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Sheet Metal Grinding – Beginners & Experts Guide

Sheet Metal Grinding

Probably, you are wondering whether sheet metal grinding is a primary or secondary operation in the metal fabrication process.

Or, you would like to know how to grind sheet metal, choose effective grinding tools, improve efficiency, and get a perfect surface finish.

Well, this guide is your go-to resource for grinding sheet metals. In case you want to be an expert in any grinding operation, then you are on the right track.

What is Sheet Metal Grinding?

Grinding is a mechanical process where;

  1. An abrasive tool removes very fine particles from the main sheet metal
  2. The final product has a custom surface finish which is mostly smooth or uniform

Therefore, in this case, you will perform a grinding operation on sheet metal.

To some extent, you may classify grinding as a sheet metal cutting technique. Where the cutting tool is the rotating disc.

Reasons for Grinding Sheet Metal

Sheet metal grinding part - Photo courtesy: Napoonline

Sheet Metal Grinding Part – Photo courtesy: Napoonline

Sheet metal fabrication processes do not produce perfect finishing. A reason you must adopt other finishing operations such as metal grinding processes.

Take for example:

  • Cutting sheet metal may leave uneven surface finish edges
  • Welding joints may have a rough finish
  • There could need for custom or sharp edges
  • Other machining operations may cause burrs on the final products

Since you need a perfect surface finish, the sheet metal grinding process will eliminate all these imperfections. As a result, you will have a polished surface, with high accuracy, low surface roughness, and zero imperfections.

Grinding will help achieve dimensional accuracy in fabricated sheet metal parts.

You can only enjoy these benefits of metal grinding by adopting the right technique, using the best equipment, and working with experts.

Choosing Sheet Metal for Grinding Process

Grinding process in sheet metal fabrication - Photo courtesy: Evanto

Grinding Process in Sheet Metal Fabrication – Photo courtesy: Evanto

Grinding sheet metal is a versatile fabrication technique. After choosing the best grinder, technique, and lubricant, the process will be straightforward.

Remember, grinding some sheet metals may require special fabrication conditions. Let’s look at the most common materials:

Sheet MetalFacts to Know Before Grinding
Aluminum sheet metal
  • Machinability varies depending on the alloy. For instance, the 6xxx series is easy to machine
  • Some alloys are not suitable for cylindrical grinding
Brass sheet metal
  • Machinability varies from fair to poor depending on the alloy
  • Not all alloys are suitable for cylindrical grinding
Cast iron sheet metal
  • Good machining properties
Mild steel sheet metal
  • Good machining properties
Stainless steel sheet metal
  • Requires special grinding wheels due to their susceptibility to work hardening. Besides, stainless steel is also tough.

Again, even as you grind sheet metal, it is important to know the implications. That is, grinding may affect certain sheet metal properties.

A reason, you may add certain finishes to improve sheet metal part performance characteristics. Some common effects include:

Altering Chemical Properties

Grinding may expose stainless steel and aluminum sheet surface to oxygen. As a result, the protective layers fail to form (which is rare). As a result, the sheet metal will be susceptible to rusting.

Changing Mechanical Properties

Being a mechanical fabrication technique, grinding will expose sheet metal parts to various stresses. At times, the high grinding temperature may cause micro-cracks.

All these may require further treatment.

Moreover, for ferromagnetic metals, grinding may compromise magnetic properties.

The good news – working with an experienced sheet metal fabricator will ensure your parts maintain desirable mechanical, chemical, and physical properties.

How to Determine the Cost of Grinding Sheet Metal

Many factors determine the cost of grinding metal parts such as:

  • Sheet metal grinding machine or tool requirement
  • Sheet metal part size
  • Surface finish requirement
  • Degree of imperfection on the fabricated sheet metal part
  • Labor requirement for the grinding process
  • Sheet metal fabrication service provider logistics costs

The best part, you can reduce the metal grinding cost. Of course, this is only possible if you follow the right metal grinding tips. We will discuss the cost-cutting tips later in this guide.

Types of Sheet Metal Grinders

Grinding forms an important aspect of the precision metal fabrication industry. Therefore, to get the best surface finish, you must choose an efficient metal grinding machine.

You can choose from the numerous sheet metal grinding wheels depending on the parts you wish to fabricate.

Although there are many sheet metal grinding machines, you can classify them as:

  • Portable sheet metal grinders
  • Stationery sheet metal grinders

Again, there are other metal grinding tools such as a metal file or any other abrasive accessories. These tools are best for small-scale and manual operations.

Whether you are planning for sheet metal grinding welds or any other operation, consider the following:

Hand Held Grinders

These are common tools you can use to grind sheet metal parts. They come in 4 main options – angle grinder, power drill, linear grinder, and die grinder.

