How 3D scanning solves production quality control problems

Interview with 3D technology expert Georgy Kazakevich

- In the first part of the interview, we talked about reverse engineering. Now let's figure out what is geometry control?

Geometry control is essentially quality control. Look here: the company receives the blanks that it must finalize. If you carry out incoming inspection of these blanks, you can greatly reduce your headache at the manufacturing stage.

Processing and casting cycleIt is a week, holes must be made on the casting, planes, and so on. Any casting has allowances, i.e. material that is removed from the workpiece during processing on the machine. Imagine that we are processing 100 elements, and it turns out that the 95th element is not enough stock. We already made 94, spent the operator’s time, electricity, worn out the cutting tool, and the whole batch goes into marriage. This happens if there is no incoming inspection of the workpieces.



Fig. 1. The process of geometry control using 3D scanning

- What does 3D scanning give us in comparison with traditional control methods?

- The bottom line is that softwareallows the above process to loop. Suppose we have a series of identical parts in the amount of a thousand pieces. What needs to be done to control with standard tools - templates, micrometers, calipers, etc.? We measure each of these thousands of details according to the list and compile a table for each. Now let's see how 3D scanning helps us .

Take a look at the diagram (Fig. 1): for the first part, the first three points are performed manually (scanning, preparing for analysis and directly analyzing), and the report is for you software. For the next 999 parts, only scanning is done manually, the remaining three stages are performed by software. Thus, you spend time only on digitization. And when monitoring geometry, scanning is usually from 5 to 15% of the time spent, not more. Therefore, with flow control or batch production control, we begin to save a ton of time.

Previously, an enterprise could afford to control one out of a thousand parts, because it took a day. By implementing 3D scanning, you can control one hundred parts out of a thousand in just two days. On the first day we do everything manually, and only one more day will be spent on 99 parts - they only need to be scanned. Then we put the CAD model in a specific folder and say to the software: “Work.”



Fig. 2. Lining geometry deviation map

- Please tell us how it works using iQB Technologies case studies.

- The task was to measure the thickness of the lining, successfully completed by the chief technical expert of our company Alexei Chekhovich. There is a mixing unit for liquids, it is metallic, because liquids are supplied under pressure. The problem is that properly processing the metal inside is, firstly, difficult, and secondly, expensive. In addition, metal is a material that interacts with many liquids, it can rust, corrode, etc. This knot is internally coated with a special plastic compound. In order to achieve the correct mixing of liquids, the coating must be uniform. If there are potholes in it, if it is uneven in thickness, turbulences will appear inside. They create additional pressure on the site, therefore, reduce its life.

Previously, the company controlled one part out of a thousand, because it took a day. By implementing 3D scanning, you can control one hundred parts out of a thousand in just two days.

So, first a 3D scan of the node was performed without coating, then with a coating, and the results were compared. The red zone on the scan (Fig. 2) is the coverage. The right picture shows that it is uneven. Based on the results, the customer can make a complaint to the subcontractor who is applying this coating.



Fig. 3. Weldment inspection

The next example is the weldment inspection I performed. I went to Nizhny Novgorod to the Liebherr plant, which manufactures metal structuresfor the assembly of industrial equipment. The metal sheets themselves come from Germany, are welded in Russia and then sent back. Due to the fact that the structure is quite large (2 m long), landing holes are provided for attachment to other structures. If any distortion occurs during welding, the part will join in one place and not in another. To avoid this, the factory decided before sending it to Germany to pre-scan all the parts and evaluate for deviations that occurred during welding. In the table on the right (Fig. 3), we see the actual sizes shown by 3D scanning. Deviations are displayed as a color map. Green is a good result, yellow is within tolerance, red is an unacceptable deviation. Specifically, the part that we scanned, of course, does not pass and is considered a marriage.

- In which other industries have you used a 3D scanner and software to control geometry?



Fig. 4. Control of the geometry of the wing of the car

- For example, we had projects related to the automotive industry . Spare parts for cars, as you know, are quite expensive. They can always be ordered from China, but it is much more convenient to establish production in Russia. Our customer, who manufactures spare parts for high-segment machines, began to receive complaints: the parts “play” when they are trying to put them in place. We scanned the wing for BMW made in Russia and the wing of the original BMW. They compared them with each other and saw that the Russian part was slightly larger in size than required. Based on this, changes were made to the production cycle.



