Polishing is the process of creating a smooth and shiny surface by rubbing the metal or using a chemical action, leaving a surface with a significant specular reflection.  Polishing is also able to reduce diffuse reflection to minimal values.

When an unpolished surface is magnified thousands of times, it usually looks like mountains and valleys. By repeated abrasion, those “mountains” are worn down until they are flat or just small “hills.” The process of polishing with abrasives starts with coarse ones and graduates to fine ones.

Parts Polishing: The Ultimate FAQ Guide

Parts polishing refers to the process of removing abrasions and scratches from surface material and forming desired finish brightness on it.

This process evens out part surface by using abrasive elements to remove the scratches and any unwater layers.

In this article, we will discuss numerous details about parts polishing, including its benefits, types, tips, surface preparation, factors to look into, etc.

How Does Parts Polishing Take Place?

You can perform parts polishing using several varieties of abrasives.

Essentially, the most appropriate abrasive material for polishing is mainly dependent on the part’s condition.

If you are polishing parts with an unfinished surface, the process will entail several phases.

During the first stage, a rougher abrasive material is used specifically to remove imperfections from the material used.

In the subsequent stages, relatively fine abrasive substances are used essentially to leave the parts unmarked.

To attain a mirror-like finish on the part, you will apply polishing and buffing compounds using polishing wheels and high-speed polishers.

Of course, you can apply some polishing materials such as wax, kerosene, and a number of lubricants.

But to attain a brighter finish performing buffing with assistance of stationary polishers, specialized automated devices, and die grinders is recommended.

If you are polishing relatively soft parts such as brass, it is advisable to use a fine-grit copper platted material to smooth out marks from impurities.

Even so, some parts, due to their unique requirements, are often subjected to different polishing processes.

Tools such as hammers, chisels, and wrenches initially need roughing using a grinding wheel and finished using dry polishing materials.

If there is a necessity for extra fine polish, greasing is performed on the part.

Polished aluminum parts

Polished aluminum parts

What Are The Main Parts Polishing Methods?

You can use different techniques to polish parts.

Ordinarily, the most suitable method depends on the features of the part material and its specific condition.

The major methods you can use include the following;

Direct Machine Polishing

It entails using specialty tooling to provide a polished finish on part with a machine.

This method is somewhat technical but most suitable for producing different complex surface profiles with flawless finishes.


It is a parts polishing method that uses an abrasive substance and a work wheel or any other component.

You can use this technique to attain a microscopic surface finish on the parts.

However, it is mostly suitable for polishing the external sections of the specific part.

Vapor Polishing

This polishing method entails use of solvent vapor flowing over the part’s surface to produce a fine finish.

The results of this technique depend on the actual initial condition of the part.

Nonetheless, this polishing method smoothens out all possible irregularities and is also ideal for parts with complex designs.

Flame Polishing

It uses a high-temperature hydrogen-based flame to polish the surface material of the part.

Technically, the flame is flowed over the part, melts it, slights, and subsequently polishes the surface.

What Are The Types Of Parts Polishing Available?

They are quite several, but the popular ones often used in many parts include the following;

Mill finish – It is the surface texture and appearance of the part in its raw form attained immediately after manufacturing. Quality of this finish often varies based on production method, manufacturer, and specific part properties.

Electro galvanization – This is a type of polishing attained through electroplating process to provide rust, corrosion, temperature, and wear resistance.

Anodized finish – It is a type of parts polishing attained by electrolytic passivation process, which creates an additional natural oxide surface layer.

Brushed finish – Usually, it is referred to as a satin or dull finish. It features a distinctive moderate luster with fine grits running parallel to brushing direction.

Bright polished – It is attained by using polishing compound and soft buffing mop to form a bright and reflective surface. This polishing is only applied to stock parts with zero defect surface.

Back steel – This type of polish has a distinctive blue surface, which features a scaly, dark iron oxide surface coating.

Mirror finish – It is a polishing finish attained by process of fine pre-grinding the part to remove imperfections and surface defects. It is followed by a buffing cycle using a polishing compound and soft mops.

Copper wash – This is a surface finish mainly applied to mild-steel parts by completing an electrolytic process cycle.

Galvanized polish – Common in steel or iron parts achieved by subjecting them to multi-stage process to produce wear, temperature, and corrosion resistance.

What Are The Best Tips For Parts Polishing?

Technically, the best tips for parts polishing often vary depending on the specific type of part material and its condition.

Nevertheless, the general tips to observe when polishing different part materials include the following;

  • Ensure you select the right application-specific tool for the particular project. In essence, it increases productivity and reduces total costs.
  • Always make sure all pre-grained parts have a consistent pattern. Hence, when you weld more than two parts, ensure you align the grain lines in same direction. Ideally, it is always difficult to correct a mistake early in the process.
  • Simple finishes like grain running the rail’s length have a lower time-cost factor than complex finishes. Thus, you should always be aware of customer’s expectations and ensure you provide preciseness.
  • Always understand that haste makes waste, and achieving the best finish requires time and patience. Using shortcuts in the process eventually reduces productivity and fails to attain desired finish.
  • Use the suitable polishing compound depending on the particular part material you are polishing. Different polishing compounds are designed for different part materials.
  • Always put on appropriate safety gear when polishing parts.

Which Materials Can You Polish?

 Polished copper parts

Polished copper parts

You can always polish a wide range of metal materials using different polishing techniques to attain desired finish.

The common materials to polish include the following;

  • Aluminum
  • Copper
  • Steel
  • Titanium
  • Gold
  • Nickel silver
  • Monel
  • Tool steels
  • Alloys
  • Bronze
  • Iron
  • Magnesium
  • Zinc
  • Brass
  • Silver

What Is The Best Abrasive For Parts Polishing?