Angle grinder

Angle Grinder – Photo coursey: Amazon

Type of Grinder for Sheet MetalUses Additional Information about Sheet Metal Grinder
Angle Grinder
  • A multi-purpose tool you can use for grinding
  • Grinding wheels remove material for most metals
  • Other options available include cutting-off wheels, sanding discs, wire brushes
  • When buying an angle grinder for sheet metal consider disc size, material type, power requirements, side handle, and safety requirements
Die grinder
  • Can grind and cut sheet metals in many configurations
  • Can grind and smoothen the metal surface
  • Die grinders may have other tools such as flap wheels for hard-to-reach surfaces, spiral bands, cross pads, and quick-change disks
  • Consider sheet metal type, tool power, safety features, and operation costs
Linear grinder
  • Can grind nearly all sheet metals
  • It has many abrasive drums for grinding such as nylon wire drums, buffing drums, non-woven drums, coated abrasive drums, and surface conditioning drums
  • Consider power requirements, grinding speed, safety features, sheet metal type, and surface finish requirements
Power drills
  • Suitable for hard-to-reach surfaces such as holes or corners
  • They may have cartridge rolls, wire wheels, spiral bands, cross pads, etc.
  • Always consider working area, sheet metal type, power requirements safety specifications, and surface finish requirements

It is important to note that these grinding tools for sheet metals are portable. However, there are other stationary grinding machines such as:

  • Bench grinder – it uses an abrasive wheel to grind sheet metal. The bench grinder also allows for tool replacement.

Bench grinder

Bench Grinder – Photo courtesy: East Wood

  • Belt grinder – this is another multi-purpose grinding tool. These tools are suitable for machining very rough surfaces.

Belt grinder

Belt Grinder – Photo courtesy: Amazon

As you can there are many tools you can use to grind metals. Choosing any particular tool will depend on your specific requirements and needs.

Step-by-step Sheet Metal Grinding Process

Simply put, how to grind metal involves these simple steps:

  1. Choosing suitable metal grinding tools
  2. Knowing the sheet metal sections you want to grind
  3. Clamping sheet metal (workpiece) in situations where you are using handheld grinding machines
  4. For stationary grinders, ensure the machine is stable
  5. Begin the grinding process – it is where the metal grinder cuts sections from the workpiece
  6. Check the quality of the metal part after grinding

For most mechanical grinders, the tooling system will move either in linear or rotary motion. As a result, it will remove all the unwanted sections.

Mostly, the main challenge comes in the metal grinding operation for sheet metal. Many grinding operations have proved efficient and economical depending on the task at hand.

Remember, you may wish to grind different part sizes and shapes or they may have very unique features. In such situations, you may require different techniques to grind sheet metal successfully.

Let’s look at some common options available:

Creep-feed Grinding Process

Creep-feed grinding removes material at a higher rate. You can compare it to the turning or milling process.

Before choosing this technique to grind sheet metal, it is worth noting:

  • Grinding depth can be 0.236 inches
  • It can achieve 1.6 μm Rma
  • Characterized by low material feeding speed

Although the technique is suitable for most grinding operations in sheet metal fabrication, the grinding wheel degrades faster. Additionally, the length is limited and the process may require more power.

In the current sheet metal fabrication industry, the creed-feed technique has witnessed significant improvements. These include adopting:

  • Continuous dress creep feed metal grinding – the process improves grinding productivity. During the process, you will dress the wheels at regular intervals.
  • High-efficiency deep grinding – this process reduces metal grinding costs, especially on the tooling. Their super abrasive wheels which are plated have a long service lifespan.
  • Peel grinding – the working principle is similar to the turning process in lathe machines. The grinding disc is thin and super abrasive.

Today, stakeholders in the sheet metal grinding industry are working in ultra-high-speed grinding. It is believed the technology will improve grinding speeds in the sheet metal fabrication industry.

Center-type Grinding or Cylindrical Grinding Process

When you have cylindrical sheet metal fabricated parts center-type grinding offers a perfect solution. With cylindrical grinding, you can achieve different tapers.

There are 5 center-type grinding options:

  1. Outside diameter grinding
  2. Inside diameter grinding
  3. Plunge grinding
  4. Creep feed grinding
  5. Centerless grinding

The grinding process involves parallel and radial movements. As a result, achieving a suitable surface finish is faster. Additionally, you can achieve very tight tolerances, which vary depending on customer requirements.

Surface Grinding Sheet Metal

A rotating abrasive material removes all unwanted imperfections from the metal surface. The tolerances vary depending on your specific requirements.

