Inline measurement at production rate
- Measuring Machines

Lathe and automatic measuring machine for a maximum of productivity

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.”

Measuring device of the measuring and automation concept BMK 5
Measuring device of the BMK 5 measurement and automation concept from Blum-Novotest GmbH

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.”

The CEO of Inventhor Ralf Prahler (l) talking to Blum-Novotest
Sales Engineer Holger Schöller
Inventhor CEO Ralf Prahler (left) and Blum-Novotest sales engineer Holger Schöller in conversation

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.”