Mechanical Processing

1. Mechanical drilling material innovation brought about by high-efficiency mechanical hole processing

Many factories mistakenly believe that mechanical drilling must be done at low intakes and at low speeds. This used to be true, but today’s carbide drills are different.

In fact, by selecting the right drill bit, users can significantly increase productivity and reduce costs per hole across the scale. For end-users, there are four basic forms of drill bits with carbide cutting edges to choose from: whole carbide, translociable blades, welded carbide drill tips, and exchangeable carbide drill tips. Each has its advantages in a particular application.

a. The first whole carbide mechanical drill bit is used in modern processing centers. It is made of fine particle carbide and has a TiAlN coating that improves tool life, and these self-centered drill bits are excellent chip control and chip removal in most workwear materials due to their specially designed cutting edges. The self-contained geometric angle and good accuracy of the overall carbide drill bit ensure that no further processing of high-quality holes is required.

b. The translatable blade drill covers a large diameter range at drilling depths from 2XD to 5XD. They can be used in both rotary applications and in cribs. For most workwear materials, these drills use a self-centered geometric angle to reduce cutting force and good chip control.

c. The welded drill holes have a fairly high surface finish, high dimensional accuracy, and good position accuracy, eliminating the need for further finishing. Due to the cooling through holes, welded drill tips can be used in machining centers, CNC cribs, or other machines with sufficient stability and speed.

d. The last form of the drill joints the steel knife body and the exchangeable holistic carbide drill tip called the crown. This mechanical drill provides the same accuracy as the welding drill bit for higher productivity at a lower processing cost. This new generation of drill bits with carbide crowns offers precise dimensional increments and a self-hearted geometric angle that guarantees high processing size accuracy.

2. Careful consideration of Mechanical machining tolerances

a. The factory should select the mechanical drill bit according to the specific tolerances on the process. Tolerances for small diameter holes are usually tighter. The drill bit manufacturer then classifies the drill bit by specifying the male aperture and upper tolerance. Of all the drill bit forms, the overall carbide group drill has the tightest tolerance. This makes them the best choice for holes with extremely tight mechanical drilling tolerances. The plant can start with a tolerance of 0 to 0.03mm for mechanical drilling holes using an overall carbide drill with a diameter of 10mm.

b. On the other hand, the tolerance for the holes machined out of the drill bit of a welded drill bit or a changeable carbide crown is from 0 to 0.07mm. These drill bits are often a good choice for drilling production and machining. Transferable blade drills are heavy-work drills in the industry. Although their upfront costs are usually lower than those of other drill bits, they also have the largest tolerances, which can range from 0 to 0.3mm depending on the diameter/hole depth ratio tolerance. This means that end-users can use a transseminable blade drill when the tolerances for the required holes are large, otherwise, they must be prepared to finish the holes with a boring knife.

3. Mechanical Stability of machine tools for machining

Together with the tolerances of the holes, the plant needs to consider the stability of the machine during the selection process. Because of stability guarantees tool life and drilling accuracy. The factory should verify the status of the machine spindles, fixtures, and accessories. They should also consider the inherent stability of the drill bit. For example, the overall carbide drill provides optimum rigidity, which allows it to achieve high accuracy.

On the other hand, the transsegratable blade drill is prone to skew. The drill bits were fitted with two blades — an inner blade in the center and one that extended outward from the inner blade to the edge — initially with only one blade for cutting.

4. The first millimeter is processed by reducing the intake and then increasing to the normal intake mechanical parameters

This creates an unstable condition that causes the drill bit body to skew. And the longer the drill, the greater the skew. Therefore, the plant should consider reducing the intake at the first millimeter of processing and then increasing it to a normal intake when using a transistorization blade drill with 4XD and above.

Welding drills and Convertable crown drills are designed to form a self-directed geometric angle cutting edge in two symmetrical forms. This highly stable cutting design allows the drill bit to enter the workpiece at full speed.

The only exception is the recommended reduction of 30% to 50% at cut-in and cut-out when the drill bit and the machined surface are not vertical. The steel drill bit body allows for a slight skew, allowing it to be successfully applied to the crib. And the rigid overall carbide drill bit may be easy to break, especially when the work parts are not well-hearted.

5. The problem of chip removal during mechanical processing

Don’t ignore chips Many factories have problems with chip removal. In fact, chip removal is the most common problem in drilling, especially when processing low-carbon steel. And no matter what drill bit is used.

The factory often uses external cooling to solve this problem, but this is only possible for holes less than 1XD deep and with reduced cutting parameters. Otherwise, they must use suitable coolant that matches the flow and pressure of the aperture. For machines that do not have spindle center cooling, the plant should use a coolant external in-turn unit. Remember, the deeper the hole, the more difficult it is to drain the chips, and requires more cooling pressure.

Always check the manufacturer’s recommended coolant minimum flow level. At lower traffic, reducing the intake may be necessary.

6, Mechanical machining tool inspection life cycle costs

a. Productivity or cost per hole is the biggest factor affecting drilling today. This means that drill bit manufacturers must find ways to combine certain processes and develop drill bits that can be adapted to high intakes and high-speed processing. The latest drill bits with an exchangeable whole carbide head provide superior economy.

b. Instead of replacing the entire drill bit body, the end-user purchases only a carbide head that is equivalent to re-grinding a welded drill or an overall carbide drill bit. These crowns are easy to replace and precise, and the factory can use multiple crowns on a single drill bit to drill several different sizes of air.

c. This modular drilling system reduces the inventory cost of drill bits from 12mm to 20mm in diameter. In addition, it eliminates the cost of backing up drill bits when welding drills or whole carbide drills are re-grinding.

d. The plant should also take into account the total tool life when reviewing the cost per hole. Typically, for a factory, a whole carbide drill can be re-grinded 7 to 10 times, while a welded drill can only be re-grinded 3 to 4 times. On the other hand, the steel body of the crown-type drill can be exchanged for at least 20 to 30 crowns when processing steel parts. There is also a productivity problem.

e, welding drills or whole carbide drills must be re-grinded; However, the drill bit of the replaceable head does not have to be re-grinded, so the factory can use sufficient intake and speed in processing without worrying about the sticky chips of carbide materials.

f. This new crown-type drill also has a more consistent tool life than welded drills or holistic carbide drills.

g. In many cases, the re-polished drill bits do not perform as well as the new drill bits. This is because it is difficult to re-grind the cutting edge shape and edge trim and the new drill bit exactly the same.

h. Improper edge grinding makes the drill more sticky, requires more torque or power to process, or generates more heat, thus reducing tool life.

7. PCB Milling during mechanical processing

8. PCB Backdrill during mechanical processing

Backdrill is the process of creating vias by removing the stub in multilayered printed wiring boards, to allow signals to flow from one layer of the board to another. It is special craftsmanship of control depth drilling.

Reduce the use of blind and buried vias to reduce the difficulty of PCB fabrication

Improve signal integrity

Reduce interference of another signal

Reduce partial plate thickness

 

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