Setting Up Different Types Of Boring Bars
A boring bar is used just like any other lathe cutting tool, with the only difference being that the operation necessitates drilling a pre-machined cavity in the workpiece. The workpiece spins on the lathe spindle while the boring bar is clamped to the tool post, which travels along the vertical plane and depth of the lathe.
Setting up a boring bar
The way a boring bar is set up has a big impact on how well the machine will work. The result of an improper setup is a bad surface finish with chatter marks along the bored hole, which further causes vibrations during the machining process. However, the setup of the boring bar is based on the kind of boring bar being used. Once decided upon, the reading on the handwheels is then set to zero before the tool post is adjusted so that the boring bar’s cutting point comes into contact with the surface to be machined. By doing this, any reading errors in calculating the depth of the cut are eliminated, guaranteeing precise measurements for the finished hole. After zeroing the machine, the boring bar is moved along the X and Z axis to achieve the desired cut while the lathe spindle is rotated at the necessary RPM.
Types of boring bars
Boring bars can be categorized based on their material, structure, and construction.
Based on the type of material
• Steel boring bars – Because of the low cost and excellent machining capabilities, steel is the most common material used. These steel bars, however, are less robust and are more susceptible to vibrations, which deteriorates the cut’s quality. Therefore, steel bars are advised for projects where low cost is valued over high accuracy. Most of the time, these bars are appropriate for boring activities where a diameter to boring length ratio of 1:4 is feasible.
• Heavy metal boring bars – Tungsten carbide is typically used to make heavy metal boring bars, which are more solid than steel bars. These bars thus offer a larger diameter to boring length ratio of approximately 1:6. Where high rigidity at an affordable price is required, heavy metal boring bars are typically preferred.
• Carbide boring bars – Because they are the most solid bars, carbide bars are excellent for machining tough materials. Furthermore, the high rigidity of carbide enables the use of boring bars with smaller diameters, resulting in higher chip evacuation clearance. Therefore, carbide boring bars are chosen over other materials for industrial uses where a highly accurate bore is needed. With these bars, a maximal diameter to length ratio of about 1:8 is possible. However, due to their expensive price, solid carbide bars with a diameter larger than 1″ are not practical.
Based on the structure
• Round bottom boring bar – The shanks of round bottom boring bars have a cylindrical shape, with the base being precisely round. These boring bars are required to be clamped using a V-groove tool holder.
• Flat bottom boring bar – The shanks of flat bottom boring bars have a partially circular shape, with the base being flat. As a result, the bar can be tightly clamped, allowing for the delivery of stronger cutting pressures with little vibration. In order to clamp these boring bars, a flat bottom tool holder is used.
Based on the construction
• Solid boring bars – Solid boring bars are made entirely of metal, giving them the durability to withstand powerful cutting pressures. They are less expensive than damping boring bars due to their simple construction.
• Damping boring bars – Damping boring bars are specialized tools that have a cavity inside of them. An inertia mass held using a unique mechanism in a dense, oily fluid is found inside the cavity. This design serves as a dampener to reduce unwanted vibrations while cutting. Damping boring bars are used in applications where a very high surface finish and excellent accuracy are necessary.
Not sure as to which boring bar type you’ll need for your application? Get in touch with FineTech Toolings, one of the best precision boring bars manufacturers in Bangalore, with whom you can discuss all your requirements and have the best and most fitting boring bar that is manufactured to the exact specification and stringently inspected and calibrated, so as to deliver quality and unmatched precision.
Tips to improve the boring process
Along with using the right kind of boring bar for your application, and setting it up all well, there are few more tips that can help improve your boring process.
• Because of the vibrations involved in the boring process, it is recommended to use a thick boring bar with a short overhang to minimize these vibrations and create a hole with close dimensional tolerance.
• Because machining parameters like cutting speed, feed rate, and cut depth affect the quality of the boring process, in order to enhance the surface finish and lessen the stress on the boring bar, it is usually advised to use a shallow depth of cut with a high feed rate and slow cutting speed. Also, using a damping, carbide, or heavy metal boring bar, instead of a solid steel bar offers more rigidity, which affects the cut quality.
• The quality of the cut is greatly influenced by choosing the proper cutting head for the boring bar. While finish-boring heads are advised for a smooth surface finish, twin-style heads are advised for roughing cuts because they enable a higher material removal rate at the cost of surface finish.
• Boring blind holes is more challenging than boring through holes. This is due to the conical profile that is left inside the cavity after drilling a blind hole. As the bore depth increases, this conical profile restricts the space available to accommodate the boring tool. Therefore, it is suggested to
eliminate the conical profile before boring using a flat bottom drill or an end mill.
With the right materials, the right methods, and the right tips, you are certain to have a smooth boring operation with better outcomes. So, be very certain about every minute detail before beginning your boring process.
Website: https://finebore.com/