Making short work of things.

Full milling instead of EDM

Increasingly complex moulds from a wide variety of branches – more and more of them in the miniature field – make immense demands on the expertise and experience of tool, die and mould makers.

It can be said, however, that many mould makers are not always aware of the latest tooling and machining techniques.

For Albert Sadowski, General Manager of Hitachi Tool, HSC technology has been used in completely the wrong applications over the past 10 years compared with its possibilities.

By way of example, whilst many mould makers produce their copper or graphite electrodes using HSC technology, they waste all the time they have gained by using the highly time-consuming EDM process plus subsequent manual machining. This is time that no maker of tools, dies or moulds will have in the future, especially those competing for the supply of car parts.

On top of this, avoidable mistakes are very frequently made when selecting the tools, the machining strategies and determining the cutting conditions.

Make the mould non-stop using HSC

Adds Sadowski: What we want to get across to the users is that HSC technology, if combined with the right machinery, CAM system, milling tools and a well-planned machining strategy, has long since offered the direct, faster and more economical way – a complete machining process from the blank to the finished mould – all without the need for any subsequent machining!

Although this is certainly not possible every single time, it is the time factor that remains the decisive criterion.

In recent years, Hitachi Tool has invested heavily in researching and developing new milling technology. A whole array of innovative, in part, ground-breaking enhancements resulted from these activities.

Among these are new milling technologies for HSC milling which, until now, had been reserved for EDM processes.

Today, Hitachi Tool solid carbide end mills are high-end products. Their performance and service life are the result of a successful mix of substrate, tolerance, coating and cutting geometry which are described below:

12 Substrate mixtures for special use

Hitachi Tool mixes and sinters the “super micro-grain” substrate for all milling blanks in its own plant. At present, 12 different types are made, especially adapted to suit the different applications, ranging from a 12 mm end milling cutter to a miniature end mill. h4 tolerance is standard at Hitachi Tool.

End Mills: EPDR EPDR

These days, every Hitachi Tool miniature end mill is produced in h5 shaft tolerance; as of April this year, even h4 tolerances will apply (the standard market tolerance is h6). The reason for this is that a precise shaft has a very high impact on the polished face of the cutting edges – the tolerances for the current Epoch Deep series are as follows:

Radius: ± 0.005mm
Corner radius: ± 0.010mm
Diameter: ± 0.010mm

Since miniature end mills are usually used in ranges of between 20,000 – 60,000 min¹, the concentricity (shaft tolerance) is especially important as it reduces the vibrations to an absolute minimum.

When it comes to finishing, cutting depths of between 20 - 50µm are generally achieved. A radius tolerance of 5µm is therefore vital so that both cutting edges can be used evenly. In addition to increasing the lifetime of the tools, it above all enhances the quality of the surface and makes highly time-consuming and cost-intensive manual subsequent finishing redundant.

Coatings up to HRC72

The NANO crystalline, amorphous TH45+ coating developed by Hitachi Tool with exceptional oxidation resistance of up to 1,100 °C, a coefficient of friction of 0.9 and a hardness of 3,600 HV is especially suited to machining cold and hot work steel types with hardnesses of between HRC45 and HRC72 and increases tool lifetime several times over.

Cutting geometries optimised

Innovative shaft geometries combining radius and taper with an effective length of up to 35xØD and three times the normal bending strength enable ribs and slots to be machined in the mould-making industry to a depth and precision that, until now, had been created using the conventional EDM process.

Diagram: Application of Epoch Deep end mills
Application of the new generation of Epoch Deep end mills

Hitachi Tool is currently underpinning its pioneering role by offering the smallest end mill currently available with a precisely cut cutting geometry with a diameter of 40µm (a human hair is approx. 100µm “thick”).
Euromold-Award, EMM Square

Machining technology

In addition to the enormous advancements made in cutting tools, machining technology has also been optimised in many respects in recent years.

The following example illustrates the benefits users can reap by milling workpieces using HSC rather than using EDM – while also saving on time and money:

The aim of the task was to fully mill an extrusion die in PM steel (1,3551 80CrMoV42-13), with a hardness of HRC62.

On hand was a DMC 70V hi-dyn, HSK-40E, 42,000 min^-1, with a feed rate of 30,000 mm. On top of this came 1 toric-shaped shell end mill with a diameter of 10 mm and a CR1.0 and 4 miniature ball-nose end mills with diameters of between 3 mm – 1.5 mm. The total cavity, including roughing, rough grinding and fine finishing applications, was milled over a total duration (in the first run!) of 5 hours and 20 minutes.

After performing the roughing applications using EPDB 2030		Semi-finish with a diameter of Ø 3 mm

Perfect surface finish after fine finishing with a diameter of Ø 1 mm		EPDB 2030 Ø 3 after 150 min. of Roughing and 30 min. of finishing: No visible wear and tear

These values can usually be enhanced through the following optimisations to achieve a further 20-30% in time savings.

Service and customer proximity

With 20 application engineers throughout Germany, Hitachi Tool currently offers customer-orientated service – enabling us to react swiftly and serve you locally.

Having undergone in-house skills training, each of these engineers is able to recommend the necessary tools, a perfectly fitting strategy and well matched cutting conditions for any pending project.

Our guaranteed supply availability rounds off our service for customers, making Hitachi Tool a dependable partner, especially when it comes to future tasks.

Outlook

In order to maintain our status as a highly efficient partner for tool, die and mould makers, Hitachi Tool always develops its products in keeping with market requirements. Here, three trends are discernible:

Miniaturisation,
Greater hardnesses, and
Optimised length ratios.

Hitachi Tool can already offer a suitably innovative solution from its range for each of these three trends.

Miniaturisation:
Epoch Micro Mill with diameters ranging from 0.04 to 0.1 mm
Greater hardnesses:

Steels (1,2379), PM steels (1,3334) and even carbides in grades ranging between HRC60-72 can already be cut economically

Length ratios:
R0.1 with an under-neck length of 1.5 mm (7,5 x D)
R0.3 with an under-neck length of 8 mm (13,3 x D)
R0.5 with an under-neck length of 35 mm (35 x D)