Machining with robots and hand-held machines

Introduction

The use of robots and hand-held machines in machining involves specific challenges not encountered with conventional machine tools. While conventional machine tools are characterised by high rigidity and absolute repeatability, robot-assisted and hand-guided systems are defined by greater flexibility. The flexibility of robots primarily arises from their serial axis arrangement, whereas in hand-guided machines it results from the limited support provided by the machine and the operator. This system property, which is critical for process design, is often not precisely known, varies with the machine’s pose, and is subject to high variability depending on system condition and external influences.

The IPMT is researching systematic solutions for machining with hand-guided machines. This includes the use of fully manual drilling machines and semi-automatic drilling feed units for producing high-precision rivet holes in aircraft construction. Additionally, the IPMT is evaluating the suitability of industrial robots for machining processes that require a high degree of automation. The goal is to achieve repeatable machining quality within specified tolerances. To this end, the specific characteristics of the described machining systems must be thoroughly investigated and documented.

Robot-guided machining

Robot-based machining systems can be employed in a wide variety of workspaces. Industrial robots are easily adaptable to different machining tasks, and thanks to versatile end effectors, they can perform a broad range of processes. Potential applications include mechanical machining, assembly, and testing tasks.

At the same time, the use of robotic machining systems introduces technical challenges. Compared to conventional machine tools, industrial robots exhibit lower absolute and repeatable positioning accuracy. Furthermore, static and dynamic compliance forces, which depend heavily on the robot’s pose, can negatively affect process stability. These system-related characteristics complicate precise path planning and increase susceptibility to dynamic effects such as chatter and vibrations during machining.

To fully exploit the potential of robot-assisted manufacturing, application-specific strategies are required to compensate for these system-related limitations.

Contact

Sebastian Junghans
M-18 Produktionsmanagement und -technik
  • Produktionsmanagement und -technik
Office Hours
nach Vereinbarung
Denickestraße 15 (K),
21073 Hamburg
Building K, Room 2501
Phone: +49 40 42878 3468
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Manual and semi-automated drilling

In many cases, full automation, for example through the use of industrial robots, is not an economically viable solution. One reason for this is limited accessibility and the need to parallelize different work steps within the same manufacturing system. Under these conditions, machining can only be performed using manually guided tools. In manual drilling, the position and angle relative to the workpiece, as well as the process execution. Therefore, the resulting machining quality are influenced by the operator. The experience level of the personnel, along with external factors such as ergonomics and individual working methods, leads to high process variability, which is reflected in fluctuations in machining quality. Additionally, process monitoring and documentation are more challenging in manual operations. Process parameters, such as the feed rate in manual drilling, are not clearly defined and are difficult to measure. At the IPMT, approaches are being developed to monitor manual drilling and support operators in their machining tasks.

In contrast to fully manual drilling machines, semi-automatic drilling feed units (ADU) are manually positioned and locked in a drilling template but execute the machining task automatically according to a predefined program. Although process parameters can be specified, the compact design and relatively low drive power of these machines can negatively affect adherence to the correct parameters. Local clamping within the drilling jig promotes deflections and vibrations in the machining system. The drilling tools used must be able to withstand these conditions. The IPMT is therefore engaged in the design and experimental investigation of drilling tools specifically for this type of machine.

Contact

Malte Flehmke
M-18 Produktionsmanagement und -technik
  • Produktionsmanagement und -technik
Denickestraße 15 (K),
21073 Hamburg
Building K, Room 2501
Phone: +49 40 42878 3494
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Philipp Klahn
M-18 Produktionsmanagement und -technik
  • Produktionsmanagement und -technik
Office Hours
nach Vereinbarung
Denickestraße 15 (K),
21073 Hamburg
Building K, Room 0554
Phone: +49 40 42878 4132
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Worker assistance systems

Digital support for workers is playing an increasingly important role in improving manual and semi-automated manufacturing processes. Information systems can provide targeted real-time assistance to operators during machining tasks through visual, acoustic, or tactile signals. This may include displaying machining steps, tolerances, or safety-relevant information. A central element of such systems is process monitoring, which enables continuous recording and evaluation of process data, allowing quality deviations to be detected and corrected at an early stage.

As part of process monitoring, external systems such as machine localization can be employed to ensure compliance with process parameters and positions stored in the information system. The IPMT is researching real-time monitoring of manual drilling processes and the integration of planning and process data through precise geolocation of the machining equipment.

Contact

Malte Flehmke
M-18 Produktionsmanagement und -technik
  • Produktionsmanagement und -technik
Denickestraße 15 (K),
21073 Hamburg
Building K, Room 2501
Phone: +49 40 42878 3494
Logo
Sebastian Junghans
M-18 Produktionsmanagement und -technik
  • Produktionsmanagement und -technik
Office Hours
nach Vereinbarung
Denickestraße 15 (K),
21073 Hamburg
Building K, Room 2501
Phone: +49 40 42878 3468
Logo