The automation of sub-steps of an SMC component production in the area of compression moulding, which were previously carried out manually by a worker. The task was to automate the individual processes of cutting, stacking and weighing the SMC material, as well as unloading the press with the moulded component and loading the press with the correct number of layers and the appropriate weight of the SMC package using FANUC robot technology.
An SMC press automation cell from Schmidt & Heinzmann consisting of two FANUC handling robots, an AutoCut cutting system with ultrasonic cutting technology, a weighing and stacking table for weight detection and control, and a flexible needle gripper for clearing the cutting system and SMC stacking. Another handling robot with a multi-gripper equipped with finger and vacuum modules takes care of loading the press with an SMC package and unloading the press with the finished SMC component. The complete cell control, as well as the cell safety, also come from Schmidt & Heinzmann.
A highly efficient and flexible automation cell with automatic weight control and regulation, including handling of the blanks and automatic loading and unloading of the press. By automating the production process with the support of FANUC robots, it was possible to both increase the overall output of the system and significantly improve the quality of the components - while at the same time reducing the unit costs.
The founders of Schmidt & Heinzmann, Bruchsal, always had a thing for the extraordinary. Fax paper machines or flanging machines for the railway industry were part of the portfolio. Beginning of the 1970s, the company specialised in "Composite Equipment & Machinery", which is also reflected in the full company name. During this time, Schmidt & Heinzmann developed its first semi-finished material production line for a well-known component manufacturer in the vicinity. Today, with 150 employees, the company is a worldwide partner in many industries including machines for processing composite materials and manufacturing composite components. Turnover in 2019 amounted to around 20 million euros.
The variety of materials processed on Schmidt & Heinzmann equipment is almost as broad as the areas of application: The spectrum ranges from Formula 1 to the aviation industry, supplier industry for the entire transport sector, electrical and construction industry to sanitary elements such as bathtubs. Between 50 and 70 per cent of production per year is accounted for the manufacturing systems of SMC material or components made of SMC (Sheet Moulding Compound).
Michael Ochs, Executive Vice President Sales and Marketing, sees a worldwide trend towards automation: "We build cells for processing thermoset semi-finished materials such as SMC and Prepreg (preimpregnated fibers), which we supply to our customers worldwide. In recent years, there has been a strong trend towards automation in component production." He should know, because Schmidt & Heinzmann has customers in over 70 countries and is constantly challenged with new demands on machines and material properties. Every year, the company therefore invests around 10 per cent of its turnover in research and development. The recognition for this is first and foremost, of course, the growing number of customers worldwide.
Cell for American automotive supplier
Schmidt & Heinzmann has automated the first two of several SMC presses for a manufacturer of pick-up and truck components in North America. Increasing quantities and higher quality demands can only be met by automation.
Even though many cell components are recurring, cells from Schmidt & Heinzmann are characterised by customer-specific design and product-oriented construction. One of the prerequisites for this is a high degree of production knowledge. Michael Ochs: "Our know-how is certainly in the handling and process control of the most diverse fiber reinforcements and semi-finished product types." This requires a lot of in-house production know-how and thus production depth.
The line for the American supplier starts with semi-finished products in roll shape. For quality reasons, many processors prefer this roll material to SMC from boxes because the fibers cannot break uncontrollably and it is free of folded edges.
In any case, the semi-finished product comes wrapped between two films, because the fiber-resin mass is sometimes quite sticky, depending on the recipe and maturity. When it is fed into the line, the foils are pulled off and the semi-finished material enters the cutting machine. Like many other cell components, the cutting equipment is also a proprietary development. When cutting SMC, there is a choice between two cutting principles: a driven circular knife or an ultrasonic knife.
The system for the American supplier uses the ultrasonic cutting technology newly developed by Schmidt & Heinzmann with a high-frequency excited knife. Michael Ochs: "This allows significantly longer production intervals with less cleaning and maintenance effort than with a circular knife."
Saving material, with appropriate "nesting" software, an NC cutting head cuts the individual blanks according to the recipe. Michael Ochs: "Our software ensures an optimal degree of material utilisation in the process, which comes into play especially with different geometries and free forms."
How fast the material can be cut depends on the thickness of the material - which can be up to 6 mm for SMC mats - and the fiber content. Cutting speeds of up to 400 mm/sec are possible.
