stainless steel polishing guide

Stainless Steel Polishing: The Ultimate Guide

Polishing stainless steel parts gives them dynamic, attractive and unique look. This page takes you through the vital aspects of stainless steel polishing.  So, before starting your next metal polishing project read this guide.

What Is Stainless Steel Polishing?

Stainless steel polishing is a process that eliminates scratches and imperfections from the surface of stainless steel. It tends to create a mirror-like finish on the surface of the polished metal.

 

Benefits Of Polishing Stainless Steel

Aesthetics
Aesthetics

Stainless steel polishing ensures that the surface of the metal is improved and ensures the final product looks luxurious.

Corrosion Reduction
Corrosion Reduction

Polishing the surface of stainless steel ensures that there is a reduction in the size and number of crevices that encourage rust in the metal.

Eliminates Contaminants
Eliminates Contaminants

When stainless steel is polished, it eliminates the possibility of contaminants from its surface thus making it suitable for given applications.

Increased Durability
Increased Durability

Polishing stainless steel serves as a protective sealant to the surface of the metal thus increasing its lifespan.

Polishing Stainless Steel To Matte Or Mill Finish

Matte or mill finish tends to be a finish that is unpretentious as it needs less time, expense, and effort as compared to other techniques. To form a smoother look, this finish normally tends to somewhat look incomplete although it can be used as a beginning for a long process of producing a great appearance.

It tends to be used for practical applications such as workbenches or kitchen sinks. To get a matte finish, the steel needs to be rolled using special rollers or dies.

Polishing Stainless Steel To Matte Or Mill Finish
Polishing Stainless Steel To Brushed Finish

Polishing Stainless Steel To Brushed Finish

Stainless steel tends to obtain decorative patterns comprising of delicate parallel lines through a brushed finish. It does not produce the typical reflective sheen which stainless steel is popular for although it works well where metals need exposure to bright indoor lights.

It is mostly used for kitchen appliances. Its disadvantage includes the reduction of the resistance of stainless steel to corrosion depending on a given application. Again, it is advisable to rust-proof stainless steel to avoid its downside and ensure that it is durable. Brushed finishes need an abrasive of high grade to ensure that the lines are uniform.

Polishing Stainless Steel To Gloss Finish

The polishing of stainless steel to a gloss finish tends to enhance corrosion resistance because it smoothens crevices in places where rust can collect. Besides, the chrome-like shine that it produces is suited for automotive parts and needs the surface to be well prepared.

Additionally, the surface should be prepared using a buffing compound of high quality and a grinder that has a polishing wheel. Remember, with stainless steel, you can also achieve a mirror-like shine once buffing has been done.

Polishing Stainless Steel To Gloss Finish
Polishing Stainless Steel To Mirror Finish

Polishing Stainless Steel To Mirror Finish

Mirror finish helps stainless steel to achieve the look which is known for; a highly reflective appearance, smooth finish, and scratch-free look. It helps in hiding welded metal and ensures cleaning the stainless steel is easier. Polishing stainless steel to obtain a mirror finish needs either a 30-grit belt or wheeler.

It can also be achieved using a progressive series of polishing compounds and abrasives. Mirror finishes are mostly used for stainless steel products which require to appear attractive such as architecture, artworks, kitchen/bathroom tap-wear, and balustrades. It ensures that stainless steel appears beautiful and is resistant to corrosion.

Step-by-Step Stainless Steel Polishing Process

Step-by-Step Stainless Steel Polishing Process
Step-by-Step Stainless Steel Polishing Process

The step-by-step stainless steel polishing process entails:

Level The Weld

First, you will require to remove the weld to ensure that the fabrication process is great and that the stainless steel obtains a mirror finish. It is important to make sure that you carefully level the weld to eliminate the chances of gauging or distorting the work. Machines that are used for this process tend to use a new generation ceramic grain for cool cutting, aggressive and long life due to the sharp crystal-shaped grain. They also make use of a specialized top coating to reduce friction, clogging, and heat build-up, and maintain the brain’s sharpness.

