Have you ever thought about how certain engineering materials — like stainless steel or aluminum — are able to be manipulated and formed into essential parts of your need?
Understanding the idea of “machinability” can help you make the most of your production time and keep costs down. So what is “machinability,” and how do you measure it?
A good manufacturing process of machining can create parts with very high tolerance and by maintaining the details, you provide. Moreover, this is a very cost-effective method for prototyping and small productions.
But before diving into this business, you MUST understand the machinability. What is machinability, and how is it measured – that is a must-know question for all manufacturers.
You just can’t blindly believe any machining service provider. There are many machining service providers, and not all of them will provide you with real information.
The machining process is different for all materials. You need to use very powerful tools in order to get your parts. Therefore, the material you are using must be soft enough so that the machine can cut it according to your design.
If the material is not machinable, you can damage the tool, also. In this article, we are going to find out these factors in detail.
1. What is Machinability?
“Machinability” is a term used to refer to how easily machine tools, such as drilling and lathing, can process a certain material. To put it another way, the machinability of a material refers to its capacity to be machined, as well as cut and shaped.
This characteristic of a material can have significant impacts on its use in manufacturing processes.
Materials that are easy to machine typically require less processing and are, therefore, more cost-effective. The ease of machining can also affect the performance and durability of a product.
Different classifications of materials will vary greatly in the complexity and difficulty involved in machining them – metals are known to be particularly challenging because they tend to be hard and strong. In contrast, plastics are often easier due to their malleability.
Additionally, the characteristics of each individual material can affect its machinability within its category; for example, some metals may have more natural lubricity than others, making them easier to work with.
As such, considering machinability as an attribute of a material is key when choosing it for a project since it can save processing time and money.
Many factors contribute to machinability, including the material’s density, grain structure, and texture. Density affects how easily a material can be compressed; for example, a dense material will require more force to cut than a less dense material.
Grain structure affects how well the material can be divided into small pieces without breaking; granular materials are easier to machine than non-granular materials.
Texture affects how easily you can rough or polish the surfaces; for example, smooth materials are harder to machine than rough materials.
Milling, drilling, and tapping are the three main machining processes. Milling is the process of cutting pieces from a solid object by rotating it around an axis.
Drilling is the process of making holes in objects by injecting pressurized water or air through small openings called drill holes. Tapping is the process of enlarging existing holes by inserting a tap into them and turning it around an axis.
Each type of machining process has its own benefits and drawbacks. Which manufacturing method is ideal for your project’s components depends on a number of factors, including how easily the material can be machined.
You can determine the machinability of the material from the followings:
Physical Properties of Machinability
- Thermal expansion
- Modulus of elasticity
- Work hardening
- Thermal conductivity
Conditional Properties of Machinability
- Grain size
- Tensile strength
- Microstructure
- Hardness
- Heat treatment
2. Why Is Machinability a Vital Parameter?
Machinability is a crucial factor when picking a suitable material for a product or manufacturing process. It describes how easily you can cut, drill, or mill a specific material and affects the process’s speed, accuracy, consistency, and efficiency.
Let us put it real scenario. For example, machinability determines how easily drills or lathes can form objects out of metal.
Additionally, machinability is essential in ensuring that products are safe to use and aesthetically pleasing. This is because a product created with less machinable materials may have weak spots and sharp edges that could lead to potential safety hazards.
When thinking about machinability parameters, manufacturers must also think about production costs.
In comparison to more easily machined materials, those with higher machinability qualities can be more cost-effective if they reduce the amount of time and effort needed to manufacture them.
You will see the automotive industry more often use easily machinable metals. Various metals and metal alloys are used to manufacture cars and other vehicles. These alloys need to be strong and light while still being able to perform well.
Metals like aluminum that are easy to shape can save time and money for companies that make cars.
Metals that are easy to work with are also useful in other industries. For example, medical equipment needs to be able to withstand repeated sterilization cycles. Stainless steel is often used in medical equipment because it doesn’t rust or corrode.
However, it isn’t always the easiest metal to work with.
You will see polycarbonate plastic as a replacement for stainless steel because it’s highly machinable and can meet stringent sterilization requirements.
3. Determining Cutting Speed
Figuring out the correct cutting speed for a certain material is vital in machining. You will need to consider variables such as the tool material. This will determine how fast the machine can spin to cut the material properly.
Other factors are grain structure, surface finish and imperfections on even brand-new pieces, heat treatment type of the workpiece material, and slot depth, as each will affect how deep you’re able to machine into the part.
Also, consider how accessible cooling can be and how much lubrication needs to be included, as both increase performance and extend longevity. The choice of cutting speed will depend on all these factors; if you make a mistake, the whole job may be ruined.
We have accumulated some factors for your consideration here:
- Identify the material type. Some materials require slower speeds to avoid damage, while others can be easily cut at high speeds.
- Pick a material that you are familiar with and make it a reference material. That will reduce the risk.
- Consider tool geometry. The shape of the tooling used can affect how quickly it cuts through the material. For example, a V-shape cutter will cut more quickly than an L-shape cutter because it has more contact points with the material.
- Determine the workpiece size and dimensions. If you’re working with a large or complex part, use a slower speed to prevent damage from occurring during machining.
- Take into account other factors, such as feed rate and spindle speed (.01-.10 Hz), which can also affect cutting speed.
4. What are The Main Factors Affecting Machinability?
You need to consider a few factors for the machinability of a material.
One of the most important factors is the tone of the material. Hard materials can be very difficult to mechanize, while you can easily shape soft materials.
Additionally, the geometry of the material can also affect how easily it can be machined. Besides, it will be harder to machine highly irregular or textured surfaces than smoother ones.
