If you are an industry worker, or if there is any case you ever work around tools, you would probably have to know what tool for what is and how are they made. Every cutting tool has its specialty and specification. Not to forget that every machinery and work need a different type of carbide insert whether in means of shape, design, coating, or manufacturing. However, if you are a newbie around the cutting tools, and want to get familiar with the jack of all tools-carbide inserts, I recommend you read this one till the end. It can be of great help.
What is a Carbide Insert?
First of all, let’s have a little introduction to carbide inserts.
A carbide insert is useful for accurately machining steels, carbon steels, steel alloys, cast iron, and a variety of non-ferrous metals. There are many styles, sizes, and quality levels of diamond inserts that can be replaced and indexed.
If we talk about the benefits being provided by carbide inserts they could be many. To sum them up, carbide inserts enable faster machining, which leads to better finishes because they can be used at high speeds. Furthermore, to avoid damaging the insert, the machine, and the workpiece, it’s vital to pick the correct carbide insert for the material that you’re cutting.
What is insert Grade?
Got enough knowledge about carbide inserts? Great! Now it is time to move towards the center of attention of this blog. Yeah, you have heard it right. I am certainly talking about the insert grades. Every manufacturing industry has its carbide insert grade. Additionally, they provide a complete carbide insert chart for its users. But what is it?
Carbide grades are generally used as a term in metallurgy when referring to sintered WC materials that are used in nozzles, dies, rollers, crushing rolls, and cutting tools.
Depending on the machining application, an insert’s grade or material is designed to be suitable for that particular task. Even though two inserts may look similar, they may be different in terms of the material used for the basis and the coating.
Selecting an Insert
Understanding carbide inserts are essential when choosing an insert. It is the most crucial thing, to begin with, the carbide insert selection guide. In insert selection, what matters is the shape of the carbide insert. In the guide below, we will be discussing the insert selection concerning its size and application.
90-Square Shaped Inserts
Square-shaped inserts are the most commonly used carbide inserts. As we all are familiar with the square shape having a 90-degree angle, a square carbide also has sturdy 90-degree angled corners. It has an amazing economy with 8 edges on a double-sided insert. Furthermore, it is usually used in roughing face procedures. specifically, roughing through square-shaped inserts is done by castings, forgings, and rough sawed blanks. Despite many plus points, it lacks some points. It has been seen that sometimes, it is unable to turn. Furthermore, it needs high force to push it against the workpieces when used for turning. Moreover, it must always be used in a stable setup.
80-Diamond Shaped Inserts
The next insert we have on our list is a diamond insert. It is a popular insert because of its versatility. It can be used on most materials with ease. It has a strong cutting edge and corners of 80 degrees each. As far as its application is concerned, it can be used for both roughing and facing. The opposite angles are 100 degrees which can be helpful for general roughing applications.
However, it can cause chip jamming because of less clearance between the trailing side and the workpiece of the insert.
Trigon Shaped Inserts
Next, we have the trigon-shaped insert. It is not very common to use. Trigon is a six cornered, 80-degree diamond-shaped insert that can help increase the economy more as compared with other types of inserts. Its application can be on moderate depths. Meanwhile, it can not go into much depth.
60-Triangle Carbide insert
You may have seen triangle carbide insert around you often. This is because it is a versatile shape that can have multiple uses including turning, facing, boring, copy turning, and basic profiling. Adding extra side clearance between the insert and the workpiece bore, these inserts are excellent choices for general boring. But, their edge is comparably weaker than those of 80-degree diamond insert. Furthermore, you must be opting for the right size of the carbide insert not a very large one.
55-Diamond Carbide Insert
A 55-degree diamond insert is preferred for profiling applications. It can plunge into a small diameter at a specific angle of 30 degrees. It can be used when machining near a tailstock. It may have the drawback of being weaker at the edges than a triangle insert.
35-Diamond Carbide Insert
A 35-degree diamond carbide insert could be a great choice for copy-turning. Similar to a 55-degree diamond insert it can also work close to the tailstock (closer than a 55-degree insert). However, it can be considered as one of the weakest shaped inserts having depths of cut lighter than others.
It is, therefore, best to use negative style inserts only externally in cavities. However, Positive Style can be used both externally and internally, and the increased cost per edge is often outweighed by the improved performance.
Types of Insert Grades
Turning Grades
As in any application, grades are vital to the success of the application. As a result, the turning section of any supplier’s catalogue will offer the most grades.
Various turning applications have led to an extensive range of turning grades. These range from continuous cutting, in which no impact is suffered but lots of heat is generated, to interrupted cuts, which have heavy impacts.
From 3-millimetre, Swiss-style machines, to 100-inch, heavy-duty industrial machines, the range of turning grades relates to the wide range of diameters in manufacturing. Depending on the diameter as well as the cutting speed, different grades are suitable for either or both.
