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Retrofitting machining centers with frequency-controlled high pressure pumps

A solution that combines efficient resource use and a high potential for energy and servicing cost savings

A challenge to be met in the interest of sustainability:

The achievement of optimum process solutions in the interest of sustainability hinges on the extensive examination of the entire machining process. The mere decision of whether the process is to be a one or two-spindle process, whether it is to be automated and after how many clamping positions a workpiece is to be complete, does have a significant impact on energy consumption and on the required production space. Consequently, customers demand innovative solutions for the machine tool and its periphery that will allow them to manufacture more efficiently and to simultaneously conserve resources and to and cut costs.

Status quo:

Almost all machining processes need cutting fluid. To date, the pumps that normally handle the supply and discharge were not controller regulated and always ran at maximum capacity regardless of the actual demands. The detrimental factors resulting from this status include the inefficient use of energy and adverse impact of the pump motors' exhaust heat on the useful life of cutting fluids.

Solution:

Technology, project and services – all aiming at sustainability:
An innovation team consisting of members from our fluid technology, electrics and mechanics divisions as well as our design and the purchase departments made the search for a practicable and cost-saving solution their business. A customer specific machining process using high pressure pumps without controls was analyzed. As a result, the team was able to obtain concise data on energy and cutting fluid consumption. Every single step of the machining process was examined and the respective minimum and maximum quantities of cutting fluid were determined. Also depicted were the specific pressure levels required for the internal supply through the tools.  After a number of experiments, the innovation team concluded that a frequency controlled pump was the viable solution that would make the process more efficient and consequently conserve resources and cut costs.

The high pressure pump without controls, which was supplying cutting fluid to two traveling columns/work spaces in this case, was replaced with two smaller frequency controlled pumps. The machining center control manages both pumps and adjusts the required volume and pressure for each machining operation with absolute precision. Given the positive energy and cost savings results, these frequency controlled high pressure pumps have become a standard option for all STAMA Centers.

Sustainable strong points:

In the case on hand, savings of 80 % were yielded in electrical energy costs. The simple and cost effective installation of or retrofitting with frequency controlled high pressure pumps and the resulting greater efficiency in energy consumption improve the overall ECO footprint of the machining center. Owners who decide to retrofit will find that their investment will have paid for itself in less than two years.

Savings in exact figures
Scenario prior to retrofitting:
A constantly running high pressure pump (14 kW) provides cutting fluid to two work spaces with one each milling and turning spindle. This is necessary because at least one spindle always demands high pressure and/or because the high pressure pump also conveys cutting fluid when not running under pressure.

Post retrofitting scenario:
Two small high pressure pumps are actuated as needed thanks to frequency control.
Retrofitting investment: approx. € 12,000
Savings: 11.5 kW per MTC and hour
Annual savings based on a 3-shift scenario: approx. 90,000 kWh
Amortization depending on price per kWh: 1 to 2 years

The inventors:

STAMA's corporate philosophy makes the development of innovative products priority one. More than 80% of all machining centers we ship to customers are turnkey projects that include process solutions. The well-founded experience we have gained from all of these projects paired with the comprehensive know-how we have acquired provide a solid foundation for excellent engineering in (virtually) every sector, including the automotive industry, medical technology, tooling technology, fluid technology, etc.
Every department has its own innovation program and every staff member is actively involved on his/her own initiative or as a result of working toward target solutions. A project may well begin in the brains of individuals – the resulting success, however, is always produced by the entire team.

Brief company profile:

Name: STAMA Maschinenfabrik GmbH
Headquarters: Schlierbach
Year established: 1938
Workforce: 392
Solutions: Vertikale Bearbeitungszentren, Fräs-Dreh-Zentren, Turnkey-Lösungen, Service

Internationality: Weltweit über 70 Service- und Ersatzteilstationen

www.stama.de