09 April 2011

Is an Economical Solution One that Saves Money?

CBER32 Boring System in a CT40 Holder
The CBER boring system is an economical solution according to a customer I worked with the other day.

Here is his story:

A new Criterion customer called asking about the proper use of his CBER boring system. He had just received it and was preparing to bore his first .875 +.0002/-.0000" in diameter bore. I asked if he had purchased a collet nut with it or was going to use one he already had in his shop. He had purchased a collet nut but his operator had not used it. He had put an existing collet nut on the system. The existing collet nut had to be replaced with the purchased collet nut as the extractor lip interfered with the CBER system fitting in the ER collet holder properly.

We then talked about how much material was left to be bored out. He had left .010" per side put it was not enough because the nose radius of his insert was .015". I explained that he would not get the proper cutting action with the insert and if he could leave .020/.025" per side it would make it easier for him to produce the bore and the finish he required. He was going to change that for the next production run of parts he had to make.

We went on to discuss how to set the tool and make small diameter adjustments using the flat on the insert side of the boring head. We also discussed the appropriate RPM and feed rate he should be using for the material he was cutting.

The next day he called back to let us know the CBER system was exactly what he needed to do the job and was easy to use. He decided he is going to leave it set for the .875" diameter size and purchased additional systems for the other 4 or 5 size bores he makes. His reasoning was the cost of the CBER system being 1/4 of the other system he had looked at he could leave them set and reduce the cost of his set-up every time he set-up a production run. Truly, an economic solution for him.

17 February 2011

Old Dog - New Trick

One of the most difficult aspects of boring is attaining the correct RPM for the cutting tool. Boring heads are design to move off center so you can enlarge the ID of a hole. This movement creates an imbalance which requires a slower RPM to ensure the bore can be produced. There are a number of approaches for correcting the imbalance. Some manufacturers restrict the amount of off-set so the boring head has minimal imbalance and others have some form of movable weights.

CB-202B Boring Head with Balance Kit
US Patent 7,309,194 B2
Criterion had a unique situation because we had been producing boring heads for over 65 years. Our philosophy was to give our customer as large a boring range as possible with one boring head.  Time has changed manufacturing technology and higher speeds have become important. We did not want to limit the range but we did want to meet the needs of today's manufacturing. Our solution was to develop a unique balancing system for our 202 series of boring heads. The US patent office agreed and issued a patent for the system. So by looking up your bore size, selecting the correct components and settings a boring head made over 50 years ago can spin at 5,000 RPM. This was unheard of when the boring head was first made but very achievable today.

So I would say the adage of "you can't teach and old dog new tricks" is not true.

What is the value of a balanced boring head? First and foremost is increased productivity. Another benefit is improved  tool life because the cutting tool now can operate at its optimum speed.