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Views: 0 Author: Site Editor Publish Time: 2024-08-20 Origin: Site
As you could see, there are a lot of different machine tools available for a wide range of purposes. The same applies to the materials used to make these tools.
Let’s dig deeper to look at the most common materials for milling bits.
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The cheapest of the bunch. And this is exactly why it still finds use. As carbon steel is not very durable, it is only suitable for low-speed operations.
Carbon steel loses its hardness at 200° C. This is the reason for lower speeds – to keep the heating effect low.
High-speed steel, a grade of tool steels, has a few alloying elements added to it to provide better response to heat and wear than regular carbon steel. While the life cycle of such a tool goes up, so does the cost.
Loses its hardness at 600° C. Therefore, higher milling speeds are suitable for these tool steels.
This material is harder than high-speed steel but the toughness qualities are not that impressive. The higher hardness provides better protection against wear but lower toughness levels make it a little more susceptible to cracking and chipping.
The upper temperature of use is at 900° C.
Cutting ceramics are even harder than cemented carbides but lose in the toughness aspect. Both aluminium oxide and silicon nitride are used to produce these tools with varying properties.
Cutting ceramic tools are prone to cracking when used on hard materials and with high temperatures. Therefore, they are not really suitable for machining steels, for example. Otherwise, a short tool life is to be expected.
As is the norm in manufacturing, the choice of method or tool comes down to a balance between speed, cost and quality. The cost depends on both the price of the tool, the wear machining results in and the time it takes (speed) to produce the parts.
Regular carbon steels are usually out of the option pool because of their limited capabilities. HSS (high-speed steel) is therefore the most inexpensive one to get the job done. At the same time, its rate of wear means that in the long run, there are better options.
Cobalt-bearing HSS, for example, are suitable for even quicker milling. This makes them sufficiently adequate for most jobs.
Cemented carbide is another step towards high performance milling because of the aforementioned properties of such milling machine tools. In the long run, they are a more cost-efficient choice while the up-front costs are higher.
This is quite simple. A tool with a large diameter is able to mill the part quicker. Limitations apply based on the geometry of the final part.
For example, if certain inside radii are necessary, the tool cannot deviate from them. At the same time, you can use a large tool for milling away the bulk of it and apply a smaller one to finish the inside corners.
There are some different coatings available to protect the tools from wear. For example, a titanium nitride coating increases the tool’s lifespan but also the cost of it.
Such a coating reduces the stickiness of the cutting material which can be a problem with aluminium. Therefore, less lubricant is necessary during the cutting process.
Flutes are the channels on a milling bit. More flutes allow a higher feed rate because less material is removed.
At the same time, this increases the overall diameter of the milling cutter. This leaves less room for swarf.
The helix angle, along with the rotation speed of the spindle, determines the cutting speed or feed rate. A steeper angle is suitable for softer materials and metals.
Choosing the right milling cutters for your job needs an understanding of the materials, parameters and definitely some experience. The final outcome depends on these choices and a machinist must understand what material cutters are suitable for cutting different mediums.
A good choice leads to high feed rates and therefore shorter cutting times as well as lower costs.
When choosing a CNC machining service, make sure that they have all the necessary tools to make your parts.
