Cellro helps customers make the transition to Industry 4.0

In its ambition to bring its automation solutions for CNC machines up to the level of Industry 4.0 and beyond, Cellro took a close look at the hardware and software of its systems. This resulted in a major transition in which the Festo Motion Terminal played a major part.

“When companies in the machining world think of growth, they mainly think of more staff and more machines.” In the meeting room of Cellro’s office in Veenendaal, The Netherlands, Director Arnoud de Kuijper explains that it is not the general response of machining companies to focus on automation and digitalisation. “Industry 4.0 is still not widely adopted in these circles and that's what opens up opportunities for us. Our mission is to enable production companies to use this innovation and to play a leading role in it.”

De Kuijper realises that this is easier said than done. “The industry is increasingly moving towards producing small batches and many different products in all sorts of sizes. How can you support that? We want to deliver the flexibility that customers need, but we don't want to reinvent the wheel for every order,” he says, outlining the challenge. “So we have to use standard products and a configure-to-order model with many variables. That is the basis for how we now deal with robotics, grippers and the rest of our technology.”

For Cellro, which for years has specialised in automation solutions for CNC machines, this insight heralded a major transition. “Software has become our biggest differentiator,” says De Kuijper. “We install the hardware at our customers' premises and, thanks to ever better software, we offer them new functionalities.” The focus right now is mainly on Europe. “Especially in the German-speaking countries, there are many machining companies which have a relatively low level of automation. We also see opportunities in the US and Asia, but initially we will concentrate on building up our presence in the region.”

Trouble-free operation

In the workshop, Product Manager Bram de Koning shows Cellro's Elevate, an impressive system that can fully automatically load one or more types of turning, milling or other machines. “We regard the Elevate mainly as a strong logistics solution,” says De Koning, pointing to the four-metre high tower. “It offers a large storage capacity so that users can easily leave it running overnight or even over the weekend without worrying about it.”

De Koning explains that he and his colleagues didn’t sit around doing nothing during the pandemic. About the electrical cabinets he says: “Everything used to be in one big box and was run by one big software project. That made scaling down more difficult. The communication to the CNC machines, which was always custom-made, was also a problem. We thought we could and should do better”.

Cellro rebuilt the hardware and software and distributed them over several electrical cabinets. “On the left is the base cabinet with the majority of the intelligence,” explains De Koning. “This is where the core processes such as the job manager, planning, etc. are run. This cabinet is the same for each machine and each cell.” Of course, the Cellro engineers continue to tinker with the software and can update systems in the field remotely and thus implement improvements.

The control of the Elevate lift has now been separated and placed in a different cabinet with its own PLC. Other product families in the Cellro range also have their own control cabinet. The machine communication is now also kept apart from the basic hardware. “The interface cabinet translates the instructions from our systems into the format in which the CNC machines want to receive them, and vice versa,” says De Koning. “The advantage of this configuration is that we can send this interface to the machine builder or system integrator in advance so that they can already arrange the handshake. That saves a lot of time. We have become much more modular.”

Long stroke

With the ever-increasing variety of products that Cellro's systems have to process, there is more and more emphasis on changeover times. De Kuijper: “If you switch to another product, you often need another gripper. These changeovers are not always fully automatic, which means that you lose valuable production time. If we can optimise and keep changeover times to a minimum, our customers will benefit greatly.”

A big contributor to the Cellro solution is a Festo long-stroke gripper that can automatically select the required gripping size over its entire working area. “You may not be able to cover the customer’s complete product range,” De Kuijper admits, “but it does give you the flexibility to, for example, finish an entire product series with one gripper. And that is how many manufacturing companies have organised their production.”

The control of the long-stroke gripper was a bit of a challenge. “A normal gripper is not rocket science,” says De Koning, showing a simple pneumatic gripper. “You install a simple valve terminal in the elbow of the robot arm so that you can regulate the opening and closing of the jaws. Choosing the elbow as the location for the valve terminal is all about finding a happy medium. In the wrist, close to the gripper, it is in the way and adds mass right where the arm moves constantly. However, if the terminal was at the base of the robotic arm, all the cables and tubing would have to be pulled all the way through the moving and rotating arm and that would be quite challenging.”

Motion Terminal

The long-stroke gripper as envisaged by Cellro offers much greater functionality. It should not only be able to open and close, but also, for example, to position its fingers very accurately. “We want to be able to do that to the millimetre,” says De Koning. “This is extremely difficult with standard pneumatics.” That is why Cellro called in the help of motion partner Festo.

Festo suggested replacing its standard valve terminal with the Motion Terminal. “This system works on the basis of apps, pre-programmed functions with which you can define all kinds of movements,” says De Koning. “The sensors that are integrated in the gripper head provide feedback on the position of the jaws, allowing the Motion Terminal to control the movement very precisely.”

Cellro now has the option of positioning the gripper's fingers to the nearest millimetre. This enables the head to pick up objects that are close together. This may sound insignificant, but it means that a customer can store products closer together and thus gain production capacity.

“We can also enter the force and speed very precisely,” continues De Koning. “You only have to set a few parameters and the Motion Terminal takes care of the actual movements. This enables you to generate special motion profiles that fit the objects you want to pick up.”

The Motion Terminal is able to adapt to changing circumstances. For instance, any small leakage between the valve and the gripper can be detected by internal pressure sensors. The Motion Terminal then determines the extent of the leakage and can compensate for it. The same happens if, over time, friction in the mechanics increases or decreases. The Motion Terminal’s closed-loop control smooths out these wrinkles.

“The Motion Terminal gives us valuable information that we can use for predictive maintenance,” says De Kuijper. “That fits in perfectly with our ambition to work towards complete digitalisation. This requires a lot of information and intelligence. With the Motion Terminal we are taking an important step in that direction and we can continue to build on that. I am sure that we will still be on the right track in a few years' time,” concludes De Kuijper.

March 2024