Ramazan Rıdvan SEKMEN, 030080083, 10th week words

1-Three-Dimensional Printing (Group: Design)

This RP technology was developed at Massachusetts In­stitute of Technology. Three-dimensional printing (3DP) builds the part in the usual layer-by-layer fashion using an ink-jet printer to eject an adhesive bonding material onto successive layers of powders. The binder is deposited in areas corresponding to the cross sections of the solid part, as determined by slicing the CAD geometric model into lay­ers. The binder holds the powders together to form the solid part, while the unbonded powders remain loose to be removed later. While the loose powders are in place during the build process, they provide support for overhanging and fragile features of the part. When the build process is completed, the part is heat treated to strengthen the bonding, followed by removal of the loose powders, To further strengthen the part, a sintering step can be applied to bond the individual powders.

The part is built on a platform whose level is controlled by a piston. A layer of powder is spread on the existing part-in-process. An ink-jet printing head moves across the surface, ejecting droplets of binder on those regions that are to become the solid part. When the printing of the current layer is completed, the piston lowers the platform for the next layer.

(Mikell P. Groover,Fundamentals of Modern Manufacturing,4th Edition,pg.793)

New and better explanation

The 3DP (three-dimensional printing) is a rapid prototyping technology, used to create complex three-dimensional parts directly from a computer model of the part, with no need for tooling [4, 5]. This method (Figure 12) combines a 3D printer, CAD development software and special materials from which the prototype will be created. Computer software splits the 3-D CAD data into a series of thin horizontal cross-sections (slices). Each new layer is fabricated through lowering of the piston by a layer thickness and tilling the resulting gap with a thin distribution of powder. An inkjet printing head then selectively prints a binder solution onto this layer of powder to form a slice of the 3-D CAD file. This method can produce high accuracy filler structures for the fabrication of complex 3D prototypes [17].

        Using the Rapid Prototyping 3D Zcorp 310 Printer system, we manufactured the prototypes for human bones (Figure 13) and one can finally obtain functional assemblies which can be used in the future work in different experiments [2, 16].

(Pisla, D. (2010). 3DP technology Used to Prototype the Knee Joint Components.  New Trends in Mechanism Science: Analysis and Design (p. 315) )

2-Wave Soldering (Group:Manufacturing) Wave soldering is a mechanical technique in which printed circuit is boards containing inserted components are moved by conveyor over a standing wave of molten solder.The position of the conveyor is such that only the underside of the board ,with component leads projecting through the holes, is in contact with the solder.The combination of the capillary action and the upward force of the wave cause the liquid solder to flow into the clearances between leads and through-holes to obtain a good solder joint.The tremendous advantage of wave soldering is that all of the solder joints on a board are made in a single pass through the process.

(Fundamentals of Modern Manufacturing.Materials,processes and system 3rd edition, Mikell Groover, p. 844) 00.49

New and better explanation

The basic principles of wave soldering:

          • contact of a fluxed solderable printed wiring board and component terminations with a continually refreshed surface of molten solder,

         • heat transfer,

         • welting and flow, and

         • drainage of excess solder

are the same for lead-(Pb)-free solder as for tin-lead (Sn-Pb) solder. The differences arise largely from the fact that:

        1.The difference between the melting point of lead-free solders that are suitable for wave soldering and the maximum temperature that the printed board assembly and the wave soldering machine itself can accommodate without damage is much smaller than it is for Sn-Ph solder.

       2. The wetting and spread properties of lead-free alloys suitable for wave soldering are not quite as good as those of Sn-Pb solder.

Despite these differences, it has been confirmed on many hundreds of wave soldering machines that have successfully soldered tens of  millions of a wide range of printed board assemblies that lead-free wave soldering is a viable process that can produce reliable products economically.

        The key to this success is process optimization, which takes into proper account the differences between lead-free and Sn-Ph wave soldering.

( Suganuma, K. (2004).Introduction. Lead-Free Soldering in Electronics: Science,Technology and Environmental Impact (p.275)

3-Design for Corrosion Resistance ( Group: Design)

There is no old explanation

New explanation The life of equipment subjected to corrosive environments can be increased by proper attention to design details. Equipment should be designed to drain freely and completely. The internal surfaces should be smooth and free from crevasses where corrosion products and other solids can accumulate. Butt joints should be used in preference to lap joints. The use of dissimilar metals in contact should be avoided, or care taken to ensure that they are effectively in to avoid galvanic corrosion. Fluid velocities and turbulence should be high enough to avoid the deposition of solids, but not so high as to cause erosion-corrosion.

