Halil_kayhan_0300700090_6thweek_part2

2. TONGUE AND GROOVE WELD(Previous)
In designing parts for vibration welding, sufficient clearance must be provided in the joint.Tongue and groove joints are commonly used for vibration welding. When a weld flash is unacceptable, a flash trap can be designed. The trap should be volumetrically sized to the amount of material displaced during welding. Tongue and Groove joints should have 2.54 mm wall and weld tongue thickness to ensure a weld strength equal to wall strenght.
( Plastic Designs Library, Handbook of Plastics Joining: A Practical Guide, p.24)


TONGUE AND GROOVE WELD (New): (Production type)

The tongue and groove flange configuration is a development of the spigot and recess flange style. The gasket is completely  constrained within the groove. Gasket blow-out is prevented and also gasket loss into the process is eliminated. The flange pair can be designed to limit gasket compression or can can be designed so the faces remain open. Flange allignment is controlled by the tolerancing of the tongue and the groove. Facing surface finish is usually limited to ''mirror'' and ''smooth''. This is not a popular flange style and its use is very
limited.

(Brian Nesbitt, Valves manual international: handbook of valves and acutators, p.243) 

 The new one is better.

3. Depression Molding:(previous) (Manufacturing type) Depression Molding consists in the simultaneous use of vacuum and atmospheric pressure. The mold is coated with release agent and the wet layup applied by either hand or spray process. Then pressure is exerted by means of porous die covered by a flexible membrane (generally made from neoprene) and a vacuum pump which sucks air out of the membrane. Heat is frequently applied to speed up the cure. If only one smooth surface is necessary, the die can be suppressed and the pressure is exerted by the flexible membrane alone. This process is also known as vacuum molding or bag molding.
(Jean-Marie Berthelot, Composite Materials: Mechanical Behavior and Structural Analysis, p. 57

Depression Molding(new):
It is the same as vacuum molding;
The V-process, or vacuum molding, is one of the newest casting processes; in it, unbonded sand is held in place in the mold by a vacuum. In this process, a thin plastic film of 0.7 to 2.0 mm is heated and placed over a pattern. The softened fikm drops over pattern with 26 to 52 kpa, and the vacuum tightly draws the film aroound the pattern. The flask is placed over the plastic-coated pattern and is fiilled with dry, unbonded, extremely fine sand and vibrated so that the sand tightly packs the pattern. The flask walls also create a vacuum chamber with the outlet shown in Fig. 2.8 at the right side of each illustration.
Another unheated sheet of plastic film is placed over the top of the sand in the flask, and the vacuum is applied to the flask. The vacuum hardens the sand so the pattern can be withdrawn. The other half of the mold is made the same way. After cores are put in place (if needed), the mold is closed. During pouring the mold is still under vacuum but the casting cavity is not. When the metal has solidified, the vacuum is turned off and the unbonded sand runs out freely, releasing a clean casting with zero draft, high - dimensional accuracy and with a 125 to 150 RMS surface finish.

This process is economical, environmentally and ecologically acceptable, energy thrifty, versatile, and clean. A disadvantage of the V-process is the necessity of plated pattern equipment. The steps of the process are shown in Figure 2.8.

(Vukota Boljanovic, Metal shaping processes, page 34)

The new one is better.

4. Valisys Program: One of the dynamic software suppliers is the Valisys Corporation which was

formed in November 1987 after a few years of development work. Since then, the company has
been developing and supporting manufacturing automation software products that validate part
designs, use design data to automate inspection processes and support quality control analysis.
 The first decision of the Valisys development team was that a universal desigh language had
to be used to allow design information from various geographical sites to be exchanged. The task
was simplified because of the universal acceptance of the ANSI standart which describes geometric
dimensioning and tolerancing. The symbols used in GDET provide labels for engineering drawings
that not only provide dimensions, but also indicate functional relationships and other characteristics.
This standart code prevents misinterpretations.
 At this time, it is useful to restate the main problem confronting computer integrated
manufacturing. it is the difficulty communicating engineering data from product designers to
manufacturing engineering to the shop floor. Now, the Valisys Corporation' s software, which is
one of the modern manufacturing software systems that improves the flow and accuracy of the
engineering data in a manufacturing environment, will be described.

(Modern Manufacturing Processes, James A. Brown, pg. 177)

Valisys Program(New)(Software)

Valisys is used to define nominal features for the CAD database, relate GD+T call-outs to nominal features and check syntax for individual features.

(George Q. Huang,Design for X: concurrent engineering imperatives,page 185)

The previous one is better.

5. Electrochemical Superfinishing(previous)(Finishing)

Conventional superfinishing by vibration grinding is a microfinishing operation in which the surface mirco-irregularities are removed by the continuous and slow reciprocation of abrasive sticks that move along the workpiece length. The sticks oscillate concurrently with short and rapid strokes with a continuously revolving workpiece. This process is however known to sustain some of the surface microirregularities such as waviness and out of roundness. In electrochemical superfinishing (ECS), the combination of electrolytic dissolution (ECD) and mechanical scrubbing (MS) improves the performance of the conventional superfinishing process. As a result of such a combination, the dissolution process assists the small stock removal rate due to the mechanical chipping action. Higher stock removal rates become achievable using either a separate cathodic tool electrode, or a diamond abrasive stick with a metallic bond. The high stock removal capabilities combined with the ability to generate close dimensions gave high merits to the ECS process in all fields of industry. The need for initial grinding, which is required before conventional superfinishing, is avoided. ECS can be used when other processes fail to yield high removal rates or generate the required size in difficult-to-machine alloys as well as tool steel. Applying ECS to parts that are susceptible to heat and distortion is advantageous because the bulk of the metal is removed electrochemically in an electrolyte-cooled atmosphere. The problem of thermal distortion, normally found in conventional superfinishing, is therefore eliminated. Burr-free components can also be obtained as a result of the ECD process.

(Advanced Machining Processes, Hassan El-Hofy; Page:192)

Electrochemical Superfinishing(new)
The top layers of a workpiece are removed[2.57]. The process is based on andic metal machining and therefore qualifies as a ''cold'' process. Thus, the workpiece does not become thermally stresssed; see also Section 2.6. The process works without contact between workpiece and mold, so no mechanical loading occurs. Since removal only occurs at the workpiece, the workpiece is subjected to virtually no abrasion[2.58].
Through the removal of material, leveling of the surface of the workpiece occurs. High dimensional and molding accurracies,as well as good surface properties, can be achieved by electrochemical polishing. The aim is often to remove impurities introduced into the outer surface layer during preceding machining processes.

 

The previous one is better.