How to Machine Deep Holes

First, What is a deep hole?

The hole called deep hole is a hole whose length-to-hole diameter ratio is larger than 10mm. In most cases, the depth diameter of the general deep hole is ≥ 100 than L/d. Such as cylinder holes, axial oil holes of shafts, hollow spindle holes, and hydraulic valve holes, and so on. Some of these holes require high machining accuracy and surface quality, and some of the processed materials have poor machinability, which often becomes a major difficulty in production. However, as long as we make fair use of the processing conditions, understand the processing characteristics of deep hole processing, and grasp the processing method of a deep hole, it can become difficult or not difficult.

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Second, the Processing Characteristics of Deep Holes

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1. The tool holder is limited by the aperture, the diameter is small, and the length is large, resulting in poor rigidity, low strength, vibration, corrugation, and taper during cutting, and affecting the straightness and surface roughness of the deep hole.

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2. During drilling and reaming, the cooling lubricant is difficult to input into the cutting area without using special devices, so the durability of the tool is reduced, and chip removal is also difficult.

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3. In the process of deep hole processing, the cutting of the tool can not be directly observed, and the sound of cutting, the chip view, the vibration of the hand and the workpiece temperature, and the instrument (oil pressure gauge and electricity meter) can only be observed by work experience to determine whether the cutting process is normal.

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4. Chip removal is difficult, reliable means must be used to break chips and control the right and wrong, and shape of chips, so as to facilitate smooth elimination and prevent chip blockage.

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5. In order to ensure the smooth progress of the deep hole in the processing process and achieve the required processing quality, the chip removal device, the tool guidance, and support device, and the high-pressure cooling and lubrication device should be added.

Third: the Difficulty of Deep Hole Processing

(1) The cutting situation cannot be directly observed. Only based on sound, look at chips, observe machine load, oil pressure and other parameters to judge chip removal and drill bit wear.

(2) Cutting heat is not easy to transmit.

(3) Chip removal is more difficult, if the chip is blocked, it will cause damage to the drill bit.

(4) Due to the long drill pipe, poor rigidity and easy vibration, the hole axis will be easily deflected, which will affect the processing accuracy and production efficiency.

Deep hole drilling is divided into two types: external chip removal and internal chip removal according to the chip removal method, and the external chip removal includes gun drill and integral alloy deep hole drilling (can be divided into two types: cooling holes and non-cooling holes); Internal chip removal is divided into three types: BTA deep hole drilling, spray suction drilling and DF system deep hole drilling.

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A Deep hole barrel drill was originally applied to the barrel (commonly known as deep hole tube, the barrel is not made of a seamless precision tube, and the precision tube manufacturing process fundamentally cannot meet the accuracy requirements. Hence the name gun drill for the manufacturing industry. With the continuous development of technology and the unremitting efforts of manufacturers of deep-hole machining systems, deep-hole machining has become a convenient and efficient processing method. And is widely used in: the automobile industry, aerospace industry, structural construction industry, medical equipment industry, mold/tool/fixture industry and oil pressure, air compression industry, and other fields.

A Gun drill is an ideal deep hole machining solution, the use of a gun drill can obtain a precision machining effect, the processed hole position is accurate, square, high coaxiality, and has a high surface finish and repeatability. It can easily process various forms of deep holes, and can also solve special deep holes, such as cross holes, blind holes, and flat-bottom blind holes.

Deep hole gun drill, deep hole drill, deep hole drill bit drill nozzle

Gun drill:

1. It belongs to the deep hole machining tool for external chip removal. The V-shaped angle is 120°.

2. Use special machine tools for gun drilling.

3. The cooling and chip removal method is a high-pressure oil cooling system.

4. There are two types of ordinary cemented carbide and coated cutter heads.

Deep hole drilling:

1. It belongs to the deep hole machining tool for external chip removal. The V-shaped angle is 160°.

2. Special for deep hole drilling system.

3. The cooling and chip removal method is pulse high-pressure mist cooling.

4. There are two types of ordinary cemented carbide and coated cutter heads.

Gun drill is an effective deep-hole machining tool with a wide range of machining ranges, from mold steel, fiberglass, and plastics such as Teflon to deep-hole machining of high-strength alloys such as P20 and Inconel. In deep hole machining where tolerances and surface roughness requirements are tight, gun drills can ensure the dimensional accuracy, position accuracy, and straightness of the hole.

Gun drills are deep-hole machining tools for external chip removal. The V-shaped angle is 120°. Gun drill special machine tool use. The cooling and chip evacuation method is a high-pressure oil cooling system. There are two types of ordinary cemented carbide and coated cutter heads.

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Deep hole drilling: 1. It belongs to the special deep hole machining tool for external chip removal. The V-shaped angle is 160°. 2. Special for deep hole drilling system. 3. The cooling and chip removal method is pulse high-pressure mist cooling. 4. There are two types of ordinary cemented carbide and coated cutter heads.

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How to use

Gun drill is an effective deep hole machining tool with a wide range of machining ranges, from mold steel, fiberglass, plastics such as Teflon to deep hole machining of high-strength alloys such as P20 and Inconel. In deep hole machining where tolerances and surface roughness requirements are tight, gun drills can ensure the dimensional accuracy, position accuracy and straightness of the hole.

In order to achieve satisfactory results when drilling deep holes, it is necessary to master the performance of the gun drilling system (including tools, machine tools, jigs, accessories, workpieces, control units, coolants, and operating procedures). The skill level of the operator is also important. According to the structure of the workpiece and the hardness of the workpiece material and the working conditions and quality requirements of the deep hole processing machine tool, the appropriate cutting speed, feed, tool geometric parameters, cemented carbide grades and coolant parameters are selected to obtain excellent machining performance.

In production, straight slot gun drills are used the most. Depending on the diameter of the gun drill and the internal cooling holes of the transmission part, shank, and cutter head, the gun drill can be made into two types: integral and welded. Its coolant erupts from small holes in the flank face. The gun drill may have one or two round cooling holes, or a separate waist-shaped hole.

Standard gun drills can machine holes from 1.5 mm to 76.2 mm in diameter and drill depths up to 100 times the diameter. The specially customized gun drill can machine deep holes with a hole diameter of 152.4mm and a depth of 5080mm. Although gun drills have a lower feed per revolution, their feed per minute is greater than that of twist drills (feed per minute is equal to feed per revolution multiplied by tool or workpiece speed).

Since the cutter bit is made of cemented carbide, the cutting speed of the gun drill is much higher than that of the high-speed steel drill bit. This increases the feed per minute of the drill. In addition, when high-pressure coolant is used, the chips can be effectively discharged from the holes to be machined, eliminating the need for periodic retracts during drilling to remove chips.

If you are interested to look for a machining factory, don’t miss Rollyu Precision Machining Co., Ltd, contact is at?[email protected] and get more details ^^