The finished cuttings are gripped by the stacking robot and placed on a table with integrated scale. Where exactly the robot has to grip is automatically "communicated" to it via the cutting machine's control system. There is no need for individual programming of the respective cutting pick-up positions. This saves an enormous amount of time during set-up and makes the system very flexible. The robot picks up the limp cuttings with a needle gripper developed by Schmidt & Heinzmann. The individual needle units are designed variably so that the gripper does not always have to be changed for different cuttings.
Normally, the robot picks up one cut from the cutting machine, or two for smaller cuts or large numbers of layers. The cut or cuttings are placed on a table with integrated scales and weighed. A target/actual comparison shows whether the target weight of the cut was adhered to during cutting. If not, the size is automatically adjusted during the following cut to compensate for the difference. Then comes the next layer. Michael Ochs: "Through the weight control and regulation, we ensure that the cutting stack that comes into the press also has the right weight and that uniform components are produced."
The mat stacks can vary in height depending on the component and consist of up to ten layers. The mass of the stack is then a good 15 to 20 kilograms; with large-area components such as the roof structure of a truck, it can easily add up to 30 to 40 kilograms.
To insert these SMC packages into the mould of the press, Schmidt & Heinzmann then uses a combination gripper on the handling robot with finger modules for loading and vacuum suction cups for unloading the finished component. There are good reasons why Schmidt & Heinzmann designs and builds the grippers themselves, as Michael Ochs explains: "As a rule, the grippers are designed specifically for one component, whereby we make use of the existing modular system. Depending on the layout and cycle time requirements, a robot may have to perform several tasks, as in this case. Then we integrate these tasks in a combined gripper, sometimes with different gripping techniques and several functions." However, it would also be possible to have a gripper station where the handling robot automatically changes the gripper if, for example, accessibility or the application requires this.
Payload and reach were therefore fundamental criteria in the selection of the robots. Two FANUC robots are used in the system for the American truck supplier, an M-410iC and an M-900iB. The optimal position of each robot in the system was determined on the screen by simulation. Schmidt & Heinzmann robot expert Thomas Weiß used the 3D simulation tool Visual Components and FANUC's own ROBOGUIDE software for layout planning. But a cell of this size or even the subsequent automation of a cell can hardly be planned "by eye" - especially if it has to be integrated into an existing production environment. The usual procedure at Schmidt & Heinzmann is then to record the complete production environment on site using a 3D scanner and enter the results into the CAD system. Michael Ochs: "Then we can show the customer his 'new' production in virtual reality at a very early stage, walk through the future cell and determine reliable values for the design."
In addition to technical reasons, other criteria spoke in favour of using FANUC robots: "For the end customer of the cell in the US, it was important for the selection of the robots that, in addition to the technical requirements such as payload, reach, accuracy and reliability, the life-cycle aspects such as service, spare parts and maintenance are also guaranteed. FANUC is highly accepted in the US and is the market leader there."
In addition, the customer already has several FANUC robots in operation and appropriately trained personnel as well as positive experience with maintenance and service.
In the current system, the M-410iC palletising robot takes over the stacking of the cuts from the AutoCut on weighing table. The M-410i robots can handle payloads of up to 700 kg with a reach of up to 3.1 metres. Another FANUC robot, an M-900iB, is responsible for loading and unloading the press. After the previous component has been unloaded, it picks up the stack and places it in the press. He then removes the component, which has been "baked" at around 200°C, from the press and places it either in a cooling station or immediately on a discharge conveyor for automatic removal. In this section of the line, if required and depending on the component, a marking for product tracking ("traceability") is also carried out as a data matrix code or as a label.
The cycle time in the line is determined by the press. A cycle takes between three and four minutes, depending on the mass and wall thickness of the component. The entire system is controlled, operated and monitored via a central control panel.
Overall, the customer plans to automate all of its automotive plants step by step. Michael Ochs sees the company's strategy of focusing on high-tech and quality confirmed: "Automation is essential to ensure output and quality." The cycle times and a consistently high level of quality cannot be maintained manually. All in all, there is no getting around the use of robots and automated processes, both for economic reasons and from an ergonomic point of view: "It's a clear saving in manpower and costs." Schmidt & Heinzmann systems are the best example of this.