Fig. 5. Bus body

In Figure 6, you see the bus body and the results of 3D scanning - this is the project that Alexei Chekhovich was engaged in. In Moscow there is an enterprise that produces buses from resin. Modern resins can compete with metals in strength, while they are much lighter, which means they are more economical in terms of fuel consumption. Such a bus is assembled from several parts. The company noticed that during assembly there are some distortions, stresses. At first, we were invited to shoot the finished workpieces. We shot them and saw that the workpiece itself is a curve. And in the future we found out that the problem is not even in the workpiece, but in the form in which it was made. That is, the workpiece with the mold fit perfectly, but the mold itself was defective, and it had to be replaced. After that, it was decided that we would check the form approximately every six months.

- Quality control includes operational control. Have you ever solved such problems with the help of 3D scanning?

Yes, and this is usually associated with complex, expensive devices, such as aircraft . During operation, enormous loads act on it, and there are restrictions on structural structural changes that the aircraft acquires during operation. S7 ordered an entire Airbus 3D scan from us. We did not perform the analysis, since these data constitute a trade secret.



Fig. 6. Airbus S7 operational control

Pay attention to the scan, where the sticker on the tail is visible (Fig. 6). The fact is that even such a thing as a sticker affects fuel consumption. The measuring systems that we have are so sensitive that they can calculate the optimal placement of the sticker. And at the request of S7, a 3D scan of the tail of the aircraft was made with and without a sticker in order to understand how correctly it is located.



Fig. 7. Control equipment in an aircraft factory

I will mention one more project from the field of aircraft manufacturing. The customer of iQB Technologies was an aircraft factory, which initially commissioned us to analyze sheet products of a rather large size (2 meters or more). Based on the measurements, we found out that the part is bent and does not fit into the required tolerances. And this despite the fact that she passed control at the plant itself.

After the part has been manufactured, it is placed on a wooden template (Fig. 9). If it lies flat, conclude that it is suitable. Since the 3D scanner showed deviations, we suggested checking the pattern. And on the scan you can see many areas with deviations. Such large-sized templates, according to which units or parts are made, have a complex profile, and therefore it is difficult to control them. The unsuitability of the template design itself is, in fact, a big problem for many enterprises.

- And here the 3D scanner comes to the rescue ...

- The 3D scanner in this case is an ideal device when it is necessary to measure products with a complex surface and large in size. This is the best solution for the production, which I talked about above.



Fig. 8. Scanners in conjunction with the Creaform MaxSHOT Next photogrammetric system are effectively used in aircraft and shipbuilding.

Since we are talking about 3D scanners, we cannot but mention a topic such as photogrammetry. This is a science that deals with determining the characteristics of objects, including measuring dimensions, from photographs. Each scanner is a kind of camera without zoom. You can shoot objects close to or far away. That is, for example, either mountains, or someone’s portrait. Because it is very important to know the exact distance between the cameras and the angle of convergence of the cameras in order to calculate the geometry. So, special devices were created, which are called - photogrammetry devices. First of all, these are just cameras that are equipped with a set of rulers (Fig. 8). The dimensions of these rulers are measured with very high accuracy by a coordinate measuring machine.



Fig. 9. Control of sheet parts.

So, you have some big object.and there is a scanner that is designed to shoot objects the size of a meter. Almost all scanners have a positioning system, i.e. in one way or another they determine their position in space relative to the object. Most often, the positioning system looks like a small round black and white mark, which is glued to the part (Fig. 7 on the right). If the part is large enough - obviously more than a meter, and we cannot scan it, then we additionally place a ruler and large square marks on this part, but at the same time we see that there are also small round marks on the part. Using the photogrammetry system, we take many pictures of the object from various angles. The more shots, the better. Photogrammetry software then recognizes the large marks and ruler,

After that, small marks are recognized, coordinates are also assigned to them relatively large, and large marks are deleted (Fig. 9). It's that simple, with a camera and software, you get the exact coordinates of each of these little tags. They are written to a separate file, which is downloaded to the scanner software. Thus, with a small 3D scanner that is guided by already known marks, you can scan parts or objects up to 20-30 meters in size. Using this simple and effective solution, geometry control problems are solved in many industries, including the aerospace industry and shipbuilding .

IQB Technologies invites you to the Metalworking-2019 exhibition at the Expocenter Fairgrounds! We will present unique 3D solutions at our booth in Pavilion 5.1, as well as hold a practical conference with a demonstration of 3D scanning and modeling (May 29 from 11:00 to 14:00). Details and registration for the conference here .