An ejector drill bit is a metal drill bit. There is no spiral flute design like in gun drill bits. Instead of that there are several cutting edges that are made with tungsten carbide material. The chips are not ejecting through the flutes. Instead of that, chip removal is back through the center of the bit with flushing water.
Ejector drilling is one of three major methods for deep hole drilling. Deep hole drilling is defined by depth to diameter ratio that exceeds five. Both traditional and CNC machines use ejector drills. With the chips being ejected through the center of the inner tube, they use an inducer to deliver coolant between the inner and outer twin tube system.
The setup for ejector drilling includes,
- A pair of concentric tubes forming the drill tube,
- A drill head to perform the actual metal cutting,
- A rotary connector (sometimes called a coolant inducer) to supply coolant from the spindle through the drill tubes
- An adapter on the front of the spindle through which the coolant and chips exit.
Ejector drilling should be your first option if you need to drill a deep hole through a non-flat surface and want a more affordable production technique than gun drilling.
It can handle depth-to-diameter ratios over 100 and sizes ranging from 19 mm to 200 mm.
Where to Use Ejector Drill Bits?
To convert existing machining centers, horizontal boring machines, lathes, or turning centers for deep hole drilling, ejector drilling is frequently employed.
Ejector drilling has been discovered to be easily adaptable to machines with a horizontal spindle. Such retrofits are seen as a cost-effective solution to set up deep-hole drilling. You can use a gun drill bit for the deep drilling. But it is not effective as an ejector drill bit.
It doesn’t take much to adapt a machine for ejector drilling as long as enough coolant pressure and filtration is available.
As mentioned earlier, the ejector bit can be used for deep-hole drilling. Deep hole drilling is a manufacturing procedure for drilling holes that are deeper beyond what can be accomplished by standard machining equipment.
Therefore, this type of drill bits is used for the following industries. Many other industries use this method, including the oil and gas industry, aerospace applications, engines, plastic injection molding, and landing gear manufacturing.
What Is the Color and Material of the Ejector Drill Bit?
The design of the ejector drill bit is distinctive. It features a carbide drill bit tip and resembles a tube inside a tube.
Material:
- Solid carbide
- Cobalt Steel Alloys
- Tungsten Carbide
There has a color treatment process for the ejector drill bit.
According to that;
- Gold -Gold-Tech surface treatment
- Blue – Dura-Blue surface treatment
What Materials Can Be Drilled Using Ejector Drill Bit?
As mentioned earlier, ejector drill bits are used in various industries. According to the industries, the ejector drill bit can be used for;
- Plastics
- Construction steel
- Heat treated steel
- Cast iron (alloyed and unalloyed)
- Aluminium and Aluminium alloys
| Manufacturer | Technical Characteristics | Material | Very Suitable | Suitable |
| Sara Tools | Diameter:12-60mmLength:77mm | Steel(<700N/mm2) | x | |
| Steel(1000N/mm2) | x | |||
| Aluminium(<8% Si) | x | |||
| Aluminium(≥8% Si) | x |
“X” indicates which category is best suited.
Each of these materials has a cutting speed recommended by the manufacturer. Using these bits between the recommended levels will help you to use them for a long time.
What Are the Sizes of Metal Ejector Drill Bits?
As previously mentioned, ejector drill bits can be used to drill holes as deep as 19mm to 102mm (3/4 to 4 inches). Some products on the market can be modified to drill holes with a range of diameters. As an example;
Type 60 Solid ejector drill bit’s head with indexable inserts and guide pads. Therefore; it has a diameter adjustment with a stop plate and it can drill deep holes in the diameter range: 18.40 – 36.20 mm.
This type of ejector drill bits is very economical, with optimal cutting capacity.
What Is the Cutting Depth of Ejector Drill Bit?
The cutting depth can be known from the details you get when buying an ejector drill bit. So choose the drill bit that suits your needs. The cutting depth should be set according to your requirement. Adjust the ejector drill bit’s height to correspond to your requirement.
Below are the values of cutting depth given with the products according to each manufacturer.
| Manufacturer | Drill Bit Diameter | Drill Bit Length | Cutting depth |
| Sara Tools | 12-60mm | 77mm | 30mm |
| Karnasch Tools | 7.98mm | 130mm | 50mm |
| 6.34mm | 90mm | 40mm | |
| WURTH | 6.3mm | 75mm | 30mm |
| 6.3mm | 85mm | 50/55mm |
