Volumetric Compensation for Aerospace Applications.

Präwest is the German High-End company located in Bremen that is specialized in the 5-axes milling of complex parts. For a significantly improved machine accuracy the company invested in an Etalon LaserTRACER-NG. Volumetric deviations are measured and effectively compensated in the Heidenhain CNC controller. The result: accurate workpieces without any adjustment in the CNC code, even for extremely complex workpieces up to 2,5 m in diameter.

PRÄWEST PRÄZISIONSWERKSTÄTTEN PROBLEM: Needed to improve machine tool accuracy

SOLUTION: Etalon’s LaserTracer-NC and KinematicsComp from Heidenhain

RESULTS: Dimensionally accurate workpieces without any readjustments

In order to implement a sophisticated manufacturing strategy for five-axis milling of complex parts, Präwest Präzisionswerkstätten of Bremen, Germany, began grinding tools in house and building its own six-axis milling machines with parallel axes. However, even though these machines were well constructed, their geometrical accuracy was not meeting demands. By capturing the machine tools’ volumetric deviations with the LaserTracer-NG from Etalon AG (which has a North American subsidiary in Kirkland, Washington) and compensating them through the KinematicsComp Software option in Heidenhain Corp.’s machine controls, Präwest can provide dimensionally accurate workpieces with-out any readjustments.

A contract manufacturer whose customers include MTU, Rolls-Royce and Mitsubishi Heavy Industries, Präwest produces impellers, blisks, turbine shovels and aerospace structural components. The company also produces workpieces for the oil and gas sector. “We solely manufacture parts with complex characteristics,” says Gaylord Klammt, head of business area industry. “Everything the market considers exceptional would be a standard issue for us.” For instance, the workpieces often are extremely big and heavy; include complicated geometries; are made from difficult-to-machine materials such as Inconel 718; or necessitate additional processing, such as chromate coating or heat treatment, even for a batch size of one. It is often necessary to apply several hundred tools, including milling tools with lengths ranging to 900 mm, as well as 60 programs or more to turn a single workpiece to the desired shape and dimensions, he says.

To optimize the production of these high-precision parts, Präwest built its own large, six-axis milling machines with parallel axes, but the company’s milling experts soon detected systematic geometry errors of the linear and rotary axes. These deviations may be acceptable on small machine tools with wide manufacturing tolerances, but for Präwest, systematic errors from different sources add up to an unacceptable total error, partly due to large movements in the six axes and partly due to the immense size of the tools.

“When machining big workpieces, you mill in different sectors and finally meet in the middle. Many parts require reversal and reclamping during manufacturing, which also leads to imprecision. When mismatch occurs, our staff has to rework the part or adjust the programming, which costs money and time,” Mr. Klammt says. Because it produces small batches and uses expensive materials, Präwest cannot test-run the NC programs. Instead, it needed to figure out how to produce dimensionally accurate parts that measure longer than 2 meters while meeting accuracy tolerances of ±50µm (±2.97 µinch) in six axes of movement.

Präwest found the solution in Etalon’s self-tracking laser interferometer, which is specifically designed to increase the accuracy of machine tools by means of volumetric compensation. With Etalon’s technology, it is possible to calculate exact compensation values for spatial errors in all degrees of freedom. With micrometer accuracy, the system analyzes position, straightness and rotation errors (pitch, yaw and roll), and squareness between the axes in the whole working volume of the machine tool. Angular positioning deviations, axial and radial movements, and wobbling of the rotational axes are comprehensively recorded as well. Thus, the LaserTracer-NG is designed to differ from conventional laser interferometers that require elaborate aligning and generate a large amount of work to determine pitch, yaw and roll, the company says.

After acquiring measurement data, Etalon’s software calculates the volumetric compensation data. As it is interfaced with the machine controller, this data is automatically transferred to the machine.

The KinematicsComp software option from Heidenhain (Schaumburg, Illinois), which is available for the company’s TNC 640 and iTNC 530 controls, corrects the kinematic description of the machine tool. “KinematicsComp makes it possible to store a detailed description of the machine errors in the control. Subsequently, it automatically compensates the position errors that result from static errors of the physical axes. It considers the positions of all rotary and linear axes as well as the current tool length,” Heidenhain’s Gero Günther says. “This procedure increases the precision of the tool center point in the whole working space.”

Mr. Klammt invited both Etalon and Heidenhain to conduct test measurements before implementing this new measurement method and was impressed by the results. “Suddenly, this milling machine started to produce with geometrical perfection. Furthermore, we were able to understand the weak points of the machine, which was a true breakthrough with respect to manufacturing quality, contour accuracy and process reliability. After the test measurement, we quickly decided to acquire a LaserTracer-NG system plus KinematicsComp,” he says.

