Blum TC76-DIGILOG touch probe at Lehmann

A complex component, incorporating four long slots among other features, was posing problems for Timo Lehmann, CEO of Karlheinz Lehmann GmbH in Oberwolfach. The solution was ultimately provided by a Cincom M32 lathe in conjunction with the TC76-DIGILOG touch probe from Blum-Novotest.

“Highly complex components are part and parcel of our business. But implementing a quick-coupler for compressed air input was a tough nut to crack,” says Timo Lehmann of the challenges posed by a project for Parker Hannifin GmbH, a world leader in drive and control technology and pneumatics. “The key components are hardened and coated free cutting steel, threads, bores, and four lightly tapered slots. The slots were the crucial point of the whole design.”

The parallelism of the slots was only allowed to vary by 2 µm from the reference values. Otherwise the fully automated machine, assembling the component unit at Parker-Hannifin, would abruptly stop. Moreover, the quick-coupling would not work if the tolerance was exceeded. When assembled, the lightly tapered slots contain balls, which must not protrude too far yet, must also never be allowed to fall through the slot. Through this design, the Parker quick-couplers prevent the otherwise common snapping noise when detaching, and also allow single-hand operation. Just as challenging as the production process is the task of measuring the slots. The BLUM TC76-DIGILOG touch probe proved the only cost-effective means of verifying the design’s dimensional accuracy.

Analogue measurement is always advantageous for assessing areas or lines. If a switching digital probe were to be used in the Lehmann application, for example, a very large number of points on the slots would have to be measured in order to attain an adequate resolution. By contrast, the TC76-DIGILOG is scanned across the surface at a measuring speed of 2 m/min. As this is happening, the system generates an extremely large number of values (50,000 per second in fact) in a fraction of the time based on analogue data acquisition.

The combination of the Cincom M32 and TC76-DIGILOG has been running smoothly and efficiently in Parker Hannifin’s production operations since February 2015. The sequence is as follows: At the start of a production run, a reference part is clamped onto the machine and the complete contour of the corresponding slot is scanned and recorded. The master profile recorded in this way is entered in the evaluation software. The subsequent production workpieces are compared against the recorded profile, and any that exceed the tolerance are discarded. As a result, the tight tolerances of the slot are reliably checked immediately after the cutting process in the lathe. In-machine measurement itself delivers enormous benefits. If it is run without problem in the idle times, as in Parker Hannifin’s quick-coupler production, it is hard to beat. It allows Lehmann to implement 100 percent checking, with error trends being detected at an early stage by evaluation software.

Incidentally: it doesn’t matter whether the TC76-DIGILOG is fitted in a grinding machine or a milling machine. And thanks to its increased scanning forces, it is even outstandingly well suited to the tough demands of applications in lathes. The TC76-DIGILOG scans the part accurately and non-directionally, measuring with supreme precision thanks to the patented shark360 measuring mechanism. “Neither coolant nor viscous oils impair the reliability of the measurement data. With its high scanning force, the touch probe simply pushes through the coolant,” adds David Cousins.

The Blum-Novotest/Citizen combination is also used for other large production lots from 10,000 to 30,000 pieces. The processed materials are wide-ranging: from stainless steels, heat-treatable steels and free cutting steel, to aluminium. “Given that we were close to having to refuse the quick-coupler order from Parker Hannifin, we are delighted to have found such a powerful solution in the combination of Blum touch probe and Citizen machine,” Timo Lehmann concludes with satisfaction.

Machining contractor Karlheinz Lehmann GmbH is based in Oberwolfach in Germany’s Black Forest. At its 1,000 square metre site, the family business employs 17 people, operating 20 state-of-the-art CNC lathes and milling machines, mostly in the manufacture of high-precision rotationally symmetrical parts. The company has been trading for over 40 years, and is now managed in the second generation by the founder’s son and daughter. Lehmann employs state-of-the-art technology to manufacture small and large production runs in a three-shift operation – though the night shift is unmanned. The traditional family company’s motto is “Cutting skills in perfect precision”, and it is based on those principles that it has established a customer base including major international corporations such as Parker Hannifin.

The demands on quality and productivity are constantly rising. Being able to produce competitively while meeting the quality standards requires outstanding expertise. Intelligent solutions that warrant safe processes are much in demand. With its Measuring Machines business division and in cooperation with the young manufacturer of turning machines, Inventhor, Blum-Novotest offers its customers individual manufacturing and measuring solutions.

