T-Slot Milling

May 31, 2018

T-Slot Milling Cutters are products developed to create cavities specially suitted for T-Nuts and their design follows the DIN 650 

What are T-Nuts?


T-Nuts are clamping elements widely used in the industry. Frequently associated with Machine Tool Builders (MTB), these pieces are used to assemble components which will suffer forces, in a safe way. “…A heavy-duty T-slot nut with a M12 bolt is rated to support 10000 N …” = Wikipedia.
Here below we can see an example of T-Nut in RED.




Example of T-Nut


This piece shown on the right is a T-Nut in accordance with DIN 508. We will show how to make the choice of tool, the process and some information regarding cutting parameters.



Example of T-Slot


For the item mentioned previously, the T-Slot to be produced must follow the dimensions below, according to DIN 650.


T-Slot – Previous Operation


 The first operation to be performed is the slot milling Width = 14, Height = 18.


It is important to keep the Height like shown below, in order to keep the T-Slot milling operation well balanced and free of undesired chattering.


           Do not exceed 1mm !






Product line - Inserts

Our T-Slot product line is compounded by 3 different inserts, divided in to Grades.


Product line – Milling Cutters
Our T-Slot product line is compounded by 5 different Milling cutters

Dimensions and Nomenclature



D = Main Diameter

Ap = Slot width

d1 = Neck Diameter

L1 = Work Length

L = Total Length

d = Shank Diameter




Difference between Z and Z(eff)




The T-Slot milling cutter line has always even number of teeth, this milling process is performed by inserts assembled in pairs. The 1st insert will machine the bottom and the 2nd insert will machine the top of T-Slot.

The table feed rate must be calculated using the Z(eff) in order to keep it in a reasonable value, avoiding insert overloading.


Process explanation



For the example we have here, we will use the milling cutter : LT 400-06 W-W-D021/1 + Insert : SPMT 060304 TN…
This milling cutter fits this dimensional needs.
Let´s do it in Grey Cast Iron GGG40 Group 8.


Cutting Data Calculation


Due to the big engagement angle and the Milling Cutter shape (T-Shape) we strongly recommend starting the operation with a reduction like below :
Cutting Speed – 20% ( or min.cutting speed )
Feed rate – 20 % 
The D.O.C. is = entire cutting edge length


Process explanation : 1st Pass

 Cutting speed (Vc) : 120 m/min ( 150m/min -20%)

Feed/Tooth (Fz) : 0.08 mm/t

( 80% of starting parameter )

Diameter = 21mm / Number of Teeth (Z) = 1

RPM = 1817 rev/min

Table Feed Rate (F) = 145 mm/min

There will be 1mm to be finished after performed the 1st pass.



Process explanation : 2nd + 3rd Passes
For the finishing passes, the side depth of cut will be approximatelly 5% of diameter and it allows us to make the corrections following the table bellow ( see tip of the week #18 )Vc : 192 m/min ( +60% ) / RPM = 2907 Fz = 0.36mm/t / Table feed rate = 1046 mm/min



Milling cutters for T-Slot x T-Nut = Range 


Our T-Slot line has comprehensive range, starting from M12 to M30




 T-Slot Milling is a distinguished type of operation, applied by MTB and general industry. We have competitive milling inserts and our T-Slot line can be successfully applied, it is important to use the cutting parameters properly, making the corrections shown here and optimize them during the application in order to achieve best results.










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