When is Sanding Preferable to Electropolishing?

February 9, 2017 | Steel Wire Products

Electropolished parts have a smooth, shiny finish compared to non-finished parts.Electropolishing is one of the most popular finishing processes out there for a reason. It leaves parts with a microscopically smooth surface, stripping away surface impurities, burrs, and sharps.

Manufacturers in the food and pharmaceutical industries use electropolished parts and trays for their enhanced non-stick properties. Other manufacturers may use electropolished parts to prevent galling or seizing in delicate mechanisms.

However, not all manufacturers prefer electropolishing for all applications. There are some situations where sanding is preferred to electropolishing, even though it is slower and somewhat less reliable than electropolishing.

When is sanding preferable to electropolishing?

When Rougher Surfaces Are Desirable

One of the biggest differences between electropolishing and sanding is that most sanding processes leave the part with a much rougher surface than electropolishing.

For some applications, a rougher surface may actually be preferable. For example, a sanded, gritted surface is a bit easier to grip manually than a smooth, featureless surface. This could make the sanded surface preferable for manual handling—although special care needs to be taken to ensure that sharps and burrs are completely removed.

Cost Effectiveness of Sanding Vs. Electropolishing

Depending on the intensity of the sanding process and the final finish desired, sanding may cost more or less than electropolishing.

A coarser finish that uses fewer passes may be less costly than electropolishing. Trying to achieve an electropolish-like finish with traditional sanding, however, can be parts and labor intensive.

To get a mirror-like finish with sanding, you’d need to use a series of progressively finer abrasive pads, from 100-200 grit pads down to 400-500 grit pads. In addition to requiring multiple passes, these pads would require frequent replacement to maintain optimum performance.

Between the time and labor required, the cost of abrasive sanding could easily exceed electropolishing over the course of making hundreds of parts.

Sandblasting is faster and easier than sanding with abrasive pads. However, it’s still inferior to electropolishing in terms of processing speed and final finish smoothness.

Electropolishing can have a higher initial setup cost to create the electrolytic bath. However, once it’s ready to go, the cost per part finished may be lower because of the reduced need for labor and replacement abrasive pads.

Which is Better?

In the vast majority of cases, Marlin Steel’s mechanical engineers would strongly recommend electropolishing over sanding or sandblasting. The smoothness of the final product makes it significantly better at preventing adhesive chemicals from sticking, and removes microfissures that could weaken the part.

However, there may be some cases where sanding may be the preferred option. So, which process is better for your particular parts washing or material handling baskets? Contact a Marlin Steel mechanical engineer with some details about your parts and processes to find out!

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