Drilling operation

January 22, 2018

Drilling is one of the most common operations in machining. The vast majority of the workpieces of any type has at least one hole and only a small part of these workpieces come already with a pre-hole made in the raw material, case of forged or cast parts.
In the tip we are going to talk about the most efficient method to make holes: drilling.

The sames drills can be used in both turning and milling machines

In turning operations the drill is static while the workpiece rotates.
As opposed to turning, in milling operations the drill rotates while the workpiece is static.

Drills with indexable inserts


Drills with indexable carbide inserts are very popular, due to the following reasons:


1. No regrinding.


2. Cost effective, because the inserts have multiple cutting edges.


3. The drill body made of steel offers more reliability and shock resistance.


4. When used in turning machines, after making the hole, the same drill can also work as a boring tool with the outer insert, thus increasing flexibility.



Drilling under unstable conditions

When drilling under unstable conditions, like showed below, it is necessary to reduce feed by 50%


Hole tolerances with indexable drills


On the bottom left, we see the expected tolerances when making holes with indexable drills.

Increase coolant flow in order to achieve more precise holes…

…and always select the shortest possible drill to achieve best performance and productivity results




Drilling chip control

Problems with too long chips
Possible solutions:

• Increase speed

• Change feed depending on material:

• Reduce feed if sticky material from groups 1,4,5,6, 9, 10 or 12

• Increase feed for other material groups

Problems with too short chips
Possible solutions:

• Increase coolant flow

• Reduce speed

• Reduce feed 

Importance of coolant in drilling


Coolant in drilling is always recommended, independent of the workpiece material, because it helps chip evacuation, improves hole quality and increases tool life.


The best results are achieved with internal coolant, when it is not available, external coolant can help to achieve acceptable results if the coolant noses are well directed to the drill flutes and if the coolant pressure is good.

Drilling without coolant is not recommended, mainly because the chips can get stuck inside the hole causing the breakage of the drill. If its unavoidable due to machine limitations, the cutting speed should be reduced and the «wood peck» drilling technique should be applied (after drilling a few millimeters, the drill is retracted out from the hole to ensure no chips are stuck on the drill, and then continue drilling).



Lamina Trigon line - WCMX


WCMX inserts are in the market since long time and although they have some disadvantages when compared with modern square inserts like our SPMG (WCMX has less cutting edges and less stability due to pocket design), they are still very popular in the market. 
Lamina offers the most popular WCMX sizes, providing highperformance in a multitude of materials

Lamina Square Line - SPMG

Fits existing drills in the market. 
• The same insert serves the inner and outer pockets
• Wide application range
• Multi-Mat™ application
• High-performance





SPMG Inserts Range


Drills Range

Drills 2xD and 3xD are available, longer drills with 4xD can be ordered on request


SPMG 060204 – Steel test 

Test done: Lamina Tech-center

 Machine: Mikron

Workpiece: Demo
Material: 42CrMo4
Op: blind hole










SPMG 060204 –Stainless steel test 


Test done: Lamina Tech-center
Machine: Mikron
Workpiece: Demo
Material: AISI 304
Op: blind hole












Drilling operation - Summary

In summary, drills with indexable inserts are very popular in the range of holes with diameter in between 12.5 and 41mm. Besides applying the right cutting parameters according to workpiece material, success in drilling operations highly depends on good coolant flow.

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Lamina Technologies is a Swiss manufacturer of carbide cutting tools, specialized in milling and turning inserts made of state-of-the-art submicron grades with PVD and CVD coatings.


rue Pythagore, 2

1400 Yverdons-les-Bains



+41 24 423 55 55


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