Hole 2 H7 x 105 long
IN SS 304 shaft of 6 dia max
Accepted answer
Hello!
In my case, the first thing that came to mind was EDM (en español: ELECTRO-EROSION)... but from talks with mechanics from specialized workshops. That is, I myself, with my bare hands, never did.
However, I leave you the following text and link that mentions sizes and tolerances (apparently holes from 0.3 mm in diameter).
Source: http://millingmachine-ar.com/index.html
The copper electrode tube of the EDM drilling machine can realize the drilling of small holes in the workpiece using high pressure discharge, in this way we can see that the surface of the workpiece is etched by the pulse discharge between the electrode and the piece to be able to complete the perforation of the hole. Generally, it is preferred to process parts immersed in dielectric fluid, as in the case of pure water, providing a better finish to the part.
This type of EDM drilling machine is widely used for fast and precise machining of small deep holes for automobile parts, medical instrument components, aerospace parts, hydraulic parts, valve parts, and more. Parts operated by the EDM drill generally require drilling prior to cutting. The diameter of the hole made by normal drilling machines ranges from 0.3 to 3.0mm. On the other hand, in the case of using the EDM drilling machine, because it is of high precision, the drilling of holes is in a diameter range below 0.1.
The EDM drill can perform the process for very hard steel (such as stamped steel, tungsten steel, etc.), and any type of conductive material (aluminum, titanium alloy, etc.).
Likewise, this type of EDM drill has 2 types, these being CNC and ZNC types. In order to differentiate between them, we say that the cost effect of ZNC EDM is usually used for single hole processing. In contrast, the CNC EDM drilling machine is used to perform multi-hole processing with high precision.
1 Other answer
2 mm diameter x 107 deep is quite deep. My first idea is deep hole drilling. Followed by reaming and then honing. That should get you the required H7 tolerance.
Deep hole drilling requires special equipment. It incorporates a special hollow boring bit and holder along with a high pressure coolant pump. It can usually be adapted to standard CNC equipment. It needs to be done in a horizontal orientation so a CNC lathe is the best machine to start with. Deep hole drilling needs very repeatable feed rates and probably a peck cycle. So a manual operation is unlikely to work and will probably result in an expensive broken bit. CNC is a requirement.
The reaming and honing operations can be done in a similar setup on a CNC lathe.
The only deep hole drilling I’ve done was for holes around 10 mm diameter and about 400 mm deep. I am making an assumption that deep hole drilling is available for 2mm diameter too
Another possibility is rotary piercing by the Mannesmann process or Stiefel process for making thick walled tubing. It’s essentially a rotary forging operation and produces tubing with a surprisingly accurate ID and straightness. Some sizing with reaming and honing will still be required. I’ve purchased tubing made by this method with about 5 mm inside diameter.