Inventhor is a manufacturer of 4-axis vertical turning machines and a system supplier of serial turned parts in medium-sized to large batches. Due to the lack of available alternatives, Ralf Prahler, owner of WZT Wendland-Zerspanungs-Technik GmbH, had developed and built a special turning machine for the production of his own serial turned parts. One of his customers for serial turned parts liked the machine called “IRIDIUM” so much that he ordered a turning machine like this also for his own production. So the trained turner and master mechanical engineer, Ralf Prahler, founded Inventhor GmbH in 2004 and began to produce turning machines.

Today, the two companies, WZT and Inventhor, are located in the town of Hitzacker and employ about 100 associates and trainees. As many as 74 turning machines are on the market, most of which in the automotive industry. The machines, which are geared to the daily manufacturing routine, combine design and proven technology in an intelligent manner. A reduction of machining time, the increase of primary processing time and the decrease of idle time resulted in a significant improvement of output.

The BMK 5 measuring and automation concept of Blum-Novotest GmbH consists of a modularly extendable measuring cell with integrated workpiece handling. Unlike in-process measurement, the BMK 5 automatic measuring machine allows cycle-time-neutral post-process tests outside of the machine. The applications of the BMK 5 cover a broad spectrum: From a flexible stand-alone device to an inline measuring and testing cell for fully integrated, highly productive serial production. Employed immediately after the maching centre, the advantages of the closed loop including correction interface with the machining centre become evident. Workpiece handling and automatic calibration of the measuring system are realised by an integrated 6-axis robot. When the corresponding modules are integrated, the BMK 5 can also assume such tasks as sorting, labelling or the transfer to packaging in addition to workpiece testing.

Holger Schöller, sales engineer in the Measuring Machines division of Blum-Novotest explains, “The BMK 5 automatic measuring machine is especially geared to and optimised according to end-customer specifications. Here the workpieces are safety-relevant components for cars for which 100 % testing and documentation of the results is mandatory.”

Here is an example of the interaction between turning machine and automatic measurement machine: The blanks enter the distribution system of the turning machine where each of the two spindles completely processes one workpiece. “While one workpiece is being processed, the next one is already fed to the other spindle,” says Ralf Prahler. “The sliding carriage concept minimises travel and idle times, so ultimately, more parts are manufactured and tested in the same time.” In the BMK 5, an articulated arm robot takes over the spindle-turned workpieces and takes them individually to the measuring device. The use of multi-point measurement on the workpiece allows the simultaneous acquisition of variables such as diameter, roundness and length or distance. Schöller adds: “Apart from the consistent separate-spindle handling, the challenge was short cycle time requirements for 100 % testing. Moreover, the testing equipment had to be designed in such a way that it could be set up for workpiece variants of already existing plants as well as future varieties within few minutes.” The tolerances according to IT6 and the uninterrupted component contour characterise the task.

After the measurement, the assessed workpieces are sorted. “The two machines communicate continuously via an integrated data interface. Based on the measured workpieces and spindle assignment, only the spindle showing any deviation is corrected. This establishes a reasonable control loop,” Schöller adds. Thanks to the combination of turning and measuring, the manual entry of correction values or the time-consuming trips to the measuring room are history. “The high workload of our associates is made easier and safer by the fully automated system,” Prahler is pleased to announce.

It takes stable, safe processes and a high output to be able to produce competitively. Floor space is only available to a limited extent and the ways have to be short: Value added per square metre plays a significant part. The highly productive turning-measuring combination created by Inventhor and Blum-Novotest meets the specifications with very low space requirements. “The customer’s cycle time was even reduced compared to the solution previously used,” says Prahler. “With very little floor space, the BMK 5 meets the automotive industry’s requirements of quality assurance systems. The required measuring accuracy is achieved directly in the machining environment.”

Good cooperation is important when combining two entirely different systems. Prahler remembers, “So far the procedure has always been very constructive, reasonable and target-oriented. Despite the harsh production conditions and an enormous output volume, the combined systems run very reliably. The customer is always entirely satisfied and has not had any trouble to date.” The result of this cooperation is a reduction of cycle times and a resulting increase in output by 20%.

