DESIGN & FINISHING GUIDE

A Guide to Surface Finishes

The finish on your part can be just as important as its geometry. This guide covers our standard and secondary finishes to help you achieve the perfect cosmetic appearance and functional performance.

Standard (As-Manufactured) Finishes

These are the most cost-effective finishes, representing the part directly as it comes off the machine.

As Machined

This is the standard finish for CNC machined parts. The surface will show fine, visible tool marks from the cutting process. The standard surface roughness is Ra 3.2 μm (125 uin). A smoother finish of Ra 1.6 μm can be requested for critical surfaces.

As Printed (3D Printing)

This is the standard finish for 3D printed parts. The appearance varies by technology. SLA parts are smooth with visible layer lines. SLS/MJF parts have a grainy, matte texture. DMLS metal parts have a rough, sand-casted-like finish.

Secondary Finishing Options

We offer a wide range of post-processing options to meet your aesthetic and functional needs.

Bead Blasting

Removes tool marks from machined parts and creates a uniform, non-reflective matte or satin finish. It's a great low-cost option for improving cosmetic appearance.

Anodizing (Type II)

Adds a corrosion-resistant, ceramic layer to aluminum parts. Can be dyed in a variety of colors like black, red, and blue for a durable cosmetic finish.

Anodizing (Type III)

Also known as "hardcoat," this creates a much thicker, harder ceramic layer. It is used for high-wear applications and typically comes in a dark gray/black color.

Powder Coating

Applies a thick, durable polymer coating that is highly resistant to scratches and corrosion. Available in a vast range of custom colors and textures.

Polishing

Manual sanding and buffing processes used to achieve a mirror-like finish on metals or optical clarity on transparent plastics like Acrylic and Polycarbonate.

Brushing

Creates a unidirectional satin finish by abrading the surface with a fine grit belt or wheel. Commonly used for decorative aluminum panels.

Surface Finish FAQ

What is "Ra" Surface Roughness?

Ra (Roughness Average) is the most common parameter for measuring surface roughness. It represents the average height of the microscopic peaks and valleys on a surface. A lower Ra value indicates a smoother surface. For reference, a standard machined finish is Ra 3.2 μm, while a polished surface can be Ra 0.1 μm or lower.

How do I specify a surface finish on my drawing?

The best way is to use the standard "check mark" surface finish symbol on your 2D drawing. You can place this symbol on the specific surfaces that require a finish different from the standard. For example, you can call out a specific Ra value or simply state "Bead Blast for Matte Finish".

Does adding a finish affect my part's dimensions?

Yes, this is a critical design consideration. Anodizing and powder coating add thickness to a part (0.005mm - 0.15mm). You must account for this in your design for features that require tight tolerances, like press-fit holes or sliding interfaces.