Often, different abrasives are used in parts polishing depending on strength of the material.

For instance, it would be ideal to use gray silicon carbide abrasives on low-tensile strength metals like copper, brass, aluminum, etc.

In contrast, grey and white aluminum oxide abrasives are suitable for high-tensile strength metals like iron, carbon steel, and nonferrous alloys.

Additionally, you may use leather and canvas, especially when polishing wheels.

Other ideal abrasive materials you may consider depending on the part you are polishing include; rubber, felt, plastic, and paper among others.

What Are The Benefits Of Parts Polishing?

The main advantages of parts polishing include the following;

  • Allows you to add a remarkable sheen on the part surface, making it aesthetically appealing.
  • Increases parts’ service lifespan since it enhances corrosion, wear, rust, and temperature resistance.
  • It is easy to clean and maintain polished parts since the polishing compound applied on the surface deter dirt and dust.
  • Decreases unnecessary breakdown in machines, which is vital in preventing downtime usually caused due to rust and corrosion of parts.

What Are The Main Surface Preparation Methods In Parts Polishing?

Surface preparation is integral in parts polishing since it determines the efficiency and ultimate results of the process.

The common methods for preparing parts surface for polishing include the following;

Wet Sanding

It involves scrubbing the part using relatively wet sandpaper.

When using this process, it is advisable to start with coarser grit sandpaper gradually into finer grit sandpaper.

Additionally, it is important to keep the sandpaper wet to avoid clogs.

Using A Grinder

This surface preparation method involves using a sanding attachment on a die grinder.

It is an ideal option to consider, especially if you are polishing parts with curved surfaces such as intake manifolds.

What Are The Common Defects In Parts Polishing?

Here are the common parts polishing defects;

Over-polishing – Often, this causes poor quality finish on the parts’ surface.

Orange peel – It refers to the irregular rough surface on a part commonly caused by overheating part surface.

Pitting corrosion – This usually arises due to hard and brittle non-metallic impurities in metal parts pulling from the surface during polishing process.

Which Factors Should You Consider In Parts Polishing?

The common factors involved in parts polishing include the following;

Metal quality – Often, the quality of part metal vary, and in many instances, a bad casting is likely to cause issues.

Part condition – It is an imperative consideration since it determines where to start the process from.

Abrasive choice – Always consider appropriate abrasives to get an even surface with zero deep scratches to guarantee a deep mirror finish.

Speed – Ensure the polishing mop runs at an ideal speed to guarantee an even surface.

Polishing direction – If possible, always alter the polishing direction for each process, albeit by a few degrees.

Why Is Quality Of Parts Polishing Critical?

  • It determines whether the part will attain the desired aesthetic appeal. Quality polishing process using right tools and substances guarantees desired results.
  • Makes it easy to establish the durability of the parts since high-quality polishing ensures extended part longevity.
  • Enhances your brand, which is critical in business sustainability, growth, and expansion.

Which Factors Determine The Cost Of Parts Polishing?

Quite a number of factors, but the main ones include the following;

  • Actual condition of the part material. Ideally, the worse the condition, the more expensive it will be.
  • Type of polishing method – The cost of different polishing techniques vary depending on the equipment used and intensity required.
  • Type of polishing compound/abrasive – Some polishing abrasive compounds are costlier, whereas others are a bit affordable.
  • Parts quantity – Ordinarily, most companies often offer discounts on bulk orders, which is somewhat more cost-effective.

What Is The Ideal Turnaround For Parts Polishing?

Usually, it depends on a wide range of prevailing factors such as the following;

 Polished zinc parts

Polished zinc parts

  • Parts quantity – Often, the more the parts, the longer this process is likely to take and vice versa.
  • Parts design – In essence, simple parts are relatively easy to polish than complex ones, which may require more time.
  • Polishing technique – Different polishing methods can take different timelines depending on the intensity and equipment used.
  • Company policies – Various companies offering parts polishing services also have stipulated timelines. Thus, you need to inquire to determine whether the turnaround suits your needs.

Essentially, there is no definite turnaround for parts polishing. It varies based on many factors, including the few ones mentioned here.

What Are The Shortcomings Of Parts Polishing?

It has a few disadvantages, which include the following;

  • Depending on the specific method you are using, it may require high labor intensity
  • Can cause severe pollution to the environment
  • Gloss cannot necessarily be consistent in complex parts

How Do You Polish Parts’ Edges?

You can use several approaches such as the following to polish parts’ edges;

  • Flame polishing – It involves milling the edges and passing them through a high-temperature flame over the edge to a high luster.
  • Machine polishing – It is a low-cost and low-stress polishing technique ideal for edges.
  • Bullnose edge – This involves rounding over the top and bottom edges of the part.
  • Hand polishing – It entails milling the edges to remove the cuts and sanding through different grits before buffing.

What Are The Main Applications Of Parts Polishing?

Parts polishing is used widely in different sectors such as the following;

  • Kitchenware
  • Handrails
  • Construction
  • Aviation
  • Cookware
  • Automobile parts

What Are The Health And Safety Requirements To Adhere To In Parts Polishing?

Ordinary parts polishing process can be harmful to your health.

Hence, it is imperative to adhere to different health and safety requirements, which include the following;

  • Ensure you wear and use safety equipment always to prevent the chemicals and related substances from getting into your body. Some of these equipment include gloves, dust masks, safety goggles, etc.
  • When polishing any part, ensure you apply it to the area of rotating mop away from you.

At Inox, we can polish all you die cast components, depending on your requirements and specifications.

Of course, this is alongside other surface treatments options.

Contact us now for any questions or inquiries about metal parts polishing.

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