( Coulson, J.M.,  Sinnott, R. K., Richardson, J.F. (). Design for corrosion resistance. Coulson & Richardson's Chemical Engineering: Chemical engineering design (p.305)

4-Integrated Design Systems ( Group: Design)
There is no old explanation

New and better explanation

To perform process automation and integrate the PSG and the FE modeling support system, an integrated design system was implemented based on the JADE [12] platform. This system meets the standard specifications of FIPA (Foundation for Intelligent Physical Agent) [13] and has various types of agents; Interface Agent, Monitoring Agent, Engineering Server Agent, Job Management Agent, and Process & Analysis Server (PAS) Agents. This system also has EDM (Engineering Data Management) to manage the data required for an engineering process and for system information. The Job Management Agent and the Engineering Server Agent enable the management of engineering jobs. which are executed with specified design parameters. On the other hand, the PAS Agents manage the engineering tasks, which are sub-processes for executing a job. There are four tasks: Task 1, CATIA modeling: Task 2, Pre-processing for CAE: Task 3, Structural analysis: and. Task 4, Durability analysis. Task 1 is performed in the PSG via ParaCAT developed as an in-house

code. The other Tasks accomplished with the FE modeling support system are integrated with corresponding PAS Agents. Fig. 7 shows the architecture of the integrated design system.                

          XML-based Resource Wrappers [10] are utilized to link the PAS Agent to the dis-tributed engineering tools, such as Tasks 1-4. The architecture of the Resource Wrapper consists of Paralnput.xml, Wrapper.xml and ParaOutput.xml, as shown in Fig.8. In the first step, the Paralnput.xml is generated using EDM data. In the Wrapper.xml the input data required for executing the engineering program are generated using a

tag, <Generate>. The engineering program, based on a batch process, then runs defined in the tag of <Run>. Consequently, the necessary data are extracted from the results obtained after running the engineering program in a tag of <Parse>, and the ParaOutput.xml is then generated. The data from the engineering results and the ParaOutput.xml are saved in the EDM.

(Yong, J. (2008). Integrated Design Systems. Computer Supported Cooperative Work in Design (pp.148-150))

5-Pneumatic gage ( Group: Tool)
There is no old explanation

New explanation
A pneumatic gage is an instrument for measuring, comparing, or checking dimensions by sensing the flow of air through the space between the gage head and workpiece surface. The gage head is applied to each workpiece in the same way, and the clearance between the two varies with the size of the piece. The amount the airflow is restricted depends on the clearance. There are four basic types of air gage sensors, shown in Figure 8.3a, b, c, and d. All have a controlled constant-pressure air supply.

       The back-pressure gage (a) responds to the increase in pressure when the air-flow is reduced. It can magnify from 1000:1 to over 5000:1, depending on range, but is somewhat slow because of the reaction of air to changing pressure.

       The differential gage (b) is more sensitive. Air passes through this gage in one line to the gage head and in a parallel line to the atmosphere though a setting valve. The pressure between the two lines is measured.

        There is no time lag in the flow gage (c), where the rate of airflow raises an indicator in a tapered tube. The dimension is read from the position of the indicating float. This gage is simple, does not have a mechanism to wear, is free from hysteresis, and can amplify to over 500,000:1 without accessories.

        The venturi gage (d) measures the drop in pressure of the air flowing through a venturi tube. It combines the elements of the back-pressure and flow gages and is fast, but sacrifices simplicity.

        A few of the many kinds of gage heads and applications are also shown in Figure 8.3 (e through i). Practically all inside and outside linear and geometric dimensions can be checked by air gauging.

        Air match gauging, depicted in Figure 8.3i, measures the clearance between two mating parts. This provides a means of controlling an operation to machine one part to a specified fit with the other. A multidimension gage has a set of cartridge or contact gage heads (Figure 8.3h) to check several dimensions on a part at the same time. The basic gage sensor can be used for a large variety of jobs, but a different gage head and setting master are needed for almost every job and size.

        A major advantage of a pneumatic gage is that the gage head does not have to tightly fit the part. A clearance of up to 0.08 mm (.003 in.) between the gage head and workpiece is permissible, and even more in some cases. Thus, there is

no pressure between the two, which causes wear, and the gage head may have a large allowance for any wear that does occur. The flowing air also helps keep surfaces clean.

      The lack of contact makes air gauging particularly suitable for checking highly finished and soft surfaces. Because of its loose fit, a pneumatic gage is easy and quick to use. An inexperienced inspector can measure the diameter of a hole to 25 µm (.000001 in.) in a few seconds with a pneumatic gage. The same measurement (to 25 µm or .001 in.) with a vernier caliper by a skilled inspector may take up to one minute. The faster types of pneumatic gages are adequate for high-rate auto-matic gauging in production.

( Walker, H.F. (2008). Pneumatic gaging. The Certified Quality Inspector Handbook (pp.80-82))