The basics of abrasive cutting
Abrasive cutting or grinding is the process of producing very fine finishes and accurate cuts and dimensions on various materials. This process is one of the core parts of manufacturing and toolmaking. Since it cuts materials in a very shallow way, it is better suited for use in the machining of hard materials. It can also help in mass production that requires shelling out large numbers of roughed out metal.
Abrasive cutting is ideal for precision shallow cutting because of its ability to cut to the metal by a thousandth of an inch or 12.7 µm. This allows the metal to be shaped as precise as possible while wasting as little amount of material as possible.
Although abrasive cutting or grinding is under the general category of cutting, cutting and grinding are considered as completely separate processes on the work floor. Cutting is regarded as the cutting of large parts of the material or macroscopic cutting while grinding is its counterpart which focuses on cutting materials in the smallest way possible or via microscopic cutting. This difference resulted into people categorizing grinding as a completely different process that is done separately.
There are a different types of machines used in grinding too. These are as follows:
- Manual/Hand-cranked knife sharpening stones
- Handheld Power Tools: Angle Grinders and Die Grinders
- Industrial Grinding Machines
- Bench Grinders for Home use
These tools are used for different levels of grinding needs. Some are used to handle simpler tasks such as sharpening knives while some are designed to handle bigger and tougher projects. However, they are all designed to do one thing and that is to refine the surface and edges of different types of metals.
Aside from the different tools, there are also a variety of processes in which they are used. They are chosen according to the size, shape, and features of the materials along with the desired rate of production. To further explain these operations, here they are in detail:
This process uses a rotating abrasive wheel in order to remove layers of material to provide a flatter surface. The allowance needed for surface grinding to be effective differ when it comes to materials used. For a flat material a tolerance of 5 µm is needed for a flat material while 8 µm is needed for a parallel surface.
This method is commonly used on different types of steel because they can be easily handled by magnetic holders. They also do not create problems like melting in to the abrasive wheels that prevents it from cutting effectively.
This method, sometimes referred to as center-type grinding, is used to grind the cylinder-shaped surfaces and shoulders of a material. This method mainly focuses on rounding out the edges of your work piece. There are also various subtypes of Cylindrical Grinding which are: Outside Diameter Grinding, Inside Diameter Grinding, plunge grinding and centerless grinding.
Just like any other kind of grinding, this also has different tolerances for different types of tasks. For example, grinding for diameter a tolerance of 13 micrometers and 0.25 micrometers for roundness.
When it comes to removing large rates of material removal, this is method to use. Its speed in removing material can be compared to that of milling and turning. This is the choice of a lot of manufacturers in terms of quick material removal.
Although quick, creep-feed grinding faces a nagging disadvantage which is the rapid wheel degradation. Fortunately, this problem has been addressed by introducing the continuous-dress creep feed grinding. This maintains the wheels sharpness to a specified state by constantly dressing the wheel. This also remove the limit on the part length you can grind.
Other types of grinding
Other less popular types of grinding are as follows:
- Form Grinding
- Internal Grinding
- Centerless Grinding
- Electrochemical Grinding
- Electrolytic In-process dressing grinding
These are the most commonly used types of abrasive cutting or grinding. The first three alone covers most of the essential needs of grinding different types of materials. Each method is aimed for a different level of grinding but they revolve on the same basic principle which is precision cutting. A certain control and discipline is needed to properly cut a material to precise measurements. A single slip up can cost you a lot of raw materials.
It is also important to remember to lubricate the grinding wheel constantly to keep it cool and in perfect condition. This process also help in removing the chips produced during the grinding process. The grinding wheel is the most important part of the grinding tools so it is important to maintain its condition.
This article covers most of the important information about grinding that you need to know initially. Remember that abrasive cutting puts a lot of stress on the tools you use. You must practice consistent maintenance to ensure that your tools are in top condition. Any tool that’s not working properly can hamper you in achieving precise cuts and will most likely damage your material.