Is hard turning a stable, predictable process for me?

Yes. In recent years hard turning has evolved to become a simple, reliable process due to the advent of super tough cutting materials, amongst other things. Hard turning has since become accepted throughout the world and is able to comply with the requirements of the ultra-precision industry, such as those demanding superior quality and shorter turnaround times.

For which products is hard turning suitable?

In principle, hard turning is suitable for all hard, cylindrical workpieces of micron (or  submicron) size, shape and surface requirements.

Are there nevertheless products for which grinding is more appropriate?

Yes, for large or long, thin products, because grinding places less pressure on a product when working on it. As a rule of thumb, a ratio of length to diameter of 2:1 must be maintained in the case of hard turning. Where optional supporting materials are required, such as a steady rest and tailstock, it may be increased to 4:1.

On what materials can hard turning be performed and which hardness variations can be used?

Hard turning can be performed on all types of hardened steel with a hardness variation of between 58 HRC and 70 HRC (+/- 2 HRC). For instance, examples are 100Cr6 and 45MnCr5. It is also possible to process hardened steel, albeit with a minimum cobalt content of 12%.

What level of precision can be achieved?

This depends on the lathe that is used, although the Mikroturn 100 is capable of achieving the following levels of precision up to 380 mm:
surface (Ra) – 0.1 to 0.4 µm;
shape – ≤ 0.1 – 2 µm;
size – ≤ 2 µm.

Do I require a cooling emulsion for hard turning?

In most cases a cooling emulsion is not necessary. However, where there are lengthy contact times between the tool and the product a cooling emulsion is sometimes required. Air cooling is a cost-effective alternative to a cooling emulsion.

Is it also possible to perform hard turning on products with interrupted cuts?

This is quite simply possible to do with the appropriate CBN insert but the precise size of that insert will depend on the product which is to be processed and the related interrupted cut.

Is it possible for a tool to simply break?

No, a tool does not simply break. However, it can happen if it is worn down and machining occurs. Nevertheless, it is possible to prevent this from happening by using a tool measuring system or by measuring the coarseness of the relevant product after machining it. Increased coarseness indicates a worn tool.

Will the first product be good right away when hard turning?

Using the appropriate program and configuration settings, the first product can be within tolerance levels after hard turning.

Does hard turning not have the disadvantage of producing a white layer?

No. You can prevent this from occurring by using the appropriate feed and feed rate parameters. In this respect it is vitally important to control wear and tear of the tool. A worn tool creates more friction, which generates more heat and consequently increases the chance of a white layer occurring.

Can I also perform hard turning on my products? Alternatively, are they suitable for hard turning?

With the aid of your product drawings, we will gladly let you know whether this is the case and, if they are suitable, we look forward to presenting you with a processing proposal. In this case please contact us at sales@hembrug.com or on +31 23 512 4911.

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