Appearance is Everything

Typical Machined Surface

This is a typical CNC Milling surface finish.  It has a characteristic arced crisscross pattern that is visible and a pass line (2 horizontal lines shown) .  A surface finish of Ra 32 is visible but, the lines are difficult to detect by touch.

Surface Textures

Above is a before and after simple textured surface. The part on the left is a stainless steel part made of  17-4PH (AMS 5643) part is shown "as turned". Right side shows part after a "fine glass bead blast".  Glass bead are round in shape creating a spherical dent, this creates an ultra matte finish.  If sand (cubic shaped) is used it creates a similar finish, but will have the occasional sparkle due the to flats from the cubic dents.

Blue Anodize and Laser Engraving

This aluminum mini flashlight has been blue anodized and then laser engraved.  When laser engraved, the letters are created in white.

Lapping and Coatings

This fuel Injector part has special coating to minimize wear and lapped surfaces for an optimized fluid seal.

Machined Surface

Machining metal and plastic creates unique marks that identify the method of manufacture. But, sometimes these marks are not desireable.  The measurement of the surface roughness in layman's terms is the average amplitude in microinches of the  surface. A typical milling operation produce finishes in the Ra 32 (Root means squared average microinches of amplitude) to Ra 64 range. A highly lapped or polished surface would be Ra 2.  By varing the feed rate, cutter technology and coolant used, Protomatic has achived a surface finish as machined in the Ra 4 to 6 range.  This can remove secondary operations such as lapping or polishing.

Sanded Finish

Another way that Protomatic changes the finish is simply a fine sanding.  This can be done to almost all materials.  With various grits of sand paper. A 240 grit paper produces a coarse finish, 320 grit a medium, 600 grit paper produces a fine, 1500 grit is ready for polish.

Textured Surface

If a uniform matte finish is desired. Glass Bead blasting is an inexpensive option. Tumbling with abrasive media or electrochemical processes  are posible.

Polished Finish

Polishing is accomplished by machining, and sucessive sanding operations. Polishing compounds typcially utilize one of four common medias: aluminum oxide, silicon carbide, sapphire or diamond.  These abrasives are commonly suspended in a lubricating solution such as water, oil, grease or wax.

Anodize and Passivation

Common surface stablization methods are anodize and passivation. Anodize is basically a controlled corrosion with an impregnated dye and seal. Passivation is an acid etch typcially used on stainess steel to create high surface chromium to prevent long-term rust.

Plating

There are hundreds of different plating processes available.  Some of the more common are:  Zinc, phosphate, black oxide, electro-less nickel, chrome, cadmium, tin, lead, silver, and gold.

Coatings and Paints

Dry Film Lubricants and CARC paints are also common. Powder Coat, and E-Coat are also available.  These coatings are very tough and provide reliable and long term coatings that are perfect for most applications.