Intelligent grippers provide all the data for optimised packing strategies

Sensors can be „printed“ directly into grippers thanks to additive manufacturing. The Fraunhofer IGCV has discovered how this technology can be used to build intelligent packaging machines.

One task of today's Packaging machines is the economical packaging of small and very small batches. This requirement can only be met to a limited extent with conventional packaging machines. Digitalisation offers one way of designing such concepts. It enables more individuality for the packaging, more flexibility in terms of formats, greater availability and less space required by the machines.
Should the Packaging technology When Industry 4.0 applications are realised, sensors play a particularly important role at the production level. Without their fundamental ability to monitor processes and collect valuable data close to the point of operation, intelligent packaging machines would be unthinkable.

This was one of the findings of the „Car paint“, which is the Fraunhofer Research Institution for Casting, Composite and Processing Technology (IGCV) with various industrial project partners in 2018. The aim of the project was to develop practical solutions for the automated packaging of customised orders in the mail order business.

At a test facility at the Fraunhofer IGCV in Augsburg Physics-based simulations to find an optimal packaging algorithm for packages that vary in size and weight and are made of different materials. Real products were taken from a storage location and automatically measured, handled and finally packed into a shipping carton using a robot-assisted suction gripper.

Systems are becoming more flexible, smarter and faster

In the course of the project, it became clear what an important role the sensors on the Grippers of the packaging machines for data acquisition. Modern sensors transform grippers into intelligent devices that simultaneously grip, measure, check and sort, thereby speeding up the entire process. Such gripper systems can pack even the smallest batches in a product-orientated manner.

The built-in functions, fully networked via IO-Link, also support complex tasks in the production environment. The smart sensors process the Process information internally in real time, without having to pass them on to a central control system over long distances as was previously the case.

One example is universally applicable Magnetic switch or flexible Position sensors with up to five independent switching points. These can differentiate not only the position of the gripper, but also workpieces of different sizes via individually adjustable switching points. Through a Teach module the switching point can be set so quickly that only a tenth of the previous set-up time is required. This significantly optimises the overall process stability. At the same time, increasingly favourable sensors are reducing the price of previously expensive force-controlled gripping systems.

The lightest possible gripper systems are the prerequisite for intelligent packaging technology in order to independently pick and pack products of different sizes and weights in any order. They allow faster movements, shorten cycle times and reduce energy consumption. In addition, smaller Robots which are financially more favourable - with the same gripping forces.

Additive manufacturing of intelligent gripper jaws

Depending on the requirements, specific Gripper jaws required. Nowadays, these can be easily ordered online using internet-based design tools and customised with additive manufacturing processes manufacture. Additively manufactured components are often up to 50 per cent lighter than conventionally manufactured components due to their specific lattice structures. They can also become intelligent if the sensors are integrated directly.

Because with the technology of additive Laser beam melting It is possible to integrate thermally sensitive sensors into the material because the thermal energy input is very limited in terms of time and location and does not damage the sensors. The resulting system consists of a sensor that is completely enclosed in a surrounding metallic structure that is almost 100 per cent impermeable.

This results in various application advantages. Depending on the environmental conditions, energy and data can be transmitted wired or wirelessly, so that the encapsulation enables use even in very harsh environments. Due to the Placement close to the centre of gravity in the component opens up new fields of application. Transmission losses are minimised. For example, modern magnetic switches can be completely integrated into a gripper and monitor the position of the piston from the inside.

A wireless Data transmission also has the advantage that seals, cable armouring, strain relief and all mechanical challenges are eliminated. Instead, wirelessly integrated sensors allow for quick commissioning and increase the Process reliability of the packaging machine.

Constant exchange of information with the process environment

Grippers utilise the potential of the Industry 4.0 only be fully utilised when they communicate with their environment in both directions. On the one hand, the grippers are controlled via the central control system. On the other hand, the sensor systems of a gripper can send information on temperature, opening status of the gripper jaws or acceleration to the controller or the cloud in the opposite direction.

Also in the area of collaborative robotics the sensors of the gripping system must work reliably to ensure process efficiency and safety. This is the only way to safely realise functions such as a kind of airbag for robots or reversible gripping force limitation.

Following the Autopack project, the Fraunhofer IGCV has now launched the new MULTIPE„ research project“ started to Multi-material gripper for packaging machine construction. The aim is to develop intelligent and bionically designed grippers that work in a resource-saving manner even with batch size 1.