9. Wiper inserts in turning
CNC: Wipe off some cutting time with wiper inserts
We want two things in finish turning: 1. Good surface finish 2. Low cutting forces so that part distortion is minimized.
A wiper inserts looks just like a normal insert, and comes in the same shapes (C, D, V, W, etc.). The difference is in the nose radius. The nose is actually a combination of radii instead of a single radius. So you can double the feed rate and achieve the same surface finish, with an increase of only 10-15 % in cutting forces. Which means you halve the cutting time, but get the same quality. Alternately, you can use the same feed rate and get a better surface finish – Ra values are typically 2 to 3 times lower. On some materials you can even eliminate a grinding operation. Also, at a higher feed rate chips are thicker and break better.
In sum, the benefits of a wiper insert are: When cutting at high feed rate – Reduced machining time – More number of workpieces with a single insert – Better chip breaking When cutting at normal feed rate (used on normal inserts) – Improved surface finish – Eliminate the finishing step by roughing and finishing together
This short article has a more detailed explanation on how a wiper insert can improve your productivity and quality.
Konfusion in Kolkata loo The things in the picture look like urinals, don’t they ? That’s what a customer in a restaurant in Kolkata thought too. These things are what you see first when you enter the men’s loo. A colleague of mine and I went to the loo, saw these things, and a man peeing into one of them. We also happened to look towards our right and saw a bank of what appeared to be the actual urinals (the second picture), partially hidden behind a wall. Obviously the first ones were wash basins.
I pointed out the mistake to the man peeing into the washbasin. I’m sure there wasn’t a more sheepish looking guy in Kolkata that night (although I don’t blame him, poor guy – the washbasins do look like urinals). I don’t remember which of the washbasins the guy peed into – would have helped so I can avoid it on my next visit to the restaurant. Luckily for me, the food in the place was so foul and expensive that I’m sure I won’t be going there again.