Sanding

Once the weld has been leveled and heavy fabrication marks removed, these areas should be made up to the base product finish by sanding the entire piece to ready it for polishing. You should set the sander to 4000-6500 RPM and move it at ninety degrees angle to the scratches which have been made in step one.

It is important to make sure that the previous scratches are eliminated. The fabricated areas are sanded well until they look like the finish of the original sheet and once done, ensure you begin sanding the entire surface. The higher the mirror finish required, the more sanding you will be required to do.

Polishing

Once the sanding of the stainless steel is done, it will be ready for polishing. In this step, you will need to use your sander with a clean polishing mop and use a slow setting to apply a polishing compound to the mop. Finally, you should set the sander to about 2000- 3000 RPM and polish the stainless steel. Some of the processes used in polishing stainless steel include:

  • Belt sanding: it uses belt grinders or belt sanding tools in the mechanical rotation of materials that are scrapped to ensure the surface of stainless steel is abraded. These belts tend to have varying grit levels such as low or rough grit levels at the beginning and high or fine grit stages at the end.
  • Edge polishing: polishing the edges of stainless steel requires the use of enough pressure to eliminate contamination and corrosion at high contact points.
  • Face polishing: it uses ceramic abrade and different polishing grits in polishing the surface of stainless steel.
  • Grinding: there are various types of grinding machines for this process that help achieve different shapes of metal such as plates and pipes. Grinding tends to be rougher as compared to other processes and is mostly used at the initial stages of the polishing process.

Some of the factors to observe to achieve the best results in the process above include:

  • Cleaning the surface of stainless steel before sanding.
  • Ensuring that sanding is carried out in the direction of the original metal grain to blend in the weld.
  • At each subsequent sanding stage, movement should be in a direction ninety degrees from the previous direction of sanding. This will eliminate all scratches.
  • Ensuring that a clean polishing mop is always used.

Characteristics Of Stainless Steel Affecting Polishing

Work Hardening
Work Hardening

It tends to develop hardness at increased levels on the application of stress to its surface for a long time. Therefore, it is important that polishing it be precise and fast in finalizing the task prior to condition changes making the abrasive agent unsuitable. Expert metal polishing operators do have processes to ensure that the process is quick to avoid overworking the metal.

Passivity
Passivity

Stainless steel tends to have passivity properties that require the use of rapid polishing speeds. Rust and corrosion majorly occur at the upper part of the stainless steel. Rapid polishing speeds are ideal when it comes to cutting the steel layer which oxidizes immediately after cutting. The hardness of this new layer might then inhibit polishing stainless steel if operators are not working fast enough.

Types Of Stainless-Steel Parts For Polish

Angles

You should polish angles especially for aesthetic purposes and also for ensuring sturdiness of the various applications of the stainless steel. Also, you should ensure that the stainless steel do not loose the measurements and placements during the polishing process.

Channels
Channels

They tend to be appropriated with either an internal or external surface that is smooth especially when required for conveyance systems or industrial equipment.

Plates
Plates

They can be finished at a lower finish type for several functional uses. A higher finish that is lustrous may be obtained for applications that need pleasing aesthetics by use of scotch-brite equipment.

Sheets
Sheets

Polishing tends to make sheets possess an aesthetic value, become clean, smooth, and neat when it comes to inspection.

Tubing And Pipe
Tubing And Pipe

It is important to ensure that polishing of pipes and tubing is done both internally and externally. This is vital for ensuring that no residue remains inside or outside the fittings. Again, it also prevents corrosion of the tubing and oxidizing the surfaces over a period.

Applications Of Stainless Steel Polishing

Architectural Industry
Architectural Industry

It produces products like reflectors and mirrors used in construction. Stainless steel also serves as the surface in clean rooms by making products such as wall panels, countertops, handles, and doors.

