Depositor Energy Savings - Real or Fiction?

Do Servo depositor energy savings sound to good too be true? That's because they are!

Steck wouldn’t normally comment on other manufacturers marketing material, but recently there have been some quite astonishing claims made by a new entrant into the depositing machinery market regarding energy usage. The claims relate to the potential energy savings made possible using servo rather than pneumatic operated depositors. The extraordinary claim is that a user can save £13,222 annually in energy costs by purchasing one of their servo depositors. Sound too good to be true? Exactly, and it isn’t true. Certainly not for a Steck depositor or any other pneumatic depositor we’ve ever seen.

The claim related to a machine depositing 80 grams at 60 per minute running 18 hours a day for 52 weeks of the year (23.6 million deposits per year, 6,552 hours running). They claimed that their servo machines would use 3,459 kWh (530 Watts) and that a pneumatic depositor would use 36,515 kWh (5,573 Watts) to generate the necessary compressed air in the plant room. The claim of 5,573 Watts bears no relation to any real-world data. A Steck Dimension HLB138 running at 60 deposits per minute and 80 grams actually uses the equivalent of 930 Watts in the plant room. So, while there is some energy saving, the savings are nothing like those claimed.

A more typical usage for a depositor is between 5 and 10 million cycles per year. That would be between 1,388 hours and 2,778 hours per year at 60 per minute. The energy consumption difference between the servo and the Steck pneumatic machine is 400 Watts, so the energy saving in electricity is between 555 kWh and 1,110 kWh. With large users paying around 19p per kWh currently, the cash savings amounts to between £105.45 and £210.90 per annum. And even this might be an overestimate if waste heat from the compressors is being recovered for process water heating.

Servo depositors have their place, Steck has one in their range for several years, but savings in energy are only a very small part of the equation in terms of cost of ownership. Capital cost/ depreciation, maintenance, size, robustness and power capability are all significant and larger considerations. As always though it is the accuracy, or lack of, that is the biggest by far cost of owning a depositor, and being servo driven or pneumatic driven makes no difference at all to this, it is the product contact parts that make the accuracy difference.