Automatic sorting of sheet metal parts: Must-have or a white elephant?
A fully automated sorting system typically costs between 400,000 and one million euros. This is a sum that rightly catches the attention of sheet metal processing companies. Yet, the question remains: In light of the shortage of skilled workers and growing competition, is automated sorting an absolute necessity—or could this major project become a white elephant if the conditions and expectations aren’t right?
The initial situation is the same for many automated laser cutting centers. The sheet change at the laser cutting machine is automated - ideally in combination with a sheet storage system - but the subsequent sorting is still firmly in human hands.
Dull, dirty, dangerous: the reality of manual sorting
Manual sorting is a physically demanding, monotonous and dirty activity with a not inconsiderable risk of injury. Cut sheet metal parts have to be separated from the scrap skeleton, sorted and stacked. It is not uncommon for impact and cutting tools to be used. "Dull, dirty, dangerous" - this is how robotics describes these activities, which are predestined for automation.
The personnel requirements are also considerable: the more complex the cutting plans and the larger and heavier the sheet metal parts, the more time and muscle power are required. In companies with two or more laser machines, this often means that one operator is responsible for two lasers and at the same time one or two other people per shift are exclusively occupied with sorting and material movement.
Before taking the step to full automation, there are various ways to make manual sorting easier and more efficient.
Belt conveyor systems: One of the most popular options is the use of a belt conveyor system. The laser automation places the cut sheet metal panel on the conveyor belt and the operator cycles the parts in piece by piece. The working height can be adjusted so that the operator does not have to lean far forward. This advantage is particularly noticeable with small parts that are connected to each other via micro joints, as several hand movements are required to separate them anyway and it helps if the parts are conveyed close to the operator.
Decentralized sorting stations and AGVs: Another option is the spatial separation of cutting machine and sorting. A sufficiently dimensioned sheet metal warehouse, in which cut sheets can be temporarily stored alongside the raw sheets, is ideal as a central distribution center. A separate station in the sheet metal store facilitates access to the sheet metal from all sides. This also makes it possible to run night shifts with few personnel. This means that manual sorting can be concentrated on the day shift and the productive times of the lasers can be maximized. As a result, laser cutting and sorting can be decoupled not only in terms of space but also time. Alternatively, forklift trucks or even AGVs can transport the cut sheets flexibly through the hall - the operator is then completely free to choose the sorting location.
Semi-automated removal of large parts: Semi-automated sorting, for example with Remmert's LaserFLEX automation, offers an elegant middle way. This system, which actually loads and unloads entire sheets at the laser, can be used to remove heavy and unwieldy sheets from the cutting plan. These can be stored again as residual sheets or palletized directly. The advantage: no additional investment is required as the existing automation is also used and manual sorting is limited to smaller parts.
Quality assurance as an argument for manual processes
However, it would be too short-sighted to view manual sorting solely as a cost factor. Manual visual inspection is a real added value, especially when processing high-quality materials such as stainless steel, as the cut surface and material surface can be assessed directly. If you want to fully automate sorting, you need to include this quality assurance aspect in the overall process.
Almost all major manufacturers of laser cutting machines and independent specialists such as Remmert, Starmatik and Isochronic now offer solutions for parts automation. Cartesian robots (also known as gantry robots) have established themselves in this application. Using linear axes, one to four tool heads move over the cut sheet metal and pick one sheet metal part after another from the cutting plan with the help of vacuum or magnetic end effectors. Multiple heads enable faster sorting of small parts on the one hand and support the picking of large and heavy parts through "group work" in which several heads are synchronized on the other. Single-head systems, such as those from Amada or Remmert, use a single head with a suction matrix. Astes4 from Mitsubishi or Isochronic use up to 2 x 2 heads, each of which can pick up individual small parts or synchronized larger parts.
The parts can be removed directly from the shuttle table of the laser machine or from a separate sorting station - depending on the space available, the machine speed and the volume of parts. The sorted parts are typically placed on Euro pallets according to order or identical parts, which can then be temporarily stored directly in the sheet metal warehouse if required.
