Essay: Mechanical fan

1. Introduction
In the final report, our aim is to indicate all of our accumulations of knowledge about the mechanical fan which we gathered in the whole term. Our results consist of production process of the mechanical fan and the raw materials hat are used in the entire process. In order to understand and analyze the process we also considered the usage of the product in the market while taking account of the current technology. In addition, we focus on the assembly methods of a common mechanical fan which basically forms from three parts; an impeller, a motor and a fan guard. We also explained the manufacturing processes of the product in our proposal report and in this report we will give further information about these processes which consists mathematical analysis. Most of the evaluations that take a part in this report are gathered in our factory visit and that’s why the information which is provided in our report is up to date.
2. Explanation of the Selected Product
In this section, we are going to explain our selected product which is the mechanical fan. It’s working principle is to create and transfer flow within a fluid which is air in our case. As we also mentioned in the previous section, it is composed of two parts; an impeller and motor. However, these parts also have different types when the requirement of the product is taken into consideration. For instance, there are three types of motors; electric motor, internal combustion engines and hydraulic motors. Moreover, mechanical fans are also divided between each other. There are many types of mechanical fans depending on its purpose such as cooling and dust removal, type of fluid and the temperature of its working location; however, three of the main types are known as radial fan, axial fan and mixed flow fan.[1] Our focus is on the radial fan. A radial fan is used in leaf blowers, blow dryers, air mattress inflators, climate control and various industrial purposes because it produces more pressure for a given air volume and quieter than others. A blade of a fan can be made by various raw materials and molding processes. After the single blades are produced, the blades with exact shapes are chosen and attached to the blade frame. The material selection has a vital role in both in the production and the cost of the product. Wood, plastic or metal are the common choices of material in fan production but the product that we chose is metal.
In order to fulfill the project requirements, we have visited the factory of ‘Helisfan’ [4]which is a company known for producing various types of air conditioning systems. They have been working for ten years in this business. They are a well-known company in the air condition industry. They mostly produce radial and axial fans; however, they also produce dust catchers and custom air conditioning products.
In this report you should mathematically analyze the selected process. One should describe fundamental parameters that affect the process. They can be process like parameters feed, speed, depth of cut or tool parameters like angles on dies, blades etc.. Their effects on constraints such as forces, power etc. should be presented mathematically. On an example case obtained from the factory or the literature, sample calculations should be presented.
3. Production Steps
Production steps of radial fans are listed above. We gain this information during our visit to Helisfan which is radial fan producing factory and there we had a chance to take pictures and witness some of the production steps of a radial fan which are;
A. Shearing Process (Laser cutting process)
B. Roll Bending Process
C. Injection Molding (for processing blade)
D. Welding Process
E. Producing Motor
F. Finishing
G. Assembly
A. Shearing Process (Laser Cutting Process)
In this process in order to produce blades and main part of the fan body sheet metal is cut by using CNC (computer numerical control) machine which is also called laser cutting.
B. Roll Bending Process
Rolling process is for making the thickness of the metal stable and for decreasing thickness of the metal. Cutting sheet metal pass through the two rolls. We need circular and cylindrical shapes for blades and the body part which is made by roll bending process.
C. Injection Molding Process
One of the most important component of the fans is blade and the production of the blade done by injection molding process. Details of all these processes will be explained in the next part which is detailed explanation of the selected processes. [2]
D. Welding Process
Welding is the process which joins parts of the fans. In the production of radial fans Shielded Metal Arc Welding (SWAW) is used.
E. Production of the motor
In Helisfan they do not produce motor they take it from another producer. But the motor used for radial fans is directly coupled motor and for the best efficiency more air with low static pressure is used.
F. Finishing Process
In the finishing process parts gone through a balancing machine to find that if there is any defect in the production. Balancing machine also calculates if there is inhomogeneity in the product and it repairs the defect. So after balancing machine product is ready to use without any cracks or any different defects. Also after balancing machine, as part of finishing product goes to dyeing process.
G. Assembly Process
In the assembly process, rotor is put into the main body part of the fan. In addition to that, assembled absorption cap connects rotor and motor parts in this process.
