Kadia Installs Deburring Automation Cells to Increase ZSO Production
October 8, 2020—
Depending on the variant, the robot guides the machined cast housings to three or four brush deburring stations. Photo courtesy of Kadia.
Besides honing, mechanical deburring is the second business area of Kadia. The company's portfolio includes a wide variety of deburring machines, most of which are designed for fully automatic operation with the aid of a robot. At Zerspanungs- und Systemtechnik GmbH (ZSO) in Oberstaufen, the Nürtingen experts implemented three deburr-automation-cells. The tasks of these systems include not only deburring the workpieces, but the robots also take over the complete handling for mechanical processing.
For ZSO, it is clear that quality, process reliability, and productivity must be raised to a maximum level, and this is only possible if processes are consistently automated. For this reason, ZSO has invested heavily in handling systems and the networking of its machinery in recent years. Of the 35 processing machines currently in use, a third are already fully automated.
One of the most recent projects was particularly important for ZSO Managing Director Carsten Binder, Ph.D.: the handling and deburring of grey cast iron housings for mobile hydraulic pumps weighing up to 26 kilograms. These are, for example, pumps for the hydraulic systems in construction machinery. The housings go directly from the foundry to ZSO, where they are manufactured - ready for assembly.
In previous automation projects at ZSO, significantly smaller and much lighter workpieces had to be moved and deburred, so that lightweight collaborating robots were the obvious choice. The grey cast iron housings, however, are too large and heavy for this approach. Consequently, the employees moved and deburred the housings by hand. Not an easy task.
Manual deburring also has some disadvantages: Each hand works differently, holds the tool at a different angle and presses the edges of the housing with individual force. This is particularly tedious when internal contours are difficult to access. There is also the risk of slipping with the hand tool and damaging the workpiece.
“Our plan was to have a robot carry out all the recurring processes,” said Binder. "Deburring would also be possible on the machine tool, but a robot is the far more cost-effective solution for this.”
In Kadia, ZSO finally found a partner with the corresponding 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 payload of 120 kg and a reach of 2.5 m. Kadia's customers receive such solutions completely from a single source. That means the scope of supply includes the process development, robot, cell, gripper, deburring stations, and tools including special solutions. Not to forget, of course, the sequence programming with all safety-relevant designs. Kadia delivered a first automation cell in April 2019, a second in September and a third in January 2020.
The project involved connecting the automation cells to three identical Heller H5000 machining centers. ZSO had gradually purchased several of these 4-axis machines especially for the pump housings, already equipped with robot interfaces. The robots were to carry out the loading and unloading of the machine tools as well as the deburring within the MC cycle time, i.e. within a time window of about 20 minutes.
Since two clamping-settings are required, the workpiece is fed via a rotary table. The housings are clamped on fixtures specifically developed by the machining specialists in Oberstaufen. All these steps also included a lot of programming and adjustment work for the project managers at Kadia. Coordination with ZSO was necessary with regard to the housing variants and the jig and fixture technology, as well as with the machine and robot supplier with regard to the connection of the robots to the MC. An effort that is now paying off for the user, because machine tools and robot cells work together as perfect production units. This close cooperation between all those involved will continue in future, for example when new workpiece variants need to be programmed.
But what do the deburr automation cells actually do? The robot picks up two unmachined parts one after the other and places them in the fixture for the first clamping. During the machining process, the gripper places two more unmachined parts in the remaining free fixture positions, so that four workpieces are always in circulation at the same time. A second robot gripper is used for the second clamping. Before the workpieces are deposited, the swarf is blown off the contact surfaces with compressed air to ensure exact clamping. The machine processes the first and second clamping-setting in constant alternation.
Once the NC program for two set-ups has been run, the robot guides the workpieces for deburring. For this purpose, Kadia has equipped the cell with either three or four self-developed brush deburring stations with automatic wear compensation, depending on the housing variant. Round steel wire brushes are used for outer edges and outer surfaces, and specially manufactured square brushes with high-strength filaments are used for holes and inner contours. Thus, all contours can be reached and deburred in a reliable way.
Since the cleanliness of the workpieces is important for the customer, the robot arm places the deburred housings in a washing basket, which it then transports out of the cell. The handling of this container was to be integrated into the automation concept as a further sequence. And that is not all: every fifth workpiece is also marked for inspection by quality assurance.
Binder lists the advantages of the concept: First and foremost is the elimination of laborious handling for the employees. As a result, less personnel are required than before automation. For manual operation, one employee was required 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 (MC and RHDC) in parallel. No one had to undergo special training to become a certified robot specialist, because Kadia and ZSO had agreed to make the operation of the systems as simple as possible.
"We included the option 'retraction strategy: home position' in the concept," said Udo Frieß, robotics and deburring expert at Kadia. "This allows the operator to return the machine to the initial position at any time in the event of an interruption and to restart it from there. He does not need a robot panel for this.”
"It is important for our customers that we were able to increase process reliability and thus product quality during deburring,” said Binder. “All edges are now deburred absolutely evenly, and according to customer requirements, there are no variations in the execution. In addition, the robot never forgets an edge or thread. This means that reworking is also a thing of the past.”
This also applies to process interruptions, which can never be avoided in manual operation. "Automation has eliminated many scheduled and unscheduled interruptions, so our output has become more continuous and we produce more parts per unit of time," Binder added.
“We usually see that the machine tool output can be increased by 30 to 50 percent with the help of deburr-automation-cells, always depending on the workpiece and the processes to be integrated,” said Dominik Landhäußer, sales engineer at Kadia.
For Binder, it is clear that things will continue along this path: "In future, we will introduce every new customer project based on an automation solution,” he added.