The joint project presented here is not the only one. The metrology specialist and the manufacturer of turning machines have been cooperating since 2011. “The first cooperation of our two companies occurred on request of a customer since Blum-Novotest had supplied Measuring Machines to a mutual end customer who, of course, wanted well-established, tried and tested equipment. The BMK 5 of Blum-Novotest is very elaborate,” explains Prahler. With its integrated measuring routines, the measuring and automation cell designed in high quality and flexibility is able to solve nearly any task. The robot guarantees careful handling of the sensitive workpieces. Even though the two companies were engaged separately, the decision to combine the technologies of Inventhor and Blum-Novotest represents a successful symbiosis for the benefit of the customer. The mutual customer mentioned in this example had four turning-measuring combinations installed already by autumn 2015. And one delivery is yet to be made in the fourth quarter of the year.

“Our joint know-how enables our customer to produce in Germany absolutely competitively,” concludes Ralf Prahler. “If one calculates all costs incurred for an individual workpiece, this combined turning and measuring machine ranges below the price per part quoted by contract manufacturers in eastern countries in the majority of cases. The initial investment is quickly amortised and pays off ultimately. In future, I would like to have numerous other orders with BLUM. Possibly even with a Blum BMK 5 on each of our turning machines.”

Blum-Novotest, the leading manufacturer of innovative and high-quality measuring and testing technology, presents brand new products and the latest application examples for all matters regarding “reliable sensor technology for Industry 4.0” at AMB 2016 in Stuttgart, Germany (Hall 1, Stand H71). The German company will, in particular, be showcasing solutions on all solutions relating to “analogue contour scanning of workpieces in machining centres”, “reliable measurements with coolants” and “greater productivity through efficient processintegrated roughness measurements”.

“The digitisation of production has been on everyone’s minds for quite some time now and is more relevant than ever after the term Industry 4.0 was coined. A cornerstone of this process is the creation of fully networked and end-to-end process chains. In machine tools, this demands the application of production metrology, as failures or unreliable measurement results contribute to a much greater loss in productivity than would be the case with conventional production processes,” explains Heribert Bucher, manager of the division Measuring Components at Blum-Novotest. “At AMB, we will use the latest application examples to show visitors why BLUM touch probes, laser, DIGILOG and roughness measurement systems are an essential part of the fourth industrial revolution.”

The challenges faced by measurement technology inside machine tools are very different to those encountered when carrying out measurements outside the machine. Cooling lubricant and oil frequently become an underestimated source of incorrect measurements when using standard touch probes. This is the reason why many users have, until now, been of the opinion that precise measurements in a machining centre can only be carried out on workpieces which are dry and free from oil and grease. Blum-Novotest GmbH shows the opposite is true at this year’s AMB event. The company will use several impressive live demonstrations to prove that current BLUM touch probes deliver reliable, efficient and ultra-precise measurements even when using coolants. The reason for this is the unique measuring mechanism technology: Pre-deflection and an increased measuring force ensure that coolant has no impact on the actual measurement even at a measuring speed of 5 m/min. The bidirectional measuring mechanism of the TC61 touch probe even enables pulling measurements of grooves and bars.

A further highlight of the BLUM exhibition at AMB will be the current capabilities of DIGILOG technology. To achieve high compression ratios in combustion engines, the contours of the sealing chamfer at the valve seat ring must meet strict tolerance requirements. The concentricity of the valve guide and the valve seat is also of major importance within this context. Until now these features have been measured much later and outside the machine; a process that resulted in high scrap rates of expensive cylinder heads. On the one hand, BLUM’s TC64 DIGILOG touch probe measures the concentricity digitally; on the other hand, the system enables analogue scanning and thus monitoring of the sealing chamfer while the workpiece is still clamped in the machine.

BLUM will also be presenting its latest solutions that focus on the hot topic of ‘machine-integrated surface roughness measurement’: When machining blisks for aircraft engine turbines, there is a need not only for dimensional accuracy but also for a defined surface roughness. In this case, surface roughness gauges such as the new TC64-RG are used to ensure machining faults and poor surface qualities are detected during the process. If ultra-precise, basically DIN-compliant measurements as small as one tenth of a micron are required, the roughness gauge is guided across the workpiece surface at a comparatively slow measuring speed. When it comes to detecting machining errors in the micron range – a role for which the BLUM roughness measurement systems have been specially developed – measurements can be carried out up to 20 times faster. Even coolant or grease on the surface only affect the result slightly.

“Industry 4.0 has been an established practice at Blum-Novotest for many years, in fact we were actually implementing these processes before the concept even had a name,” Heribert Bucher claims. “Ultimate reliability in the harshest environments is a matter of course for BLUM products. We can therefore offer a process integrated, Industry 4.0 suitable solution for numerous measurement activities.”

