Transport of blanking plugs and elimination of unnecessary activities

The Balluff Case Study series are articles written by Balluff experts, our company's partners, integrators, specialists implementing dedicated solutions for manufacturing companies using Balluff tools and solutions.

The main goal of process automation is to relieve employees from monotonous activities and unnecessary tasks. A major challenge during the implementation of changes - according to the WCM methodology (World Class Manufacturing) - is to give additional value in every decision, in every movement. We faced this challenge during the development of a conveyor for process plugs in an automotive company.

The idea to create this type of machine came when the maintenance staff noticed that the operator was doing "container walks," that is, manually moving the process plugs, which had to be taken off the engine at one point to be put back on at the end of the production line, for shipping. We decided to relieve the employee of an absorbing activity, which was met with enthusiasm by the decision-makers.

Process flow

From the beginning, we considered two transportation concepts. The first was the idea of creating a mechanical lift-truck. However, we decided that the second idea, which involved bringing the plugs over the existing section of the line using a pneumatic system, was preferable. In order not to use additional mechanical-electrical drives for the conveyor, we decided to use a simple solution based on a pneumatic pump.

The maintenance team designed and built the entire pneumatic system for transporting the plugs themselves. I always emphasise that any idea, product, machine is not just mechanical, electrical, pneumatic or hydraulic parts - it is a whole - a team that brings everything together and must work perfectly together, just like in a car. The next component of this system was to be a machine - an installation for the automatic transport of the process plugs.

Solving the problem

Having already defined the idea of transport using vacuum hoses and ejectors, we had a dilemma whether to install them at a height of three meters, or to run them down into the floor. We decided on the first solution in order to avoid "sticking" into the floor. The first tests of transporting the plugs took place in the maintenance workshop. The system consisted of a transport tube, a vacuum pump (ejector) and a hose to feed the pump. On such a trial design it began to work for us, although the efficiency of transport was not always good - the plugs did not reach the end of the transport pipe. So we modified the ejectors - we added two new feed holes to the existing hole, allowing us to achieve much higher flow rates. The main executive element for transporting the plugs is the pump, or ejector. The pump operates by feeding an air supply to three points, creating a vacuum on one side of the ejector and a positive pressure of air on the other.

The plugs come in different shapes and weights. Contrary to appearances, the largest volume cap causes the least problems, and the small needle causes the most trouble. A separate topic is the selection of hoses and ejectors for a given blanking plug. Fitting too large a hose (diameter) means generating unnecessary additional costs. Similarly, in the case of ejectors. According to the methodology ofWCMcomponents must be optimally selected and matched. The same applies to the process of optimising the blanking transfer, once the device is built.

Ultimately, a PLC is responsible for the functionality of the entire transfer plant. Initially, we turned on the entire transfer installation for 30 seconds, but later we created pages in the PLC where we program the length of the transfer time, that is, the air blowing of each ejector on each plug transfer line. We can vary this from a few seconds to a minute.

The length of each transmission line is about 100m. We have six tracks because of the six types of plugs. The number of vacuum pumps on each transmission line varies from 2 to 4 - ejectors, due to the capacity and, of course, the type of blanking plug. The process of transporting blanking plugs is completely automatic: the operator drops a blanking plug into a given, labeled hopper, a sensor detects this and starts blowing on that line (triggering the air supply to the ejectors on that line).

Use of tools and cooperation with Balluff

To simplify the entire process, we used IO-Link technology consisting of buttons and lights. The lamp indicates to us what colour the plug is (there are three types). In the PLC mentioned above, we can program them freely. A red light indicates the presence of a red blank in the container. The change of colour (colour sweeping effect) of a given lamp, signals the operation of a given transport line and informs that air is being blown in a given pipe. If the operator notices the absence of blanking plugs in the container, he has the opportunity to bring his hand closer to a particular button and then start an additional blowing cycle. The plugs, which may have stopped in an intermediate position, arrive at the target container.

IO-link technology is excellent because it doesn't cause any problems - it just works. The ability to program the lights also gives you far more options and, as an added bonus, it's just pleasing to the eyes. IO-Link is also a great device for maintenance, and one of the key advantages is that it is very easy to detect a failure with it.

In the creation of the machine, testing was an important issue. It turned out to be real advantage to be able to conduct tests and prove concepts at Balluff's headquarters, and here the help of Mr. Rafal Korcz, our supervisor at Balluff, proved invaluable. He performed tests regarding the selection and functionality of sensors and the presence of hose plugs at Balluff. He also helped us with the selection and equipment of the control cabinet. The operation of the conveying system is carried out in the electrical cabinet by means of a Siemens PLC, a monitor - i.e., an operator panel, buttons, and limiters that signal us when a plug is dropped into the hopper.

In our unit, the transport hoses have iron spirals. It was very important that the sensing process takes place outside the operators reach. So that no extremity or laser beam would shine on the operators hand when putting the plug into the funnel. Here, too, we could count on Balluff's help. Mr. Rafal also tested wires and plugs at Balluff and tested his solution in combination with our materials. In this way, he gave us rectangular end caps that work perfectly. It was a tailor-made project, just like the buttons and lights.

SMC also helped us a lot with the selection of pneumatic apparatus, i.e.: air preparation station, valve pneumatics and valve island, among other things.

Benefits for the company

As is usually the case at the very beginning, employees were skeptical about the use of this device. However, now the employees have forgotten the old way of transporting plugs and cannot imagine any other way of working. Of course, it was not without problems due to habits, but nevertheless, any automation ultimately brings positive results and speeds up work. That's why I'm glad that our management is open to all kinds of ideas for improvements and technical innovations.