Metal Grinding

Metal Grinding: The Complete Guide

Metal grinding is an important metal fabrication process. Before starting any metal grinding process, it’s prudent to understand techniques, applications, and benefits, just to mention a few. So, if you want to learn about grinding metal, read this guide.

What Is Metal Grinding?

Metal grinding refers to an abrasive method that uses abrasive wheels in eliminating materials from workpieces. Each abrasive grain offers a sharp cutting edge which removes tiny chips from the surface of parts.  It removes little material amounts to obtain dimensions of tight tolerance on the surface of parts.

Benefits Of Metal Grinding

Effective
Effective

The removal rate of material in metal grinding tends to be higher as compared to traditional files thus making it a preferred method.

Smooth Surface Finish
Smooth Surface Finish

The surface finish that is got in metal grinding tends to be much better as compared to finishes obtained through a file or chisel.

Good For Hardened Surfaces
Good For Hardened Surfaces

It tends to be quite hard to remove metal from a surface when it has become hard. Metal grinding tends to be one of the solutions for fulfilling this function.

Requires Little Pressure
Requires Little Pressure

Metal grinding needs a very small amount of pressure thus making it easier in holding the metal, especially in processes that are automated by the use of techniques like magnetic chunks.

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Metal Grinding Safety Precautions

Inspection
Inspection

Each metal grinding machine must be regularly inspected before being used. It should also be color-coded and well maintained to ensure efficiency.

Machine Switch
Machine Switch

All-metal grinding machines need to be equipped with a ‘dead man switch’ which is a self-modification of the toggle switch. This is always strictly restricted to ensure that the machine serves the right function.

Machine Guard
Machine Guard

It is important to have a suitable guard as recommended by the manufacturer for your metal grinding machine. This guard should cover about seventy percent of the rotating disk’s circumference to ensure safety.

Unbreakable Glass
Unbreakable Glass

It is important to ensure that all static grinding machines are fitted with unbreakable glass or plastic screens that can be adjusted for protection from flying particles.

Choosing Metal Grinding Disc

It is important to select a metal grinding disk that is suited to the given function and will ensure that there are no production delays, quality issues, or material waste. You should determine the part that you need to grind such as tubes, wires, rods, or extrusions, and select the most suitable disk.

The type of material you want to grind is also essential as its physical properties have a great impact on the process of grinding. Additionally, ensure that the dimensions of the parts used are compatible with the process as grinding gives tolerance finishes on the surface.

Choosing Metal Grinding Disc
Metal Grinding Disc Vs. Metal Grinding Bits

Metal Grinding Disc Vs. Metal Grinding Bits

Metal grinding discs use open-web, abrasive infused construction, in giving flexibility and finesse during the metal grinding process. Each metal grinding disk tends to be manufactured with materials of high quality.

Metal grinding bits tend to be made from heavy material and can drill materials of any nature. Metal drilling bits tend to be suitable for the removal of flat surfaces, contour finishing, and removal of right corners angled and contours. The metal grinding bits are also able to process arc and contour surfaces at a given angle and machine round edges and end preprocessing before blazing.

Grinding Metal With Drill

Grinding metal with a drill ensures that the flat surface on the metal is removed and is well suited for contour finishing. When metals are ground with a drill, their round edges will be removed in both long and narrow positions thus ensuring it serves the required function.

Some types of drills are well suited for chamfering inner holes which are otherwise difficult to access with other grinding machines. Manufacturers tend to come up with diverse shapes of metal drills to ensure efficiency by making it seamless to drill very many hard-to-drill materials.

Grinding Metal With Drill
Metal Grinding Tolerances

Metal Grinding Tolerances

Depending on the final use of a given part, it may not be important to hold tolerances that are very tight on a given metal grinding machine. In effect, when a metal part is over-engineered, the costs may unnecessarily increase.

Therefore, it is important to be realistic and specific about the metal grinding tolerances required rather than always going for tight tolerances. It is not common to get one part with different attributes which need tolerances like surface finish and diameter. However, it is essential to focus on the feature which will have a bigger impact on the part’s functionality.

Metal Grinding Cost Considerations

Metal grinding tends to be a manual task that involves the use of a lot of labor and time. This labor-intensive part tends to make the metal grinding fabrication process quite costly as most parts require smoothing of edges and deburring.

Costs that are related to these grinding operations tend to directly relate to the general cost of the part. It will be essential for the separate calculation of costs where a part significant edge treatment like beveling as this will increase the overall cost.

Metal Grinding Cost Considerations
Difference Between Metal Grinding And Metal Cutting

Difference Between Metal Grinding And Metal Cutting

Some of the differences between metal grinding and metal cutting include:

  • The metal grinding process uses tools such as grinding wheels while metal cutting uses cutting tools. Functionally, the abrasive function served by the grinding wheel in metal grinding is similar to the tips of the cutting tools.
  • Metal cutting tends to be used as the pre-process processing while metal grinding serves as the post-process finishing.
  • Metal grinding tends to give better dimensional accuracy and surface finish, especially for workpieces with hard material as compared to metal cutting.

Metal Grinding Tips

Metal Grinding Tips
Metal Grinding Tips

Some of the metal grinding tips include:

  • Use of the right tool for the job: it is important to ensure the suitable grinder which can effectively carry out the task is used to achieve the desired results.
  • Be safe: when the right metal grinding tool is used, it will ensure that operations are safe. When grinders are used without guarding, they may result in injuries.
  • Listen to the grinder: the sound produced by a grinder might indicate similar problems thus it is possible to be keen on it. A good grinder when well engaged should emit the sound of a constant pitch.
  • Pay attention to the working angle: ensure that the grinding discs are used at an angle of about five to ten degrees from the horizontal. The wear pattern which is on the disc should be relatively double its thickness.
  • Adapt your technique and consumables for the material: ensure that the method which you use in moving the disc is suitable for the material which you are using. This is because the back and forth method may not be suitable for use with all metals.