Although surface grinding is suitable for most materials, it is not a popular technique for aluminum sheet metal, stainless steel sheet metal, and brass sheet metal.

Electromechanical Sheet Metal Grinding

In this technique, a negatively charged grinding wheel grinds a positively charged sheet metal part.

Electrolytic In-process Dressing Grinding

If you are focusing on precision sheet metal fabrication, then consider electrolytic in-process dressing technology. It is one of the most accurate sheet metal grinding technologies.

It is a precision grinding technology. It is a unique process where grinding, electrochemical dressing, and metallic bond dissolution take place at the same time.

With these grinding technologies, you must know the sheet metal part you want to grind. After that, you will choose an appropriate technology for all your grinding operations.

Tips for Successful Metal Grinding Process

Grinding fabricated sheet metal parts

Grinding Fabricated Sheet Metal Parts

Even with the best sheet metal grinder, you will still need certain tips for a successful fabrication process. The tips range from technical specifications to safety aspects.

Take a look:

Metal Grinding TipHow to Benefit from the Grinding Tip
Choose the right tool
  • Choose the right grinding wheel for the metal since they come in different grits.
  • 16 to 24 grits best for coarse grinding
  • 36 to 60 grit suitable for medium
  • 80 to 120 grit for fine grinding
  • 150 or higher grit is best for super fine grinding
  • Choosing the wrong metal grinding wheel may damage the surface
  • Invest in high-quality metal grinding tool
Wear appropriate safety gear
  • You need safety gear such as gloves, safety goggles, dust masks, boots, and overall.
  • They will ensure you are safe when grinding metal
Grind metal using better technologies
  • A good example is the double-disc metal can reduce cost by half. That is, you will grind two metal surfaces at the same time
Check the spark flow
  • In an ideal situation, you should check the ammeter reading. That is, as you grind metal, the tool should use current ranging from 8 amps to 10 amps.
  • Alternatively, you can use a spark from a metal grinder as an indicator. On average, the sparks fall about 3 to 4 feet from the sheet metal you are grinding.
  • By following this simple rule, you will prevent possible overloading, and overheating of the metal grinder.
Know the sheet metal type to grind
  • The knowledge will help you adopt the perfect technique when grinding sheet metal.
  • Mild steel works well with most conventional grinding operations, which is not the case with stainless steel. Stainless steel or aluminum tends to have “gummy” characteristics.
  • Therefore, you will choose a suitable grinder for your unique finishing requirement and metal type.
  • Additionally, changing sheet metal material may require an adjustment in the technique you use
  • Again, there are heat-sensitive materials like stainless steel. Therefore, you must be cautious when grinding such metals.
Pay attention to the sound from the metal grinder
  • When grinding metal properly, the sound should have a constant pitch
  • Low pitch simply implies you are pushing the grinder too “hard” hence overworking the tool.
  • High pitch may imply the metal grinder blade is not in good contact with the workpiece.
Consider sheet metal grinding angle
  • As you grind metal, the disc angle should be about 5 to 10 degrees. Of course, you should determine this from the horizontal surface.
Grinding pressure should remain constant
  • Always apply reasonable pressure since overdoing it will cause overheating. Additionally, it will glaze the grinding disc grains.
  • At any given moment, the pressure should be constant either when moving the grinding disk forward or backward
  • Even as you consider pressure, it is vital to evaluate the feed and speed when grinding sheet metal
Know the grinding wheel material
  • High-quality grinding wheels will yield better results. For instance, most grinding wheels for machining sheet metals are made from aluminum oxide, silicon carbide, cork, or diamond.
  • A quality grinding wheel must not be too hard to cause plastic deformation on sheet metal. At the same time, it should not be too soft to an extent that it cannot withstand the grinding forces.
  • Additionally, even as you dress the grinding wheel, it must not affect the abrasive cutting edge or required surface roughness.

Remember, these tips for grinding metal will help you reduce operational costs. In most cases, working closely with your metal fabrication company will help reduce operational costs.

Common Sheet Metal Grinding Problems

Like any other sheet metal fabrication process, during grinding, you may experience certain problems. They may be due to:

  • Machine error especially when there are inconsistent configuration settings
  • Human error
  • Metal grinding tool malfunction
  • Poor material quality
  • Failure to follow instructions as per the design

As a result, you may experience the following problems:

  1. Uneven surface finish
  2. Possible plastic deformation during grinding
  3. Removing excess material than recommended
  4. Damaging toiling system for grinding
  5. Burred edges
  6. Possible twisting or bowing
  7. Grinding chatter

Well, you can solve all these by following the grinding tips we mentioned earlier. Just ensure you clamp the workpiece properly, know the sheet metal properties you are grinding, and use the right tool.