Touch probes automate the production of hand-held measuring equipment

The production of hand-held measuring equipment means large volumes and high demands on the accuracy of the workpieces. In this context, the production measurement technology used is faced with the challenging task of working fast and with a high degree of precision. The solution chosen by HELIOS-PREISSER is BLUM touch probes which are used in the machining centres for continuous measurements integrated into the process.

In 2008, HELIOS-PREISSER, a manufacturer of high-quality hand-held measuring equipment for professional use, became aware that the capacity of its three machining centres previously used for production was no longer sufficient – they were operating around the clock in three shifts. Due to its positive experience with the existing machines, the company based in Gammertingen decided once more to rely on the products of Heller, a machine tool manufacturer in Nuertingen.

A 14-metre long pallet magazine connects the machining centres, which are supplied with clamped workpieces by a robot. This ensured the automated supply, but an opportunity to satisfy the high quality requirements was still lacking. The HELIOS-PREISSER employees already had many years of good experience with BLUM touch probes in the old machining centres which are still operating with great reliability today. The new four-axis machine was also equipped with a BLUM measuring probe. It was only the five-axis centre which used a probe from another manufacturer. However, this did not meet with great approval at HELIOS- PREISSER. “Where possible, I endeavour to make regional purchases. In BLUM, we have found a partner that can offer us high-quality products and corresponding service within a close distance,” emphasises CEO Siegfried Lorch. “Particularly as, wherever possible, we would like to have just one point of contact. In addition, we have been extremely satisfied with the BLUM touch probes for years.” In the end, BLUM’s sales representative Erhard Strobel proposed a solution –  an engineer would install the probe and receiver in the new machining centre.

HELIOS-PREISSER uses TC50 and TC60 touch probes. The first transmit data via infrared, the latter via radio technology. The touch probes are fitted on tool holders and can be substituted if necessary, in order to execute measuring tasks before, during and after machining. The infrared system can always be used when a line of sight can be guaranteed between the touch probe and receiver. A measuring system with radio transmission is installed on the five-axis machining centre. This reliably transmits the signals from the touch probe to the receiver – even when the line of sight is disrupted by the large swivel head.

The BLUM touch probes are used for a whole range of tasks in Gammertingen. For example, they check whether the workpieces are correctly clamped prior to the commencement of machining. “We also use the probe to measure the result of the machining. After casting, the dimensions of the cast blanks are often very different,” explains Tobias Weber, foreman of the milling shop. “This is why, prior to machining, the position of the blank is captured using the probe and the compensation values for the NC program are transmitted to the machine controller. Thanks to the BLUM touch probes, we have been able to reduce the rejection rate for these components from ten percent to one to two percent.”

Another example are the tail stocks of the bench centres. Here, a hole must be positioned accurately to one hundredth for a channel on the same part. Previously, there had always been fluctuations, often due only to the temperature response of the machine. If the dimension was correct in the morning with a cold machine and hall, by noon with a hot machine and warm weather the dimension would be outside the tolerance. At HELIOS-PREISSER, the channel is now machined and measured before finally being drilled using the measurement data. This enables the desired precision to be reliably achieved despite the effects of temperature.

The large volumes manufactured in Gammertingen require short cycle times, so measurement must not take too long. BLUM touch probes are designed for maximum measuring speed and are not sensitive to the widely used coolant, which is simply pushed away by the high measuring pressure. Measurements can also be taken directly after machining. “The touch probe is moved at a top speed of 60 metres per minute until shortly before measuring point; touching then takes place at up to 3 m/min – so not much time is lost. After machining, we check almost all fits using the BLUM touch probe,” reports Tobias Weber. “Our manufacturing process has now become so precise, that we no longer have to grind many parts. Previously, in contrast, many parts were milled with an allowance and then ground to the finished size on grinding machines in order to be able to achieve the required precision for our measuring equipment – this saves a great deal of time.”

If a machine determines that a tolerance has not been complied with, the pallet is automatically removed and placed in the pallet store with an inspection record. The next morning it can be inspected to determine where the fault is and, in the meantime, the machine can continue to process further pallets. With respect to unmanned production, the touch probes from Blum have completely proven themselves at HELIOS-PREISSER: “Overnight, and often for parts of the weekend, the machines run unmanned. We only operate one shift, but we produce more than we previously did in three shifts,” concludes Siegfried Lorch. “The systems run very reliably during unmanned operation, which relieves the pressure on us and makes it possible to manufacture the required volumes without needing a night shift. The BLUM probes are essential to unmanned operation, especially as we are also very satisfied with the service offered by BLUM.”