Usually, major suppliers provide their range of grades for the different materials. Grades range from tough to hard for interrupted cuts in each series.
Milling Grades
For milling applications, there are fewer grades available compared to other applications. The fundamentally interrupted nature of milling tools calls for grades that are hard, impact-resistant, and able to withstand severe conditions. A thin coating is also important for the properties of the coating to withstand impacts, otherwise, it won’t be able to do its job.
It is common for suppliers to use a variety of coatings and tough substrates to mill a large array of metals and other materials.
Parting Grades
It is important to note that due to the speed factors involved in cutting, the grade selection during cutting is limited. The diameter, as the cutting direction moves closer to the point, will become smaller. The cutting speed correspondingly decreases as the cutting direction moves closer to the point. Partitioning to the centre results in zero speed at the end of the cut, and instead of cutting, the operation involves shearing.
In other words, a grade for parting off should be able to handle a wide range of cutting speeds, and the substrate should be tough enough to withstand shearing after the operation.
Drilling Grades
A drilling tool has a cutting speed of zero at the center but varies at the periphery based on its diameter and spindle speed. It is not recommended to use grades designed for high cutting speeds. It is not recommended to use grades designed for high cutting speeds.
Grade Selection Charts
Consider the supplier’s catalogue or website for assistance in choosing the correct carbide grade for a given application. It is important to note that there is no formal international standard, but most suppliers use systems that describe grades’ recommended working envelopes by using their three-character “application range” i.e. P05-P20.
Following the ISO standard, the first letter on the list represents the material group. There are letters associated with every material group.
| Letter | Material |
| P | Steel |
| M | Stainless Steel |
| K | Cast Iron |
| N | Non-Ferrous |
| S | Super-Alloy |
| H | Hardened Steel |
Based on a scale of 05 to 45 in increments of 5, these numbers show the relative hardness level of the grade. It is recommended that a hard grade suitable for favorable and stable conditions be used for a 05 application. Considering the conditions that exist in a 45 application, a very tough grade is required to handle potentially adverse ones.
As is the case with these types of values, there is no standard for them, so they should be interpreted as coming from the specific table of grades within the term they are used in. There could be a difference in hardness between grades marked as P10-P20 in two catalogs of two different suppliers.
Carbide Grade Designations
Grade designations are also not governed by any official standard, just as grade ranges are not governed by an official standard. However, most major carbide insert suppliers follow common grade designation guidelines. Classic designations follow the format BBSSNN, where:
- BB —Brand Code: Each of the major suppliers has its letter.
- SS —Grade Series Number: A Grade Series Number is usually represented by two random digits that are assigned randomly. Generally, a series is made up of grades created for a single raw material and having the same type of coating.
- NN —Hardness Level: It normally indicates the hardness level of the grades within the series of digits that appear at the end of the standard number. In the same way, as the grade charts explained above, the number usually ranges from 05 to 45.
It should be noted that this is true for the most part. It is advisable to keep an eye out for these changes since this is not an ISO/ANSI standard.
Choosing Insert Angle
Before choosing the correct insert angle, it is vital to consider many parameters first. To achieve good chip control and machining performance, carefully select insert geometry, insert grade, insert shape (nose angle), insert size, nose radius, and enter angle (lead angle).
- For example, if the operation is finished, you can select the insert geometry according to it.
- For strength and economy, select the insert with the largest possible nose angle.
- Based on the depth of cut you expect, select the insert size accordingly.
- You want the nose radius of the insert to be as large as possible to maximize strength.
- If vibrations are a frequent occurrence, it may be prudent to select a smaller nose radius.
Turning insert grade
Essentially, the grade of the insert is determined by several factors such as:
- Materials for component construction (ISO P, M, K, N, S, H)
- Method of processing (finishing, medium, roughing)
- Machine conditions (good, average, hard)Machine conditions (good, average, hard)
There are several advantages to having inserts with optimum geometries and grades. An insert geometry lacking strength can be compensated for by a grade with high toughness.
Final Verdict
The type of steel grade to be used as part of an application should be carefully considered before selecting the material. In selecting the right tool, it is critical to consider the application as well as grade, cutting data, and tool wear. To make the right choice, it is also important to consider the existing grade, cutting data, and tool wear.
A hard and wear-resistant grade, such as CH0550, should be the right selection in a continuous H05 application, like turning the face of a gear and its internal diameter. Our testing wasn’t successful. Therefore, we can say that the main thing to consider when choosing a grade is to look at the application as well as to see what the competition is using. In terms of wear resistance versus toughness (ISO application area) chart, CBN060K has been available for a while, but it is still a very good grade in the HPT-chain, and fully capable of beating any competitor in the H15 area. A hard and wear-resistant grade such as CH0550 should be the right choice in continuous applications, such as turning the face and inner diameter of gear, a typical H05 application. But testing did not succeed. So making the right choice depends on your application and the material.
