Waterjet Group

rubic_pl · Newbie

A Comparision Between Intensifier and Crank Drive Pumps

gzsame · Newbie

efficiency of the machines are nearly the same. In China most of the machine's efficiency is 70% around

We are a waterjet machine manufacturer in China. If anything we can help please visit my profile for contact

rubic_pl · Newbie

Well, i don't think that both pumps have the same efficency. Different solutions give different efficency.. i think.

First of all hydraulic systems have the theoretical efficency of 80% maximum. And maybe the crank drive pumps have a higher efficency. Producers claim it's true, and it equals above 90%.

And this leads us to the issue,how to calculate the theoretical efficency of both pumps.

TFabian · Veteran Member

Crankshaft are more efficient, by about 10-15%. That does not equate into cutting speed though, as that is dependent on things other than effieciency. Efficiency of a waterjet pump is like a fuel economy on a car. If you are looking for "fuel economy" for your waterjet, Direct Drive is a pump worth considering. If you are looking for ultimate reliability, there is another choice (60k Intensifiers). If you are looking for power, speed, and lowest cost per part, there is another choice (Hyperpressure Intensifiers). I have a formula for calculating effieciency. I'll locate it and post it on the board.

rubic_pl · Newbie

If you find the formula please send it to me, or post it in this topic. I would be grateful.

splashandburn · Member

Gentlemen,

I am sure there are people better qualified than I to answer this (Maybe Mr Hasish?)

The formula for all waterjet cutting is fairly simple.

The other thing is where does all the wasted energy go? HEAT

Well most intensifiers need a big chiller or a huge cooling flow. Sometimes up to 12 times the cutting volume. This cost should be factored in for this reson the hyplex type pump will prove to be the future of waterjt technology in the short term (IMOHO)

There is also a new breed of pump a high enertia servo driven pump. While this is a novel idea the realisation could take some years to figure out how to efficienly control such a load and how to exploit this properly. It could spell the end for both trditional intensifiers and direct drive unit in the coming years

Input power to output power is a straightforward calculation. The question i am more interested in is how does higher pressure 90Ksi cut more efficiently.

We have done some testing and even using the RocTec 500 mixing tubes with elongated inlet bodies and as short a 2" mixing tubes to help focus the jet better the tubes only last 20ish hours. Then there is the fatigue factor, once the crack has started reducing pressure will not halt progression. The fact the tubing is going to cost 3 times more to replace and last under 1000 hours. If you wind the 90ksi intensifier back it will not run a larger jewel so you end up cutting slower than a 60KSI pump or paying dearly for the bragging rites. I understand the increase in nozzle velocity will increase abrasive acceleration but this does not add up to a faster cut.

We found more down time, more expensive consumables, less user maintainable pump parts.

I have found the Omax Direct drive pumps with the intelli-max software cut as fast or faster than any other system on the market at less than a third of the cost of the hyperpressure systems.

FYI
HP = approx .58 x Thousand psi x Gallons. This is fairly unversally accepted in waterjet terms.

Therefore a 50hp intensifier running at 70% (guessing high) is actually delivering only 35 hp to the nozzle after attenuation. so at 90ksi the flow would max out at about .66 gallons per minute. not even enough flow to run a #0.013" orifice so you are limited to a 10 thou hole and 40 thou tube. the you get entrainment problems as the jet does not have the phsical persence to efficintly entrain the abrasive. so you crank it back to say 70 thousand with a 10 thou and now you only got about .3 gallon US do the sums!!!