Metal Grinding Process

Metal Grinding Process
Metal Grinding Process

The metal grinding process entails the following series of steps:

Cylindrical Grinding

  • It is conducted using a cylindrical grinding machine in a cylindrical grinding operation.
  • First, the part between two centers in the cylindrical grinding operation and then rotated.
  • A grinding wheel is then mounted on a spindle and allowed to rotate at a higher speed of about 2000 meters per minute than the part.
  • The part centers tend to be mounted on a table that can traverse at given feeds to ensure the whole length of the part enters and leaves the wheel. At this point, the depth of the cut is too small, about 0.015 mm.
  • Once the entire part has passed in the front of the wheel, it advances by an additional 0.015mm at the traverse’s end and the cycle continues repetitively. This is done until the diameter of the part which you desire is obtained.
  • After this step, the end product is a cylinder that has a perfect circular profile and fine finish on the surface.

Internal Grinding

  • In this step, the surface of bores whether tapered or plain is ground using a small grinding wheel with a slender that penetrates the bore.
  • The grinding wheel uses a speed of about 700 to 100 meters per minute to ensure that the internal surface is smooth.
  • This is done until the holes of the part obtain improved geometry and its surface has a soon finish.

Surface Grinding

  • Surfaces of parts that are flat are ground by use of either the end of a cup-shaped wheel or the periphery of a disc.
  • In this step, the grinding wheel uses a speed of about 1200 to 1600 meters per minute to ensure the external surface of the metal part is well ground.
  • It is done continuously until the surface of the metal obtains a smooth surface as desired for use.

Small Metal Parts Grinding Techniques

OD Grinding
OD Grinding

OD grinding is a method of cylindrical grinding that makes use of a wheel in shaping objects outside the surface between the centers. The workpiece for use in OD grinding should possess a central axis of sufficient diameter to enable the rotation of an object. Either the wheel or workpiece traverses concerning the other.

Centerless Grinding
Centerless Grinding

It refers to an abrasive process that eliminates the material and gives a specific finish to the external diameter of small metal parts. Centerless grinding is used in enhancing the surface finish of parts that were initially machined. Again, centerless grinding tends to incorporate actions of a smaller diameter regulating wheel and an abrasive grinding wheel.

Surface Grinding
Surface Grinding

It is a machining method that is used a lot in generating a smooth finish on small metal parts. The surface grinding process entails the rotation of a wheel which is covered in abrasive particles that are rough to cut tiny chips from small metal parts.

Internal Grinding
Internal Grinding

It is a process of abrasion that eliminates material on the internal diameter of small metal parts. Internal grinding is used in the creation of smooth surface finishes and achieves tight tolerances on the inside diameter. Internal grinding requires the small metal parts to be rotated and held in place thus limiting the appearance of their diameter.

Double Disk Grinding
Double Disk Grinding

It is used in obtaining dimensions that are highly accurate and small metal parts which need flatness, tight tolerances, parallelism, and thickness control. Double disk grinding uses two pieces that are opposite each other and grinds two sides of small metal parts at the same time.

Electrochemical Grinding
Electrochemical Grinding

It is a method that is highly specialized and mostly used in the medical device industry. It combines chemical and electrical reactivity by using the abrasive action of a grinding wheel. Electrochemical grinding forms an environment where small metal parts are eroded to get a smooth surface finish.

Application Of Metal Grinding

Medical
Medical

Used in the medical industry to make dental drill bits, hip balls, surgical drills, femoral knee joints, hip stems, and needles.

Aerospace
Aerospace

It is used in the production of Aerospace parts such as turbine rings, inner and outer rings, and turbine shafts.

Machine Tool Manufacturers
Machine Tool Manufacturers

Manufacturers of machine tools tend to use ground components for linear guideways, spindles, ball screws, rotary tables, cams, roller bearings, pistons, and valve spools.

Mold Industry
Die/Mold Industry

It uses grinding to make stamping dies, the thread dies, draw dies, thread rolling dies, press brake tools, and mold inserts.

Tooling Industry
Tooling Industry

It is used in the production of profile inserts, drill points, four-jaw chucks, step drills, taps, reamers, collets, and ring gages.

Automotive Industry
Automotive Industry

It is mostly used in automotive applications like brake pistons, brake cylinders, selector shafts, hydraulic steering pistons, gear shafts, spline, camshafts, connecting rods, and crankshafts.

Metal Grinding

People Also Ask:

Which Tool Is Best For Metal Grinding?

The best tool for metal will depend on the function that you would like to achieve this it is essential to liaise with the manufacturer. It is important to ensure that the tool should be able to handle all metal types with ease and enable you to cut and grind all kinds of metal.

Which Is The Fastest Way Of Grinding Metal?

The fastest way of grinding metal is by use of an angle grinder as it can carry out the task effectively and handle several types of metal.

Can You Grind Metal Without Sparks?

It is unlikely to grind metal without producing sparks. However, when grinding metal, it is important to use protective gear and ensure that the environment has safety features in place for protection from the sparks emitted.

What is precision Metal Grinding?

Precision metal grinding refers to a process that is used in eliminating small material amounts to obtain a given finish or dimensions of tight tolerance on surfaces of parts.

More Resources:

Grinding In Metal Machining

Ways Of Grinding Metals

Grinding Tips

Grinding (Abrassive Cutting)

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