High metal removal rates at high feeds with durable tools from Hitachi Tool.
“Fierce competition in the fields of tools, dies and mould-making make it necessary for users to come up with increasingly more sophisticated machining strategies to complete the daily changing production tasks if they want to lower their production costs.
With this in mind, our application engineers, when at the customer’s location, find themselves confronted with the difficult task of shortening machining times while, at the same time, designing a dependable process,” explains Markus Fischer, Technical Application Manager Europe at Hitachi Tool, who has been serving users throughout Europe on behalf of Hitachi Tool for over 13 years.
Adds Fischer: “The days when all you needed to do was limit yourself to the day shift to perform the roughing and then preferably move the finishing work to the second shift are over. With the right choice of tools, coupled with an improved or optimised strategy, it is possible to perform the roughing work with virtually no manpower and, above all, with dependability.
The following description of a sample machining operation is telling proof of how this works.
| Fig. 1: | Valve control housing |
|---|---|
| Material: | 1.2344 |
| Hardness: | HRC52 |
| Dimensions: | 50 x 75 x 55m |
The aim of the task was to produce the component shown in Fig. 1 more economically and, above all, more dependably.
Until now, the customer had used several ball-nose end mills for this moulded part in order to gradually achieve the desired shape. This led to the problem that the follow-on tools were subjected to constant changes in cutting pressure caused by the tool going into areas that tools had previously been unable to reach (see also Fig. 2). This made the process undependable as it was susceptible to stress variations causing the cutting edge to chip.
What’s more, the surface usually showed signs of chattering vibrations that were the result of the end mill constantly bending.
Inevitably, this not only had a significant impact on the lifetime of the tool, but the process also became less dependable.
Fig. 2: Residual material ball-nose end mill Ø6
The use of the ETM Epoch Turbo Mill, together with a different production strategy, dramatically improved the results.
Instead of a variety of ball-nose end mills, toric end mills from the ETM Epoch Turbo Mill series with a diameter of 2 mm and 5 different effective lengths were then used. This made it easily possible to mill close to the final shape from the very beginning - to the final dimensions after micro-finishing (see also Fig. 3).
As a result of this change in strategy, there was no need to run previously milled areas any more, even when different lengths were used, as no residual material had been left behind.
For all of the 5 effective lengths used in this case, the same cutting conditions were selected. Only the ap infeed fell as the overhang increased.
Fig. 3: Residual material ETM Epoch Turbo Mill Ø2
The machining work was performed on an HSC machining centre with an HSK63A spindle (20,000 rpm).
At 12,700 rpm, a relatively low speed was chosen because, even on hardened steel, HSC milling and machining does not always require full use of the spindle’s output. Given the special design of its radius geometry, a feed of 4060 mm/min was achieved using the toric-shaped ETM Epoch Turbo Mill 4-cutter (fz 0.08).
With effective length ratios of between 6 and 13.5 x Ø, the initial ap of 0.07 mm was adjusted to 0.025 mm.
The overall milling time for the quality shown was less than 5 hours.
Fig. 4: End mill wear and tear:
Ø2 x 27 mm after 80 min
No tools were destroyed and an inspection of the mills used revealed that all of the tools could easily be used for further machining operations (see also Fig. 4).
There are many machining strategies in existence which have so far been considered to be state of the art in plants. However, the new generations of end mill with ultra-hard materials and coatings, as well as optimised cutting edge geometries make it necessary to rethink the process. They enable new, forward-thinking production solutions that advance the user’s technology and allow him to maintain or even build on his market lead. This is not achieved simply by selling tools at a certain price but by forging a team with the user. Conveying this message is the primary task of our application engineers.
In addition to the innovative range of tools, each Hitachi Tool application engineer has local access to engineering expertise throughout Europe. Our field staff can select a highly diverse range of applications and projects from over 1000 digitally imaged application reports, all of which are summarised in a database. Given the numerous means of retrieving information by tool, material, hardness, machine, type of customer, etc., it is possible to search for the machining centre used by the customer either strictly by application, for example, or applications can be retrieved that are similar to the envisaged form of machining.
This enables the user to understand exactly what the Hitachi Tool products are capable of before committing to any form of cooperation.
“This is very often the cornerstone of a successful partnership.“
Mr. Dilek Serifoglu
Hitachi Tool Engineering Europe GmbH
Itterpark 12
40724 Hilden
