Grooving

Grooving

During heat treatment, many features of machined components

suffer distortion. If the position or dimensions of a groove are

critical to the performance of a hardened component. David Richards

can offer a simple solution to this problem - ‘Hard Grooving’.

Based on the Top Notch system, David Richards supply grooving

tools in a wide range of sizes from 0.5 mm width upwards.

David Richards supply tools for circlip and ‘O’ring grooves with controlled corners or full radii, either full form for plunging or undersize for profiling.

Using such surface speeds typical for turning, grooves are machined

at low feed rates (0.01/0.05 mm/rev).

The low feed rate ensures that the swarf is very weak and brittle,

decreasing the likelihood of it breaking the tool.

Where there are no interruptions to the cutting path, coolant should

be used to aid evacuation of the swarf and ensure that the component remains at a stable temperature for ease of measuring. If the cutting

path is interrupted, an air blast will serve the same purpose without

the risk of thermally shocking the PCBN tool.

If practical, it is better to finish a groove that has been pre-

formed at the soft stage. This ensures uniform hardness around

the groove and maintains the structural integrity of the component.

However, if it is acceptable, satisfactory results are achieved

grooving through a hardened layer into the core material.

Successful applications include grooving case hardened (58 / 63 HRc) splined shafts and gear teeth, internal circlip

grooving hardened EN31 (58 / 60 HRc) bearing components, and producing profiles in the face of D2 tools steel

tools using Full radii face grooving tools. All operations that would be time consuming and difficult to grind.

Whilst the Top Notch system offers an ideal base for most grooving tools, other systems have been

employed with excellent results.

It naturally follows that, since David Richards can produce tools for ‘Hard Grooving’ full and partial form threading

tools, both external and internal, are available for ‘Hard Threading’. Where the pitch of the thread is large, or the

diameter of the component is small, it must be remembered that the feed rate required, at the required surface

speed for ‘Hard Turning’ will be relatively fast. But, producing a 90 mm diameter internal stub Acme thread 150 mm

deep, with a 6 mm pitch in 58 HRc Ni-Hard iron, at 120 m/min from blank bore, though somewhat exciting, proved

a major cost saver.

David Richards have wide experience in the application of these tools and will be delighted to discuss specific examples on request.