In addition to the hardware, specialized software plays a central role: it analyses the cutting plan, transfers the coordinates to the robotics and calculates the optimal placement of the pick-up tool and the best storage location for each part. As a rule, the nesting must also be adapted to the requirements of the automatic pick-up - even design specifications for individual parts can become relevant. For example, it may be useful to round off corners so that the parts are easier to remove from the metal sheets.
The selection of a suitable sorting system is complex. The relevant criteria can be divided into three areas:
Technical criteria
The range of parts is the central starting point. The size and weight of the parts influence the choice of robotics, the number and design of the heads and the type of tools. The available area for suction cup placement is also crucial, as many hole cuts can make automatic pick-up considerably more difficult. It is generally advisable to have cutting plans analyzed for feasibility by the supplier of the automation solution before purchasing.
Overall process view
The integration of the sorting robot into the overall process requires careful planning. How fast does the laser machine work - and must the robotics absorb at the same speed without delaying the plate change? Are the cutting plans suitable for automatic sorting or do they need to be re-clustered if necessary? All these material flow issues need to be thought through in advance. The quantity and position of the load carriers provided is also crucial for the overall setup, as the robot only has a limited radius of action for depositing the parts.
Commercial consideration
The investment for a fully automated sorting solution is usually between 400,000 and one million euros for technology and implementation, plus operating costs. This is offset by the savings in personnel costs. The better starting point for higher machine utilization through multi-shift operation with lights-out shifts is also an argument for the investment.
However, the following applies: fully automated systems significantly reduce personnel requirements, but do not replace them completely. There will always be problems - technological challenges, parts that tilt or tilt on the shuttle table - that require manual intervention. This is an important factor when calculating profitability.
Looking to the future: dynamic market and new technologies
The market for laser cutting machines and automation solutions is in a highly dynamic phase. For years, more and more manufacturers of laser cutting machines have been entering the market with inexpensive alternatives - especially from Asia. This also opens the door for small and medium-sized companies to enter the field of prefabrication with their own laser machines. Internet portals such as Laserhub are expanding the market for both suppliers and customers. This increases the competitive pressure on contract manufacturers: they have to expand their range, remain attractive in terms of price and score points with short delivery times and high quality.
At the same time, competition is driving innovation. High-power lasers with 20, 30 kW and more are being used more and more frequently and are cutting sheet metal at a speed that puts downstream processes under pressure in terms of time. Sorting directly from the shuttle table could become a bottleneck and limit the potential of fast lasers. More flexible concepts with a separate sorting station have an advantage here.
Laser cutting machines with bevel cut technology offer a number of design advantages, also with regard to reducing downstream processing steps. However, phase cuts can be an obstacle to automated parts sorting.
This is where future concepts from some manufacturers such as Trumpf or Eagle come into play, which provide for the mechanical removal of the skeleton before sorting. Automatic sorting of the sheet metal parts is then no longer based on the coordinates of the cutting plan, but the robotics are guided by 3D vision.
Humanoid robots as a future option
The prospect of humanoid robots is particularly exciting. The technological advances in this area are enormous and humanoid systems could represent a real alternative to permanently installed gantry robots for SMEs in this sector in just two to three years' time. They could be used much more flexibly for different tasks and would also be comparatively easy to integrate into existing production environments. Combined with the removal of large parts using laser automation, for example, they could one day be able to pick up manageable sheet metal parts - even in cooperation with their human colleagues.
Conclusion
The automatic sorting of sheet metal parts remains one of the most complex challenges in sheet metal processing. There is no one-size-fits-all solution, as the requirements vary too much depending on the range of parts, machinery and operating strategy. A sensible start often begins with a well thought-out material flow, ergonomic improvements or semi-automated solutions. Anyone who dares to take the step towards full automation should carefully weigh up the technical, process-related and commercial criteria.
Another important aspect is that in most cases the laser machine is replaced earlier than the surrounding automation. Users are therefore well advised to pay attention to flexibility when selecting their automation solution in order to be able to integrate future generations of machines or to take advantage of the freedom to change suppliers.