra-precise plastic components. A prime example is in microscopic optic lens applications, where this technology is used to create optical axis pitches as small as 100 µm.

💡 With nano-machining, mold surface finishes are as smooth as Ra 1.5 nano meters.

These specialized machining center work similar to regular machining centers, but sets themselves apart with their extraordinary nano capabilities. With nano linear resolution and five axes control, nano-machining employs diamond cutters to achieve astonishingly smooth surfaces (Ra 1.5 nm). This eliminates the need for additional polishing. As a result, this manufacturing technology is capable of producing precision lenses, free-form surfaces, and their accompanying mold cavity structures. Nano-machining also enables the creation of ultra-precise mold inserts, making optical components and biomedical parts more accessible than ever before.

Applications of nano scale smooth mold surface finishes

Precision Engineering and Optics:

Industries involved in precision engineering, optical components, and high-precision instruments utilize molds with the smoothest surface finish. This includes applications like lenses, micro-optics, mirrors, and other components requiring exceptional surface quality and optical performance.

Medical Device Industry:

Manufacturers of medical devices, equipment, and implants prioritize smooth mold surface finishes to ensure sterile, biocompatible, and minimally invasive products. Smooth surfaces minimize the risk of bacterial growth, facilitate easy cleaning, and promote optimal performance.

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