Another major factor that affects machinability is the hardness of the material. The harder a material is, the more wear and tear it will experience during machining.
This wear and tear will cause problems with accuracy and precision, which can lead to delays in production or even entire projects being scrapped due to poor quality control.
Finally, the geometry of the material can also affect how easy it is to a machine. Highly irregular or textured surfaces can be more difficult to machine than smoother surfaces.
Additionally, round objects may require different machines and techniques than objects that are Square or Rectangular in shape.
Understanding these factors will help you choose materials that are best suited to your specific project requirements.
5. Machinable Materials
Machinability is a key factor when selecting materials for a machining project. Aluminum, steel, other metals, and plastics can be machined using a variety of methods, but each has its own advantages and disadvantages.
Aluminum
Aluminum is the most easily machinable metal. Its high strength-to-weight ratio and low density make it ideal for applications where lightweight components are needed, such as aircraft parts and engine mounts.
However, aluminum is not as strong as steel or other metals, so it must be carefully machined to avoid damage.
Aluminum 6061 is the most standard alloy you will see in various applications. However, 8280 and 2011 are more machinable than 6061.
Steel
Steel is the most durable of the common metals used in manufacturing. It has a high strength-to-weight ratio, so it can be used to create parts that are tough and resistant to wear and tear.
However, steel is also difficult to machine because it has a grain structure that can cause problems during cutting and drilling operations.
You can use grades like 303 stainless steel, which comes with moderate carbon content and is more machinable than other stainless steel versions.
Other Metals
Metals like brass or titanium are also good candidates for machining due to their hardness and rigidity, making perfecting even highly detailed models or parts possible.
Plastics
plastics can also offer excellent adaptability when machining them into any shape you desire.
However, some plastic compounds may show a lower coefficient of friction than others, thus making some more suitable for the application than others, depending on the design endeavor.
For example, PET (polyethylene terephthalate) is a common type of plastic that can be machinable with standard tools and machines. This makes PET ideal for products such as drink bottles and food containers.
6. Improving the Machinability of Materials
Many people in the manufacturing industry want to make materials easier to work with by making them easier for a machine. Technology has made it possible to do very precise machining, and there are many ways to improve machinability and make production more efficient.
Additives
Most of the time, the first step is to change the material’s natural properties, like adding sulfur, manganese, or lead.
These additives are small things that are added during manufacturing to change or improve certain qualities. These additives make it easier to work with material by making it easier to cut.
To make steel more suitable to machining, for instance, you can incorporate lead and sulfur into the material beforehand.
Heat Treatment
Another technique for improving the workability of a material by increasing its strength and decreasing its fragility is heat treatment. High temperatures can be used to change crystallization points and make things harder or more flexible, depending on how they are used.
Other Factors
You can change the machinability of a material by using some external factors. A combination of consistency in material properties, along with an ideal cutting environment and machine setup, all contribute to effective results when attempting to produce a finished product.
7. How do you Measure the Machinability of a Material?
Machinability is a key factor in determining the success of a cutting tool. Multiple metrics can be used to evaluate machinability, but two of the most prominent are cutting tool life and energy usage.. Other methods include surface finish and cutting tool geometry.
Power consumption is typically measured using an electric motor or an air-powered machine. The power consumed can be used to calculate the speed at which the tool has to move to create a cut.
The faster the machine moves, the more wear and tear it will cause on the cutting tool. Cutting tools that require high speeds are typically less machinable.
Cutting tool life is also affected by how easily the sharp edges of the blade chip or wear away. Poorly machined parts will often have blades that wear quickly, leading to dulled blades and reduced cutting performance. It is important to consider both power and cutting tool life when selecting a cutting tool for a particular application.
Surface finish is also important when considering machinability. Poorly finished parts will often require more work than well-finished parts to produce a satisfactory result.
It is important to choose a surface finish that best suits the requirements of the application being performed. Surface finishes can range from rough, unpolished surfaces to mirror-like finishes.
There are some other standard methods to check machinability.
“Joints-At-Web” (JAW) test. This test measures how easily two pieces of metal can be pressed together without bending or breaking. The higher the score, the more machinable the metal is.
One downside to using the JAW test is that it only assesses how easy it is to press two pieces of metal together. It doesn’t take into account other factors, like how well the metal bends or how difficult it is to cut through. For this reason, other tests are often used to measure machinability.
One such test is the “Shear Test”. This test measures how well a metal resists being sheared apart when subjected to a lateral force. The higher the score, the more machinable the metal is.
Another test often used to measure machinability is “The Yield Point Test”. This test uses a machine called an indexing turntable and a cutting edge that moves back and forth across the metal surface.
The goal is to create cuts at specific points on the object so that they can determine how much material was removed by each cut and calculate its yield point value.
But it is not easy to find the exact machinability of a material with any test. Therefore, based on turning tests, the American Iron and Steel Institute (AISI) has also made a rating system for how easy it is to machine something.
These ratings are given as a percentage compared to the machinability of 160 Brinell B1112 steel, which was chosen at random and had a rating of 100%.
Metals that are easier to work with than B1112 have ratings above 100%, while metals that are harder to work with have ratings below 100%.
Conclusion
Good machinability is determined by the ease with which a material can be cut without breaking, cracking, or otherwise becoming damaged. This quality is important in many industries where parts must be produced quickly and efficiently.
There are several ways to measure machinability, including the Machinability Index, Cutting Speed Rating, and Tool Life Rating.
If you would like to learn more about how we can help you improve your machining process, send us a message. We would be happy to provide you with more information about our services.
