Energy saving comparison

How efficient are Yizumi machines?

Along with many other manufacturers, Yizumi machines utilise servo drive technology to maximise energy efficiency.  At STV Machinery we’re asked on a regular basis “How much energy can I save with your Yizumi machines?”  The typical answer you’ll see around the industry is “up to 80%”, which is true, but we wanted to look at how likely this was to achieve for the average moulder.  After all, we don’t all get the advertised mpg from our cars do we?

Background information - Servo drive vs variable displacement

Older machines in our industry (80’s & early 90’s) used a standard constant pump, then variable displacement pumps (which are still commonly seen today) came in and now we’re dealing with servo driven pumps.  Each was an improvement on the last in terms of efficiency and it is the most recent two technologies we’re going to compare.  There are other technologies available, but these have proved to be the most popular.  The reason we expect to see an energy saving with servo drive is illustrated in the graph below;

In the illustration above, you should be able to see where the energy saving from this technology is achieved.  During points in the cycle where little or no pressure is required from the pump, the energy consumption drops off to almost zero.  This combined with the fact that the servo drive in Yizumi machines can deliver maximum torque incredibly quickly, means that the energy saving potential is maximised at every point of the cycle.  The constant drive cannot alter its pressure delivery and the variable displacement pump does not react as quickly as the servo drive.

The comparison

To separate energy saving myth from fact, we decided to test a servo driven machine against a variable displacement pump machine in our workshop.  The facts of the test;

  • Same tool used in both machines (one after the other obviously)
  • Set to the same cycle time (16 secs)
    • 2.7 seconds mould close time
    • 3.1 seconds for carriage movement and injection
    • 6 seconds cooling & holding
    • 2.2 seconds mould opening
    • 2 seconds open & ejecting
  • Same temperature setting on the barrel heats
  • The test was started once the machines were warmed up with the oil temperature and barrel heats at the same set points.
  • Energy monitor was reset to zero and the test started on mould close after 5 cycles
  • Duration of the test was 2 minutes

Machine one

Yizumi UN60A5 295/600

  • 60T clamp force
  • Manufactured 2017
  • 40 run hours
  • Servo driven pump
  • 35mm screw
  • 159g shot weight

Machine two

European manufactured

  • 55T clamp force
  • Manufactured 2005
  • 2600 run hours
  • Variable displacement pump
  • 38mm screw
  • 122g shot weight

The test

The results

As can be seen in the video above, the servo drive equipped Yizumi machine required 0.056 kW of energy over the two minutes compared to 0.345 kW of energy for the variable displacement pump equipped machine.  That equates to 1.68kWh for the Yizumi and 10.35kWh for the other manufacturer.

That's an energy saving of 83.76%!!!

Not convinced?

With this type of saving, we anticipate and appreciate scepticism.  We did this test to satisfy our own curiosity and assumed others may have the same burning question.  There is no doubt that a few holes can be found in our methodology (we’re not scientists after all), but we think it’s a good relatable example.  We did our best to control the variables of the experiment as much as possible and tried to give the results with as much evidence as possible. 

An independent view on the importance of energy saving from AMI can be downloaded here.

We’ve demonstrated that a massive energy saving is possible, but it depends on the characteristics of the cycle.  We’ll be doing more tests on larger machines when we have comparable machines available in our workshop.

In the meantime – Why not give us a call for a potential mould trial?

If we have a suitable machine in stock, then we’d be happy to run a customer’s tool for a small trial to see if similar savings can be achieved.  The forms below, just drop us a line.