4. Detailed Explanation of the Selected Processes
Shearing process is the first step of production. In order to make blades, main and ridge parts of the body, sheet metal is cut by using a CNC. At first, the desired shape which reminds a two dimensional snail is drawn on computer and CNC starts to cut accordingly the data on computer. Having implemented the blanking method to the main parts of the body of the fan, the ridge part and blades are started to cut by using blanking method as well. At the end of the Shearing process , we had obtained blanked sheet metal in order to make blades and ridge part of the body. The blades are supposed to be bent accordingly a specific angle to provide the air flow. Also ,the ridge part of the body must have a shape of circle to be the connection wall between two main body part. For these reasons , rolling process is implemented on each of them .There is a machine for this process and according to the angle you set , sheet metal is bent and thin out . Finally , several blades and the ridge which is like body of a fat cylinder are obtained .In addition to that , blades can also be produced by using injection molding method. In injection molding, metal is heated until it reaches desired viscosity and injected into the mold which is determined according to demand (in our project, it is rotor blade).Injection molding consists of some part which are ; the hopper where the molten metal is poured ,the screw which moves backwards and forwards to push forward the molten metal, the mold cavity which give the shape of the product, the clamping system which applies pressure to close the halves during injection and the hydraulic motor.[3] After having the blades ready , Welding process is used to bring the body parts together. While doing this merger, shielded metal arc welding (SMAW) which is most common way of welding steels is used. Welding done in high temperature and it is done with the effect of electrodes. Two main parts are welded to the ridge part separately in a way to form a kind of fat cylindrical shape. Also the blades are welded to the rotor part which is going to be connected to motor at the assembly process. In the assembly process, rotor is put into the main body part of the fan. In addition to that, assembled absorption cap connects rotor and motor parts in this process. As we mentioned above the motor is bought from another company in Helisfan and then joined to the fan. Finally, the motor tested by balance machine whether there is a defection or not. The balance machine detects if there is an inhomogeneity and according to information given by the machine the problems get solved.
5. Overview of Selected Process for Mathematical Analysis
Production and Cutting Rates in Laser Cutting
While cutting the sheet metal with CNC machine, maximum efficiency should be considered. So we want to find maximum cutting rate to minimize scrap. Parameters in this production rate is;
-laser power
-material thickness
-process type (if it is reactive or inert)
Table of cutting rates for different materials and thicknesses are given above. Production rate is cm per second. Helisfan uses stainless steel for workpiece material and sheet metal thickness is 1.0 mm. So production rate is 23.28 cm/second.
Workpiece material Material thickness
0.51 mm 1.0 mm 2.0 mm 3.2 mm 6.4 mm 13 mm
Stainless steel 42.3 23.28 13.76 7.83 3.4 0.76
Aluminium 33.87 14.82 6.35 4.23 1.69 1.27
Mild steel ‘ 8.89 7.83 6.35 4.23 2.1
Titanium 12.7 12.7 4.23 3.4 2.5 1.7
By using this information Helisfan is able to produce five blades of radial one from one standard sheet metal in maximum efficiency.
CALCULATION OF CLAMPING FORCE
When we are doing injection molding clamping force is important facility for manufacturing the blade. By finding clamping force we can talk about how much maximum we can make mold cavity.
Parameters for doing the calculation is;
-number of cavities
-part projected area
-runner projected area
-shot projected area
-cavity pressure
-separating force
-coefficient of security
From the information we take from Helisfan they use 150 mm diameter for making blades in injection molding. Capacity of the molding machine is between 250-300 tons.
Clamped force is calculated by this formula:
Clamped force=coefficient of security* Area*cavity pressure*
-Cavity pressure is depends on material type, hence we use stainless steel cavity pressure for our product is nearly, 45 MPa.
-Area is from ??D^2/4 = 3,14* (0,15)2/4 = 0,0176 m2
-Because of the material we use is steel it has coefficient value between 1.1 and 1.6. So for more accurate result we take the average of them and take the coefficient 1.35 from (1.1 + 1.6) / 2
-Clamped Force= 0,0176*1.35*45=1,06= 1.069.200 N [5]
Clamped force is important because it tells us maximum number of cavity we can use while doing injection molding.
Our machine capacity has range between 250-300 tons. Let assume its capacity as minimum.
250.000 kg= 2.500.000 N
2.500.000/1.069.200= 2,33 if we round the number to the closest. Maximum number of cavity is 2.
This is important while manufacturing because, to maximize the profit we understand that we can produce 2 mold cavities. If we looked at the production rates of the Helisfan, they have used 1 mold cavity. We proposed them to increase the number, but they said that even if good for high production rate increasing number of mold cavity is his cost operation and when they make calculations they do not need such development as a small fan factory. But die cavity number is very important for effective production rate, so it may be considered while producing fans.
