Gripper from the printer Mechanically manufactured aluminum components at ASS are being replaced by 3D printing

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By using 3D printing, ASS Mechanical Engineering can almost completely do without aluminium in custom-made robot grippers. The components reinforced with carbon continuous fibers offer far more benefits for the machine builder and its customers.

ASS Maschinenbau has been developing intelligent solutions for automation & robotics for over 40 years. The range extends from gripper parts from the robot hand construction kit to end-of-arm-tooling and complete automation solutions for the automotive and plastics industry. As a company with great manufacturing depth, most components are made directly at ASS Maschinenbau in-house. Typically, the solutions for the customer are in the area of standard parts of the robot construction kit, as these are the easiest and most cost-effective to realize.

However, among ASS's solutions, many gripping solutions have to be developed, designed and manufactured specifically for the customer. This is because different contours are often required to move components from or into an injection molding machine or gripping jaws that perform specific pick-&-place tasks in presses. 90 percent of these customer-specific applications were made from aluminium.

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The high variety of variants as well as the complex geometries have long been a challenge in manufacturing. As an alternative, ASS Maschinenbau has previously and for many years used the SLS process in the form of laser-sintered parts. With this process, 3D printed components are also manufactured for final assembly. However, a different solution is required for more mechanically robust components and structures.

Printed components with aluminum strengths

Initially, there were concerns and rumors that 3D-printed parts would not be industrially suitable in terms of strength, quality, cost, reliability, and durability. But today, the individual components, which were previously made of aluminum, come from the industrial 3D printer from Markforged at ASS almost 100 percent of the time.

It was initially doubted, and then put to the test, whether components that exceed the strength of aluminum could be manufactured with the Markforged technology. The project began completely risk-free with individual sample parts from Mark3D that were tested under real conditions. For example, a set of gripper jaws was tested that had to grip a screw. After about 300,000 cycles, no traces could be found on the gripper jaws. Subsequently, additional components were obtained from a 3D print service provider from Mark3D and tested in practice.

After the experts were convinced of the technology internally, the company defined this technology for themselves as the current state of the art and began to equip certain gripping solutions with 3D printed jaws. Gradually, further applications such as mounting brackets or fixtures were added which had previously been mechanically processed.

Fast learning curve in design

Since the powder bed process has been used in the company for decades, the new technology was established very quickly and a good understanding for the additive design was already present. The design freedom is increasingly being exploited and corresponding know-how in the design of components with carbon continuous fibers is being built. Thus, the components are now constructed not only with a focus on manufacturing, but primarily optimized for function.

What stresses is the component subject to and in which direction must the continuous fibers be laid? The optimal orientation of the component in the 3D printer results from these questions. All components are designed with the maximum fiber content in order to achieve the highest possible strength. The innovative technology with its clear advantages is also well received by the customers of ASS. "We were unable to find any comparable 3D printer on the market during our evaluation that was delivered with this level of maturity and the promise of stability. Everything we had hoped for has indeed come true", says Thilo Puchert, Head of Automation, ASS Maschinenbau.

We were unable to find any comparable 3D printer on the market during our evaluation that was delivered with this level of maturity and the promise of stability. Everything we had hoped for has indeed come true.

A product line with 3D printed parts of its own

All gripping solutions where the standard kit cannot be used are now primarily equipped with 3D printed jaws. On average, the printed grippers save about a third of the weight compared to conventionally produced grippers.

The customer receives the parallel jaw gripper PGR combined with 3D printed jaws, which are individually adapted to the customer's component —at a fixed price. The customer just needs to send a CAD file of the component to be gripped. From this, ASS generates the matching gripping jaws.

This gripper is then delivered to the customer within 3 to 6 days. So far, customers have bought the gripper and then had gripper jaws made themselves in the tool shop. Customers now benefit from the all-inclusive package from ASS.

The printed parts contribute to almost all technical solutions at ASS and are therefore integrated into almost all solutions. So far, almost 1,300 customer-specific applications have been successfully printed, which were previously manufactured mechanically.

Customer projects are being realized due to 3D printing

A decisive project contributed to the acceptance of 3D printing throughout the company. The request of an existing customer was not feasible with the standard solutions due to weight restrictions in the load capacity of the robot, as the gripper including aluminium profiles would have weighed around 6.5 kg.

Finally, the gripper was designed as a compact part, with all functional surfaces individually adjusted to the customer's requirements and then printed. After another iteration loop, the customer received a gripper with a total weight of 2.1 kg (46.3 pounds) compared to the original weight of 6.5 kg (143.3 pounds).

Additional EP coating ensures durability

Many of the components are coated with a highly abrasion-resistant and wear-resistant coating, the so-called EP coating. This can be used universally and is available in two Shore hardnesses and colors: Shore A hardness 90 in the color blue and Shore A hardness 60 in the color black. This coating is applied in-house in a paint-like process when particularly abrasive or sensitive component surfaces need to be handled. For the blue variant, there is a laboratory test certificate for paint compatibility (Labs).

Fiber-reinforced 3D printing

The material behind the high-strength components is Markforged Onyx. It is a polyamide 6 with about 15 percent short carbon fibers.

However, its special advantage lies in the carbon continuous fibers. The grippers and applications at ASS are reinforced with the carbon continuous fiber via a second nozzle in the print head. In this process, the long fiber is inserted into the component and the loads are distributed over the entire area. These strengths go far beyond what is known from the areas of GFK and CFK. Aluminium has been largely replaced as a material.

Growing range—thanks to 3D printing

After having been using the industrial 3D printer intensively for some time now, ASS Maschinenbau wants to use it ever more fully. This will be ensured in the future by the recently developed and new Micro-Light product line—an ultra-light micro gripping system.

The focus in the development of the new, ultra-light gripping system was on ultra-light construction, assembly-friendliness, maximum flexibility and compatibility in terms of connection and application possibilities.

Grippers from this system can be easily connected to all common types of industrially used robots, such as linear systems, articulated arm robots or cobots. The ASS Robot Hand Kit offers cross-system connection options to enable economic and simple integration of the robot hand (EOAT). The 3D-printed components made of high-strength, resistant material reinforced with continuous fibers offer the required stability and lightness. This now also allows the operation of smaller injection molding machines, which was previously not possible.