Report / Case study

A vision tool for all caps

Counting tasks cleverly handled with the CS-60 Vision Sensor and the flexible nVision-i software

Counting large, small, colorful, white and transparent plastic caps on a running belt sounds easier than it actually is. As with so many other things, the devil is in the details. Brilliant solutions for this would be those that implement the specified requirements without overly demanding hardware and software. With the new CS-60 Vision Sensor and the flexible nVision-i software, the sensor specialist di-soric is demonstrating together with plastic parts manufacturer KM Packaging just how simple, reliable and cost-efficient counting can be.

di-soric Vision Sensor CS-60 Applikation

Sealing caps reach the end of the belt in series, are detected by the CS-60 Vision Sensor, counted and then fall into the box

A plastic smell typical for plastic processing hangs in the air: The robot removes finished sealing caps from the injection molding machine and places them on a conveyor belt. This is done in rows of three, four, five or six depending on the type and current injection molding machine. This includes lids and caps in different sizes and shapes as well as in all imaginable colors depending on the respective customer wishes. At the end of the belt, they fall into the boxes that are then prepared for transport. Nevertheless, they still need to be counted beforehand – the customer is relying on the fact that the quantity in the box actually matches the quantity listed on the delivery note.

Counting moving plastic parts seems simple at first glance. However, this is more complicated when you take a closer look: The variety of shapes, colors and spacings of the caps in rows pose special challenges for automatic systems. Marginal lighting conditions and reflections complicate object detection, and transparent parts sometimes remain invisible. 

“So far we had been using light barriers to count the caps. Unfortunately, this has the disadvantage that we would have to reset and realign them every time there is a batch change. Because of our product spectrum and the current requirements for flexible production, the time needed for this was steadily rising,” remembers Eugen Knaus, who is responsible for electrical engineering at KM Packaging. 

An innovative, powerful alternative was needed in order to save time and costs in the future as well as be able to immediately react to current customer requests. In principle, several automation solutions are possible for this – however, which application can actually get the job done in a particularly simple, fast, reliable, efficient and economical manner? Which solution requires no or only minimal retrofitting effort for product changes? What are the requirements for the hardware and software?

Customers mostly still know KM Packaging GmbH as Kutterer Mauer AG. The plastic parts manufacturer has been operating under a new name since its acquisition by Capiton AG Berlin in 2021. KM Packaging supplies companies worldwide in the cosmetics, pharmaceutical and food industries. It focuses on the development and production of high-quality, sometimes innovative, closure solutions for tubes, bottles, pans, etc. Other well-known and prominent flap and screw caps, such as Uhu’s Flinker bottle or those from Thomy Senf, also come from the specialists at KM Packaging, which is headquartered in Ubstadt-Weiher near Bruchsal.

Some of the distinguishing features of the company include, among others, its own tool making department as well as an automation department that develops and implements solutions in the areas of assembly, packaging and inspection. Both departments are integrated into a Technical Center and work closely together. There, they started on the development of a new solution for automatic detection and counting of sealing caps in February 2021. The requirements were clearly laid out: All product variants need to be able to be detected and counted via a flexible, integrated hardware and software application. The effort for a job change should be nearly zero for the hardware and minimal for the software adaption. In addition, the new application must be fast, reliable, low-maintenance and finally economical.

This made a compelling argument for a camera-based solution, but what kind and what technology? This is the point in which external expertise was required: KM Packaging has long been relying on the products and solutions from di-soric. It made sense to clarify the specified requirements and initial ideas with the manufacturer of innovative sensors and powerful image processing light components from Swabian Urbach.

“We have gotten to know the processes at KM Packaging very well over several years now. It was clear to us that there would not be any off-the-shelf solution for the task at hand,” says Thomas Friedel from di-soric. “We detailed the task formulation together with our colleagues at KM Packaging, tested the first trial variants in the testing lab, optimized and then finally brought to life a practical, working solution.” 

The heart of the new counting application is the CS-60 Vision Sensor from di-soric: This sensor offers users maximum flexibility for demanding inspection tasks with a resolution of up to 1.6 megapixels. With M12 optics that can be exchanged as needed and integrated, high-performance illumination that can be switched in the software, it guarantees high-quality image results and is well-suited for a wide range of applications.

However, undoubtedly the CS-60 Vision Sensor by itself is not the complete solution. Initially, clarification was needed as to where and how the sensor would be ideally installed to best meet its intended task. “The particular challenge was that we wanted to detect all types with one camera setting and only one set of parameters,” emphasizes Eugen Knaus. “For this we had to find one position or rather one detection mode in which the objects are clearly highlighted, and color, size and shape do not play any role.” 

di-soric Vision-Sensor CS-60 Applikation, Aufbau

Image 1: The parts in view: The CS-60 Vision Sensor (right, center) focuses on the objects arriving at the end of the belt at a 45 degree angle.

Die Reflexionslichtschranke löst die Hochleistungsbeleuchtung des Vision Sensor CS-60 aus: Das Licht trifft auf die Verschlusskappen sowie auf die im 45 Grad Winkel darüber angebrachte Reflexfolie.

Image 2: The retro-reflective sensor triggers the high-performance lighting of the CS-60 Vision Sensor: The light hits the sealing caps as well as the reflective film placed over them at a 45 degree angle.

In the course of task specification, the optimal camera position for counting parts was quickly found: The CS-60 Vision Sensor was installed at a distance of 700 mm (with a belt width of 500 mm) opposite and parallel to the belt discharge (see image 1). With an angle of 45 degrees, the sensor has a complete view of the objects arriving at the end of the belt. Triggered by a retro-reflective sensor,  (see image 2) the high-performance lighting emits a flash exactly when the plastic parts present themselves in series as they are about to fall. This light hits both the objects as well as the reflective film installed behind. The light reflected by the reflective film omits the objects: The image captured by the sensor shows the silhouette of the individual components in black, completely independent of their actual color (see image 3). It is at this point that the nVision-i software developed by di-soric comes into play: It stands for easy adaption to the respective task, fast set-up and it ensures the CS-60 Vision Sensor functions at peak performance. 

di-soric Vision Sensor CS-60: Software nVision-i Benutzeroberfläche

Image: 3: The image captured by the CS-60 Vision Sensor with the area counting tool (green): The number of objects can all be detected and counted regardless of the object color.

In the present case, a rectangular area counting tool previously created at the operating level detects the silhouette of the parts and correctly determines their quantity. Counting with a set of parameters functions for all part variants and does not require a cumbersome recipe selection. The user only has to adjust the frame scope to the size of the sealing caps expected one time (for installation and set-up of the Vision system). In addition, users can also implement corresponding upgrades via download, depending on the licensing and respective needs: For example, the modules “Measurement” and “1D and 2D code Reading” can be acquired separately or together as a software expansion to the standard module (Localization, Detection, Counting) with a simple license model.

“The intelligent linking of the CS-60 Vision Sensor with the flexible and easy-to-use area tool is part of the charm of this efficient counting application. Another real plus is the integrated Profinet interface for data transmission,” summarizes Eugen Knaus. “In addition, the cooperation with our colleagues from di-soric has always been exemplary and trouble-free.” Six installed counting applications have been running without errors or malfunctions at KM Packaging since March 2021.