The LaserTracer-NG high-resolution interferometer automatically follows a reflector and continuously measures the distance to it. The system’s center-of-rotation accuracy is realized by means of a reflective sphere with a form uncertainty of less than 0.1 µm. The beam guide ensures that this sphere can serve as reference for the interferometric displacement measurement, which is conducted with high dimensional precision to the tool center point (TCP), the company says. Consequently, mechanical deviations of the rotation and swivel axes are also acquired with high precision. Measuring uncertainty for spatial displacement (95 percent) amounts to 0.2 µm + 0.3 µm per meter.

According to Stephan Kunath, head of industrial machine tooling at Präwest, Etalon’s training helped turn the seemingly complex measurements into a routine for him. He says he can do the whole compensation of a large six-axis machine on his own in a very short period of time. First, he places the compact LaserTracer-NG in the machine several times without any particular fine alignment.

Instead of a tool, the reflector is clamped in the spindle. Then, the measurement system is ready to start the automated measurement process, tracking the actual path of the machine in its entire working volume. The required NC programs are automatically generated by Etalon’s software, and the respective distances to the tool centerpoint are determined interferometrically. Etalon’s system transfers the recorded data to the connected Trac-Cal measuring software, which automatically analyzes that data and transfers the volumetric compensation values to the Heidenhain iTNC 530 controller via KinematicsComp.

Präwest conducts volumetric compensation in predefined intervals and on demand. For instance, whenever deviations are discovered in preliminary stages of production that cannot result from any other processes, the company conducts volumetric compensation, Mr. Klammt says. Previously, iterative adjustments were part of the process. Today, the LaserTracer-NG and KinematicsComp make this superfluous, he says.

Performing volumetric compensation on milling machines has improved the geometric accuracy of the workpiece significantly, particularly when machining complex parts, Mr. Klammt says. “We are speaking about dimensions that would never have been possible with other methods.”
Thanks to the improved machining accuracy, Präwest is planning to begin prototype manufacturing for the aerospace industry. “Our customers long for the highest precision. Meanwhile, we want to keep up our profitability,” Mr. Klammt says. “Thanks to volumetric compensation, we are in the position to realize maximum quality in production with manageable effort, even in the case of extremely tight geometric tolerances. The technology helps us reliably uphold our reputation as a precision manufacturer.”

Increasing Six Axis Machine Tools Accuracy with Laser Tracer. Etalon’s LaserTracer-NG was specially designed to increase the accuracy of machine tools and coordinate measuring machines.

ISO verification with Etalon LaserTracer

Rotation axis calibration with Etalon LaserTracer. This example shows rotation-axis calibration of a large machine tool with axis travels measuring 2.5 by 2.3 by 0.8 meters. The LaserTracer-NG, which is mounted on a rotary table with a diameter of 1.2 meters, is positioned stationary in the machine several times.

Präwest specializes in manufacturing complex parts. To effectively do so, the company began grinding tools in house and built its own six-axis milling machines with parallel axes. However, Etalon’s LaserTracer-NC and KinematicsComp from Heidenhain help the company perform volumetric compensation, which it says has improved the geometric accuracy of such workpieces significantly.

The KinematicsComp feature, here on Heidenhain’s TNC 640 control, has enabled Präwest to reach dimensions that it says never would have been possible using other measurement methods.

Etalon North America Inc., call 425-985-5223 or visit etalon-na.com.
Heidenhain Corp., call 800-219-0858 or visit heidenhain.us.

Reprinted from the February 2017 MODERN MACHINE SHOP Magazine and Copyright © 2017 by Gardner Business Media, Inc., 6915 Valley Ave., Cincinnati, Ohio 45244-3029
Read the publication: Download application story Modern Machine Shop (PDF, 2 MB)

EDITOR EMILY PROBST, @MMS_Emily eprobst@mmsonline.com

Today: International Day of Energy Efficiency 2017

Today on March 5 Energy Efficiency needs to be central in energy policies around the world. Energy Efficiency Day is an opportunity for companies and individuals to improve their energy consumption habits. It’s also a day to learn how to use electronic devices correctly both at home and at work.

Reducing energy consumption should be an important goal for our society. Energy Efficiency Day encourages a more sustainable society based off of renewable energy sources and more ecologically—friendly technology.

With actual Power Peak Prices  all of the core imperatives of energy policy — reducing energy bills, decarbonisation, air pollution, energy security, and energy access — are made more attainable if led by strong energy efficiency policy. As the world transitions to clean energy, efficiency can make the transition cheaper, faster and more beneficial across all sectors of our economies. Indeed, there is no realistic, or affordable, energy development strategy that is not led by energy efficiency. For the IEA, it is the first fuel, as the last report indicates.