Food And Catering Industry
Food And Catering Industry

Stainless steel polishing is used as kitchen accessories, cookware, and cutlery. Its use ranges from blades to molded shapes such as saucepans, grills, sinks, and cookers.

Offshore Technology Industry
Offshore Technology Industry

It is used in pipework for the transportation of hydrocarbons and petrochemicals for seawater systems.

Storage Tanks
Storage Tanks

It is used in holding corrosive substances like gases, chemicals, food, water, and several other bulk materials.

Medical Industry
Medical Industry

It is alloyed with chromium, molybdenum, and nickel to form essential qualities required by surgeons. Chromium is important for sterilizing and cleansing, nickel for machine precision, and molybdenum for cutting edges like scalpels.

Power Plants
Power Plants

Stainless steel polishing is a perfect choice in heat exchanges, pressure tubes, reactor tanks, and transformer enclosures.

Stainless Steel Polishing
Stainless Steel Polishing FAQ
What Are The Types of Stainless Steel Polishing Finishes?

Some of the types of stainless steel polishing finishes that are measured on a scale of 0-10 include:

  • #0: used for hot-rolled plates which are thicker.
  • #1: mainly applied for plates that are hot rolled.
  • #2: it is subdivided into the following categories
    • #2D: it is pickled, annealed, and passivated.
    • #2B: involves several steps and also incorporation of the #2D metal.
    • #2A: ideal for oxygen free environment to minimize corrosion.
  • #3: it uses coarse mechanical abrasion.

types of stainless steel polishing

The finishing categories which are remaining are defined by the result rather than the methodology and they include:

  • #4: resembles #3 although it features a higher reflectivity and polish.
  • #5: satin
  • #6: satin (scotch-Brite)
  • #7: is reflective but not clear
  • #8: mirrored
  • #9: is ultra-mirrored with a bead-blasted surface.
  • #10: heat-coloured and electropolished
Which Compounds Do You Use In Stainless Steel Polishing?

Some of the compounds used in polishing stainless steel include:

  • Brown tripoli: it is used in refining and cleaning and it tends to remove scratches and form a slick finish.
  • Green rouge: it deals with burnishes and helps to create an improved and high-quality polish for stainless steel.

Green rouge

  • Greystar: it helps in giving fine abrasives and elimination of fire scale. It should be used with a fixed buffing wheel to achieve better results.
  • Polina: it is an orange compound that gives stainless steel a gorgeous sparkling finish.
Do Polished Stainless Steel Rust?

Generally, polished stainless steel does not rust but if maintained or used improperly or in harsh environmental conditions, it may tarnish. It is therefore important to make sure that polished stainless steel is maintained and cleaned using the instructions given by the manufacturer to ensure durability.

Why Is Buffing Stainless Steel Important?

Buffing stainless steel is important because it makes it possible to smoothen out any flaws like small shallow cracks, burrs, or scratches.  This eliminates the possibility of debris from collecting and ensures that there is a restoration of the quality of stainless steel.

Why Is Buffing Stainless Steel Important

How Can You Get Brushed Or Matter Finish In Stainless Steel Polishing?

This is obtained using either one or two buffing levels such as 240 grit and then 300 or 400 grit. A brushed pr matte finish is generated using 150 to 240 abrasive belts that are coated or medium-fine nonwoven abrasives or drums.

How Do You Machine Polish Stainless Steel?

Machine polishing stainless steel entails the following steps:

  • Polishing stainless steel using a machine tends to be more efficient and produces a shiny final product.
  • In case the buffing stage was carried out correctly, inclusive of the cut and color buffing, then your stainless steel will be looking well. However, if the compound used left behind something which inhibits some of the shine, you will be required to eliminate it using the machine.
  • Once this is done, use a quality stainless steel polish and a buffing pad or polishing wheel.
  • Repeat this process over your piece for about five or ten minutes to eliminate residual compounds and any other remaining features.
  • Ensure that any excess polish is wiped out well.
  • All the above steps will make sure that no matter the finish selected, the final product will appear shiny without any notable streaks and blemishes.

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