6.Achieved Work Distribution
The very first thing we decided was the distribution of tasks in which our primary aim was to give each member an individual task to complete. As it is also stated in the work distribution chart given below Ba??ak, Ege and Burakcan researched in order to understand the industry better whereas Sezen with her research enabled the implementation and the continuity of the project. In detail, in the 5th week Ba??ak researched about the usage of the product and made a general analysis on how the types and manufacturing processes of mechanical fans changed according to the usage of the product. In week 6 Sezen contacted with each factory given in our Proposal Report and found out that ‘Helisfan’ as the most suitable one in terms of availability and closeness. After discussing with the other group members and taking their ideas into consideration Sezen arranged a factory visit to Helisfan for the 11th week. Afterwards, in the 7the week Ege and Burakcan, just like their other group member Ba??ak, researched in order to learn more about the industry of mechanical fans. These researches which were then discussed and shared among the group members during the group meeting increased the productivity of the following factory visit. Furthermore, all 4 group members after the group meeting researched on different types of the product in order to complete the Progress Report. As it was stated in the Progress Report, in week 11 another group meeting is held on Monday and the group members visited the factory on Wednesday. During the Factory visit Ba??ak made a voice recording in order to listen and analyze afterwards. Sezen took photos for the Final Report. Ege asked questions about the manufacturing process to the General Coordinator in order to learn the process in detail while Burakcan took notes on the Coordinator’s answers. After the factory visit in week 13 a final group meeting is arranged in which Ba??ak, Sezen and Burakcan shared their notes, photos and voice notes with the other group members in order to reach the same level of knowledge to start the Final Report.
Ba??ak Do??ruo??lu Sezen Kurt Ege Yi??itel Burakcan Ert??rk
Week 4 Project Proposal (22.03.2015)
Week 5 Research about the Usage of the Product & Learning the Industry
Week 6 Factory Research & Contacting
Week 7 Research of Product Materials & Learning the Industry Research of Product Assembly & Learning the Industry
Week 8 Group Meeting: Discussion Based on the Research Topics,
Research on Different Types of the Product
Week 10 Progress Report
Week 11 Group Meeting: Discussion about the Upcoming Factory Visit and going through the Progress Report
Week 11 Factory Visit
Week 13 Group Meeting: Consolidation of Factory Visit and personal views
Week 14 Final Report
7.The State-of-the-Art
Roughly, the manufacturing processes follow the same pattern all around the world. However the connection between the processes differ in large and small companies. The steps can be self-automated in large companies whereas in small companies manpower is essential. Although self-automated system requires high initial investment it actually decreases the labor cost. Although the decrease in the labor cost doesn’t balance the increase in the investment done, the increase in the efficiency and profit of production can actually make the investment pretty reasonable. Thus, such a system would be appropriate for high production rates. Moreover, by the developing technology 3D printing can be used during the manufacturing process of mechanical fans. Again just like the self-automated system 3D printing also requires a high initial investment. However, such a method will decrease the man made errors which causes an increase in the efficiency. Such an efficiency increase will reflect on the profit, too.
8. Conclusion
To conclude, during the project we have had the opportunity to learn about the possible manufacturing processes of mechanical fans and examine particular one in detail during our factory visit to ‘Helisfan’. According to our observations Helisfan is a rather small factory which is suitable for low production rates. (We could tell this by looking at the amount of machines used and the number of workers) It is somewhat up to date in terms of the technology used. For example, as it is stated in the State-of-the-Art part of the Final Report the manufacturing process could have been self-automated. However, because it is a small company which works for low production rates, at this point such an investment would be unnecessary. In general, the project enabled us to see how detailed the manufacturing processes actually are in which the materials undergo different steps in order to not just look like the final product but also in order to function in the desired way. We’ve seen that every detail is measured and transmitted to the factory before the manufacturing process actually starts and such mathematical analysis are essential in the manufacturing process. Moreover, most importantly while preparing the project we found the opportunity to connect the things that we’ve been learning in MS309 lectures to the daily life. Such a background knowledge on the field made us feel more comfortable, open and more willingly to learn everything in detail.
References
[1] Gupta,N.Y., 2009, Manufacturing Processes, New Age International Press
[2] http://www.gokser.com/yonetim/katalog/forward%20curved%20blade%20fan%20catalogue%20pdf.pdf
[3] http://www.boldrocchi.it/products/radial_axial_fans.php
[4] http://www.helisfan.com/
[5] http://www.custompartnet.com/calculator/clamp-force
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