There are several elements required to achieve the ideal microfinish on metal surfaces. The perfect microfinish can greatly increase the longevity of many components and help businesses meet industry standards, but it's important to know what to look for when seeking metal finishing services.
Here are some of the things you should consider to make sure you get the right finish for your equipment.
All manufacturing equipment needs occasional microfinishing
Over long periods of time, manufacturing machinery experiences wear through heavy use like many other types of equipment. However, the type of finish depends on the manufacturing the process and the kind of damage it causes. For example, electrical discharge machining tends to leave recast layers on metal components, which make the surface rougher.
While many perceive blasting as an effective way to improve metal surfaces and make them smoother, the fact is that this process simply masks scratches and other types of wear while actually making the surface rougher. Because of this, blasting is not advisable for Ra improvement on metal surfaces.
Achieve high-quality finishes with microfinishing processes
Metal parts involved in medical, hydraulic, pneumatic, and other processes require low Ra values to function optimally and avoid potential breakdowns. The right Ra value keeps the metal conductive and helps avoid arcing that can actually damage machinery.
The medical industry utilizes MRI imaging machines that produce high voltage that can easily damage internal components if there isn't sufficient conductivity between parts. Other applications such as pneumatics require parts with minimal friction to function well. Microfinishing can help reduce friction through smoother surfaces.
Some processes are more suitable than others
The Ra of a metal part is largely dependent on the manufacturing process used to fabricate it. Metal components may have an initial Ra value that is far from ideal, and parts with a higher Ra value will need to go through secondary operation to lower it.
To help achieve the desired Ra value, electropolishing and mechanical polishing are available. Mechanical polishing involves the use of grit sizes in wheels or belts to provide smoother surfaces for parts. Electropolishing is a similar process that removes a layer of metal from a component's surface to lower the peak to valley ratio and subsequently lower the part's Ra value.
While mechanical polishing may be better for certain components, it can be a costly service, and electropolishing is as effective while remaining less expensive. In many cases, both mechanical polishing and electropolishing are combined to help reduce costs.
The electropolishing process is capable of lowering Ra values by up to 50%, producing a high-quality part that's in almost new condition. However, this service is more suitable for parts with Ra values at a maximum of 32. Parts that have a Ra value greater than 32 may benefit from secondary services to achieve a desirable surface smoothness.
In addition to lowered Ra values, electropolishing can provide several benefits such as deburring, fatigue life improvement, and improved resistance to corrosion.
Taking each of these aspects into consideration, you can determine which metal finishing process will provide the best microfinish for your metal parts and keep your equipment running the way it should.
This story is reprinted from material from Able Electropolishing, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