Source: iea.org Energy Efficiency 2016

And yet energy efficiency is far from fulfilling its potential. Globally, two—thirds of the economic potential remains untapped. An entire 70% of the world’s energy use takes place outside of any efficiency performance requirements. For instance, two—thirds of energy consumption from buildings being built today has no codes or standards applied to it. A mere one—third of NDCs include energy efficiency related targets, despite IEA analysis that shows it is the single largest action in the optimal pathway to a decarbonised energy system. The IEA report is an important step in understanding global trends in energy efficiency. It tracks the key indicators of energy intensity, energy efficiency investment and their impact. IEA report finds — despite lower energy prices — progress is being made, but not fast enough. It shows where policy has made a real difference, but also highlights that much more can be achieved. It highlights the threat of a continuation of lower energy prices to the energy efficiency agenda, but also demonstrates clearly that strong, well—designed policy, can mitigate that threat.

The greatest efficiency gains have been led by policy, and the greatest untapped potentials lie where policy is absent or inadequate. There are lessons of success from around the world, including US vehicle standards, Japan’s progressive Top-Runner program, and China’s Top 10 000 program. The report focuses on the progress made in China. China’s energy efficiency story is told in great detail for the first time by this report. It is a story of great progress, achieving huge efficiency gains over the last ten years, but also revealing the opportunity for China to achieve much more on a path to the efficiency levels of other countries.

«I hope this report will be of great interest to energy policy makers and professionals in all sectors and in all regions. It quantifies the latest trends, tracks global progress, and examines key drivers and market issues. It provides answers to the central question: how can the world achieve more? In this sense, it is a call to action. Energy Efficiency is the one energy resource that every country possesses in abundance. The IEA is well determined that all countries fully exploit it.»

Source: Dr Fatih Birol

Executive Director,   

International Energy Agency

Poor results for Spain in Energy Efficiency

The RISE report (Regulatory Indicators for Sustainable Energy) prepared by the World Bank has recently been published, reflecting in a hierarchical way the positioning of the different countries in terms of access to energy, commitment to renewable energies and energy efficiency. Spain occupies the position 22, of the 111 countries analyzed, in terms of energy efficiency behavior, behind the countries of our economic and territorial environment. This position is consistent with the lack of an energy policy and a lax concern for improving our energy performance.

PhotoCredits: Flickr/ Adriano Agulló

Energy inefficiency does not correspond to our position in the world Gross Domestic Product or of course with reality as a country, having one of the highest degrees of energy dependence of the European Union from which we separate more than 20 percentage points, 73% of Spain compared to 53% of European average, and that considering in this calculation to nuclear energy as an autochthonous source, which is not. This dependence means that for every 10$ rise on the price of a barrel of oil, our balance of trade balance deteriorates by 6,000 million euros.

To be efficient in Spain in the matter of energy consumption should be one of the priorities of energy policy, as has repeatedly been stated by the Renewables Foundation, not only to be able to compete with the countries of our environment, but also to be able to carry out Policies that are more environmentally sustainable and less exposed to the volatility of fuel prices that we have to import.

Spain has sufficient legislation to have a better energy efficiency behavior, as a consequence of the mandatory transposition of the different European Directives, mainly the 2010/31/EU on energy efficiency in buildings and the 2012/27/EU energy efficiency. The problem is that we have been unable by our own decision to implement the operational instruments required by the legislative framework.

Thermometer in a shopping center in Madrid. The label below shows the RD regulations that fails to comply with.

The lines of action put in place are insufficient and inefficient and are based on the development of diffusion campaigns and the creation of a Fund for Energy Efficiency that has not been able to apply to its purpose, in fact in the failed electric reform of the Current government used the cumulative funds to reduce the tariff deficit, and allow us to predict that Spain will not meet the demand reduction target set for the European Union countries by 2020.

A goal which, fortunately for the Government, is non-binding although, both for its responsibility and for its importance, it should be considered as one of the basic elements of any energy policy, if it existed.

