Outer length of drill bit towards the roughness

  The grinding angle of gun drill has a big influence towards the inside hole roughness. But under some special condition, the length of the gun drill bit has a guide influence towards the hole processing. Here are some examples:

1. Information of the parts

           Material: Q235, hot rolling state.

          Size of parts: φ20（outside diameter）×100（length）

          Processing hole diameter: φ10×90

   Processing requirement: φ10±0.025. Roughness: ≤Ra0.8

   Machine: ZK2115X4B/500

2.Changes of drill bit influence analysis towards the processing quality

   1) Standard gun drill: φ10 standard angle gun drill, the length of inner blade and outer blade is the same, TiN coating(take the following picture for reference )

Processing result: inside hole diameter roughness is very poor with greatly scratch; poor size consistency, inside hole is uneven distribution, the hole size is 0.1mm bigger or smaller.

Take the following picture for reference:  

And here is the picture of opening side 

     Long outer drill bit:when the outer gun drill bit is too long, its diameter is 1/3 hole diameter, TiN coating(see as below)

2) When finish processing, apply for the same rotary speed,feed volume, oil pressure etc, but the processing efficiency has been greatly improved.

Processing result: inside hole roughness:Ra0.4～Ra0.8

Good hole diameter consistency, the deviation is around 0.02mm, and it has get a good concentricity. 

As a result, in some low carbon processing procedure, use the long outer drill bit, the processing quality has a good improvement.            

 When the customer has a high requirement of roughness and size precision, we can think about to apply for such kind of processing  method.

If any more question, please feel free to contact us.

Email: gsmsxoffice@gmail.com