Machine tool and robot - a perfect team

From left to right: Udo Frieß, robotics and deburring expert at Kadia; Dr. Carsten Binder, Managing Director of ZSO; Michael Stark, Project Manager at ZSO. © Kadia

In Kadia, ZSO finally found a partner with the appropriate expertise in the fully automatic deburring of heavy workpieces. After a short time, the design engineers in Nürtingen presented a concept that convinced the ZSO managers. It is based on a 6-axis robot with a load capacity of 120 kg and a reach of 2.5 m. Kadia's customers receive such solutions from a single source. The scope of supply includes process development, robot, cell, gripper, deburring stations and tools, including special solutions. Not forgetting, of course, the sequence programming with all safety-relevant versions. Kadia delivered its first automation cell in April 2019, a second in September and a third in January 2020.

The aim of the project was to connect the automation cells to three identical H5000 machining centers from Heller. ZSO had gradually purchased several of these 4-axis machines specifically for the pump housings, already equipped with a robot interface. The robots were to carry out the loading and unloading of the machine tools as well as deburring within the machining center cycle time, i.e. within a time window of around 20 minutes.

As two clamping operations are required, the workpiece is fed via a rotary table. The housings are clamped on fixtures specially developed by the machining specialists in Oberstaufen. All these steps also involved a lot of programming and adjustment work for the project managers at Kadia. Coordination was required with ZSO regarding the housing variants and the fixture technology, as well as with the machine and robot supplier regarding the connection of the robots to the machining center. An effort that is now paying off for the user, as machine tools and robot cells work together as perfect production units. This close cooperation between all those involved will continue in the future, for example when new workpiece variants need to be programmed.

But what do the deburring automation cells do? The most important work steps are as follows: The robot picks up two blanks one after the other and places them in the fixture for the first clamping. During machining, the gripper places two more blanks in the free fixture positions so that there are always four workpieces in the cycle at the same time. A second robot gripper is used for the second clamping operation. Before the workpieces are set down, the chips are blown off the contact surfaces with compressed air to ensure precise clamping. The machine continuously alternates between the first and second clamping.

Once the NC program for two clamping operations has been completed, the robot guides the workpieces to the deburring station. For this purpose, Kadia has equipped the cell with three or four brush deburring stations with automatic wear compensation, depending on the housing variant. Cup brushes with steel wire filaments are used for outer edges and outer surfaces, while specially manufactured square brushes with high-strength filaments are used for bores and inner contours. This means that all contours can be reached and deburred reliably.

As the cleanliness of the workpieces is an important aspect for the customer, the robot arm places the finished deburred housings in a washing basket, which it then transports out of the cell. The handling of this container had to be integrated into the automation concept as a further sequence. And that's not all: every fifth workpiece also receives a mark for quality assurance.

Complex processes, simple operation

Dr. Carsten Binder lists the advantages of the concept: First and foremost is the elimination of tedious handling for employees. As a result, fewer staff are now required than before automation. Manual operation required one employee per processing machine. A three-shift operation with three machines would therefore require a total of nine operators. However, thanks to automation, one operator now looks after all three production systems (BAZ and EAZ) in parallel. Importantly, no one had to undergo extra training to become a certified robot specialist, as Kadia and ZSO had agreed to make operating the systems as simple as possible. "We included the 'home position retraction strategy' option in the concept," explains Udo Frieß, robotics and deburring expert at Kadia. "This allows the operator to return the system to the starting position at any time in the event of an interruption and restart it from there. He does not need a robot panel for this."

The ZSO Managing Director continues: "What is important for our customers is that we have been able to increase process reliability and therefore also product quality when deburring. All edges are now deburred absolutely evenly and according to customer requirements; there are no fluctuations in the finish. In addition, the robot does not miss any edges or threads. This also makes reworking a thing of the past." This also applies to process interruptions, which can never be avoided in manual operation. "Automation eliminates many scheduled and unscheduled interruptions, so our output has become more continuous and we produce more parts per unit of time," confirms Binder. Dominik Landhäußer, Sales Engineer at Kadia, adds: "We see that the output of machine tools can be increased by 30 to 50 percent with the help of deburring automation cells, depending on the workpiece and the processes to be integrated." For ZSO Managing Director Binder, it is clear that this is the way forward: "In future, we will introduce every new customer project on the basis of an automation solution."