HOW TO FINISH PRECISION PARTS

How to Finish Precision Parts

Many industry sectors utilise precision turned parts in their machinery and equipment. These components are usually made to order by precision engineers using incredibly-accurate laser measuring and cutting technology. Since these parts are produced to meet the exact specifications of the client, there can be little room for error.

As important as these components are, it is essential that they are properly protected when being put to their intended use. Fortunately, there are several finishing techniques that can be applied to these precision parts that will not negatively impact their performance.

Electroless nickel plating is a popular choice for finishing milled and turned components. The process involves submerging the machined parts into a chemical bath containing a catalyst that deposits nickel ions onto the surface of the substrate. The process is a highly versatile one – depending on the make-up of the chemical bath, it is possible to impart a range of properties to the components, including a harder finish, greater corrosion resistance, and so on.

The main benefit of electroless nickel plating when dealing with precision parts, is that the nickel is deposited uniformly across the substrate. This allows engineers to calculate precisely the thickness of plating required and account for that in their calculations and design.

Electroplating

For large turned components, electroplating is another popular technique. Several metals can be plated onto the substrate using this method, including silver, copper, gold, and zinc, among others. As with electroless plating, the components are submerged into a chemical vat, through which an electronic current is passed, joining the target parts with a piece of pure plating material in a circuit. Whilst less effective on smaller precision components, this method offers greater versatility in the types of metal used for plating.

Passivation

Unlike plating, which deposits a layer of new material onto the substrate, passivation is a technique that chemically changes the surface layer of the substrate itself. The parts are, again, dipped into a chemical solution, and this changes the nature of the substrate. Different base metals and chemical solutions can create different effects on the substrate, but are all useful when dealing with small, precision parts.

Strictly speaking, anodising is a form of passivation, but it deserves a separate mention here. Anodising increases the thickness of the oxide layer on the substrate’s surface. Not only does this increase the component’s resistance to wear and corrosion, it also reduces the risk of galling on threaded screws and fasteners. For precision turned components, this is particularly important.

Get in touch

For advice on the best coating technique for your precision components, contact Karas Plating today. Call us on 0333 121 0151 or a free, no-obligation quote.