Machinability of Materials: A Detailed Guide
The process of manufacturing components using machining requires an assessment of machinability. Machinability is the concept of materials to be processed conveniently. It requires assessing various factors when the material is selected.
The guide below is for you if you are starting a new project and want to learn about the machinability of materials. So, let's read.
What is the Machinability of a Material?
Machinability of materials is the convenience through which a material can be machined so that the required quality of the component is achieved. In terms of part quality, you need to analyze the surface finish, tolerance, and dimensional accuracy.
Materials that are highly machinable take less time and power, and hence, the tool wear is also less. These materials generate components that have a refined surface finish.
Understanding Machinability Ratings
There are many materials around, and among them, selecting the right material in terms of machinability could be challenging for engineers. Hence, the machinability ratings are considered when analyzing suitable materials.
Machinability ratings have a standard feature in which the reference material is considered for convenience. For instance, the C36000 brass grade has a 100% machinability rating. When the materials get hard to cut, the machinability rating they possess reduces.
How to Improve the Machinability of Materials?
In order to improve the machinability of materials, some of the ways that can be considered are as follows:
Material Additives
Material additives enhance the machinability of materials by modifying the lattice structure of these materials and enhancing their mechanical properties. For example, copper alloys are enriched with zinc to improve their machinability.
Heat Treatment
Heat treatments like annealing of aluminum and steel tend to reduce their hardness, which makes them more machinable. It enhances the grain structure and also releases internal stress, which makes materials easy to machine.
Coolant/Lubricant
Cutting conditions can be optimized to make the material more machinable, like using coolants and lubricants. Using lubricants tends to reduce friction, and the tool wear also decreases. Similarly, coolant helps with heat dissipation and reduces thermal stress.
Cutting Parameter Optimization
The right selection of cutting parameters also impacts the machinability of materials. When you consider the high speed and high feed rate, the machinability decreases. Whereas when you lower the speed and feed rates, the machinability increases.
External Factors
Even if you don't want to change the material of the workpiece, you can adjust the other factors, like speed, angle, and operating condition of the cutting tool. It helps to make it easier to cut the materials that are hard to machine.
Factors Affecting Machinability
There are various factors on which the machinability is dependent, and some of these factors that affect the machinability are as follows:
Material Properties
The properties of materials impact the machinability to a greater extent, and some of these properties are as follows:
Material Hardness
The hardness of the material determines the machinability. Hard materials are challenging to machine. Such materials need more power, and the tool has to exert a high force, leading to quick tool wear.
Toughness
Toughness is also a very critical parameter in determining machinability. Materials that have high toughness are the ones that need more cutting force– like carbon steel, which is not machinable.
Moreover, such materials even produce a lot of chips, which cause them to tangle in the tool, making the surface of the tools wear out.
Tensile Strength
If the tensile strength of the material is high, it makes it difficult to machine them. They consume high power and resist deformation, which causes challenges during machining.
Thermal Properties
The heat dissipation ability of the material also determines its machinability. Some materials are very soft, and they cannot handle heat, making machining difficult.
Machining Conditions
The behavior of material when it is cut also impacts the machinability. Some of these factors are discussed below.
Cutting Parameters
The cutting parameters are composed of feed, cut depth, and speed. It is essential to optimize them to attain enhanced machining. When you cut materials at high speed, the material offers less machinability. Similarly, the depth of cut also plays an important role, as high depth leads to an impact on surface integrity.
Cutting Tool
CNC machining has cutters that have an impact on machinability. The strength and sharpness of the cutter is vital. The cutting angle even leads to improving the chip formation and makes the tools weak.
Coolant and Lubricant
The application of lubricants and coolants enhances the machinability of materials. The heat is dissipated, and the friction is enhanced. It helps to enhance the surface finish and makes the cutting process smooth.
Machine Tool Condition
The tool condition also determines machinability. Machines that are older have more vibration when subjected to dynamic cutting loads and this makes it difficult to cut materials.
Typical Materials with Excellent Machinability
Materials offering high machinability are featured in the table below.
| Material | Machinability |
| Aluminum | 90-95% |
| Steel | 30-40% |
| Plastics | 70-90% |
| Other Metals:
Titanium Free-cutting brass Magnesium |
20-25%
100% 50-55% |
How to Measure the Machinability of Materials?
There are various factors that affect the machinability of materials. There are different ways that can help measure the machinability of the materials. Parameters like power consumption, cutting tool life, and surface finish help with this measurement.
- Power consumption helps assess the machinability by the forces that are required to cut the material using the standard energy metrics.
- Cutting tool life also helps in assessing the machinability of how long the tool lasts when it cuts the material.
- Machinability is also assessed through surface finishing, whether there is a built-up edge or not, as machinable materials do not leave this edge.
However, these are not entirely reliable means of measurement. AISI has created a rating system based on turning tests. Such ratings are expressed in the form of percentages.
Efficient Processing for Hard-to-Machine Parts by DEK
DEK offers machining materials of various types using its experience and advanced tools. Hence, if there are materials that are hard to machine but an integral requirement of your project, contact us. We will help you manufacture these components with high quality, precision, and surface finish.
Conclusion
Machinability is one of the very crucial aspects of manufacturing, regardless of which industry you need the component for. The need for machining is essential so that the desired shape is achieved.