This little concern to put in place mechanisms that promote the saving and the efficiency of energy has been able to see from:

  *  The non-fulfillment of objectives that the Directive marked for public buildings and that marks that had to be rehabilitated 3% each year from the inventory made in 2014. Spain has more than 1.7 million m2 of buildings for public use without anyone doing Nothing with the exception of a couple of contests facing the gallery.
   * The lack of demand by public bodies and municipalities that their electricity supply contracts include the obligation that it be of renewable origin and incorporate objectives of saving and improving efficiency as a fundamental element to be awarded.
   * The non-legislative finalist development of the magnificent Law 8/2013 on "Rehabilitation, Regeneration and Urban Renewal" known as Law 3R that allowed open work procedures and public-private collaboration to advance the rehabilitation of more than 18 million buildings, Of which even 3% does not exceed the established standards of energy behavior that marks the current legislation. In fact, the evolution of the management from the first NBE standard CT 79 to the last CTE of 2013 supposes an average reduction of the consumption per m² of 53%.
   * By increasing the fixed part of the electricity tariff by losing the incentive to save energy by reducing consumption and taxing the situation of those vulnerable groups who have to pay more without consuming.
   * The non-application of the Efficiency Fund for its purpose as a consequence of "the absence of projects" that can benefit from it by not mobilizing the energy sector in this work.
   * Considering that the improvement of energy efficiency increases the risk of the appearance of the tariff deficit of the electrical system by reducing energy consumption
   * The real ineffectiveness of rehabilitation grant schemes which in many cases have not been effective leaving a financial problem to communities who believed that it was a good idea to have a more efficient energy performance.

If we analyze what countries of our environment have done with highly positive results and the measures available in our system and not carried out, the Ministry of Industry, Commerce, Energy, Tourism and Digital Agenda should be responsible for binding energy supply companies to fulfill the objectives set by The Efficiency Directive.

Companies that provide us with energy have to take on this challenge not only because of the proximity to the consumer they sell energy but also to their own benefit as a new business line, in which the sale of energy services is replacing or accompanying the Sale of energy.

Our marketers are more focused on brokering processes than working for their clients. Situation that shows its little concern to assume the energetic challenges that as a country we have assumed.

Well, we will never be efficient but we do not involve all the agents that have to do with the energy supply, starting with the public consumption and following the unplanned implementation of the electrification of the energy demand. Coverage of energy needs is more efficient if the energy used is electricity in both the climate, heat pump, and transportation with the electric vehicle.

Inefficient Spain is the result of our behavior as consumers, poorly informed, and a legislative development more focused on "programmed neglect" as an energy policy than in promoting efficiency.

Source: 20minutos: Energy as Right: @ferrandovitales @frenovables VP. The Renewables Foundation is a citizen movement with a vocation for dialogue in the debate on the inevitable change of energy model that tries to transfer to the Spanish society a new vision of the energy that is more linked to the ethics than to the economy, to the future that to the Present, to the urgency that to the complacency. In this blog, which contains a great plurality of voices and opinions, which do not have to coincide with those of the Renewable Foundation, we approach in a simple way what is often very complex with a group of experts in the very diverse aspects in the That energy is present in our daily life, but also in strategic and political issues.

Since 1998, every 5 March, World Energy Efficiency Day has been celebrated. It was during the First International Conference on Energy Efficiency held in Austria where it was decided to set a date for all citizens to reflect on the problem of the abuse of fossil fuels and the importance of starting to exploit renewable energy sources.

According to the IDAE, an efficient use of energy should not compromise our quality of life but should provide us with the same goods and services but in a cleaner and more sustainable way.

Both companies and ordinary citizens should establish the necessary measures and policies to achieve a reduction in energy consumption, favoring the saving of individuals and increasing the competitiveness of companies, promoting access to renewable energies, redirecting production processes aimed at achieving cleaner results, with the aim of making energy efficiency a reality.

Energy poverty is the "inability of a household to meet a minimum amount of energy services for its basic needs, such as maintaining housing in adequate climatic conditions for health (18 to 20°C in winter and 25°C in summer)" One of the causes responsible for the increase of people in situations of energy poverty is the electricity price increase.

With the electrical reform in Spain, in which the renewables were left aside, completely ignoring the objective with which it was created today, and with electricity price increasing while promoting the use of fossil fuels as a source Energy, this situation will worsen.

Due to the geographical situation of Spain, our country has the right conditions to be able to successfully exploit renewable energies, which can be an excellent energy source.

On June 1, 2013, Royal Decree 235/2013 was approved regarding the energy certification of buildings. Since 2007 new buildings were obliged to issue this certificate, however with this new regulation all people who intend to sell or rent a home must obtain this certificate in advance. Thanks to this certificate we can aproach an idea of ​​the amount of our future invoices.

As measures of Energy Efficiency we can highlight:

- Use of efficient LED bulbs.
- To install self-consumption equipment, which is already partially liberalized from the sun tax for installations of less than 10kW since 2015.
- Use of far infrared heat plates, which reduce the consumption of so-called lorites or braziers up to 90%
- Do not wash at high temperatures.
- Acquiring low consumption appliances.

- Unplug appliances when not in use; In stand-by also consume.

EGA is registered as 14,302 Engineer at COITIMadrid