# Optimization of Customized Industrial Pneumatic Nozzle to Reduce Noise Emissions
## 2 Materials and Methods  
### Description of Ejection Process and Components  
The capsuling machine produced by Robino & Galandrino places caps on bottles that are already fitted with corks and encased in cages. This process is composed of four main stages: placement, prefixing, folding, and smoothing.  
During placement, the caps, which are arranged in a long stack, are inserted on a slide and positioned individually on the necks of the bottles, which move at a constant speed under the structure responsible for this first operation. During prefixing, the cap is rotated until its brand is correctly aligned with the bottle's label. It is then pressed against the cage to avoid possible relative motion between the cap and bottle. Folding and smoothing, which involve removing all creases and making the cap adhere perfectly to the neck of the bottle, are responsible for the final appearance of the product. The last three stages of the machine are performed using pneumatic muscles.  
The noisiest stage is placement (Figure 2), which is composed of three stages: ejection (No. 1 in Figure 2), cap holding (No. 2 in Figure 2), and distribution (No. 3 in Figure 2).  
The main component responsible for the ejection phase in the capsuling machine comprises an upper nozzle and lower nozzle (Figure 3). This operation consists of separating caps that were previously collected in a stack by pressing them on the sides and immediately shooting them into a series of rotating cylinders for the next process. The  
Figure 1: Normal equal-loudness-level contours, ISO 226 [11].  
Figure 2: Placement stage.  
pressure on the sides generates a small empty gap between the first capsule in the stack and the next one, and the two nozzles are aligned to shoot the air in this gap, sending the first cap into the empty cylinder installed inside the six black rings shown in Figure 2. For the correct execution of this process, the air shot from the two nozzles must be powerful and precise because it must hit the small gap between two consecutive caps and throw the first cap into the cylinder very quickly.  
The cap-holding process consists of a continuous air flux coming out of the green fork (Figure 2), which prevents the caps from falling out of the cylinders during the rotation of the central wheel.  
Finally, the distribution phase occurs when the cylinders are in the bottom part of the wheel and a bottle is placed exactly beneath it (this synchronization is always guaranteed). At this moment, the central gray nozzle (No. 3 in Figure 2) generates an air shot that shoots the cap onto the neck of the bottle.  
Figure 3 shows the upper nozzle at the top and the lower nozzle below for the ejection process; the two final small holes from which the air flows out are visible.  
The geometry of the upper nozzle is simple. It is composed of a main duct with a diameter of 8.7 mm, a length of 10 mm, and a 90\({}^{\circ}\) turn with a radius of 5 mm, followed by another straight section with a length of 6.3 mm. Then, the duct splits in two, resulting in two final smaller ducts with a diameter of 2.5 mm, a length of 17.7 mm, and a direction of divergence of 3.4\({}^{\circ}\) from the axis of the straight section. Air flows from the main duct and exits from the final ducts.  
The lower nozzle is a hollow cylinder that ends with two small holes with a diameter of 2.5 mm at the front. The air enters from the cylinder side and flows out from the two holes.  
Figure 4 shows the inner geometry of the previously described upper nozzle.  
Figure 4: Inner geometry of the upper nozzle.  
Figure 3: Ejection: lower nozzle (below) and upper nozzle (above).