Applications of Sheet Metal Grinding

Using angle grinder

Using an Angle Grinder

Well, when you grind metals there are certain specific objectives you wish to achieve. Normally, grinding forms part of sheet metal fabrication activities.

You can use grinding alongside other metal fabrication techniques to make parts in:

  • Aerospace industry
  • Automotive industry
  • Medical and pharmaceutical industry
  • Home appliances
  • Food industry
  • Oil and gas industry
  • Lighting industry, just to mention a few.

In all these industries, grinding plays an integral role in removing unwanted sections on a metal surface.

How to Choose Sheet Metal Grinding Service Provider

Many metal fabricators are claiming to be knowledgeable in grinding sheet metal. In most cases, it becomes virtually impossible to judge whether the sheet metal fabricator is qualified for the job or not.

Here is a quick checklist you should consider:

  1. Sheet metal fabricator experience in the industry
  2. Accuracy and precision – it should include tight tolerance (e.g. +/- 0.001) and surface roughness (e.g. <6.3 Ra).
  3. Ability to incorporate suitable surface finish
  4. Experienced team to help in design, drawing, and other technical support
  5. Metal surface grinding capability – the ability to grind different surfaces such as welded sections, complex geometrical shapes, etc.
  6. Ability to grind any material such as stainless steel, aluminum, brass, copper, etc.
  7. Fully equipped metal grinding workshop with all tools and equipment
  8. Daily production capacity

At KDM, we can handle all your sheet metal fabrication needs. From normal to precision grinding metals, our team has years of experience in the metal fabrication industry.

We can grind all metal types depending on your custom requirements – talk to us now.

Quick FAQs

Are there Standard Tolerances for Precision Metal Grinding?

No.

The section accuracy will depend on the machine type. However, there it is possible to achieve +/- 0.003 inches, +/- 0.001 inches, or +/-0.0005 inches.  You remember that tolerance is critical in precision metal grinding.

Are Grinding and Surface Finishing Metal Parts the same?

Although some metal fabricating companies use grinding as a finishing operation, it does not imply the two processes are synonymous.

The two metal fabrication processes have different goals and objectives. For instance, you apply a surface finish on metal parts after finishing the whole fabrication process.

On the other hand, grinding metal may be part of the fabrication process before applying the final surface finish.

In some instances, a grinding process can leave deep scratches on a metal surface.

Can you Recommend a Suitable Disc for Grinding Steel?

An angle grinder is suitable for the steel sheet metal grinding process.

If you are grinding thin steel sheet metals – a 1.0 to 0.8mm will help. However, for normal grinding operations, a 1mm or 1.6 mm grinder can work.

Of course, the situation is slightly different when grinding aluminum sheet metal. Here, you will apply lubricant to preserve the cutting grinder’s lifespan.

Is Lubrication Important when Grinding Sheet Metal Parts?

Yes, lubrication plays an integral role in sheet metal grading. For instance, metal grinding lubrication will:

  • Cool both sheet metal and grinder
  • Help increase tooling system service lifespan
  • Prevent sheet metal parts from damage due to overheating and friction.

Some common grinding fluids for lubrication include:

  • Synthetic oils
  • Water soluble fluids
  • Petroleum based oils
  • Water soluble oils

Depending on the sheet metal type, you must choose a suitable lubricant. Let’s look at some common examples:

  • Light-duty oil – it is a perfect choice when grinding aluminum sheet metal, and brass sheet metal
  • Heavy-duty emulsifiable oil – you can use the oil to grind cast iron sheet metal and stainless steel sheet metal
  • Light-duty chemical oil – it is a perfect choice for cast iron sheet metal,
  • Synthetic oil – this is a good lubricate for grinding cast iron sheet metal and stainless steel sheet metal
  • Heavy-duty water-soluble oil – usually, it is best for mild steel sheet metal
  • Heavy-duty chemical oil – you can use this for grinding stainless steel sheet metal

Conclusion

Grinding plays an integral role in modern sheet metal fabrication processes.

By choosing a perfect grinding tool, understating how the grinding process work, and knowing material properties – the process will be seamless.

More Resources:

Ways to Grind Metal – Wiki How

Grinding Methods & Machines – American Machinist

Effective Grinding Tips – The Fabricator

Sheet Metal Fabrication – KDMFAB

Grinding – Wikipedia

Metal Grinding Tools – Benchmark Abrasives

What is Grinding – Metal Prospects

Metal Grinding Tools Guide – Empire Abrasives

Metal Grinding in Machining – Science Direct

Grinding Process – Summary Planet

Precision Metal Grinding – Metal Cutting

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