The Cutting & Stacking Center at Schmidt & Heinzmann GmbH & Co. KG has created a successful interplay between hardware and software. The flexible preform production cell features material-specific cutting with optimised nesting over several tables and precise placement of the cuts on the stack in optimised cycles.
At the same time, it reacts to any changes in the workflow and performs all necessary recalculations. As an enabler of cost-efficient lightweight technologies, it has now been presented the ThinKing Award for December 2021.
The State Agency for Lightweight Technology Baden-Württemberg is pleased to present this innovation with its ThinKing Award for the month of December 2021. Every month, Leichtbau BW GmbH promotes innovative lightweight technology products and services in Baden-Württemberg under this label.
At a glance:
The first step in the process chain for manufacturing a lightweight component using the RTM (resin transfer moulding) procedure is to cut the fibre material. Preforms can comprise up to 40 layers and many individual cuts, with the fibre direction in the component being determined by the load path in the parts design.
Cost-efficient lightweight technology using flexible production cells
Cutting and stacking are complex work sequences and are therefore often still performed manually. However, not only has the Cutting & Stacking Center at Schmidt & Heinzmann GmbH & Co. KG mastered these complex process steps but it is also able to produce a variety of preforms - even simultaneously - thanks to the use of this generic approach. It is for this reason that the system concept has been presented with the ThinKing Award for December 2021.
The system cuts out the individual layers from the various fibre materials - for instance glass fibre, carbon fibre and natural fibre - making precise and efficient use of the raw materials, and places them into preform blanks, or stacks, according to the load path. The production cell comprises a robot with a gripper module, a controller, several cutting tables and a stacking table with discharger.
After the component data has been transferred, intelligent nesting enables an optimised cutting plan to be calculated for each cutting table. Efficient use is made of each material, and the volume of scrap is reduced significantly.
Previously, either a cutting table with a store of different fibre materials was used or else all the layers were placed on top of each other in the correct sequence on a long cutting table and the cutting performed through all the layers together. Both of these variants resulted in a large quantity of scrap, not to mention cutting inaccuracies.
However, with several cutting tables available at the Cutting & Stacking Center, each table can now be supplied with and used to cut a different material. Similarly, the cutting technology used is configured precisely for the respective material. The system can be tooled with polygonal, circular or ultrasonic blades. This results in clean cut edges.
A variable gripper module holds the cuts using either needles, a vacuum or an air stream and positions them precisely to form the stack.
Precise stacking and a high level of automation
All process steps are fully automated. The processes are automated by an evolutionary algorithm, while the boundary conditions for the optimised process sequence are similarly variable. The decisive parameter is not necessarily always the cycle time; efficient material use can sometimes have a higher priority. Various sensors then ensure process stability and correct the workflows and process parameters autonomously where required.
The control software was developed in-house by Schmidt & Heinzmann GmbH & Co. KG. It means that the company can now produce more complex components with minimum raw material input. “We begin with the CAD data, after which the user is guided step by step through the setup and parameterising process. The great thing about this is that the user does not have to concern himself with any programming,” explains Dr. David Bücheler, head of the process department at & Schmidt & Heinzmann GmbH & Co. KG.
The integrated production scheduler monitors the entire process and optimises the cutting, handling and stacking procedures along the boundary conditions specified by the user. The main goal is not necessarily to achieve the fastest cycle time. The digital production planner monitors the supply of fibre material at the cutting tables while also keeping an eye on the nesting and refilling times.
The robot picks up the cuts in exactly the right sequence required for placing. This not only increases process reliability but also ensures a consistent stack quality.
New potential for competitive lightweight technology components
With its Cutting & Stacking Center, Schmidt & Heinzmann GmbH & Co. KG has given supplier firms in typical lightweight technology application sectors, such as the automobile and aviation industries as well as the sports and leisure industry, new ways of producing competitive lightweight components. can now once again be produced in high-price countries thanks to the significant reduction in cost per weight.
Component production costs are considerably lower than those of semi-automated manufacturing. Around 75 percent can now be saved in personnel costs. The investment can be recouped in approximately 18 months. Moreover, optimal utilisation leads to savings in both raw material costs and resources.
The first cell to be delivered serves a Tier 1 as a laboratory system for researching into the production of fibre composite leaf springs with large series capability for the automobile industry. Leaf springs made of fibre composite are already being used in the construction of sports cars, such as the Chevrolet Corvette or the off-road Volvo XC 90. The second cell to be delivered has been in use for only a few months and produces spoilers for the Airbus A320 by Spirit Aero Systems.
Dr. David Bücheler is sure that, “even the sports article industry with its high levels of product variance and moderate to high unit volumes would also benefit greatly from installing a production cell.” In this case, it is the flexibility and scalability of the concept that would benefit potential users
About Schmidt & Heinzmann GmbH & Co. KG
For more than 40 years, Schmidt & Heinzmann has been developing and producing innovative custom-made production systems and automation solutions for the fibre-reinforced plastics industry. The company’s portfolio comprises:
Schmidt & Heinzmann employs more than 130 people at its headquarters in Bruchsal and its subsidiaries in the USA and China, generating sales of approximately 20 million EUR in 2020.