CNC turning – Speed, feed selection

CNC – The right cutting parameters can reduce cycle time, drastically

Even animals use tools properly, but humans on a typical CNC shop floor totally misuse cutting tools.

Crow using a stick to get ants, and Chimp using a stone to break a nut

Using the right cutting parameters can reduce cycle time and machining cost. For example, if you are using a cutting speed of 100 m/min when you should be using 200 m/min, it means your machining time and machining cost are twice what they can be.

The reality on most shop floors is that we select any available insert that fits into the holder that we are using, with some cutting parameters that WE are comfortable with, not what the tool is comfortable with. E.g., “You’re cutting steel with a carbide insert? Use a cutting speed of 100”. What steel, what carbide – who knows and who cares, yaar ?

Every cutting tool manufacturer’s catalog tells you what insert grade, chip breaker geometry and cutting parameters to use. Manufacturers like Sandvik, Kennametal, taegutec, Iscar have their own individual catalogs in PDF or printed form. It takes a few minutes to refer to the catalog and select these. You’ll often hear this remark “Oh, those tool manufacturers just recommend very high speeds to sell their stuff – those parameters don’t actually work”. The fact is that the cutting speed in manufacturers’ catalogs is typically for a tool life of 15 minutes. If you want a longer tool life, just reduce the cutting speed.

This short document shows you how to select the insert grade, chip breaker geometry and cutting parameters for Turning and Boring. Once you understand this, you can apply the knowledge to other operations. Before you read this document you might want to read these posts too: insert grades, chip breaker geometry, and positive/negative inserts.

Action point

Get your manufacturer’s catalog right away, and start using the recommended cutting parameters. You can get the catalog in printed form, or download it from the manufacturer’s web site as a PDF file. Cutting parameters are automatically selected in Cadem’s CAPSturn CNC lathe programming software and CAPSmill CNC milling programming software.


Non-motorozied transport in Kolkata

I love lots of things about Kolkata, it is one of my favourite cities, and NO, I’m not a Bengali. One of the things I like is that it still has a lot of non-motorized transport (NMT), carrying people and goods. Sensible cities worldwide promote NMT because it is non-polluting, consumes low energy, and is benign in various other ways.

The city I live in, Bangalore, with its aspirations to be a ‘world class city’ (whatever that means), thinks NMT is not fashionable, and the result is this, an example of pollution on Bangalore’s roads. Bangalore has the dubious distinction of being among the top 5 polluted cities in India, while Kolkata does not.